Author name code: toth
ADS astronomy entries on 2022-09-14
author:"Toth, Gabor" 
------------------------------------------------------------------------  

Title: Simulation of Magnetospheric Sawtooth Oscillations: The Role
    of Kinetic Reconnection in the Magnetotail
Authors: Wang, Xiantong; Chen, Yuxi; Tóth, Gábor
Bibcode: 2022GeoRL..4999638W
Altcode:
  Magnetospheric sawtooth oscillations are observed during strong and
  steady solar wind driving conditions. The simulation results of our
  global magnetohydrodynamics (MHD) model with embedded kinetic physics
  show that when the total magnetic flux carried by constant solar wind
  exceeds a threshold, sawtooth-like magnetospheric oscillations are
  generated. Different from previous works, this result is obtained
  without involving time-varying ionospheric outflow in the model. The
  oscillation period and amplitude agree well with observations. The
  simulated oscillations cover a wide range of local times, although
  the distribution of magnitude as a function of longitude is different
  from observations. Our comparative simulations using ideal or Hall MHD
  models do not produce global time-varying features, which suggests that
  kinetic reconnection physics in the magnetotail is a major contributing
  factor to sawtooth oscillations.

Title: Global Magnetohydrodynamic Magnetosphere Simulation With an
    Adaptively Embedded Particle-In-Cell Model
Authors: Wang, Xiantong; Chen, Yuxi; Tóth, Gábor
Bibcode: 2022JGRA..12730091W
Altcode:
  We perform a geomagnetic event simulation using a newly developed
  magnetohydrodynamic with adaptively embedded particle-in-cell
  (MHD-AEPIC) model. We have developed effective criteria to identify
  reconnection sites in the magnetotail and cover them with the PIC
  model. The MHD-AEPIC simulation results are compared with Hall MHD and
  ideal MHD simulations to study the impacts of kinetic reconnection at
  multiple physical scales. At the global scale, the three models produce
  very similar SYM-H and SuperMag Electrojet indexes, which indicates
  that the global magnetic field configurations from the three models
  are very close to each other. We also compare the ionospheric solver
  results and all three models generate similar polar cap potentials and
  field-aligned currents. At the mesoscale, we compare the simulations
  with in situ Geotail observations in the tail. All three models
  produce reasonable agreement with the Geotail observations. At the
  kinetic scales, the MHD-AEPIC simulation can produce a crescent
  shape distribution of the electron velocity space at the electron
  diffusion region, which agrees very well with MMS observations near
  a tail reconnection site. These electron scale kinetic features are
  not available in either the Hall MHD or ideal MHD models. Overall,
  the MHD-AEPIC model compares well with observations at all scales, it
  works robustly, and the computational cost is acceptable due to the
  adaptive adjustment of the PIC domain. It remains to be determined
  whether kinetic physics can play a more significant role in other
  types of events, including but not limited to substorms.

Title: SOFIE (Solar-wind with Field-lines and Energetic-particles):
    A data-driven and self-consistent SEP modeling and forecasting tool
Authors: Zhao, Lulu; Manchester, Ward, IV; Sokolov, Igor; Van der
   Holst, Bart; Toth, Gabor; Tenishev, Valeriy; Gombosi, Tamas; Mays,
   M. Leila; Huang, Zhenguang; Whitman, Kathryn; Sachdeva, Nishtha
Bibcode: 2022cosp...44.1190Z
Altcode:
  We present a data-driven and self-consistent SEP model, SOFIE,
  to simulate the acceleration and transport processes of energetic
  particles using the Space Weather Modeling Framework (SWMF) developed
  at the University of Michigan. In this model, the background solar
  wind plasma in the solar corona and interplanetary space is modeled
  by the Alfven Wave Solar-atmosphere Model(-Realtime) (AWSoM(-R)),
  which is driven by the near-real-time hourly updated GONG (bihourly
  ADAPT-GONG) magnetogram. In the background solar wind, the CMEs
  are launched employing the Eruptive Event Generator using Gibson-Low
  configuration (EEGGL), by inserting a flux rope estimated from the free
  magnetic energy in the active region. The acceleration and transport
  processes are then modeled self-consistently by the multiple magnetic
  field line tracker (M-FLAMPA) and the Adaptive Mesh Particle Simulator
  (AMPS). We will demonstrate the capability of SOFIE to demystify the
  acceleration processes by the CME-driven shock in the low corona and the
  modulation of energetic particles by the solar wind structures. Besides,
  using selected historical SEP events, e.g. 2013 Apr 11 event, we will
  illustrate the progresses toward a faster-than-real-time prediction
  of SEPs.

Title: The helicity sign of flux transfer events flux ropes and
    its relationship to the guide field and Hall physics in magnetic
    reconnection at the magnetopause
Authors: Dahani, Souhail; Toth, Gabor; Cassak, . Paul; Fear, Robert;
   Burch, James; Giles, . Barbara; Genot, Vincent; Lavraud, Benoit;
   Torbert, Roy; Gershman, Dan; Chen, Yuxi; Kieokaew, Rungployphan;
   Fargette, Naïs; Marchaudon, Aurelie
Bibcode: 2022cosp...44.1618D
Altcode:
  Flux Transfer Events (FTEs) are transient magnetic flux ropes
  typically found at the Earth's magnetopause on the dayside. While
  it is known that FTEs are generated by magnetic reconnection, it
  remains unclear how the details of magnetic reconnection controls
  their properties. A recent study showed that the helicity sign of
  the FTEs positively correlates with the east-west (By) component of
  the Interplanetary Magnetic Field (IMF). With data from the Cluster
  and Magnetospheric MultiScale missions, we performed a statistical
  study of 166 quasi force-free FTEs. We focus on their helicity sign
  and possible correlations with upstream solar wind conditions and
  local magnetic reconnection properties. Using both in situ data and
  the Maximum Magnetic Shear model, we find that FTEs whose helicity
  sign positively correlates with the IMF By show moderate magnetic
  shears while those uncorrelated to the IMF By have higher magnetic
  shears. We propose that for small IMF By, which corresponds to high
  shear and low guide field, the Hall pattern of magnetic reconnection
  determines the FTE core field and helicity sign. This work highlights
  a fundamental connection between the kinetic processes at work in
  magnetic reconnection and the macroscale structure of FTEs.

Title: Can Physics-Based SWx Models Predict Space Weather Variations?
Authors: Gombosi, Tamas; Manchester, Ward, IV; Sokolov, Igor; Van
   der Holst, Bart; Toth, Gabor; Huang, Zhenguang; Zhao, Lulu; Sachdeva,
   Nishtha; Wang, Xiantong
Bibcode: 2022cosp...44.3217G
Altcode:
  Over the space age, we have accumulated extensive knowledge of the
  regions of space surrounding the Earth and the Sun, and the governing
  physical processes controlling space weather in these regions. However,
  this knowledge has not been translated into an operational forecast
  capability. By combining our expertise in space weather modeling and
  data science/machine learning we can not only address the "holy grail"
  of space weather prediction and extend the forecast horizon from
  minutes to days, but also transition the results to space weather
  operations. The current space weather predictive capabilities are
  either short term and/or not accurate and reliable. How can we forecast
  the severity of the terrestrial impact (geo-effectiveness) of solar
  storms? When an active region on the Sun will produce eruptions, and
  how large these will be? We only learn about the magnetic field and
  exact timing at the L1 point (about 1 million miles away) when the
  eruption reaches the ACE or DSCOVR satellites, which provides only
  a 20 minute to 1 hour forecast time, depending on the CME speed. We
  initiated a research program that aims to answer these questions using
  a unique combination of modeling, computation, and massive amounts of
  space weather data collected by satellites that will be used to train
  state-of-the-art machine learning algorithms.

Title: NOAA SWPC's Operational Geospace Model: Assessing and Improving
    Performance
Authors: Singer, Howard; Millward, George; Toth, Gabor; Huang,
   Zhenguang; Cash, Michele; Balch, Christopher; Camporeale, Enrico;
   Adamson, Eric
Bibcode: 2022cosp...44.3445S
Altcode:
  Since 2016, in the United States, the National Oceanic and Atmospheric
  Administration's (NOAA) Space Weather Prediction Center (SWPC) has
  been continuously running an operational Geospace model. The coupled
  model developed at the University of Michigan, and part of their Space
  Weather Modeling Framework (SWMF), is driven by solar wind observations
  measured at L1 to provide short-term regional predictions of magnetic
  variations in space and at Earth's surface. The surface magnetic
  variations, when combined with Earth conductivity models, can be used
  to model geoelectric fields that drive geomagnetically induced currents
  (GICs) in long-line conductors such as power grids. The model is an
  important tool, useful for predicting space weather impacts on the
  power grids--one of societies top priority space weather problems. In
  this presentation, we will describe the continuous activities needed
  to assess model performance and to validate and improve model skill to
  more accurately determine regional activity that supports space weather
  customers. We will discuss the processes within NOAA for model upgrades
  as well as current model performance, pathways for future improvements
  and the challenges for both the research and operational communities.

Title: Magnetospheric storm and substorm simulations using the MHD
    with Adaptively Embedded Particle-in-Cell (MHD-AEPIC) model
Authors: Toth, Gabor; Wang, Xiantong; Chen, Yuxi
Bibcode: 2022cosp...44.1725T
Altcode:
  The Magnetohydrodynamic with Embedded Particle-In-Cell (MHD-EPIC) model
  has been developed and applied successfully to Earth, Mercury, Mars
  and Ganymede magnetosphere simulations. While MHD-EPIC is many orders
  of magnitude faster than a fully kinetic global model, it can become
  prohibitively slow if the potential region of interest where kinetic
  phenomena, such as magnetic reconnection, can occur is large. This is
  due to the fact that the PIC domain in MHD-EPIC is restricted to a set
  of static Cartesian boxes. For example, a very large PIC box would be
  needed to accommodate the flapping motion of the magnetotail current
  sheet during a geomagnetic storm simulation. To tackle this problem,
  we have developed a new MHD with Adaptively Embedded Particle-In-Cell
  (MHD-AEPIC) model. MHD-AEPIC inherits all numerical algorithms from
  MHD-EPIC and incorporates a new adaptive PIC model, the Flexible
  Kinetic Simulator (FLEKS). FLEKS allows the PIC cells to be activated
  and deactivated during a simulation. The coupling between the MHD
  model and the adaptive PIC grid has been developed and implemented
  into the Space Weather Modeling Framework. We have also developed
  physics-based criteria to identify potential reconnection sites,
  which makes the adaptation fully automatic. In this work, we apply
  the new MHD-AEPIC model to geomagnetic storm and substorm simulations
  and demonstrate how adaptation makes this simulation feasible. In
  particular, we demonstrate that MHD-AEPIC is capable of reproducing
  global sawtooth oscillations as well as electron-scale physics.

Title: Michigan Sun-to-Earth Model with Data Assimilation and
    Quantified Uncertainty
Authors: Toth, Gabor
Bibcode: 2022cosp...44.3440T
Altcode:
  As part of the Space Weather with Quantified Uncertainty NSF program,
  we have been developing the Michigan Sun-to-Earth Model with Data
  Assimilation and Quantified Uncertainty (MSTEM-QUDA). The main
  goal of the project is to provide useful probabilistic forecast of
  major space weather events about 24 hours before the geospace impact
  occurs. We are using the first-principles models in the Space Weather
  Modeling Framework in combination with uncertainty quantification and
  data assimilation. Using sophisticated experimental design and fully
  automated scripts, we have performed about a thousand simulations with
  our solar corona and heliosphere model generating steady state solar
  wind solutions and coronal mass ejections. Based on these simulations,
  we have performed the uncertainty quantification analysis. One important
  finding is that the physically meaningful range of the background solar
  wind model parameters depends on the solar cycle. Our CME simulations
  show reasonably good arrival times and velocity structures. While the
  amplitude of the magnetic field is similar to the observations, the
  temporal profiles are challenging to match. Data assimilation provides
  an opportunity to improve the predictions. We are using in-situ
  observations at L1 prior to the CME and coronal while-light image
  observations right after the eruption to find the optimal parameters
  for the ensemble simulations. To make ensemble simulations feasible, the
  model should take advantage of GPUs. We have already ported the Geospace
  model, a large part of MSTEM-QUDA, to run efficiently on a GPU. The
  operational Geospace model can run on a single GPU significantly faster
  than real time at the same speed as using about 100 CPU cores. The
  Michigan Sun-to-Earth Model is available as an open-source distribution
  at https://github.com/MSTEM-QUDA to the entire community.

Title: Global Driving of Auroral Precipitation: 1. Balance of Sources
Authors: Mukhopadhyay, Agnit; Welling, Daniel; Liemohn, Michael;
   Ridley, Aaron; Burleigh, Meghan; Wu, Chen; Zou, Shasha; Connor,
   Hyunju; Vandegriff, Elizabeth; Dredger, Pauline; Tóth, Gabor
Bibcode: 2022JGRA..12730323M
Altcode:
  The accurate determination of auroral precipitation in global models has
  remained a daunting and rather inexplicable obstacle. Understanding
  the calculation and balance of multiple sources that constitute
  the aurora, and their eventual conversion into ionospheric
  electrical conductance, is critical for improved prediction of
  space weather events. In this study, we present a semi-physical
  global modeling approach that characterizes contributions by
  four types of precipitation—monoenergetic, broadband, electron,
  and ion diffuse—to ionospheric electrodynamics. The model uses a
  combination of adiabatic kinetic theory and loss parameters derived
  from historical energy flux patterns to estimate auroral precipitation
  from magnetohydrodynamic (MHD) quantities. It then converts them into
  ionospheric conductance that is used to compute the ionospheric feedback
  to the magnetosphere. The model has been employed to simulate the 5-7
  April 2010 Galaxy15 space weather event. Comparison of auroral fluxes
  show good agreement with observational data sets like NOAA-DMSP and
  OVATION Prime. The study shows a dominant contribution by electron
  diffuse precipitation, accounting for ∼74% of the auroral energy
  flux. However, contributions by monoenergetic and broadband sources
  dominate during times of active upstream solar conditions, providing
  for up to 61% of the total hemispheric power. The study also finds
  a greater role played by broadband precipitation in ionospheric
  electrodynamics which accounts for ∼31% of the Pedersen conductance.

Title: MHD simulation of solar wind interaction with Mars and
    comparison with MAVEN observations
Authors: Ma, Yingjuan; Luhmann, Janet G.; Russell, C. T.; Nagy,
   Andrew; Toth, Gabor; Fang, Xiaohua
Bibcode: 2022cosp...44..936M
Altcode:
  Since Mars has no global intrinsic magnetic field, the solar wind plasma
  interacts with the Martian upper atmosphere/ionosphere in a more direct
  manner. Therefore, it is important to incorporate ionospheric processes
  into global interaction models so that ionospheric responses/changes
  can be captured self-consistently. There are two well-known numerical
  challenges in modeling the global interaction of the solar wind
  with Mars: 1) resolve the ionospheric structure with sufficient
  radial resolution; and 2) include the effect of the Martian crustal
  field. Various missions to Mars, especially the ongoing MAVEN mission,
  provide excellent datasets to improve our understanding of solar wind
  interactions with Mars and to validate numerical models of Mars. In
  this presentation, we will discuss some recent advances in MHD modeling
  efforts, including time dependent MHD, multi-fluid MHD, multi-fluid
  MHD with electronic pressure equations, and global MHD with embedded
  PIC model, and the comparison with spacecraft observation.

Title: MSWIM2D: Two-dimensional Outer Heliosphere Solar Wind Modeling
Authors: Keebler, Timothy B.; Tóth, Gábor; Zieger, Bertalan;
   Opher, Merav
Bibcode: 2022ApJS..260...43K
Altcode:
  The vast size of the Sun's heliosphere, combined with sparse
  spacecraft measurements over that large domain, makes numerical
  modeling a critical tool to predict solar wind conditions where there
  are no measurements. This study models the solar wind propagation
  in 2D using the BATSRUS MHD solver to form the MSWIM2D data set of
  solar wind in the outer heliosphere. Representing the solar wind
  from 1 to 75 au in the ecliptic plane, a continuous model run from
  1995-present has been performed. The results are available for free
  at http://csem.engin.umich.edu/mswim2d/. The web interface extracts
  output at desired locations and times. In addition to solar wind ions,
  the model includes neutrals coming from the interstellar medium to
  reproduce the slowing of the solar wind in the outer heliosphere and
  to extend the utility of the model to larger radial distances. The
  inclusion of neutral hydrogen is critical to recreating the solar
  wind accurately outside of ~4 au. The inner boundary is filled by
  interpolating and time-shifting in situ observations from L1 and
  STEREO spacecraft when available. Using multiple spacecraft provides
  a more accurate boundary condition than a single spacecraft with time
  shifting alone. Validations of MSWIM2D are performed using MAVEN and
  New Horizons observations. The results demonstrate the efficacy of
  this model to propagate the solar wind to large distances and obtain
  practical, useful solar wind predictions. For example, the rms error
  of solar wind speed prediction at Mars is only 66 km s<SUP>-1</SUP>
  and at Pluto is a mere 25 km s<SUP>-1</SUP>.

Title: Energy-momentum tensor and duality symmetry of linearized
    gravity in the Fierz formalism
Authors: Tóth, Gábor Zsolt
Bibcode: 2022CQGra..39g5003T
Altcode: 2021arXiv210802124T
  A formulation of linearized gravity in flat background, based on the
  Fierz tensor as a counterpart of the electromagnetic field strength,
  is discussed in detail and used to study fundamental properties of the
  linearized gravitational field. In particular, the linearized Einstein
  equations are written as first order partial differential equations
  in terms of the Fierz tensor, in analogy with the first order Maxwell
  equations. An energy-momentum tensor $({{T}_{\mathrm{lg}}}^{ab})$
  with favourable properties and exhibiting remarkable similarity to the
  standard energy-momentum tensor of the electromagnetic field is found
  for the linearized gravitational field. ${{T}_{\mathrm{lg}}}^{ab}$
  is quadratic in the Fierz tensor (which is constructed from the first
  derivatives of the linearized metric), traceless, and satisfies the
  dominant energy condition in a gauge that contains the transverse
  traceless (TT) gauge. It is further shown that in suitable gauges,
  including the TT gauge, linearized gravity in the absence of matter has
  a duality symmetry that maps the Fierz tensor, which is antisymmetric
  in its first two indices, into its dual. Conserved currents associated
  with the gauge and duality symmetries of linearized gravity are also
  determined. These currents show good analogy with the corresponding
  currents in electrodynamics.

Title: AWSoM Magnetohydrodynamic Simulation of a Solar Active Region
    with Realistic Spectral Synthesis
Authors: Shi, Tong; Manchester, Ward, IV; Landi, Enrico; van der
   Holst, Bart; Szente, Judit; Chen, Yuxi; Tóth, Gábor; Bertello,
   Luca; Pevtsov, Alexander
Bibcode: 2022ApJ...928...34S
Altcode:
  For the first time, we simulate the detailed spectral line emission
  from a solar active region (AR) with the Alfvén Wave Solar Model
  (AWSoM). We select an AR appearing near disk center on 2018 July 13
  and use the National Solar Observatory's Helioseismic and Magnetic
  Imager synoptic magnetogram to specify the magnetic field at the
  model's inner boundary. To resolve small-scale magnetic features, we
  apply adaptive mesh refinement with a horizontal spatial resolution
  of 0°.35 (4.5 Mm), four times higher than the background corona. We
  then apply the SPECTRUM code, using CHIANTI spectral emissivities,
  to calculate spectral lines forming at temperatures ranging from 0.5
  to 3 MK. Comparisons are made between the simulated line intensities
  and those observed by Hinode/Extreme-ultraviolet Imaging Spectrometer
  where we find close agreement across a wide range of loop sizes and
  temperatures (about 20% relative error for both the loop top and
  footpoints at a temperature of about 1.5 MK). We also simulate and
  compare Doppler velocities and find that simulated flow patterns are
  of comparable magnitude to what is observed. Our results demonstrate
  the broad applicability of the low-frequency AWSoM for explaining the
  heating of coronal loops.

Title: The Solar Wind with Hydrogen Ion Exchange and Large-scale
Dynamics (SHIELD) Code: A Self-consistent Kinetic-Magnetohydrodynamic
    Model of the Outer Heliosphere
Authors: Michael, A. T.; Opher, M.; Tóth, G.; Tenishev, V.;
   Borovikov, D.
Bibcode: 2022ApJ...924..105M
Altcode:
  Neutral hydrogen has been shown to greatly impact the plasma flow in
  the heliosphere and the location of the heliospheric boundaries. We
  present the results of the Solar Wind with Hydrogen Ion Exchange
  and Large-scale Dynamics (SHIELD) model, a new, self-consistent,
  kinetic-MHD model of the outer heliosphere within the Space Weather
  Modeling Framework. The charge exchange mean free path is on the
  order of the size of the heliosphere; therefore, the neutral atoms
  cannot be described as a fluid. The numerical code SHIELD couples
  the MHD solution for a single plasma fluid to the kinetic solution
  for neutral hydrogen atoms streaming through the system. The kinetic
  code is based on the Adaptive Mesh Particle Simulator, a Monte Carlo
  method for solving the Boltzmann equation. The numerical code SHIELD
  accurately predicts the increased filtration of interstellar neutrals
  into the heliosphere. In order to verify the correct implementation
  within the model, we compare the results of the numerical code SHIELD
  to those of other, well-established kinetic-MHD models. The numerical
  code SHIELD matches the neutral hydrogen solution of these studies
  as well as the shift in all heliospheric boundaries closer to the
  Sun in comparison with the multi-fluid treatment of neutral hydrogen
  atoms. Overall the numerical code SHIELD shows excellent agreement with
  these models and is a significant improvement to the fluid treatment
  of interstellar hydrogen.

Title: Effect of different simulation configurations on the
    prediction performance of the Space Weather Modeling Framework on
    ground magnetic perturbations
Authors: Kwagala, Norah; Tenfjord, Paul; Norgren, Cecilia; Hesse,
   Michael; Moretto Jorgensen, Therese; Toth, Gabor; Kolsto, Hakon;
   Fl Spinnangr, Susanne; Perez-Coll Jimenez, Judit; Kuniyoshi, Hidetaka
Bibcode: 2021AGUFMSH55C1850K
Altcode:
  This study investigates how different simulation configurations of
  the Space Weather Modeling Framework (SWMF) affect the predicted
  magnetic perturbations (dB and dB/dt) on the ground. The SWMF
  configurations investigated include numerical integration schemes and
  grid resolutions. Different simulations of two historic geomagnetic
  storms are studied: the extreme activity halloween storm on 29 October
  2003 and a relatively low activity storm on 31 August 2001. Our region
  of investigation is the northern hemisphere above 50 degrees magnetic
  latitude using all 88 available geomagnetic ground stations provided
  by the superMAG network. The performance of the model predictions
  with the different parameter settings is compared using different
  metrics including the normalised root mean square error, correlation
  coefficient, probability of detection, probability of false detection,
  Heidke skill score, and frequency bias.

Title: A Predictive Geoelectric Field Model: Development, Results,
    and Challenges
Authors: Singer, Howard; Balch, Christopher; Camporeale, Enrico;
   Adamson, Eric; Millward, George; Cash, Michele; Toth, Gabor; Huang,
   Zhenguang; Kelbert, Anna; Rigler, Erin
Bibcode: 2021AGUFMSM41A..02S
Altcode:
  Historically, there are numerous documented examples of geomagnetic
  storms causing geomagnetically induced currents (GICs) in power
  grids resulting in power outages, service disruption, and impacts on
  routine operations. As a result, space weather impacts on the power
  grids are one of the top priority problems in today's society. To
  address this problem, NOAAs Space Weather Prediction Center (SWPC)
  has provided products and services that forecast, warn, and alert
  power grid operators of impending geomagnetic storms. However, during
  a meeting with grid operators in 2011, nowcasts and forecasts of the
  surface geoelectric field were identified as the key input needed for
  determining GICs since the regional geoelectric field can be used
  as input to power grid system models for determining the level of
  geomagnetically induced currents. SWPC, working with our partners has
  addressed this problem by: 1) working with the University of Michigan in
  2016 to transition into operations a Geospace Model that was driven by
  solar wind observations at L1 to provide short-term regional predictions
  of magnetic variations at Earths surface that drive the geoelectric
  field; and 2) working with partners at the US Geological Survey (USGS)
  in 2020 to introduce a near real-time Geoelectric Model that used
  ground-based magnetometer data from the USGS and Natural Resources
  Canada (NRCan), along with a 3D empirical ground conductivity model,
  to estimate the regional geoelectric field in the US. Then, in June
  2021, instead of using near-real time ground observed magnetic field
  data to drive the geoelectric model, we use predicted magnetic fields
  from the Geospace Model to drive the Geoelectric Model in a predictive
  mode. In this presentation, we show the first results from the coupled
  Geospace/Geoelectric model that can provide short-term predictions of
  the regional geoelectric field to support power grid operators. First
  results indicate that the model does surprisingly well at predicting
  the more slowly varying geoelectric field (many minutes); however,
  as expected, the model does not do as well with minute-by-minute
  variations. In addition to showing these results, we discuss model
  limitations, next steps towards producing useful geoelectric products,
  and the challenges for the research community to improve geoelectric
  forecasting.

Title: Simulating the dawn-dusk asymmetry of Mercurys magnetotail
    reconnection with MHD-AEPIC model
Authors: Chen, Yuxi; Jia, Xianzhe; Toth, Gabor; Dong, Chuanfei; Sun,
   Weijie; Slavin, James; Li, Changkun; Wang, Xiantong
Bibcode: 2021AGUFMSM55C1788C
Altcode:
  Since the kinetic scales of Mercury's magnetospheric plasma can be
  comparable to Mercury's radius, kinetic effects play an important role
  in Mercury's magnetosphere. Chen et al. (2019) studied the dawn-dusk
  asymmetries of Mercurys magnetotail using the magnetohydrodynamics
  with embedded particle-in-cell (MHD-EPIC) simulations, and showed
  the asymmetries of the tail current-sheet thickness, plasma density
  and electron pressure clearly. The MHD-EPIC simulations also show the
  asymmetries of reconnection products, the dipolarization events and
  planetward reconnection jets, but the asymmetries are less obvious
  than MESSENGER observations. To further explore the physics behind
  the reconnection asymmetries, we use the newly developed MHD with
  adaptively embedded particle-in-cell (MHD-AEPIC) model to simulate
  Mercurys magnetotail dynamics. The MHD-AEPIC model supports a PIC
  region of any shape so that Mercurys inner magnetosphere can be also
  covered by the PIC code. Compared to Chen et al. (2019), the larger
  PIC region in the MHD-AEPIC model allows us to study the evolution of
  the dipolarization events and reconnection jets after they penetrate
  into the inner magnetosphere. Since the ion-electron mass ratio may
  be crucial for the dawn-dusk asymmetries, we will examine its role by
  varying this model parameter in a series of simulations.

Title: Predicting the Optimal Poynting Flux for Different Solar
    Activity Conditions for Realtime Solar Wind Prediction
Authors: Huang, Zhenguang; Toth, Gabor; Gombosi, Tamas; Sachdeva,
   Nishtha; Zhao, Lulu; Manchester, Ward; van der Holst, Bart; Sokolov,
   Igor
Bibcode: 2021AGUFMSH45D2395H
Altcode:
  Its critical to have an accurate solar wind background in the inner
  heliosphere for space weather prediction, from the arrival of Corotating
  Interaction Regions (CIRs), to the Coronal Mass Ejections (CMEs),
  and Solar Energetic Particles (SEPs). In the space weather community,
  there are two major approaches to predict the solar wind background:
  one uses empirical or semi-empirical models, e.g., the Wang-Sheeley-Arge
  (WSA) model; the other is based on first-principles model, e.g., the
  Alfven Wave Solar atmosphere Model (AWSoM) developed at the University
  of Michigan. In the past, it was difficult for physics models to
  perform real-time solar wind predictions, because the computational
  cost is much higher for physics-based models than for empirical or
  semi-empirical models, and the optimal input parameters could be
  different for different solar rotations in which case the user would
  need to run the model with different input parameters to best predict
  the solar wind. Nowadays, the computational cost is not a big issue
  as super computers are much more powerful than before. The remaining
  issue is that the input parameters could vary. In real-time solar
  wind prediction, it is necessary to have optimal input parameters in
  advance. In this presentation, we study the relation between one of the
  most important parameters for AWSoM, the Poynting flux at the inner
  boundary, and the magnetic field structure of the solar corona. We
  obtain the optimal Poynting flux value for nine Carrington rotations
  in the last solar cycle and correlate it with various characteristics
  of the solar magnetic field, such as open flux, area of coronal holes,
  etc.. The preliminary results are encouraging, and suggest that the
  optimal parameter can be estimated from the magnetograms.

Title: SOFIE (Solar-wind with Field-lines and Energetic-particles):
    A data-driven and self-consistent SEP modeling and forecasting tool
Authors: Zhao, Lulu; Sokolov, Igor; Gombosi, Tamas; Tenishev, Valeriy;
   Huang, Zhenguang; Toth, Gabor; Sachdeva, Nishtha; Manchester, Ward;
   van der Holst, Bart
Bibcode: 2021AGUFMSH55F1900Z
Altcode:
  We present a data-driven and self-consistent SEP model, SOFIE, to
  simulate the acceleration and transport processes of energetic particles
  using the Space Weather Modeling Framework (SWMF). In this model, the
  background solar wind plasma in the solar corona and interplanetary
  space are modeled by the Alfven Wave Solar-atmosphere Model(-Realtime)
  (AWSoM(-R)) driven by the near-real-time hourly updated GONG (bihourly
  ADAPT-GONG) magnetograms. In the background solar wind, the CMEs
  are launched employing the Eruptive Event Generator using Gibson-Low
  configuration (EEGGL), by inserting a flux rope estimated from the free
  magnetic energy in the active region. The acceleration and transport
  processes are then modeled self-consistently by the multiple magnetic
  field line tracker (M-FLAMPA) and the Adaptive Mesh Particle Simulator
  (AMPS). We will demonstrate the capability of SOFIE to demystify the
  acceleration processes by the CME-driven shock in the low corona and the
  modulation of energetic particles by the solar wind structures. Besides,
  using selected historical SEP events, e.g. 2013 Apr 11 event, we will
  illustrate the progresses toward a faster-than-real-time prediction
  of SEPs.

Title: 2D Michigan Solar Wind Propagation Model for the Outer
    Heliosphere
Authors: Keebler, Timothy; Toth, Gabor; Opher, Merav; Zieger, Bertalan
Bibcode: 2021AGUFMSH25C2105K
Altcode:
  Modeling of the solar wind propagation through the Outer Heliosphere
  is critical for comparison with limited spacecraft data and to fill
  in an area with sparse in-situ observations. Following the MSWiM
  one-dimensional solar wind advection model, the Michigan Solar WInd
  Model in 2D (MSWIM2D) is presented to improve solar wind representation
  for the outer heliosphere in the ecliptic plane. This model is driven
  using data from observatories at the first Earth-Sun Lagrangian point,
  as well as the STEREO spacecraft, to fill the inner boundary at 1
  AU. By time-shifting the point observations and interpolating between
  multiple observatories, the entire inner boundary of Earth's orbit
  can be constantly populated by solar wind observations, permitting
  the driving of a 2D model. Interstellar neutrals are also included to
  interact with the solar wind, extending the model utility to larger
  radial distances. Validation at Mars using MAVEN data shows good
  agreement, and validation at New Horizons is presented here to assess
  model performance over longer propagations. The model output is publicly
  accessible for use by the broader planetary and heliospheric community,
  available at http://csem.engin.umich.edu/mswim2d. This interface allows
  interpolation of the model results along user-defined trajectories
  at one hour output cadence. Timeseries along the trajectories can be
  created between 1995 and 2020, and include solar wind density, vector
  velocity, vector magnetic field, and ion temperature.

Title: A comparison of heliotail configurations arising from different
    treatments of non-ideal MHD effects with ENA maps at IBEX energies
Authors: Kornbleuth, Marc; Opher, Merav; Baliukin, Igor; Dayeh,
   Maher; Zirnstein, Eric; Gkioulidou, Matina; Dialynas, Kostas; Galli,
   Andre; Richardson, John; Izmodenov, Vladislav; Zank, Gary; Fuselier,
   Stephen A.; Michael, Adam; Toth, Gabor; Tenishev, Valeriy; Alexashov,
   Dmitry; Drake, James
Bibcode: 2021AGUFMSH21B..02K
Altcode:
  The role of the solar magnetic field in the heliosheath has long
  been considered passive, but recent studies indicate it may play an
  active role in collimating the heliosheath plasma into two lobes at
  high latitudes. We compare results from two MHD models, the BU and
  Moscow models, which treat non-ideal MHD effects differently. The BU
  model allows for magnetic reconnection at the heliopause between the
  solar and interstellar magnetic fields, while the Moscow model does not
  allow for direct communication between the solar wind and interstellar
  medium. We use the same boundary conditions, 22-year averaged solar
  cycle conditions from 1995 to 2017. An important result is that
  both models show that the plasma in the heliosheath and heliotail is
  confined by the solar magnetic field in two lobes. The plasma solutions
  in the nose of the heliosphere are similar. However, the Moscow model
  displays a long, thousands of AU comet-like tail whereas the BU model
  shows the heliotail is shortened to about 400 AU where the interstellar
  medium flows between the two lobes. The ENA maps from the two models
  show both qualitative and quantitative agreement at IBEX energies,
  despite the different configurations of the heliotail. The modeled
  ENA maps agree qualitatively, but not quantitatively, with IBEX ENA
  observations. At higher energies the ENA maps from the two models
  differ, so higher energy ENA data (from INCA or IMAP) may be able to
  determine which model heliotail best fits the data.

Title: Magnetosphere Energy Dynamics in 3D, Comparison to the Virial
    Theorem and Quantification of Macro Scale Dynamics During a Simulated
    Storm Event
Authors: Brenner, Austin; Pulkkinen, Tuija; Al Shidi, Qusai; Toth,
   Gabor
Bibcode: 2021AGUFMSM35C1984B
Altcode:
  Ground magnetic perturbations are due to dynamics within the
  magnetosphere ionosphere system as well as coupling with the solar
  wind. Global simulation is well suited to study the entire system
  at once with self-consistent physics. In this work the magnetopause
  location is identified from Space Weather Modeling Framework (SWMF)
  output at 1min cadence for a simulated event to a fixed downstream
  distance. Preliminary results of total energy integrated over the
  magnetosphere volume correlates well with Disturbance Storm Time
  (DST) index (attached figure). Following up on the initial results the
  magnetosphere volume is analyzed for spatial distribution of energy
  in terms of total energy, as well as hydrodynamic energy and magnetic
  energy. The relative contribution to magnetic perturbation at the
  Earth's center is determined for subregions and energy types using
  the Biot-Savart law and Virial Theorem. Comparisons with in situ and
  ground based observations are made to identify areas of high and low
  simulation confidence.

Title: AWSoM MHD simulation of a solar active region with realistic
    spectral synthesis
Authors: Manchester, Ward; Shi, Tong; Landi, Enrico; Szente, Judit;
   van der Holst, Bart; Chen, Yuxi; Toth, Gabor; Bertello, Luca; Pevtsov,
   Alexander
Bibcode: 2021AGUFMSH12B..02M
Altcode:
  For the first time, we simulate the detailed spectral line emission
  from a solar active region (AR) with the Alfven Wave Solar Model
  (AWSoM). We select an active region appearing near disk center on
  2018 July 13 and use an NSO-HMI synoptic magnetogram to specify the
  magnetic field at the model's inner boundary. To resolve smaller-scale
  magnetic features, we apply adaptive mesh refinement to resolve the
  AR with a spatial resolution of 0.37 degrees, four times higher than
  the background corona. We then apply the SPECTRUM code informed with
  Chianti spectral emissivities to calculate more than a dozen spectral
  lines forming at temperatures ranging from 0.5 to 3+ MK. Comparisons
  are made between these simulated line profiles and those observed by
  the Hinode/EIS instrument where we find close agreement (within a
  20% margin of error of peak intensity) across a wide range of loop
  sizes and temperatures. We also compare the differential emission
  measure calculated from both the simulation and EIS observation to
  further show the model's ability to capture the plasma temperature and
  density. Finally, we simulate and compare Doppler velocities and find
  that simulated flow patterns to be of comparable magnitude to what
  is observed. Our results demonstrate the broad applicability of the
  low-frequency Alfven wave balanced turbulence theory for explaining
  the heating of coronal loops.

Title: Magnetohydrodynamic with Adaptively Embedded Particle-in-Cell
model: MHD-AEPIC
Authors: Shou, Yinsi; Tenishev, Valeriy; Chen, Yuxi; Toth, Gabor;
   Ganushkina, Natalia
Bibcode: 2021JCoPh.44610656S
Altcode: 2021arXiv210805425S
  Space plasma simulations have seen an increase in the use of
  magnetohydrodynamic (MHD) with embedded Particle-in-Cell (PIC)
  models. This combined MHD-EPIC algorithm simulates some regions
  of interest using the kinetic PIC method while employing the MHD
  description in the rest of the domain. The MHD models are highly
  efficient and their fluid descriptions are valid for most part of
  the computational domain, thus making large-scale global simulations
  feasible. <P />However, in practical applications, the regions where the
  kinetic effects are critical can be changing, appearing, disappearing
  and moving in the computational domain. If a static PIC region is used,
  this requires a much larger PIC domain than actually needed, which
  can increase the computational cost dramatically. <P />To address the
  problem, we have developed a new method that is able to dynamically
  change the region of the computational domain where a PIC model is
  applied. We have implemented this new MHD with Adaptively Embedded PIC
  (MHD-AEPIC) algorithm using the BATS-R-US Hall MHD and the Adaptive
  Mesh Particle Simulator (AMPS) as the semi-implicit PIC models. We
  describe the algorithm and present a test case of two merging flux
  ropes to demonstrate its accuracy. The implementation uses dynamic
  allocation/deallocation of memory and load balancing for efficient
  parallel execution. We evaluate the performance of MHD-AEPIC compared
  to MHD-EPIC and the scaling properties of the model to large number
  of computational cores.

Title: Dependence of Mercurys magnetopause reconnection on the
upstream conditions: 3D Hall-MHD simulations
Authors: Li, Changkun; Jia, Xianzhe; Chen, Yuxi; Zhou, Hongyang;
   Toth, Gabor; Slavin, James; Sun, Weijie
Bibcode: 2021AGUFM.P24B..03L
Altcode:
  Observations from NASAs MESSENGER spacecraft reveal that Mercury
  has a miniature magnetosphere arising from the interaction of its
  intrinsic dipole field with the inner heliosphere solar wind. Compared
  to the terrestrial magnetosphere, Mercurys magnetosphere appears to be
  more dynamic in that the global timescales for plasma and magnetic
  flux circulation are much shorter, and the dayside magnetopause
  reconnection occurs at higher rates and under a wider range of
  magnetic shear angles. As a product of multiple X-line reconnection,
  flux transfer events (FTEs) are found to arise much more frequently
  with an occurrence rate of about 50 times higher than that detected
  at Earth. MESSENGER observations suggest that the different upstream
  solar wind conditions are likely the cause for large differences
  in reconnection-driven dynamics between Mercurys magnetosphere
  and Earths. In order to understand how reconnection rate and the
  characteristics of resultant FTEs vary with the upstream conditions,
  we have employed the BATSRUS Hall-MHD model with a high-resolution
  grid to simulate Mercurys magnetopause dynamics under a wide range of
  upstream solar wind and IMF conditions. Flux ropes are found to form
  due to multiple X-line reconnection in all our time-dependent Hall MHD
  simulations under fixed wind conditions, but their properties, such
  as occurrence rate and spatial scale, vary depending on the upstream
  parameters. We have developed automated techniques to identify and
  analyze FTEs in our simulations. The results of our analyses are
  compared directly with MESSENGER observations (e.g., Sun et al. 2020)
  and the comparison yields generally good agreement in terms of FTE
  spatial size, occurrence frequency, flux content, etc. The carefully
  designed Hall-MHD simulations allow us to examine how the properties of
  FTEs depend on parameters such as the solar wind Alfvenic Mach number,
  IMF orientation, and the magnetosheath plasma . With the global model,
  we also evaluate the global reconnection rate and the contribution
  of FTEs to the global circulation of magnetic flux at Mercury and how
  these properties vary in response to changes in the external conditions.

Title: A Turbulent Heliosheath Driven by Rayleigh Taylor Instability
Authors: Opher, Merav; Drake, James; Zank, Gary; Toth, Gabor; Powell,
   Erick; Kornbleuth, Marc; Florinski, Vladimir; Izmodenov, Vladislav;
   Giacalone, Joe; Fuselier, Stephen A.; Dialynas, Kostas; Loeb, Abraham;
   Richardson, John
Bibcode: 2021AGUFMSH21B..06O
Altcode:
  The heliosphere is the bubble formed by the solar wind as it interacts
  with the interstellar medium (ISM). Studies show that the solar
  magnetic field funnels the heliosheath solar wind (the shocked solar
  wind at the edge of the heliosphere) into two jet-like structures
  (1-2). Magnetohydrodynamic simulations show that these heliospheric
  jets become unstable as they move down the heliotail (1-3) and drive
  large-scale turbulence. However, the mechanism that produces of this
  turbulence had not been identified. Here we show that the driver of
  the turbulence is the Rayleigh-Taylor (RT) instability caused by the
  interaction of neutral H atoms streaming from the ISM with the ionized
  matter in the heliosheath (HS). The drag between the neutral and ionized
  matter acts as an effective gravity which causes a RT instability to
  develop along the axis of the HS magnetic field. A density gradient
  exists perpendicular to this axis due to the confinement of the solar
  wind by the solar magnetic field. The characteristic time scale of
  the instability depends on the neutral H density in the ISM and for
  typical values the growth rate is ~ 3 years. The instability destroys
  the coherence of the heliospheric jets and magnetic reconnection ensues,
  allowing ISM material to penetrate the heliospheric tail. Signatures of
  this instability should be observable in Energetic Neutral Atom (ENA)
  maps from future missions such as IMAP (4). The turbulence driven by the
  instability is macroscopic and potentially has important implications
  for particle acceleration.

Title: Geomagnetic storm event simulation using a global MHD with
    Adaptively Embedded Particle-In-Cell (MHD-AEPIC) model
Authors: Wang, Xiantong; Chen, Yuxi; Toth, Gabor
Bibcode: 2021AGUFMSM42C..09W
Altcode:
  The MHD with Embedded Particle-In-Cell (MHD-EPIC) model has been
  successfully applied to Earth, Mercury, Mars and Ganymede magnetosphere
  simulations to study reconnection physics in a global context. However,
  the PIC region in MHD-EPIC is restricted to be a Cartesian box, which
  is not flexible enough to cover the whole domain of interest due to
  massive computational cost. For example, a very large PIC box would be
  needed to accommodate the flapping motion of the magnetotail current
  sheet during a geomagnetic storm simulation. To tackle this problem,
  we have developed a new MHD with Adaptively Embedded Particle-In-Cell
  (MHD-AEPIC) model that inherits all numerical algorithms from MHD-EPIC,
  and also accommodates an adaptive PIC grid that allows PIC cells to
  be turned on and off during the simulation. We have also developed
  physics-based criteria for the identification of reconnection sites
  that makes the adaptation fully automatic. In this work, we apply the
  MHD-AEPIC model to a geomagnetic storm simulation and demonstrate how
  adaptation works in a real-world scenario. Furthermore, we provide
  comparison with observations ranging from electron scales to global
  scales.

Title: A Time-Dependent Split Tail Heliosphere
Authors: Powell, Erick; Opher, Merav; Toth, Gabor; Tenishev, Valeriy;
   Michael, Adam; Kornbleuth, Marc; Richardson, John
Bibcode: 2021AGUFMSH15F2075P
Altcode:
  There is a current debate on the shape of the heliosphere. Current
  models provide different solutions to the heliotail. These
  models assume different numerical techniques as well as physical
  assumptions. Kornbleuth et al. (2021) show that both BU and Moscow
  models show collimation of the heliotail plasma by the magnetic
  field as first found by Opher et al. (2015). The BU model has the
  ISM plasma flowing between the two lobes at around 400AU downtail,
  what is known as the croissant-like heliosphere. The BU model was
  first extended to include a treatment to the neutral H in a kinetic
  fashion by Michael et al. (2021) where they show that the croissant-like
  heliotail remain. In this work, within the SHIELD project, we extend
  the work of Michael et al. (2021) with the newly updated BU model to
  investigate the effect of time dependent solar wind conditions on the
  two-lobed heliotail. The BU model in this work was a kinetic-MHD model
  that self consistently coupled an MHD treatment of ions to a kinetic
  treatment of the neutrals in a long-term solution. We have improved
  the statistics in the BU model, through implementation of a lookup
  table for the charge exchange rate and resulting source terms for the
  plasma, that is more computationally efficient and allows us to capture
  shorter time scales necessary to accurately model the evolution of the
  time-dependent heliotail. We extend the work of Michael et al. (2021)
  with the newly updated SHIELD model to investigate the effect of time
  dependent solar wind conditions on the two-lobed heliotail. We comment
  on the structure of the heliotail and the differences between long-term
  and and time-dependent solutions.

Title: Formation and evolution of the large-scale magnetic fields
in Venus Ionosphere: Results from a 3D global multi-species MHD model
Authors: Ma, Yingjuan; Toth, Gabor; Nagy, Andrew; Luhmann, Janet;
   Russell, Christopher
Bibcode: 2021AGUFMSM52C..04M
Altcode:
  Large-scale magnetic fields have been observed at Venus ionosphere by
  both the Pioneer Venus Orbiter (PVO) and Venus Express spacecraft. In
  this study, we examine the formation and evolution of the large-scale
  magnetic field in the Venus ionosphere using a sophisticated
  global multi-species MHD model that has been developed for Venus. A
  time-dependent model run is performed under varying solar wind dynamic
  pressure. Based on model results, we find that: 1) Both the locations
  of plasma boundaries (such as bow shock and induced magnetospheric
  boundary) and plasma conditions in the magnetosheath and the outer part
  of the induced magnetosphere adjust quickly (~ minutes) to solar wind
  dynamic pressure change; 2) a large-scale magnetic field gradually forms
  in the ionosphere during the time when the solar wind dynamic pressure
  exceeds the ionospheric thermal pressure; 3) both the penetration and
  decay of the large-scale magnetic field in the ionosphere are slow (~
  hours); 4) the ion escape rate has a non-linear response to the change
  of solar wind dynamic pressure.

Title: Global Sensitivity Analysis for Solar-Wind Simulations in
    the Space Weather Modelling Framework
Authors: Jivani, Aniket; Huan, Xun; Chen, Yang; van der Holst, Bart;
   Zou, Shasha; Huang, Zhenguang; Sachdeva, Nishtha; Iong, Daniel;
   Manchester, Ward; Toth, Gabor
Bibcode: 2021AGUFMSH55C1851J
Altcode:
  The Space Weather Modelling Framework (SWMF) offers efficient and
  flexible sun-to-earth simulations based on coupled first principles
  and/or empirical models. This encompasses computing the quiet solar
  wind, generating a coronal mass ejection (CME), propagating the CME
  through the heliosphere, and calculating the magnetospheric impact via
  geospace models. The predictions from these different steps and models
  are affected by uncertainty and variation of many model inputs and
  parameters, such as the Poynting flux emanating from the photosphere
  and driving and heating the solar wind. In this presentation, as part
  of the NextGen SWMF project funded by NSF, we perform uncertainty
  quantification (UQ) for the quiet solar wind simulations produced by
  our Alfven Wave Solar atmosphere Model (AWSoM). We first catalogue
  the various sources of uncertainty and their distributions, and then
  propagate the uncertainty to key predictive quantities of interest, the
  in-situ solar wind and magnetic field at 1 au, through space-filling
  designs of high-fidelity simulations. Using this dataset, we then
  build polynomial chaos surrogate models that offer a convenient route
  to global sensitivity analysis, which quantifies the contribution
  of each input parameters uncertainty towards the variability of the
  QoIs. The resulting Sobol sensitivity index allows us to rank and retain
  only the most impactful parameters going forward, thereby achieving
  dimension-reduction of the stochastic space. We have performed this
  UQ analysis for both solar maximum and solar minimum conditions,
  and we will summarize our findings in this presentation.

Title: Terrestrial Impacts of Global Geospace Modeling of an Ensemble
    of Storms
Authors: Al Shidi, Qusai; Pulkkinen, Tuija; Brenner, Austin; Toth,
   Gabor; Zou, Shasha; Gombosi, Tamas
Bibcode: 2021AGUFMSH45E2408A
Altcode:
  Modeling the terrestrial impacts of the sun's solar wind is critical
  to understanding geomagnetic storms. We use a database of 144 storms
  from 2010-2019 and showed how these storms affect magnetometers on
  the ground. We also extracted profiles of the magnetic field along the
  magnetotail. Skill scores are assigned to the individual stations on
  the ground based on how well they can forecast magnetic indeces like
  SYM-H and AL. We us our Space Weather Modeling Framework's geospace
  configuration. Our model includes coupling of 3D MHD solver (BATSRUS),
  the Rice Convection Model, and the Ridley Ionospheric Model. We have
  found that all stations have a positive Heidke Skill Score which is
  encouraging in terms of space weather forecasting.

Title: Developing the Michigan Sun-to-Earth Model with Data
    Assimilation and Quantified Uncertainty
Authors: Toth, Gabor; Chen, Yang; Huan, Xun; van der Holst, Bart;
   Zou, Shasha; Jivani, Aniket; Iong, Daniel; Sachdeva, Nishtha; Huang,
   Zhenguang; Chen, Yuxi; Gaenko, Alexander; Manchester, Ward
Bibcode: 2021AGUFMSH53B..06T
Altcode:
  As part of the Space Weather with Quantified Uncertainty program, our
  project, funded by NSF, has been working on developing the Michigan
  Sun-to-Earth Model with Data Assimilation and Quantified Uncertainty
  (MSTEM-QUDA). In this talk we will summarize the main goals of the
  project and report our progress. Using sophisticated experimental
  design and fully automated scripts, we have performed many hundreds
  of simulations with our solar corona and heliosphere model generating
  steady state solar wind solutions. Based on these simulations, we have
  completed the uncertainty quantification analysis. One important finding
  is that the physically meaningful range of certain model parameters
  depends on the solar cycle. We will use an ensemble of background
  solar wind model solutions as a starting point for simulating coronal
  mass ejections. Our preliminary model runs show promising accuracy for
  the CME arrival time. We have also ported the Geospace model, a large
  part of MSTEM-QUDA, to run efficiently on a GPU. In fact, we can run
  the operational Geospace model on a single GPU significantly faster
  than real time at the same speed as using about 100 CPU cores. The
  Michigan Sun-to-Earth Model is available as an open-source distribution
  at https://github.com/MSTEM-QUDA to the entire community.

Title: How will the crustal magnetic field affect the tail
    reconnection process at Mars?
Authors: Ma, Yingjuan; Toth, Gabor; Chen, Yuxi; Nagy, Andrew; Russell,
   Christopher
Bibcode: 2021AGUFM.P45F2498M
Altcode:
  We use a fully coupled global MHD model with an embedded Particle in
  Cell (PIC) code to further understand the magnetic reconnection process
  on Mars and its consequences, especially how will the crustal magnetic
  field affect the tail reconnection process. This two-way coupled
  MHD-EPIC model has been applied to Mars and performed a detailed
  study for a tail reconnection event observed by MAVEN [Harada et al.,
  2015]. In this study, four more cases will be studied with the same
  solar wind condition but for different crustal field orientations. The
  subsolar longitude for the baseline case is at 73.1 east longitude. For
  the four cases, the subsolar longitude is set to 0, 90, 180 and 270
  degrees east longitude, with the strong crustal field located in
  the nightside, dawn, dayside and dusk side, respectively. Detailed
  analysis of the model results will then be presented to show the
  relation between crustal field and tail reconnection process at Mars.

Title: The Development of a Split-tail Heliosphere and the Role of
Non-ideal Processes: A Comparison of the BU and Moscow Models
Authors: Kornbleuth, M.; Opher, M.; Baliukin, I.; Gkioulidou, M.;
   Richardson, J. D.; Zank, G. P.; Michael, A. T.; Tóth, G.; Tenishev,
   V.; Izmodenov, V.; Alexashov, D.; Fuselier, S.; Drake, J. F.;
   Dialynas, K.
Bibcode: 2021ApJ...923..179K
Altcode: 2021arXiv211013962K
  Global models of the heliosphere are critical tools used in the
  interpretation of heliospheric observations. There are several
  three-dimensional magnetohydrodynamic (MHD) heliospheric models that
  rely on different strategies and assumptions. Until now only one paper
  has compared global heliosphere models, but without magnetic field
  effects. We compare the results of two different MHD models, the BU
  and Moscow models. Both models use identical boundary conditions to
  compare how different numerical approaches and physical assumptions
  contribute to the heliospheric solution. Based on the different
  numerical treatments of discontinuities, the BU model allows for the
  presence of magnetic reconnection, while the Moscow model does not. Both
  models predict collimation of the solar outflow in the heliosheath
  by the solar magnetic field and produce a split tail where the solar
  magnetic field confines the charged solar particles into distinct north
  and south columns that become lobes. In the BU model, the interstellar
  medium (ISM) flows between the two lobes at large distances due to
  MHD instabilities and reconnection. Reconnection in the BU model at
  the port flank affects the draping of the interstellar magnetic field
  in the immediate vicinity of the heliopause. Different draping in the
  models cause different ISM pressures, yielding different heliosheath
  thicknesses and boundary locations, with the largest effects at high
  latitudes. The BU model heliosheath is 15% thinner and the heliopause is
  7% more inwards at the north pole relative to the Moscow model. These
  differences in the two plasma solutions may manifest themselves in
  energetic neutral atom measurements of the heliosphere.

Title: Simulating Solar Maximum Conditions Using the Alfvén Wave
    Solar Atmosphere Model (AWSoM)
Authors: Sachdeva, Nishtha; Tóth, Gábor; Manchester, Ward B.; van
   der Holst, Bart; Huang, Zhenguang; Sokolov, Igor V.; Zhao, Lulu;
   Shidi, Qusai Al; Chen, Yuxi; Gombosi, Tamas I.; Henney, Carl J.;
   Lloveras, Diego G.; Vásquez, Alberto M.
Bibcode: 2021ApJ...923..176S
Altcode:
  To simulate solar coronal mass ejections (CMEs) and predict their
  time of arrival and geomagnetic impact, it is important to accurately
  model the background solar wind conditions in which CMEs propagate. We
  use the Alfvén Wave Solar atmosphere Model (AWSoM) within the the
  Space Weather Modeling Framework to simulate solar maximum conditions
  during two Carrington rotations and produce solar wind background
  conditions comparable to the observations. We describe the inner
  boundary conditions for AWSoM using the ADAPT global magnetic maps
  and validate the simulated results with EUV observations in the low
  corona and measured plasma parameters at L1 as well as at the position
  of the Solar Terrestrial Relations Observatory spacecraft. This
  work complements our prior AWSoM validation study for solar minimum
  conditions and shows that during periods of higher magnetic activity,
  AWSoM can reproduce the solar plasma conditions (using properly
  adjusted photospheric Poynting flux) suitable for providing proper
  initial conditions for launching CMEs.

Title: Predicting the Background Solar Wind for Solar Maximum
    Conditions with the Alfven Wave Solar atmosphere model (AWSoM)
Authors: Sachdeva, Nishtha; Toth, Gabor; Manchester, Ward; van der
   Holst, Bart; Huang, Zhenguang; Sokolov, Igor; Zhao, Lulu; Al Shidi,
   Qusai; Chen, Yuxi; Gombosi, Tamas; Henney, Carl
Bibcode: 2021AGUFMSH45D2396S
Altcode:
  For physics-based simulations of the coronal mass ejections (CMEs)
  it is essential to start with realistic background solar wind
  conditions. To achieve this goal, we use the 3D extended MHD Alfven
  Wave Solar atmosphere Model (AWSoM) to simulate the background plasma
  environment during the magnetically active phase of solar cycle 24 and
  validate the results with in situ and remote observations. Representing
  the solar maximum conditions by two Carrington Rotations, we use the
  ADAPT-HMI photospheric magnetic-field maps to drive AWSoM and simulate
  the solar wind from the low corona to Earths orbit. We compare the AWSoM
  predicted solar wind with EUV observations near the Sun as well as with
  observed plasma and magnetic field parameters at L1 and at the STEREO
  spacecraft location. We find that the optimal value for the Poynting
  flux parameter of the model depends on the solar activity: for solar
  maximum it has to be reduced by about a factor of two compared to the
  solar minimum. Using properly adjusted Poynting flux parameters for the
  solar maximum period results in a reasonable match with observations
  for which quantitative comparisons show small margins of error. These
  provide a reasonably accurate background solar wind into which a CME
  will be launched.

Title: Stormtime energetics: Energy transport across the magnetopause
    in a global MHD simulation
Authors: Brenner, Austin; Pulkkinen, Tuija I.; Al Shidi, Qusai;
   Toth, Gabor
Bibcode: 2021FrASS...8..180B
Altcode:
  Coupling between the solar wind and magnetosphere can be expressed
  in terms of energy transfer through the separating boundary known as
  the magnetopause. Geospace simulation is performed using the Space
  Weather Modeling Framework (SWMF) of a multi-ICME impact event on
  February 18-20, 2014 in order to study the energy transfer through
  the magnetopause during storm conditions. The magnetopause boundary
  is identified using a modified plasma β and fully closed field
  line criteria to a downstream distance of −20Re. Observations
  from Geotail, Themis, and Cluster are used as well as the Shue 1998
  model to verify the simulation field data results and magnetopause
  boundary location. Once the boundary is identified, energy transfer
  is calculated in terms of total energy flux K, Poynting flux S,
  and hydrodynamic flux H. Surface motion effects are considered and
  the spatial distribution is explored in terms of dayside (X &gt; 0),
  flank (X &lt; 0), and tail cap (X = Xmin) regions. It is found that
  total integrated energy flux over the boundary is nearly balanced
  between injection and escape, and flank contributions dominate the
  Poynting flux injection. Poynting flux dominates net energy input,
  while hydrodynamic flux dominates energy output. Surface fluctuations
  contribute significantly to net energy transfer and comparison with
  the Shue model reveals varying levels of cylindrical asymmetry in
  the magnetopause flank throughout the event. Finally existing energy
  coupling proxies such as the Akasofu ε parameter and Newell coupling
  function are compared with the energy transfer results.

Title: Challenges in Modeling the Outer Magnetosphere
Authors: Tóth, Gábor; Chen, Yuxi; Huang, Zhenguang; van der Holst,
   Bart
Bibcode: 2021GMS...259..717T
Altcode:
  No abstract at ADS

Title: Multi Fluid MHD Simulations of Europa's Plasma Interaction
    Under Different Magnetospheric Conditions
Authors: Harris, Camilla D. K.; Jia, Xianzhe; Slavin, James A.; Toth,
   Gabor; Huang, Zhenguang; Rubin, Martin
Bibcode: 2021JGRA..12628888H
Altcode:
  Europa hosts a periodically changing plasma interaction driven
  by the variations of Jupiter's magnetic field and magnetospheric
  plasma. We have developed a multi fluid magnetohydrodynamic (MHD)
  model for Europa to characterize the global configuration of the
  plasma interaction with the moon and its tenuous atmosphere. The model
  solves the multi fluid MHD equations for electrons and three ion fluids
  (Jupiter's magnetospheric O<SUP>+</SUP>, as well as O<SUP>+</SUP> and
  O<SUB>2</SUB><SUP>+</SUP> originating from Europa's atmosphere) while
  incorporating sources and losses in the MHD equations due to electron
  impact and photo ionization, charge exchange, recombination and other
  relevant collisional effects. Using input parameters constrained by the
  Galileo magnetic field and plasma observations, we first demonstrate the
  accuracy of our model by simulating the Galileo E4 and E14 flybys, which
  took place under different upstream conditions and sampled different
  regions of Europa's interaction. Our model produces 3D magnetic field
  and plasma bulk parameters that agree with and provide context for the
  flyby observations. We next present the results of a parameter study of
  Europa's plasma interaction at three different excursions from Jupiter's
  central plasma sheet, for three different global magnetospheric states,
  comprising nine steady state simulations. By separately tracking
  multiple ion fluids, our MHD model allows us to quantify the access of
  the Jovian magnetospheric plasma to Europa's surface and determine how
  that access is affected by changing magnetospheric conditions. We find
  that the thermal magnetospheric O<SUP>+</SUP> precipitation rate ranges
  from (1.8-26) × 10<SUP>24</SUP> ions/s, and that the precipitation
  rate increases with the density of the ambient magnetospheric plasma.

Title: What sustained multi-disciplinary research can achieve:
    The space weather modeling framework
Authors: Gombosi, Tamas I.; Chen, Yuxi; Glocer, Alex; Huang, Zhenguang;
   Jia, Xianzhe; Liemohn, Michael W.; Manchester, Ward B.; Pulkkinen,
   Tuija; Sachdeva, Nishtha; Al Shidi, Qusai; Sokolov, Igor V.; Szente,
   Judit; Tenishev, Valeriy; Toth, Gabor; van der Holst, Bart; Welling,
   Daniel T.; Zhao, Lulu; Zou, Shasha
Bibcode: 2021JSWSC..11...42G
Altcode: 2021arXiv210513227G
  Magnetohydrodynamics (MHD)-based global space weather models have
  mostly been developed and maintained at academic institutions. While
  the "free spirit" approach of academia enables the rapid emergence
  and testing of new ideas and methods, the lack of long-term stability
  and support makes this arrangement very challenging. This paper
  describes a successful example of a university-based group, the Center
  of Space Environment Modeling (CSEM) at the University of Michigan,
  that developed and maintained the Space Weather Modeling Framework
  (SWMF) and its core element, the BATS-R-US extended MHD code. It took
  a quarter of a century to develop this capability and reach its present
  level of maturity that makes it suitable for research use by the space
  physics community through the Community Coordinated Modeling Center
  (CCMC) as well as operational use by the NOAA Space Weather Prediction
  Center (SWPC).

Title: Kinetic Modeling in the Magnetosphere
Authors: Markidis, Stefano; Olshevsky, Vyacheslav; Tóth, Gábor;
   Chen, Yuxi; Peng, Ivy Bo; Lapenta, Giovanni; Gombosi, Tamas
Bibcode: 2021GMS...259..607M
Altcode: 2020arXiv201206669M
  This paper presents the state of the art of kinetic modeling
  techniques for simulating plasma kinetic dynamics in magnetospheres. We
  describe the critical numerical techniques for enabling large-scale
  kinetic simulations of magnetospheres: parameter scaling, implicit
  Particle-in-Cell schemes, and fluid-kinetic coupling. We show an
  application of these techniques to study particle acceleration
  and heating in asymmetric magnetic reconnection in the Ganymede
  magnetosphere.

Title: Estimating Maximum Extent of Auroral Equatorward Boundary
    Using Historical and Simulated Surface Magnetic Field Data
Authors: Blake, Seán. P.; Pulkkinen, Antti; Schuck, Peter W.; Glocer,
   Alex; Tóth, Gabor
Bibcode: 2021JGRA..12628284B
Altcode:
  The equatorward extent of the auroral oval, the region which separates
  the open field polar cap regions with the closed field subauroral
  regions, is an important factor to take into account when assessing the
  risk posed by space weather to ground infrastructure. During storms, the
  auroral oval is known to move equatorward, accompanied by ionospheric
  current systems and significant magnetic field variations. Here we
  outline a simple algorithm which can be used to estimate the maximum
  extent of the auroral equatorward boundary (MEAEB) using magnetic
  field data from ground based observatories. We apply this algorithm
  to three decades of INTERMAGNET data, and show how the auroral oval
  in the Northern hemisphere moves South with larger (more negative Dst)
  storms. We simulate a number of storms with different magnitudes using
  the Space Weather Modeling Framework (SWMF), and apply the same auroral
  boundary detection algorithm. For SWMF simulated storms with Dst &gt;
  -600nT, the estimates of the MEAEB are broadly in line with the same
  estimates for historical events. For the extreme scaled storms (with
  Dst &lt; -1,000 nT), there is considerable scatter in the estimated
  location of the auroral equatorward boundary. Our largest storm
  simulation was calculated using Carrington like estimates for the
  solar wind conditions. This resulted in a minimum Dst = -1,142 nT,
  and a minimum estimated auroral boundary of 35.5° MLAT in places.

Title: Threaded-field-line Model for the Low Solar Corona Powered
    by the Alfvén Wave Turbulence
Authors: Sokolov, Igor V.; Holst, Bart van der; Manchester, Ward B.;
   Su Ozturk, Doga Can; Szente, Judit; Taktakishvili, Aleksandre; Tóth,
   Gábor; Jin, Meng; Gombosi, Tamas I.
Bibcode: 2021ApJ...908..172S
Altcode:
  We present an updated global model of the solar corona, including the
  transition region. We simulate the realistic three-dimensional (3D)
  magnetic field using the data from the photospheric magnetic field
  measurements and assume the magnetohydrodynamic (MHD) Alfvén wave
  turbulence and its nonlinear dissipation to be the only source for
  heating the coronal plasma and driving the solar wind. In closed-field
  regions, the dissipation efficiency in a balanced turbulence is
  enhanced. In the coronal holes, we account for a reflection of the
  outward-propagating waves, which is accompanied by the generation
  of weaker counterpropagating waves. The nonlinear cascade rate
  degrades in strongly imbalanced turbulence, thus resulting in colder
  coronal holes. The distinctive feature of the presented model is the
  description of the low corona as almost-steady-state low-beta plasma
  motion and heat flux transfer along the magnetic field lines. We trace
  the magnetic field lines through each grid point of the lower boundary
  of the global corona model, chosen at some heliocentric distance,
  R = R<SUB>b</SUB> ∼ 1.1R<SUB>⊙</SUB>, well above the transition
  region. One can readily solve the plasma parameters along the magnetic
  field line from 1D equations for the plasma motion and heat transport
  together with the Alfvén wave propagation, which adequately describe
  the physics within the heliocentric distance range R<SUB>⊙</SUB>
  &lt; R &lt; R<SUB>b</SUB>, in the low solar corona. By interfacing
  this threaded-field-line model with the full MHD global corona model
  at r = R<SUB>b</SUB>, we find the global solution and achieve a
  faster-than-real-time performance of the model on ∼200 cores.

Title: Advances and challenges in global magnetosphere simulations.
Authors: Kuznetsova, Maria; Sibeck, David; Toth, Gabor; Rastaetter,
   Lutz; Chen, Li-Jen
Bibcode: 2021cosp...43E1079K
Altcode:
  Global magnetospheric simulation is an essential tool that enables
  researches to put data from fleets of multi-spacecraft missions such
  as Cluster, THEMIS, MMS into a global context. The presentation will
  discuss utilization of magnetosphere missions to review the state of
  global magnetosphere modeling. High resolution observations of electron
  diffusion region crossings by MMS can be utilized to validate global
  magnetosphere models' capability to simulate locations of separatrix
  surfaces and magnetic reconnection sites. Multi-spacecraft observations
  can be utilized to evaluate capabilities to simulate reconnection sites
  motion and plasmoid dynamics. The presentation will include overview of
  new tools, services and models implemented at the Community Coordinated
  Modeling Center (CCMC) to facilitate magnetospheric mission science. We
  will discuss advances and challenges in global magnetosphere simulations
  for moderate and extreme solar wind driving conditions. Strong solar
  wind driving can push the magnetopause boundary into inner magnetosphere
  and even upper atmosphere where single fluid MHD approach is not
  applicable. One of the major challenges is to quantify the interaction
  between global evolution of the magnetosphere and microphysical
  kinetic processes in diffusion regions near reconnection sites. Our
  past studies of magnetosphere dynamics during moderate steady southward
  driving demonstrated that incorporation of kinetic nongyrotropic effects
  near reconnection sites in magnetotail significantly alter the global
  magnetosphere evolution. To study characteristics of loading/unloading
  cycle in response to extreme solar wind driving we utilize the global
  MHD component of the Space Weather Modeling Framework (SWMF) with
  incorporated kinetic corrections.

Title: Structure of the Heliotail
Authors: Opher, Merav; Richardson, John; Krimigis, Stamatios;
   Toth, Gabor; Tenishev, Valeriy; Zank, Gary; Drake, James; Izmodenov,
   Vladislav; Fuselier, Stephen; Dialynas, Konstantinos; Baliukin, Igor;
   Dayeh, Maher A.; Zieger, Bertalan; Michael, Adam; Kornbleuth, Marc;
   Gkioulidou, Matina
Bibcode: 2021cosp...43E.880O
Altcode:
  The canonical view of the structure of the heliosphere is that it
  has a long comet-like tail. This view is not universally accepted and
  there is vigorous debate as to whether it possesses a long comet-like
  structure, is bubble shaped, or is "croissant"-like, a debate that
  is driven by observations and modeling. Opher et al. (2015) suggest a
  heliosphere with two lobes, described as "croissant"-like. An extension
  of the single ion global 3D MHD model that treats PUIs created in
  the supersonic solar wind as a fluid separate and distinct from the
  thermal solar wind plasma yields a heliosphere that is reduced in
  size and rounder in shape (Opher et al. 2020). In contrast, Izmodenov
  et al. 2020 argue that a long/extended tail confines the plasma. One
  direct way to probe the structure of the tail is through energetic
  neutral atom (ENA) maps. ENA images of the tail by Interstellar
  Boundary Explorer (IBEX) at energies of 0.5-6keV exhibit a multi-lobe
  structure. These lobes are attributed to signatures of slow and fast
  wind within the extended heliospheric tail as part of the 11-year
  solar cycle (McComas et al. 2013; Zirnstein et al. 2017). Higher
  energy ENA observations (&gt;5.2 keV) from the Cassini spacecraft, in
  conjunction with &gt;28 keV in-situ ions from V1&amp;2/LECP (Dialynas
  et al. 2017), in contrast, support the interpretation of bubble-like
  heliosphere, with few substantial tail-like features, although there are
  interpretations otherwise (Bzowski &amp; Schwadron 2018). Regardless of
  the shape of the heliotail, there is an agreement between models that
  the solar magnetic field in the inner heliosheath (IHS) possesses a
  "slinky-like" structure (Opher et al. 2015; Pogorelov et al. 2015;
  Izmodenov et al. 2015) that helps confine the plasma in the IHS. In
  this work, as part of a recently funded project SHIELD (Solar-wind
  with Hydrogen Ion Exchange and Large-scale Dynamics), we revisit
  two different MHD models (Izmodenov et al. 2018; Opher et al. 2020)
  and investigate instabilities possibly responsible for the different
  solutions. We investigate how the different physical assumptions are
  manifested in ENA maps derived from IBEX and Cassini ENA data and
  predict what could be observed by the upcoming IMAP mission.

Title: The Impact of Kinetic Neutrals on the Heliotail
Authors: Michael, A. T.; Opher, M.; Tóth, G.; Tenishev, V.; Drake,
   J. F.
Bibcode: 2021ApJ...906...37M
Altcode:
  The shape of the heliosphere is thought to resemble a long, comet
  tail, however, recently it has been suggested that the heliosphere is
  tailless with a two-lobe structure. The latter study was done with
  a three-dimensional (3D) magnetohydrodynamic code, which treats the
  ionized and neutral hydrogen atoms as fluids. Previous studies that
  described the neutrals kinetically claim that this removes the two-lobe
  structure of the heliosphere. In this work, we use the newly developed
  Solar-wind with Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD)
  model. SHIELD is a self-consistent kinetic-MHD model of the outer
  heliosphere that couples the MHD solution for a single plasma fluid from
  the BATS-R-US MHD code to the kinetic solution for neutral hydrogen
  atoms solved by the Adaptive Mesh Particle Simulator, a 3D, direct
  simulation Monte Carlo model that solves the Boltzmann equation. We
  use the same boundary conditions as our previous simulations using
  multi-fluid neutrals to test whether the two-lobe structure of the
  heliotail is removed with a kinetic treatment of the neutrals. Our
  results show that despite the large difference in the neutral hydrogen
  solutions, the two-lobe structure remains. These results are contrary
  to previous kinetic-MHD models. One such model maintains a perfectly
  ideal heliopause and does not allow for communication between the
  solar wind and interstellar medium. This indicates that magnetic
  reconnection or instabilities downtail play a role for the formation
  of the two-lobe structure.

Title: The Structure of the Heliosphere as revealed by modeled ENA
    maps at IBEX energies
Authors: Kornbleuth, Marc; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Izmodenov, Vladislav; Baliukin, Igor; Michael, Adam
Bibcode: 2021cosp...43E.896K
Altcode:
  The heliosphere is indirectly probed in all directions by energetic
  neutral atom (ENA) observations by spacecraft such as the Interstellar
  Boundary Explorer (IBEX). Energetic neutral atom (ENA) modeling is
  an important tool in understanding these ENA observations. Most MHD
  models describe the ionized components as a single ion characterized by
  a single Maxwellian distribution. This is clearly an approximation,
  a "recipe" is needed to translate the single ion to the full ion
  distribution present in the solar wind. In this work, we explore how
  different treatment of ions in ENA models and heliospheric solutions
  from two separate MHD models manifest in ENA maps. Here we use two
  different models: one from Boston University (Michael et al. 2020;
  2019) and the other from Moscow University (Izmodenov &amp; Alexashov
  2018) to probe the effect of the MHD solution in the ENA maps. The
  two MHD models treat the heliospheric boundaries differently, with
  the Moscow University model suppressing all non-ideal MHD effects
  such as reconnection and instabilities. We use same the boundary
  conditions (corresponding to solar minima) and same ISM conditions and
  investigate the differences in the modeled ENA maps, and whether IBEX
  can observe these features. The treatment of ions in the ENA model is
  also crucial. Including multiple ion species, such as using several
  pick-up ion (PUI) populations, has been shown to provide the best
  agreement between ENA models and IBEX observations. Ion propagation
  across the termination shock and downstream in the heliosheath is an
  important element in ENA production, yet there are various methods for
  modeling this propagation. We compare two separate ENA map "recipes"
  to understand the role of each population in contributing to IBEX
  observations.

Title: Understanding the Limitations of System Models for Geomagnetic
    Index Prediction
Authors: Brenner, A.; Pulkkinen, T. I.; Al Shidi, Q.; Toth, G.;
   Gombosi, T. I.
Bibcode: 2020AGUFMSA0210021B
Altcode:
  The WINDMI physics based system model is an "instant" prediction tool
  that takes solar wind input data and predicts geomagnetic indices such
  as Dst. It does this by modeling the solar wind-magnetosphere-ionosphere
  system as a connected set of circuit elements. These components take
  into account the average amount of energy contained in a region and
  estimate an effective resistance, capacitance, or inductance. The Space
  Weather Modeling Framework (SWMF) couples several models to create
  a self-consistent system mostly derived from first principles. By
  using SWMF to reconstruct and analyze the energy contained in the
  various circuit elements of the WINDMI model allows us to make a
  direct comparison to understand under what conditions the circuit
  assumption performs well, and what features are missing. First,
  geomagnetic indices are compared for the two models along with OMNI
  data for a real series of events beginning on Feb 18, 2014. Then,
  several circuit elements are recreated within SWMF and compared over
  the simulation time. We discuss implications and limitations for the
  use of system models as prediction tools, along with suggestions for
  a possible new application of machine learning.

Title: How Pickup Ions Generate Turbulence in the Inner Heliosheath:
    A Multi-Fluid Approach
Authors: Zieger, B.; Opher, M.; Toth, G.; Florinski, V. A.
Bibcode: 2020AGUFMSH0160017Z
Altcode:
  The solar wind in the inner heliosheath beyond the termination
  shock (TS) is a non-equilibrium collisionless plasma consisting of
  thermal solar wind ions, suprathermal pickup ions and electrons. In
  such multi-ion plasma, two fast magnetosonic wave modes exist: the
  low-frequency fast mode that propagates in the thermal ion component
  and the high-frequency fast mode that propagates in the suprathermal
  pickup ion component. Both fast modes are dispersive on fluid and
  ion scales, which results in nonlinear dispersive shock waves. We
  present high-resolution three-fluid simulations of the TS and the inner
  heliosheath up to 2.2 AU downstream of the TS. We show that downstream
  propagating nonlinear fast magnetosonic waves grow until they steepen
  into shocklets, overturn, and start to propagate backward in the frame
  of the downstream propagating wave. The counter-propagating nonlinear
  waves result in 2-D fast magnetosonic turbulence, which is driven
  by the ion-ion hybrid resonance instability. Energy is transferred
  from small scales to large scales in the inverse cascade range and
  enstrophy is transferred from large scales to small scales in the direct
  cascade range. We validate our three-fluid simulations with in-situ
  high-resolution Voyager 2 magnetic field observations in the inner
  heliosheath. Our simulations reproduce the observed magnetic turbulence
  spectrum with a spectral slope of -5/3 in frequency domain. However,
  the fluid-scale turbulence spectrum is not a Kolmogorov spectrum in
  wave number domain because Taylor's hypothesis breaks down in the
  inner heliosheath. The magnetic structure functions of the simulated
  and observed turbulence follow the Kolmogorov-Kraichnan scaling,
  which implies self-similarity.

Title: Geomagnetic simulation using MHD with Adaptively Embedded
    PIC model
Authors: Wang, X.; Chen, Y.; Toth, G.
Bibcode: 2020AGUFMSM0050004W
Altcode:
  The MHD with embedded PIC (MHD-EPIC) model makes it feasible
  to incorporate kinetic physics into a global simulation. Still,
  this requires a large enough box-shaped PIC domain to accommodate
  the movement and changes of the magnetic reconnection regions over
  time. This wastes computational resources on simulating regions with
  the expensive PIC model where MHD would be sufficient to describe
  the physics. We have developed a new MHD with Adaptively Embedded PIC
  (MHD-AEPIC) algorithm that couples the BATS-R-US MHD model with the
  new FLexible Exascale Kinetic Simulator (FLEKS) PIC code. In the new
  coupled model the PIC domains can move with the magnetic reconnection
  regions and adapt to them with an arbitrary shape. In this work, we
  will first introduce the algorithms for selecting the reconnection
  regions in the MHD model that need to be resolved with the kinetic PIC
  model. Then we will compare simulations obtained with MHD-EPIC using
  fixed PIC regions versus MHD-AEPIC employing adaptive PIC regions to
  verify that the new model generates reliable results. Finally, we will
  apply the MHD-AEPIC model to a global magnetic storm simulation and
  demonstrate the improved efficiency.

Title: How does planetary magnetic field impact on Ion escape rate?
Authors: Ma, Y.; Russell, C. T.; Toth, G.; Nagy, A. F.; Brain, D.
Bibcode: 2020AGUFMSM043..05M
Altcode:
  We use an advanced multi-fluid MHD model of Mars to examine the
  planetary magnetic field impact on the ion escape rate. The multi-fluid
  MHD model has been recently improved by solving an additional electron
  pressure equation [Ma et al., 2019], and is the first global model
  that enables a self-consistent calculation of both ion and electron
  temperatures and pressure gradient force terms. The improved model has
  also been validated with a MAVEN event study, and is found to match
  the best with corresponding MAVEN plasma observations as compared
  with previous versions of the code. To examine the effect of planetary
  magnetic field, we use the new model to run a total of ten simulation
  cases with identical solar wind parameters but different planetary
  dipole moments with surface equatorial field strengths ranging from
  0 to 5000 nT. We also examine how different IMF orientations modulate
  the impact of planetary magnetic field on the ion escape rates.

Title: Modeling sources of magnetospheric plasma during storms
    and substorms
Authors: Glocer, A.; Chappell, C. R.; Fok, M. C. H.; Welling, D. T.;
   Huddleston, M.; Toth, G.
Bibcode: 2020AGUFMSM045..01G
Altcode:
  It is well accepted that all of the plasma in Earth's magnetosphere
  derives from either the solar wind or the planet itself via the
  processes of ionospheric outflow. Indeed, the presence of O+ in the
  magnetosphere, which can only come from the ionosphere, is a clear
  indicator of an ionospheric source of plasma. Unlike O+ which only
  has one source of plasma, H+ can come from both the solar wind and the
  ionosphere. The solar wind H+ must enter the magnetosphere through the
  dayside magnetopause interactions, whereas ionospheric H+ is constantly
  flowing out of the ionosphere where can either be recirculated in the
  magnetosphere or lost down the magnetotail. In this presentation we
  will use merged global models combining ionospheric outflow (PWOM),
  multi-fluid MHD (BATS-R-US), and a ring current model (CIMI) to examine
  the relative importance of ionospheric and solar wind plasma in defining
  magnetospheric composition. We will moreover examine the pathways ions
  take to reach different regions of the magnetosphere and timescales
  required for different source populations to be effective contributors
  to magnetospheric composition in that region. The simulations presented
  consider a real event case study (2018-08-25/28) which features a
  large storm with comparisons to MMS observations. We also consider
  an idealized substorm using idealized inputs and both isotropic and
  anisotropic outflow conditions.

Title: Time-dependent global MHD simulations of Jupiter's
    magnetosphere with a realistic internal field model
Authors: Sarkango, Y.; Jia, X.; Toth, G.; Chen, Y.
Bibcode: 2020AGUFMSM0540005S
Altcode:
  Jupiter's internal field, which has strong higher-order components,
  together with the fast rotation of the planet introduces a periodic
  modulation ("wobbling") to the magnetosphere which has been observed
  in the crossing of the Jovian current sheet by in-situ spacecraft. Our
  understanding of the current sheet is largely based on in-situ data
  that has limited spatial coverage and empirical models, which consider
  two main factors in fitting the magnetic field observations. Firstly,
  it is known that information about the changing magnetic field would
  propagate at a finite speed through the inhomogeneous, ambient plasma
  environment. Secondly, it was shown that the inclusion of current
  sheet hinging, which limits the latitudinal excursions of the current
  sheet beyond a certain distance, improves the fit to observations. In
  particular, better fits were obtained by assuming that the degree
  of hinging changes along the Sun-Jupiter line, rather than radial
  distance. This hints that current sheet hinging is likely due to
  solar-wind influence on the outer magnetosphere. <P />In this work, we
  incorporate a non-axisymmetric internal field model into our Jupiter
  global simulation to understand the contribution of the two factors
  described above in a self-consistent manner. Our simulation includes
  the mass loading due to Io in the form of source and loss terms in
  the MHD equations and solves the semi-relativistic MHD equations
  using the BATSRUS code (Sarkango et al., 2019). To understand how
  solar wind forcing influences the hinging of the current sheet,
  we drive our simulations with time-dependent solar wind input and
  systematically analyze the response of the current sheet to varying
  solar wind conditions.

Title: Simulating Solar Maximum Conditions with the Alfven Wave
    Solar Atmosphere Model (AWSoM)
Authors: Sachdeva, N.; van der Holst, B.; Toth, G.; Manchester, W.;
   Sokolov, I.
Bibcode: 2020AGUFMSH0290015S
Altcode:
  The Alfven Wave Solar atmosphere Model (AWSoM) within the Space Weather
  Modeling Framework (SWMF) is a physics-based solar corona model
  that solves magnetohydrodynamic (MHD) equations along with Alfven
  wave turbulence, radiative cooling and heat conduction. The Alfven
  wave pressure and dissipation account for solar wind acceleration and
  heating. AWSoM extends from the upper chromosphere up to 1 AU and beyond
  and includes the description of electron temperature and perpendicular
  and parallel proton temperature. AWSoM is driven by observations of the
  photospheric magnetic field, which are applied at the inner boundary. In
  this study, we use the ADAPT (Air Force Data Assimilative Photospheric
  Flux Transport) synchronic maps to drive our solar corona model. The
  ADAPT model uses observations of the solar photospheric magnetic field
  to produce an ensemble of magnetic field maps using a flux-transport
  model and data assimilation. We simulate solar maximum conditions using
  AWSoM and compare the results with SDO/AIA observations in the low
  corona and observations of solar wind density, speed and magnetic field
  at 1 AU (OMNI data). The background solar wind derived from our model
  provides the plasma environment into which Coronal Mass Ejections (CMEs)
  can be launched. We use the Gibson-Low Flux Rope model to initiate a
  CME and propagate it into the inner heliosphere. We validate the CME
  simulation by comparing the results with remote as well as in-situ
  observations from SOHO, SDO, STEREO, and WIND.

Title: The Effect of Changing Solar Magnetic Field Intensity on
    ENA Maps
Authors: Kornbleuth, M. Z.; Opher, M.; Michael, A. T.; Sokol, J. M.;
   Toth, G.; Tenishev, V.
Bibcode: 2020AGUFMSH0230008K
Altcode:
  Opher et al. (2015) showed that the solar magnetic field can confine and
  collimate the solar wind plasma in the heliosheath. IBEX observations
  of the heliotail have shown the presence of two high latitude
  lobes of enhanced ENA flux in the heliotail at high energies (&gt;2
  keV). Numerous studies have investigated how the latitudinal variation
  of the solar wind during the solar cycle affects the latitudinal profile
  of ENAs in the heliotail. Kornbleuth et al. (2020) showed that while
  the solar wind profile does contribute to the high latitude lobes
  observed by IBEX in the heliotail, the solar magnetic field plays a
  significant role as well. In this work we use steady state MHD solutions
  corresponding to solar wind conditions from particular years to isolate
  how conditions corresponding to different periods of the solar cycle
  influence ENA maps. We find the variations in the intensity of the
  solar magnetic field play an important role in not only influencing
  observations of the heliotail, but also in affecting the thickness
  of the heliosheath in the direction of the nose. The variations not
  only affect the ENA intensity observed in the high latitude tail, but
  also the size and location of the high latitude lobes. Additionally,
  as noted by previous studies, we find the changes in the solar wind
  dynamic pressure influence the observed ENA flux and that asymmetries
  in the dynamic pressure can be discerned from ENA maps.

Title: Flexible Kinetic Coupling Model with FLEKS for Simulating
    Ganymede's Magnetosphere
Authors: Zhou, H.; Jia, X.; Chen, Y.; Toth, G.
Bibcode: 2020AGUFMSM0540015Z
Altcode:
  To capture the local kinetic processes within fluid simulations,
  we couple the MHD model BATS-R-US to the recently developed implicit
  kinetic particle-in-cell (PIC) model Flexible Exascale Kinetic Simulator
  (FLEKS). This new model allows the users to set flexible PIC regions
  based on geometric and physical criteria, and is more efficient in doing
  large scale parallelized simulations. The coupled model is applied to
  the magnetosphere simulation of Ganymede, with the high-resolution PIC
  region covering the entire magnetopause and tail current sheet. The
  prolific outputs of electrons and ions from kinetic simulation shed
  light on the reconnection driven physics across the entire magnetosphere
  that are not available in the simplified fluid description.

Title: NextGen Space Weather Modeling Framework Using Physics,
    Data Assimilation, Uncertainty Quantification and GPUs
Authors: Toth, G.; Zou, S.; Chen, Y.; Huan, X.; van der Holst, B.;
   Manchester, W.; Liemohn, M. W.; Chen, Y.; Huang, Z.; Gaenko, A.
Bibcode: 2020AGUFMSM015..05T
Altcode:
  We have been recently awarded a major NSF/NASA grant from the SWQU
  program to develop the NextGen Space Weather Modeling Framework that
  will employ computational models from the surface of the Sun to the
  surface of Earth in combination with assimilation of observational
  data to provide optimal probabilistic space weather forecasting. The
  model will run efficiently on the next generation of supercomputers
  to predict space weather about one day or more before the impact
  occurs. The new project will concentrate on forecasting major space
  weather events generated by coronal mass ejections (CMEs). Current space
  weather prediction tools employ first-principles and/or empirical
  models. While these provide useful information, their accuracy,
  reliability and forecast window need major improvements. Data
  assimilation has the potential to significantly improve model
  performance, as it has been successfully done in terrestrial weather
  forecast. To allow for the sparsity of satellite observations, however,
  a different data assimilation method will be employed. The new model
  will start from the Sun with an ensemble of simulations that span
  the uncertain observational and model parameters. Using real time and
  past observations, the model will strategically down-select to a high
  performing subset. Next, the down-selected ensemble will be extended by
  varying uncertain parameters and the simulation continued to the next
  data assimilation point. The final ensemble will provide a probabilistic
  forecast of the space weather impacts. While the concept is simple,
  finding the optimal algorithm that produces the best prediction with
  minimal uncertainty is a complex and very challenging task that requires
  developing, implementing and perfecting novel data assimilation and
  uncertainty quantification methods. To make these ensemble simulations
  run faster than real time, the most expensive parts of the model
  need to run efficiently on the current and future supercomputers,
  which employ graphical processing units (GPUs) in addition to the
  traditional multi-core CPUs. The main product of this project will be
  the Michigan Sun-To-Earth Model with Quantified Uncertainty and Data
  Assimilation (MSTEM-QUDA) that will be made available to the space
  physics community with an open source license. We will describe the
  main concept of the project and our initial progress.

Title: Role of Inductive Electric Field on the Build-up of Storm
    Time Ring Current
Authors: Liu, J.; Ilie, R.; Toth, G.
Bibcode: 2020AGUFMSM037..11L
Altcode:
  During geomagnetic storms, plasma is energized and transported from
  the night side plasma sheet to the inner magnetosphere, resulting in a
  build-up of plasma density and pressure. The magnetic gradient-curvature
  further drives the energetic ions westward, therefore creating
  a pressure accumulation in the evening sector. Continuous inward
  adiabatic transport from the plasma sheet to the inner magnetosphere
  can be a major contributor to the pressure build up on night side,
  which suggests that convection electric field plays a significant
  role in developing the storm time ring current. However, during the
  storm time, the inductive nature can overwhelm the electrostatic
  nature of convection electric field, due to the temporal change of
  magnetic field. Thus, regarding the electrostatic component of electric
  field as the total convection field is not sufficient nor accurate for
  modeling the dynamics of inner magnetosphere system, and it may lead to
  mis-estimation of the transport and energization of ring current hot
  ion species, and associated storm time ring current build-up. Both
  theoretical and numerical modifications to an inner magnetosphere
  kinetic model --- Hot Electron-Ion Drift Integrator (HEIDI) has been
  made to account for the effect of inductive electric field, in order
  to assess how much inductive electric is relative to electro-static
  field, in addition with investigating the role of inductive electric
  field on the build-up and evolution of storm time inner magnetospheric
  ring current. We found that, during the intensifying southward IMF
  period, magnetic field is stretched away from dipole, and the associated
  inductive electric field further accumulates ion pressure in the evening
  sector and depletes ion pressure in the morning sector. The reverse
  is true as the magnetic field dipolarizes back to dipole configuration.

Title: Heliospheric Ly α Absorption in a Split Tail Heliosphere
Authors: Powell, E.; Opher, M.; Michael, A. T.; Kornbleuth, M. Z.;
   Wood, B. E.; Izmodenov, V.; Toth, G.; Tenishev, V.; Richardson, J. D.
Bibcode: 2020AGUFMSH0170013P
Altcode:
  Neutral hydrogen in the hydrogen wall and heliosheath absorb wavelengths
  of light near Ly α from nearby stars. Heliospheric models are essential
  to understand these observations since the observations are an indirect
  method of probing the the heliosphere. Opher et al. (2015) suggested
  that the solar magnetic field can collimate the solar wind plasma,
  resulting in a heliosphere with a split tail. We compare the Ly α
  predictions made by multi-fluid kinetic-MHD models of Opher et al. 2020,
  Michael et al. 2020 that present a "Croissant-like" (split tail)
  shape with long tail models used in Izmodenov et al. 2018. Previous
  studies have shown that the interstellar magnetic field can affect the
  distribution of neutral hydrogen in the hydrogen wall just outside
  the heliosphere. In this study our models use a grid that extends
  1500 AU downwind and vary the Interstellar magnetic field strength
  and direction. The split tail model successfully reproduce the LY α
  profiles in upwind and sidewind line of sights and have good agreement
  in downwind line of sights. We comment on the differences between
  the two MHD models and which directions can be more sensitive to the
  heliospheric shape as well from the interstellar magnetic field.

Title: Multi-fluid MHD Modeling of Europa's Plasma Interaction
Authors: Harris, C. D. K.; Jia, X.; Toth, G.; Huang, Z.; Slavin,
   J. A.; Rubin, M.
Bibcode: 2020AGUFMSM049..06H
Altcode:
  Europa hosts a periodically changing plasma interaction driven by the
  variations of Jupiter's magnetic field and magnetospheric plasma. We
  have developed a multi-fluid MHD model for the plasma interaction to
  investigate its response to these magnetic field and plasma variations
  at Europa's orbit. The model solves the multi-fluid MHD equations
  for electrons and three ion fluids (magnetospheric O<SUP>+</SUP> as
  well as O<SUP>+</SUP> and O<SUB>2</SUB><SUP>+</SUP> originating from
  Europa's ionosphere) while incorporating sources and losses in the
  fluid equations due to ionization, electron heat conduction, charge
  exchange, recombination and other relevant collisional effects. Using
  input parameters constrained by the Galileo MAG and PLS observations,
  we first demonstrate the accuracy of our model's representation of the
  plasma interaction by simulating the Galileo E4 and E14 flybys, which
  took place under different upstream conditions and sampled different
  regions of Europa's interaction. Our model produces 3D magnetic field
  and plasma bulk parameters that agree with and provide context for
  the flyby observations. We next present the results of a parameter
  study of Europa's plasma interaction at three different System-III
  longitudes within Jupiter's magnetosphere, for three different
  global magnetospheric states, comprising 9 steady-state simulations
  in total. We describe how Europa's ionosphere is self-consistently
  generated in response to the external plasma conditions, and show how
  the relative strengths of the magnetospheric plasma versus Europa's
  ionosphere control Europa's global interaction with Jupiter's
  magnetosphere.

Title: Quantitative Investigation of the Effect on Ground Magnetic
    Perturbations of IMF Bx
Authors: Kwagala, N. K.; Moretto, T.; Hesse, M.; Tenfjord, P.; Norgren,
   C.; Toth, G.; Gombosi, T. I.; Kolsto, H.; Flø Spinnangr, S.
Bibcode: 2020AGUFMSH0030007K
Altcode:
  In this work, we investigate quantitatively the effect of IMF Bx on
  magnetospheric dynamics, ionospheric currents, and the resulting
  magnetic perturbations measured at magnetometer stations on the
  ground. Using the University of Michigan's space weather modeling
  framework (SWMF), two historic geomagnetic storms are simulated and
  compared to ground-based magnetic observations. For each storm two
  separate simulations are carried out, one with IMF Bx artificially
  set to zero throughout the event and the other keeping the measured
  variable IMF Bx in the driving conditions. The difference between the
  outputs from the two runs in the magnetosphere, ionosphere and magnetic
  perturbations on the ground will be presented and discussed.

Title: The lunar crustal magnetic anomalies were not produced by
    impact plasmas
Authors: Oran, R.; Weiss, B. P.; Shprits, Y.; Miljkovic, K.; Toth, G.
Bibcode: 2020AGUFMGP015..01O
Altcode:
  The crusts of the Moon, Mercury, Mars, and many meteorites parent bodies
  are magnetized. Although the magnetizing field is commonly attributed
  to that of an ancient core dynamo, a longstanding hypothesized
  alternative is that the remanent magnetization may have been produced
  by impact plasmas that can transiently induce fields or amplify the
  background interplanetary magnetic field. However, the dynamics of
  such impact-plasma fields have not been studied self-consistently in
  the context of the coupled interaction of the impact plume, solar wind,
  and the non-uniform electrical resistivity inside the body. To address
  this gap, we combined hydrocode impact-physics and magnetohydrodynamic
  (MHD) simulations to study impact field generation and amplification on
  the Moon. Considering a diversity of different impact and solar wind
  conditions 3.5-4 Ga ago, we demonstrate that the resulting fields are
  weaker than previously predicted. Field strengths are limited due to
  solar wind variability, the formation of a diamagnetic cavity around
  the moon by the expanding plasma cloud, and the fact that the induced
  field is dissipated by ohmic dissipation in the crust. As a result,
  the maximum crustal field is at least 3 orders of magnitude too weak
  to explain the magnetization. The elimination of impact plasmas as
  the sole source of lunar magnetism leaves a core dynamo as the only
  plausible source of the majority of magnetization on the Moon. This
  result may challenge impact-magnetization scenarios considered for
  other bodies, such as Mercury.

Title: A Statistical Comparison of Global MHD Simulations and
    Geomagnetic Storm Indices
Authors: Al Shidi, Q. A.; Pulkkinen, T. I.; Brenner, A.; Toth, G.;
   Zou, S.
Bibcode: 2020AGUFMSM022..07A
Altcode:
  Space weather monitoring and predictions largely rely on ground
  magnetic measurements and geomagnetic indices such as the Disturbance
  Storm Time index (Dst or SYM-H), Auroral Electrojet Index (AL) or the
  Polar Cap Index (PCI) all constructed using the individual station
  data. The global MHD simulations such as the Space Weather Modeling
  Framework (SWMF) can give predictions of these indices, driven by
  solar wind observations obtained at L1 giving roughly one hour lead
  time. The accuracy of these predictions especially during geomagnetic
  storms is a key metric for the model performance, and critical to
  operational space weather forecasts. <P />In this presentation, we
  perform the largest statistical study of global simulation results
  using a database of 140 storms with minimum Dst below -50 nT during
  the years from 2010 to 2020. We compare SWMF results with indices
  derived from the SuperMAG network, which with its denser station
  network provides a more accurate representation of the true level
  of activity in the ring current and in the auroral electrojets. We
  show that the SWMF generally gives good results for the SYM-H index,
  whereas the AL index is typically underestimated by the model with
  the model predicting lower than observed ionospheric activity. We
  also examine the Cross Polar Cap Potential (CPCP) and compare it with
  a model derived using the PCI (Ridley et al., 2004) as well as with
  results obtained from the SuperDARN network. We show that the Ridley
  et al. CPCP model is much closer to the SWMF values. The results are
  used to discuss factors governing energy dissipation in magnetosphere -
  ionosphere system as well as possibilities to improve on the operational
  space weather forecasts.

Title: FLEKS: A Flexible Particle-in-Cell code for Multi-Scale Space
    Plasma Simulations
Authors: Chen, Y.; Toth, G.; Wang, X.
Bibcode: 2020AGUFMSM0050003C
Altcode:
  The Magnetohydrodynamics with embedded particle-in-cell (MHD-EPIC)
  model has been successfully applied to global magnetospheric simulations
  in recent years. However, the PIC region was restricted to be a box,
  and it is not always feasible to cover the whole physical structure
  of interest with a box due to the limitation of the computational
  resources. The FLexible Exascale Kinetic Simulator (FLEKS), which is
  a new PIC code and allows a PIC region of any shape, is designed to
  break this restriction and extend the capabilities of the MHD-EPIC
  model. <P />FLEKS uses the Gauss's law satisfying energy-conserving
  semi-implicit method (GL-ECSIM) as the base PIC solver. We have
  also designed extra numerical techniques, such as the adaptive time
  stepping and particle resampling algorithms, to further improve the
  accuracy and flexibility of the PIC solver. The grid of FLEKS has to
  be Cartesian, but the active PIC region is not necessarily to be a
  box anymore since any Cartesian cells can be turned off. Furthermore,
  FLEKS supports switching on or switching off grid cells adaptively
  during a simulation. The initial conditions and boundary conditions
  of the active PIC region are provided by the coupled MHD code. FLEKS
  and the coupled MHD code constitute the MHD with adaptively embedded
  particle-in-cell (MHD-AEPIC) model. FLEKS is implemented in C++ in the
  object-oriented design, and it is based on a third-party open source
  library AMReX, which provides FLEKS high-performance parallel data
  structures. We will present the numerical and implementation details,
  show its parallel performance, and demonstrate its capabilities with
  3D magnetospheric simulations.

Title: 3D Hall-MHD Simulations of Mercury's Dayside Magnetopause
    Reconnection and Its Impact on the Global Magnetospheric Dynamics
Authors: Li, C.; Jia, X.; Chen, Y.; Zhou, H.; Toth, G.; Slavin, J. A.;
   Sun, W.
Bibcode: 2020AGUFMP078.0004L
Altcode:
  Observations from NASA's MESSENGER spacecraft reveal that Mercury has
  a miniature magnetosphere arising from the interaction of its dipolar
  intrinsic field with the inner heliosphere solar wind. Compared to the
  terrestrial magnetosphere, Mercury's magnetosphere appears to be more
  dynamic in that the typical timescales for global plasma and magnetic
  flux circulation are much shorter, and the dayside magnetopause
  reconnection occurs at faster rates and under a wider range of
  magnetic shear angles. As a product of multiple X-line reconnection,
  flux transfer events (FTEs) are found to arise much more frequently
  with occurrence rates of about 50 times higher than detected at
  Earth. MESSENGER observations suggest that aside from the apparent
  difference in system size, the large differences in reconnection-driven
  dynamics between Mercury's magnetosphere and the Earth's are likely
  related to the upstream solar wind conditions. In order to obtain a
  quantitative, global understanding of how magnetopause reconnection
  occurs at Mercury and its large-scale consequences, we have used the
  BATSRUS Hall-MHD code with a high resolution grid that resolves ion
  kinetic scales to simulate Mercury's magnetopause dynamics under a
  variety of upstream solar wind and IMF conditions. Flux ropes are found
  to form in all of our time-dependent Hall MHD simulations under steady
  solar wind conditions, but their properties, such as occurrence rate
  and spatial structure, vary depending on the upstream parameters. We
  have developed techniques to identify flux ropes in our simulations and
  extract their magnetic field and plasma properties that can be compared
  directly with MESSENGER observations of FTEs. The set of carefully
  designed Hall MHD simulations allow us to examine how the properties of
  FTEs depend on such parameters as the solar wind Alfvénic Mach number,
  IMF orientation, and the magnetosheath plasma . With the global model,
  we also evaluate the contribution of FTEs to the global circulation of
  plasma and magnetic flux at Mercury and how it might vary in response
  to changes in the external conditions.

Title: Comparing the best ADAPT realizations from WSA, AWSoM and
    AWSoM-R
Authors: Huang, Z.; Sokolov, I.; van der Holst, B.; Toth, G.; Arge,
   C. N.; Sachdeva, N.; Jones, S. I.; Manchester, W.; Gombosi, T. I.
Bibcode: 2020AGUFMSH0290028H
Altcode:
  Solar corona models are typically driven by global photospheric
  magnetic field maps assembled from magnetograms. Magnetic field maps
  derived from different magnetogram sources (e.g. MDI, GONG, etc)
  can produce different results when used as boundary conditions. One
  of the commonly used synchronic maps is provided by the ADAPT (Air
  Force Data Assimilative Photospheric Flux Transport) model, which
  makes use of a flux transport model to evolve the regions where there
  are no observations. The ADAPT model uses the ensemble least-squares
  data assimilation method that account for model and observational
  uncertainties and provides 12 different realizations for a given
  moment in time. Previous studies have shown the same solar corona
  model running with 12 different realizations also provide different
  predicted solar wind values at 1 AU. In this presentation, we will
  use the ADAPT maps to drive the WSA (Wang-Sheeley-Arge) model, the
  AWSoM (Alfven-Wave driven Solar atmosphere Model) and the AWSoM-R
  (Alfven-Wave driven Solar atmosphere Model - Realtime) model. The
  coronal portion of the WSA model makes use of the coupled potential
  field source surface and Schatten current sheet models to derive the
  global coronal magnetic field from global maps of the photospheric
  field. The model then applies empirical formulas to specify the solar
  wind at the outer coronal boundary and a 1D kinematic model to predict
  solar wind speed and interplanetary magnetic polarity anywhere in
  the inner heliosphere. AWSoM is a physics-based model solving the
  MHD equations together with radiative cooling, heat conduction and a
  phenomenological Alfven wave turbulence and dissipation model including
  wave reflection (proportional to the Alfvén speed gradients) and
  turbulent dissipation from the chromosphere to the heliosphere. The
  AWSoM-R model uses 1-D field line threads to simulate the region in
  the lower chromosphere to speed up the simulations. We will compare
  the predicted solar wind values at 1 AU with observations and use the
  WSA Prediction Metric developed at NASA Goddard Space Flight Center to
  select the best ADAPT map realization(s) for the three models. We will
  investigate whether we can improve the prediction capability of the
  complex physics-based models like AWSoM and AWSoM-R using the insight
  gained from the inexpensive empirical WSA model.

Title: A Gray-Box Model for a Probabilistic Estimate of Regional
Ground Magnetic Perturbations: Enhancing the NOAA Operational Geospace
    Model With Machine Learning
Authors: Camporeale, E.; Cash, M. D.; Singer, H. J.; Balch, C. C.;
   Huang, Z.; Toth, G.
Bibcode: 2020JGRA..12527684C
Altcode: 2019arXiv191201038C
  We present a novel algorithm that predicts the probability that the
  time derivative of the horizontal component of the ground magnetic
  field dB/dt exceeds a specified threshold at a given location. This
  quantity provides important information that is physically relevant to
  geomagnetically induced currents (GICs), which are electric currents
  associated with sudden changes in the Earth's magnetic field due
  to space weather events. The model follows a "gray-box" approach
  by combining the output of a physics-based model with machine
  learning. Specifically, we combine the University of Michigan's
  Geospace model that is operational at the National Oceanic and
  Atmospheric Administration (NOAA) Space Weather Prediction Center,
  with a boosted ensemble of classification trees. We discuss the
  problem of recalibrating the output of the decision tree to obtain
  reliable probabilities. The performance of the model is assessed by
  typical metrics for probabilistic forecasts: Probability of Detection
  and False Detection, True Skill Statistic, Heidke Skill Score, and
  Receiver Operating Characteristic curve. We show that the ML-enhanced
  algorithm consistently improves all the metrics considered.

Title: A Case Study on the Origin of Near-Earth Plasma
Authors: Glocer, A.; Welling, D.; Chappell, C. R.; Toth, G.; Fok,
   M. -C.; Komar, C.; Kang, S. -B.; Buzulukova, N.; Ferradas, C.; Bingham,
   S.; Mouikis, C.
Bibcode: 2020JGRA..12528205G
Altcode:
  This study presents simulations of the coupled space environment
  during a geomagnetic storm that separates the different sources
  of near-Earth plasma. These simulations include separate fluids
  for solar wind and ionospheric protons, ionospheric oxygen, and the
  plasmasphere. Additionally, they include the effects of both a hot ring
  current population and a cold plasmaspheric population simultaneously
  for a geomagnetic storm. The modeled ring current population represents
  the solution of bounce-averaged kinetic solution; the core plasmaspheric
  model assumes a fixed temperature of 1 eV and constant pressure along
  the field line. We find that during the storm, ionospheric protons can
  be a major contributor to the plasmasheet and ring current and that
  ionospheric plasma can largely displace solar wind protons in much of
  the magnetosphere under certain conditions. Indeed, the ionospheric
  source of plasma cannot be ignored. Significant hemispheric asymmetry
  is found between the outflow calculated in the summer and winter
  hemispheres, consistent with past observations. That asymmetric
  outflow is found to lead to asymmetric filling of the lobes, with
  the northern (summer) lobe receiving more outflow that has a higher
  proportion of O<SUP>+</SUP> and the southern (winter) lobe receiving
  less outflow with a higher proportion of H<SUP>+</SUP>. We moreover
  find that the inclusion of the plasmasphere can have a system-wide
  impact. Specifically, when the plasmasphere drainage plume reaches the
  magnetopause, it can reduce the reconnection rate, suppress ionospheric
  outflow and change its composition, change the composition in the
  magnetosphere, and reduce the ring current intensity.

Title: Magnetohydrodynamic With Embedded Particle-In-Cell Simulation
    of the Geospace Environment Modeling Dayside Kinetic Processes
    Challenge Event
Authors: Chen, Yuxi; Tóth, Gábor; Hietala, Heli; Vines, Sarah K.;
   Zou, Ying; Nishimura, Yukitoshi; Silveira, Marcos V. D.; Guo, Zhifang;
   Lin, Yu; Markidis, Stefano
Bibcode: 2020E&SS....701331C
Altcode: 2020arXiv200104563C
  We use the magnetohydrodynamic (MHD) with embedded particle-in-cell
  model (MHD-EPIC) to study the Geospace Environment Modeling (GEM)
  dayside kinetic processes challenge event at 01:50-03:00 UT on 18
  November 2015, when the magnetosphere was driven by a steady southward
  interplanetary magnetic field (IMF). In the MHD-EPIC simulation, the
  dayside magnetopause is covered by a PIC code so that the dayside
  reconnection is properly handled. We compare the magnetic fields
  and the plasma profiles of the magnetopause crossing with the MMS3
  spacecraft observations. Most variables match the observations well in
  the magnetosphere, in the magnetosheath, and also during the current
  sheet crossing. The MHD-EPIC simulation produces flux ropes, and we
  demonstrate that some magnetic field and plasma features observed by
  the MMS3 spacecraft can be reproduced by a flux rope crossing event. We
  use an algorithm to automatically identify the reconnection sites from
  the simulation results. It turns out that there are usually multiple
  X-lines at the magnetopause. By tracing the locations of the X-lines,
  we find that the typical moving speed of the X-line endpoints is
  about 70 km/s, which is higher than but still comparable with the
  ground-based observations.

Title: Dispersive Fast Magnetosonic Waves and Shock-Driven
    Compressible Turbulence in the Inner Heliosheath
Authors: Zieger, Bertalan; Opher, Merav; Tóth, Gábor; Florinski,
   Vladimir
Bibcode: 2020JGRA..12528393Z
Altcode:
  The solar wind in the inner heliosheath beyond the termination
  shock (TS) is a nonequilibrium collisionless plasma consisting of
  thermal solar wind ions, suprathermal pickup ions, and electrons. In
  such multi-ion plasma, two fast magnetosonic wave modes exist,
  the low-frequency fast mode and the high-frequency fast mode. Both
  fast modes are dispersive on fluid and ion scales, which results
  in nonlinear dispersive shock waves. We present high-resolution
  three-fluid simulations of the TS and the inner heliosheath up to a few
  astronomical units (AU) downstream of the TS. We show that downstream
  propagating nonlinear fast magnetosonic waves grow until they steepen
  into shocklets, overturn, and start to propagate backward in the frame
  of the downstream propagating wave. The counterpropagating nonlinear
  waves result in 2-D fast magnetosonic turbulence, which is driven
  by the ion-ion hybrid resonance instability. Energy is transferred
  from small scales to large scales in the inverse cascade range, and
  enstrophy is transferred from large scales to small scales in the
  direct cascade range. We validate our three-fluid simulations with in
  situ high-resolution Voyager 2 magnetic field observations in the inner
  heliosheath. Our simulations reproduce the observed magnetic turbulence
  spectrum with a spectral slope of -5/3 in frequency domain. However,
  the fluid-scale turbulence spectrum is not a Kolmogorov spectrum in
  wave number domain because Taylor's hypothesis breaks down in the
  inner heliosheath. The magnetic structure functions of the simulated
  and observed turbulence follow the Kolmogorov-Kraichnan scaling,
  which implies self-similarity.

Title: Coupled MHD - Hybrid Simulations of Space Plasmas
Authors: Moschou, S. P.; Sokolov, I. V.; Cohen, O.; Toth, G.; Drake,
   J. J.; Huang, Z.; Garraffo, C.; Alvarado-Gómez, J. D.; Gombosi, T.
Bibcode: 2020JPhCS1623a2008M
Altcode: 2019arXiv191108660M
  Heliospheric plasmas require multi-scale and multi-physics
  considerations. On one hand, MHD codes are widely used for global
  simulations of the solar-terrestrial environments, but do not provide
  the most elaborate physical description of space plasmas. Hybrid
  codes, on the other hand, capture important physical processes, such
  as electric currents and effects of finite Larmor radius, but they can
  be used locally only, since the limitations in available computational
  resources do not allow for their use throughout a global computational
  domain. In the present work, we present a new coupled scheme which
  allows to switch blocks in the block-adaptive grids from fluid MHD to
  hybrid simulations, without modifying the self-consistent computation
  of the electromagnetic fields acting on fluids (in MHD simulation)
  or charged ion macroparticles (in hybrid simulation). In this way,
  the hybrid scheme can refine the description in specified regions of
  interest without compromising the efficiency of the global MHD code.

Title: Reconnection-Driven Dynamics at Ganymede's Upstream
Magnetosphere: 3-D Global Hall MHD and MHD-EPIC Simulations
Authors: Zhou, Hongyang; Tóth, Gábor; Jia, Xianzhe; Chen, Yuxi
Bibcode: 2020JGRA..12528162Z
Altcode:
  The largest moon in the solar system, Ganymede, is the only moon known
  to possess a strong intrinsic magnetic field and a corresponding
  magnetosphere. Using the latest version of Space Weather Modeling
  Framework (SWMF), we study the upstream plasma interactions and dynamics
  in this sub-Alfvénic system. Results from the Hall magnetohydrodynamics
  (MHD) and the coupled MHD with embedded particle-in-cell (MHD-EPIC)
  models are compared. We find that under steady upstream conditions,
  magnetopause reconnection occurs in a nonsteady manner, and the
  energy partition between electrons and ions is different in the
  two models. Flux ropes of Ganymede's radius in length form on the
  magnetopause at a rate about 3 min and create spatiotemporal variations
  in plasma and field properties. Upon reaching proper grid resolutions,
  the MHD-EPIC model can resolve both electron and ion kinetics at the
  magnetopause and show localized nongyrotropic behavior inside the
  diffusion region. The estimated global reconnection rate from the
  models is about 80 kV with 60% efficiency, and there is weak evidence
  of ∼1 min periodicity in the temporal variations due to the dynamic
  reconnection process.

Title: The Confinement of the Heliosheath Plasma by the Solar Magnetic
    Field as Revealed by Energetic Neutral Atom Simulations
Authors: Kornbleuth, M.; Opher, M.; Michael, A. T.; Sokół, J. M.;
   Tóth, G.; Tenishev, V.; Drake, J. F.
Bibcode: 2020ApJ...895L..26K
Altcode: 2020arXiv200506643K
  Traditionally, the solar magnetic field has been considered to have
  a negligible effect in the outer regions of the heliosphere. Recent
  works have shown that the solar magnetic field may play a crucial role
  in collimating the plasma in the heliosheath. Interstellar Boundary
  Explorer (IBEX) observations of the heliotail indicated a latitudinal
  structure varying with energy in the energetic neutral atom (ENA)
  fluxes. At energies ∼1 keV, the ENA fluxes show an enhancement at
  low latitudes and a deficit of ENAs near the poles. At energies &gt;2.7
  keV, ENA fluxes had a deficit within low latitudes, and lobes of higher
  ENA flux near the poles. This ENA structure was initially interpreted
  to be a result of the latitudinal profile of the solar wind during
  solar minimum. We extend the work of Kornbleuth et al. by using solar
  minimum-like conditions and the recently developed Solar-wind with
  Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD) model. The
  SHIELD model couples the magnetohydrodynamic plasma solution with
  a kinetic description of neutral hydrogen. We show that while the
  latitudinal profile of the solar wind during solar minimum contributes
  to the lobes in ENA maps, the collimation by the solar magnetic
  field is important in creating and shaping the two high-latitude
  lobes of enhanced ENA flux observed by IBEX. This is the first work
  to explore the effect of the changing solar magnetic field strength
  on ENA maps. Our findings suggest that IBEX is providing the first
  observational evidence of the collimation of the heliosheath plasma
  by the solar magnetic field.

Title: Formation and Evolution of the Large-Scale Magnetic Fields
in Venus' Ionosphere: Results From a Three Dimensional Global
    Multispecies MHD Model
Authors: Ma, Yingjuan; Toth, Gabor; Nagy, Andrew; Luhmann, Janet;
   Russell, Christopher
Bibcode: 2020GeoRL..4787593M
Altcode:
  Large-scale magnetic fields have been observed in Venus'
  ionosphere by both the Pioneer Venus Orbiter (PVO) and Venus
  Express spacecraft. In this study, we examine the formation and
  evolution of the large-scale magnetic field in the Venus ionosphere
  using a sophisticated global multispecies Magnetohydrodynamics
  (MHD) model that has been developed for Venus (Ma et al., 2013, <A
  href="https://doi.org/10.1029/2012JA018265">https://doi.org/10.1029/2012JA018265</A>).
  A time-dependent model run is performed under varying solar wind
  dynamic pressure. Based on model results, we find that (1) the initial
  response of the induced magnetosphere is fast (~min), (2) a large-scale
  magnetic field gradually forms in the ionosphere when the solar wind
  dynamic pressure suddenly exceeds the ionospheric thermal pressure,
  (3) both the penetration and decay of the large-scale magnetic field
  in the ionosphere are slow (~hr), and (4) the ion escape rate has a
  nonlinear response to the change of solar wind dynamic pressure.

Title: Validating the Space Weather Modeling Framework (SWMF)
    for applications in northern Europe. Ground magnetic perturbation
    validation
Authors: Kwagala, Norah Kaggwa; Hesse, Michael; Moretto, Therese;
   Tenfjord, Paul; Norgren, Cecilia; Tóth, Gabor; Gombosi, Tamas;
   Kolstø, Håkon M.; Spinnangr, Susanne F.
Bibcode: 2020JSWSC..10...33K
Altcode:
  In this study we investigate the performance of the University of
  Michigan's Space Weather Modeling Framework (SWMF) in prediction of
  ground magnetic perturbations (ΔB) and their rate of change with
  time (dB/dt), which is directly connected to geomagnetically induced
  currents (GICs). We use the SWMF set-up where the global magnetosphere
  provided by the Block Adaptive Tree Solar-wind Roe-type Upwind Scheme
  (BATS-R-US) MHD code, is coupled to the inner magnetosphere and the
  ionospheric electrodynamics. The validation is done for ΔB and dB/dt
  separately. The performance is evaluated via data-model comparison
  through a metrics-based approach. For ΔB, the normalized root mean
  square error (nRMS) and the correlation coefficient are used. For dB/dt,
  the probability of detection, the probability of false detection,
  the Heidke skill score, and the frequency bias are used for different
  dB/dt thresholds. The performance is evaluated for eleven ground
  magnetometer stations located between 59° and 85° magnetic latitude
  and spanning about five magnetic local times. Eight geomagnetic storms
  are studied. Our results show that the SWMF predicts the northward
  component of the perturbations better at lower latitudes (59°-67°)
  than at higher latitudes (&gt;67°), whereas for the eastward component,
  the model performs better at high latitudes. Generally, the SWMF
  performs well in the prediction of dB/dt for a 0.3 nT/s threshold,
  with a high probability of detection ≈0.8, low probability of false
  detection (&lt;0.4), and Heidke skill score above zero. To a large
  extent the model tends to predict events as often as they are actually
  occurring in nature (frequency bias 1). With respect to the metrics
  measures, the dB/dt prediction performance generally decreases as the
  threshold is raised, except for the probability of false detection,
  which improves.

Title: MHD Predictions of Plasma Conditions Above Insight Landing
    Site based on MAVEN observations
Authors: Ma, Yingjuan; Russell, Chris; Yu, Yanan; Nagy, Andrew; Toth,
   Gabor; Jakosky2, Bruce
Bibcode: 2020EGUGA..2220751M
Altcode:
  The Interior Exploration using Seismic Investigations, Geodesy
  and Heat Transport (InSight) mission was launched on 5 May 2018 and
  successfully landed at Elysium Planitia (4.5oN, 135.9oE)on Mars on 26
  November 2018. The InSight Lander carries a magnetometer to measure
  disturbances from the Martian ionosphere. In order to understand the
  daily variations in the magnet field measurements on Martian surface,
  in this study, we use the time-dependent MHD model to study how plasma
  conditions vary with local time above insight landing site using solar
  wind condition from MAVEN observation. Significant diurnal variations
  can be seen in all plasma quantities due to solar wind interactions and
  planetary rotation. The induced magnetic field is mainly in the same
  direction as the upstream IMF. However, it seems that the variations
  seen by the Insight magnetometer cannot be only due to the interaction
  of the solar wind. We also add a neutral wind effect in our simulations
  to further investigate possible causes of surface field changes.

Title: Predicting Solar Flares with Machine Learning: Investigating
    Solar Cycle Dependence
Authors: Wang, Xiantong; Chen, Yang; Toth, Gabor; Manchester, Ward
   B.; Gombosi, Tamas I.; Hero, Alfred O.; Jiao, Zhenbang; Sun, Hu; Jin,
   Meng; Liu, Yang
Bibcode: 2020ApJ...895....3W
Altcode: 2019arXiv191200502W
  A deep learning network, long short-term memory (LSTM), is used to
  predict whether an active region (AR) will produce a flare of class
  Γ in the next 24 hr. We consider Γ to be ≥M (strong flare), ≥C
  (medium flare), and ≥A (any flare) class. The essence of using LSTM,
  which is a recurrent neural network, is its ability to capture temporal
  information on the data samples. The input features are time sequences
  of 20 magnetic parameters from the space weather Helioseismic and
  Magnetic Imager AR patches. We analyze ARs from 2010 June to 2018
  December and their associated flares identified in the Geostationary
  Operational Environmental Satellite X-ray flare catalogs. Our results
  produce skill scores consistent with recently published results using
  LSTMs and are better than the previous results using a single time
  input. The skill scores from the model show statistically significant
  variation when different years of data are chosen for training and
  testing. In particular, 2015-2018 have better true skill statistic and
  Heidke skill scores for predicting ≥C medium flares than 2011-2014,
  when the difference in flare occurrence rates is properly taken into
  account.

Title: Publisher Correction: A small and round heliosphere suggested
    by magnetohydrodynamic modelling of pick-up ions
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
Bibcode: 2020NatAs...4..719O
Altcode: 2020NatAs.tmp...96O
  An amendment to this paper has been published and can be accessed via
  a link at the top of the paper.

Title: Is the Relation Between the Solar Wind Dynamic Pressure and
    the Magnetopause Standoff Distance so Straightforward?
Authors: Samsonov, A. A.; Bogdanova, Y. V.; Branduardi-Raymont, G.;
   Sibeck, D. G.; Toth, G.
Bibcode: 2020GeoRL..4786474S
Altcode:
  We present results of global magnetohydrodynamic simulations which
  reconsider the relationship between the solar wind dynamic pressure
  (P<SUB>d</SUB>) and magnetopause standoff distance (R<SUB>SUB</SUB>). We
  simulate the magnetospheric response to increases in the dynamic
  pressure by varying separately the solar wind density or velocity
  for northward and southward interplanetary magnetic field (IMF). We
  obtain different values of the power law indices N in the relation
  RSUB∼Pd-1&gt;/N depending on which parameter, density, or velocity,
  has been varied and for which IMF orientation. The changes in the
  standoff distance are smaller (higher N) for a density increase for
  southward IMF and greater (smaller N) for a velocity increase. An
  enhancement of the solar wind velocity for a southward IMF increases
  the magnetopause reconnection rate and Region 1 current that move
  the magnetopause closer to the Earth than it appears in the case of
  density increase for the same dynamic pressure.

Title: The Solar-wind with Hydrogen Ion Exchange and Large-scale
Dynamics (SHIELD) model: A Self-Consistent Kinetic-MHD Model of the
    Outer Heliosphere
Authors: Michael, Adam T.; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Borovikov, Dmitry
Bibcode: 2020arXiv200401152M
Altcode:
  Neutral hydrogen has been shown to greatly impact the plasma flow in
  the heliopshere and the location of the heliospheric boundaries. We
  present the results of the Solar-wind with Hydrogen Ion Exchange
  and Large-scale Dynamics (SHIELD) model, a new, self-consistent,
  kinetic-MHD model of the outer heliosphere within the Space Weather
  Modeling Framework. The charge-exchange mean free path is on order
  of the size of the heliosphere; therefore, the neutral atoms cannot
  be described as a fluid. The SHIELD model couples the MHD solution
  for a single plasma fluid to the kinetic solution from for neutral
  hydrogen atoms streaming through the system. The kinetic code is based
  on the Adaptive Mesh Particle Simulator (AMPS), a Monte Carlo method for
  solving the Boltzmann equation. The SHIELD model accurately predicts the
  increased filtration of interstellar neutrals into the heliosphere. In
  order to verify the correct implementation within the model, we compare
  the results of the SHIELD model to other, well-established kinetic-MHD
  models. The SHIELD model matches the neutral hydrogen solution of these
  studies as well as the shift in all heliospheric boundaries closer
  to the Sun in comparison the the multi-fluid treatment of the neutral
  hydrogen atoms. Overall the SHIELD model shows excellent agreement to
  these models and is a significant improvement to the fluid treatment
  of interstellar hydrogen.

Title: A small and round heliosphere suggested by magnetohydrodynamic
    modelling of pick-up ions
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
Bibcode: 2020NatAs...4..675O
Altcode: 2020NatAs.tmp...55O; 2020NatAs.tmp...90O
  As the Sun moves through the surrounding partially ionized medium,
  neutral hydrogen atoms penetrate the heliosphere, and through charge
  exchange with the supersonic solar wind, create a population of hot
  pick-up ions (PUIs). Until recently, the consensus was that the shape
  of the heliosphere is comet-like. The termination shock crossing by
  Voyager 2 demonstrated that the heliosheath (the region of shocked
  solar wind) pressure is dominated by PUIs; however, the impact of
  the PUIs on the global structure of the heliosphere has not been
  explored. Here we use a novel magnetohydrodynamic model that treats
  the PUIs as a separate fluid from the thermal component of the solar
  wind. The depletion of PUIs, due to charge exchange with the neutral
  hydrogen atoms of the interstellar medium in the heliosheath, cools the
  heliosphere, `deflating' it and leading to a narrower heliosheath and
  a smaller and rounder shape, confirming the shape suggested by Cassini
  observations. The new model reproduces both the properties of the PUIs,
  based on the New Horizons observations, and the solar wind ions, based
  on the Voyager 2 spacecraft observations as well as the solar-like
  magnetic field data outside the heliosphere at Voyager 1 and Voyager 2.

Title: The surface distributions of the production of the
    major volatile species, H<SUB>2</SUB>O, CO<SUB>2</SUB>, CO and
    O<SUB>2</SUB>, from the nucleus of comet 67P/Churyumov-Gerasimenko
    throughout the Rosetta Mission as measured by the ROSINA double
    focusing mass spectrometer
Authors: Combi, Michael; Shou, Yinsi; Fougere, Nicolas; Tenishev,
   Valeriy; Altwegg, Kathrin; Rubin, Martin; Bockelée-Morvan, Dominique;
   Capaccioni, Fabrizio; Cheng, Yu-Chi; Fink, Uwe; Gombosi, Tamas;
   Hansen, Kenneth C.; Huang, Zhenguang; Marshall, David; Toth, Gabor
Bibcode: 2020Icar..33513421C
Altcode: 2019arXiv190902082C
  The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
  (ROSINA) suite of instruments operated throughout the over two
  years of the Rosetta mission operations in the vicinity of comet
  67P/Churyumov-Gerasimenko. It measured gas densities and composition
  throughout the comet's atmosphere, or coma. Here we present
  two-years' worth of measurements of the relative densities of the
  four major volatile species in the coma of the comet, H<SUB>2</SUB>O,
  CO<SUB>2</SUB>, CO and O<SUB>2</SUB>, by one of the ROSINA sub-systems
  called the Double Focusing Mass Spectrometer (DFMS). The absolute
  total gas densities were provided by the Comet Pressure Sensor (COPS),
  another ROSINA sub-system. DFMS is a very high mass resolution and
  high sensitivity mass spectrometer able to resolve at a tiny fraction
  of an atomic mass unit. We have analyzed the combined DFMS and COPS
  measurements using an inversion scheme based on spherical harmonics
  that solves for the distribution of potential surface activity of
  each species as the comet rotates, changing solar illumination, over
  short time intervals and as the comet changes distance from the sun
  and orientation of its spin axis over long time intervals. We also
  use the surface boundary conditions derived from the inversion scheme
  to simulate the whole coma with our fully kinetic Direct Simulation
  Monte Carlo model and calculate the production rates of the four major
  species throughout the mission. We compare the derived production rates
  with revised remote sensing observations by the Visible and Infrared
  Thermal Imaging Spectrometer (VIRTIS) as well as with published
  observations from the Microwave Instrument for the Rosetta Orbiter
  (MIRO). Finally we use the variation of the surface production of the
  major species to calculate the total mass loss over the mission and,
  for different estimates of the dust/gas ratio, calculate the variation
  of surface loss all over the nucleus.

Title: 3D global Hall-MHD simulations of Mercury's magnetopause
    dynamics
Authors: Li, C.; Jia, X.; Chen, Y.; Toth, G.; Slavin, J. A.; Sun, W.
Bibcode: 2019AGUFMSM33D3217L
Altcode:
  As the innermost planet of the solar system, Mercury's magnetosphere
  has long been considered a very unique system due to its proximity to
  Sun. At Mercury's orbit, the solar wind plasma density, ram pressure,
  and IMF strength typically are much higher than those encountered
  by the terrestrial magnetosphere. Because of the small size of the
  magnetosphere, the low Alfven Mach number upstream flow and resultant
  low-beta magnetosheath plasma, the interaction between Mercury's
  magnetosphere and the solar wind is extremely dynamic and the dynamics
  is dominated by effects associated with magnetic reconnection. Previous
  analyses of the MESSENGER observations have revealed extraordinarily
  high occurrence rate of Flux Transfer Events (FTEs) at the magnetopause,
  which were observed to arise on a timescale of a few seconds (e.g.,
  Slavin et al., 2012). In order to gain a better understanding of the
  generation mechanism of the frequently observed FTEs and the overall
  magnetopause dynamics, we have employed the BATSRUS Hall-MHD code to
  simulate Mercury's interaction with the solar wind. A high-resolution
  grid with cell size of ~ 30 km (or ~ 0.01 R<SUB>M</SUB>) is used at the
  dayside magnetopause in order to resolve ion-scale physics, which is
  important for reconnection. Our Hall-MHD model also includes Mercury's
  interior that allows us to self-consistently simulate the induction
  effects of the conducting core (Jia et al., 2015, 2019). Our initial
  simulations using steady solar wind with southward IMF conditions show
  that reconnection at the magnetopause occurs in a non-steady fashion,
  which then leads to flux ropes of varying sizes being generated on
  timescale of seconds, which is generally consistent with what has
  been reported based on MESSENGER observations. The dynamic behavior
  of the magnetopause is not seen in ideal MHD simulations that use
  the same input parameters. The differences between these two sets of
  simulations suggest that the Hall physics may play an important role
  in magnetopause reconnection and large-scale dynamics at Mercury.

Title: Systematic Study of the Magnetopause Reconnection and FTEs
    from 3D Simulations of Ganymede's Magnetosphere
Authors: Zhou, H.; Toth, G.; Jia, X.
Bibcode: 2019AGUFMSM41B..09Z
Altcode:
  The largest moon in the solar system, Ganymede, is also the only
  moon known to possess a strong intrinsic magnetic field and a
  corresponding magnetosphere. Previous results have shown that
  even under steady upstream conditions, magnetopause reconnection
  at Ganymede occurs in a non-steady manner. Simulation results from
  Hall MHD and MHD-E(mbedded)Particle-In-Cell models have shown clear
  signatures of flux ropes on the magnetopause, with a fluctuation of
  global reconnection rate in the 20min runs. In this study, we will
  present a detailed comparison on the direct and indirect reconnection
  rate calculation from several numerical models and give insights into
  the flux transfer events (FTEs) and the responses from Ganymede's
  magnetosphere. With the techniques of tracking the reconnection
  sites, the relation between spatiotemporal variations in plasma and
  field properties across the magnetopause, the flux rope generation,
  and the reconnection rate will be discussed. These would be useful
  for the future JUICE mission for aiding the in-situ measurements and
  detecting plasma interaction processes.

Title: The response of Jupiter's coupled magnetosphere-ionosphere
    system to changes in the solar wind and the release of plasmoids in
the magnetotail: Results from global MHD simulations
Authors: Sarkango, Y.; Jia, X.; Toth, G.
Bibcode: 2019AGUFMSM33G3289S
Altcode:
  Joint observations by the HST and in situ spacecraft have shown that
  the brightness of Jupiter's aurora appears to be correlated with
  solar wind dynamic pressure enhancement, despite theoretical work
  predicting the opposite. In this study, we use a time-dependent global
  MHD model (Sarkango et al., 2019, JGR) to investigate the response
  of Jupiter's coupled magnetosphere-ionosphere system to different
  types of changes in the upstream conditions, such as IMF rotation
  and forward interplanetary shock. Our model solves the single fluid
  semi-relativistic ideal MHD equations and self-consistently includes
  the mass loading associated with the Io plasma torus through the
  addition of source and loss terms. Using our model, we show that
  the response of the corotation enforcement currents (which we assume
  are a proxy for auroral brightness) to a shock-induced compression
  varies significantly with local time, with currents being depleted
  on the dayside and moderately enhanced on the nightside. Plasmoids
  are frequently seen in our model due to tail reconnection and plasmoid
  release occurs more frequently during periods of high solar wind dynamic
  pressure. The release of plasmoids is often accompanied with reduction
  of the net open flux in the polar regions as well as decrease in the
  intensity of corotation enforcement currents, consistent with the
  idea that the magnetosphere returns to a less stressed state after
  plasmoid release. Plasmoids originating on closed field lines are
  found to temporarily create a region of closed flux deep inside the
  polar cap that originally only contains open magnetic field lines,
  which diminishes in size as the plasmoid moves tailward and interacts
  with the surrounding plasma. Our results together show that the polar
  regions of Jupiter are highly dynamic and the formation and release
  of plasmoids further complicates the dynamics through large-scale
  reconfiguration of the magnetic field topology.

Title: Exploring the physics of sawtooth oscillations from MHD-EPIC
    simulations
Authors: Chen, Y.; Toth, G.; Wang, X.; Gombosi, T. I.; Welling, D. T.;
   Henderson, M. G.; Markidis, S.; Cassak, P.
Bibcode: 2019AGUFMSM21B3144C
Altcode:
  The sawtooth events are global magnetospheric oscillations with a 2~4
  hour period identified by the saw blade like signature of the energetic
  particle flux and magnetic field near geosynchronous orbit. Previous
  global numerical simulations suggest that the oscillations are generated
  by the ionospheric O + outflows (Brambles et al. [2011]). However,
  recent satellite observations demonstrated the ionospheric outflow is
  neither a necessary nor a sufficient condition for the generation of the
  sawtooth oscillations (Liao et al. [2014], Lund et al. [2017]). We use
  the MHD with embedded particle-in-cell (MHD-EPIC) model, which simulates
  Earth's magnetotail with a PIC code, to show the periodic magnetospheric
  oscillations can be generated even without the ionospheric outflow. We
  show that the magnetotail reconnection is not fast enough to balance
  the incoming magnetic flux during the stretching phase of a sawtooth,
  and the dipolarization phase is triggered by the onset of reconnection
  around x=-20 R E , where the reconnection rate is fast enough to
  release the magnetic flux due to the high ambient magnetic field
  strength. We will present the spatial features and temporal variations
  of the sawtooth oscillations from the MHD-EPIC simulation results,
  and compare the simulations with the observations.

Title: How small changes in the magnetopause current help trap the
    ring current population
Authors: Ilie, R.; Liu, J.; Chen, L., , Dr; Zhu, H.; Toth, G.; Bashir,
   M. F.; Liemohn, M. W.
Bibcode: 2019AGUFMSM41D3272I
Altcode:
  Particle energization is one of the open questions in heliophysics
  research, whether it pertains to coronal heating, polar wind outflow,
  or magnetospheric transport. The terrestrial magnetosphere acts as
  an efficient particle accelerator, as it can rapidly accelerate
  charged particles up to very high energies over relatively short
  times and distances. While the magnetic field topology is critical for
  understanding the particle drifts, knowing the source and structure of
  the electric field is crucial for interpreting the flow of particles
  in this region. Assessing the relative contribution of potential
  versus inductive electric fields at the energization of the hot ion
  population in the inner magnetosphere is only possible by thorough
  examination of the time varying magnetic field and current systems
  using global modeling of the entire system. Based on the Helmholtz
  vector decomposition of the motional electric field as calculated by
  the BATS-R-US model, we differentiate the electric field based on its
  source (electrostatic vs. inductive). Electric field coupling between
  the BATS-R-US and the Hot Electron and Ion Drift Integrator model
  reveals the crucial role of time varying magnetic fields, and hence the
  inductive electric field, in trapping of energetic particle and in the
  overall particle energization. <P />We show that inductive electric
  fields, even if not impulsive in nature, contribute significantly
  to the total field, and in the absence of strong dipolarizations,
  most of the contribution comes from the intensification of the
  magnetopause current. In addition, the inductive electric field acts
  to stabilize the ring current, and it plays a significant role in
  particle trapping. These results indicate a potential paradigm shift in
  our knowledge of particle energization in the context of ring current
  development and decay.

Title: Global Magnetospheric Model with Microscopic Physics: MHD-EPIC
Authors: Toth, G.; Chen, Y.; Zhou, H.; Wang, X.; Tenishev, V.; Shou,
   Y.; Markidis, S.
Bibcode: 2019AGUFMSM12B..06T
Altcode:
  In the last 5 years we have developed and implemented the
  magnetohydrodynamics with embedded particle-in-cell (MHD-EPIC)
  model. MHD-EPIC allows performing global MHD simulations two-way
  coupled with local PIC simulations covering one or more regions where
  kinetic effects are important, such as magnetic reconnection sites. We
  have improved the PIC algorithm to conserve energy and satisfy Gauss'
  law at the same time, generalized the MHD-PIC coupling to arbitrary
  MHD grids and rotated PIC regions, and improved the efficiency of the
  coupler. We have also studied the technique of artificially increasing
  the kinetic scales by changing the mass per charge ratio for the ions
  and electrons, and we found that the global solution remains essentially
  the same as long as the global and kinetic scales are reasonably well
  separated. <P />The combination of these new technologies and insights
  enabled us to perform MHD-EPIC simulations for several magnetospheres,
  including Ganymede, Mercury, Mars, Earth and Saturn. In this talk we
  will demonstrate these capabilities for modeling Earth's magnetosphere
  with the PIC region covering the dayside or tail reconnection sites. On
  the dayside we compare the model with observations of flux transfer
  events and kinetic scale observations by the MMS space craft. For the
  magnetotail we study the dynamics of the reconnection process that
  appears to reproduce several features of sawtooth events for strong
  but steady driving with negative Bz field. Our work is supported by
  the NSF INSPIRE and PRE-EVENTS grants.

Title: Modeling an Extreme Coronal Mass Ejection and its Consequences
    for the Earth's Inner Magnetosphere
Authors: Komar, C. M.; Kang, S. B.; Oliveira, D. M.; Bhaskar, A. T.;
   Fok, M. C. H.; Glocer, A.; Buzulukova, N.; Toth, G.
Bibcode: 2019AGUFMSM13E3356K
Altcode:
  Interplanetary coronal mass ejections (CMEs) can have a variety of
  different impacts upon Geospace. The most extreme CME on record to have
  struck the Earth is the well-known Carrington event of 1859. However,
  in the sixty or so years since the Space Age began, we have thus
  far been exceptionally lucky that no extreme CME has impacted the
  Earth's space environment. The work by Tsurutani and Lakhina, GRL, 2014
  estimates some of the potential impacts that an extreme CME could have
  on Geospace. Tsurutani and Lakhina, 2014 utilize empirical relations
  to provide best estimates of: (1) the magnetopause's location, (2)
  the sudden impulse intensity, and (3) the magnetospheric electric
  field. The CME conditions described by Tsurutani and Lakhina, 2014
  is the most extreme CME conceived by our current theoretical and
  empirical knowledge; such a CME is likely to be MORE extreme than
  the Carrington event. Global magnetospheric models are now capable
  of simulating such events to give insight into the effects of extreme
  space weather conditions. <P />This work will present the results of
  simulations with the Space Weather Modeling Framework using the global
  magnetohydrodynamic (MHD) Block Adaptive Tree Solar wind Roe-type
  Upwind Scheme (BATS-R-US) code. The simulation uses the exact extreme
  CME conditions presented in Tsurutani and Lakhina, 2014 to model the
  impact of an extreme CME on the magnetosphere. We will present the
  successful simulation of these extreme space weather conditions. We will
  directly compare and contrast the predicted values from the empirical
  relations presented in Tsurutani and Lakhina, 2017 with the results of
  the MHD simulations: the sudden impulse dB/dt, magnetopause location,
  and the magnetospheric electric field. We will discuss the response
  of the inner magnetospheric system to extreme space weather events.

Title: Multi-fluid MHD Modeling of Europa's Plasma Interaction:
    Effects of Asymmetric Density in the Neutral Atmosphere
Authors: Harris, C. D. K.; Jia, X.; Slavin, J. A.; Toth, G.; Rubin, M.
Bibcode: 2019AGUFMSM33F3279H
Altcode:
  Europa orbits Jupiter within the Jovian magnetosphere, that region
  of space dominated by the planetary magnetic field and by plasma
  originating from Jupiter's moon Io. Europa's subsurface ocean and weak
  atmosphere interact with Jupiter's magnetic field and magnetospheric
  plasma. Here we investigate the role of Europa's neutral O<SUB>2</SUB>
  atmosphere in the generation of Europa's ionosphere and its interaction
  with Jupiter's magnetosphere. We have developed a 3D multi-fluid
  magnetohydrodynamic (MHD) model for the plasma interaction that solves
  for the bulk properties of 3 ion fluids (magnetospheric O<SUP>+</SUP>,
  ionospheric O<SUP>+</SUP> and O<SUB>2</SUB><SUP>+</SUP>), an electron
  fluid, and the electromagnetic fields near the moon. We include
  a static distribution of neutral O<SUB>2</SUB> that represents
  Europa's atmosphere and provides the neutral source for ionization
  and charge exchange source terms that populate the ionosphere in our
  simulation. We use our MHD model to demonstrate the effects of variation
  in the neutral atmosphere on the plasma interaction during two different
  flybys conducted by the Galileo mission. During the E4 flyby Europa was
  located outside the plasma sheet and the trailing hemisphere was sunlit,
  while during the E15 flyby Europa was embedded within the plasma sheet
  and the trailing hemisphere was in shadow. By comparing our simulation
  results to the in situ magnetometer and plasma data collected by the
  Galileo spacecraft, we show that the E4 flyby is readily modeled with a
  neutral atmosphere with enhanced O<SUB>2</SUB> density on the trailing
  hemisphere; conversely, the E15 flyby is better modeled by a neutral
  atmosphere that is enhanced on the leading hemisphere. This finding is
  consistent with results from recent modeling of Europa's atmosphere that
  incorporates the effects of solar illumination on Europa's spatially
  non-uniform atmosphere as the moon rotates (Oza et al., 2019). Our
  work demonstrates that the state of Europa's neutral atmosphere is a
  crucial factor in the generation of Europa's ionosphere and, ultimately,
  the magnetic field perturbations associated with the plasma interaction.

Title: The Current State of Operational Geospace Modeling Efforts
    at NOAA SWPC
Authors: Cash, M. D.; Singer, H. J.; Balch, C. C.; Millward, G. H.;
   Camporeale, E.; Toth, G.; Huang, Z.
Bibcode: 2019AGUFMSM12B..01C
Altcode:
  The operational Geospace model, which has been running in real-time
  at NOAA's Space Weather Prediction Center (SWPC) since 2016,
  will undergo a significant upgrade in 2020 to a higher resolution
  version. The Geospace model is comprised of three coupled components
  from University of Michigan's Space Weather Modeling Framework (SWMF),
  and having run the model continuously for the past three years, we
  have been able to assess the strengths and limitations of running
  the model in such a real-time mode. In this presentation, we discuss
  the successes and limitations experienced running with the current
  low-resolution version of the model, and present examples of the
  expected model improvements associated with upgrading the model to
  a higher resolution. In particular, we will discuss improvements to
  our regional forecasting capabilities and the implications that such
  improvements have on down-stream modeling efforts such as predicting
  the regional geoelectric field in a predictive mode using output from
  the Geospace model.

Title: Global modeling of the drivers and impacts of storm-time
    plasma composition
Authors: Glocer, A.; Welling, D. T.; Toth, G.; Fok, M. C. H.; Chappell,
   C. R.; Kang, S. B.; Komar, C. M.; Buzulukova, N.; Ferradas, C.
Bibcode: 2019AGUFMSM11A..06G
Altcode:
  Earth's space environment system is comprised of a myriad of plasma
  populations. These populations encompass characteristic energies ranging
  over 6 orders of magnitude; from sub-eV plasma in the ionosphere, to
  10-100 keV plasma in the ring current, and MeV and higher particles in
  the radiation belts. Further complicating this picture is the fact that
  the origin of near-Earth plasma, be it the ionosphere or solar wind,
  remains a subject of significant debate. Simulating these disparate
  plasma populations in a single global simulation requires a fusion of
  fluid and kinetic models. In this presentation we present an improved
  coupling of the Polar Wind Outflow Model (PWOM), the Comprehensive
  Ionosphere Magnetosphere Interaction (CIMI) model, and BATSRUS model
  of the magnetosphere. These models are coupled together using the Space
  Weather Modeling Framework (SWMF), and represent a comprehensive model
  of the Earth's space environment. The improved coupling allows us to
  investigate the origin of near-Earth plasma by separately tracking
  solar wind plasma (H+) from ionospheric plasma (highlatitude H+ and
  O+, as well as plasmaspheric H+). Focusing on storm-time simulations,
  we will examine hemispheric asymmetries in the outflow, the relative
  role of wave-particle interactions and solar EUV in driving ionospheric
  outflow, and the impact on the ring current and radiation belts. We
  will moreover highlight the kinetic features embedded in the model
  and discuss current limitations future directions.

Title: Predicting Solar Flares using Time Sequence Based Machine
    Learning Models
Authors: Wang, X.; Toth, G.; Chen, Y.; Manchester, W.; Jiao, Z.; Sun,
   H.; Sun, Z.; Hero, A. O.; Gombosi, T. I.
Bibcode: 2019AGUFMSH34A..03W
Altcode:
  In the last few years machine learning methods are becoming popular
  for predicting solar flares. We use the Space-weather HMI Active Region
  Patches (SHARP) dataset to analyze thousands of active regions' magnetic
  field and derived parameters (total unsigned flux, free magnetic
  energy, etc) using various machine learning algorithms. In this work
  we first use the SHARP summary parameters to predict the maximum flare
  intensity in a certain time window through a Long Short-Term Memory
  (LSTM) algorithm, which is a particular type of a recurrent neural
  network. The dataset we are using contains 3399 active regions from
  2010 to 2015. Furthermore, we will use the full vector magnetogram
  images to train a combined LSTM and feature extraction convolutional
  neural network (CNN). This approach allows capturing more detailed
  spatial-temporal features of the magnetic field. Our results show
  that using a time sequence to predict the maximum flare intensity can
  achieve a better Heidke Skill Score (HSS) than using a single frame
  as the input. The HSS for predicting the maximum flare class in the
  next 24 hours is about 0.35 for M/X flares and 0.55 for C/M/X flares.

Title: Validation of the Alfvén Wave Solar Atmosphere Model (AWSoM)
    with Observations from the Low Corona to 1 au
Authors: Sachdeva, Nishtha; van der Holst, Bart; Manchester, Ward B.;
   Tóth, Gabor; Chen, Yuxi; Lloveras, Diego G.; Vásquez, Alberto M.;
   Lamy, Philippe; Wojak, Julien; Jackson, Bernard V.; Yu, Hsiu-Shan;
   Henney, Carl J.
Bibcode: 2019ApJ...887...83S
Altcode: 2019arXiv191008110S
  We perform a validation study of the latest version of the Alfvén
  Wave Solar atmosphere Model (AWSoM) within the Space Weather Modeling
  Framework. To do so, we compare the simulation results of the model
  with a comprehensive suite of observations for Carrington rotations
  representative of the solar minimum conditions extending from the
  solar corona to the heliosphere up to the Earth. In the low corona
  (r &lt; 1.25 {\text{}}{R}<SUB>⊙ </SUB>), we compare with EUV
  images from both Solar-Terrestrial Relations Observatory-A/EUVI
  and Solar Dynamics Observatory/Atmospheric Imaging Assembly and to
  three-dimensional (3D) tomographic reconstructions of the electron
  temperature and density based on these same data. We also compare the
  model to tomographic reconstructions of the electron density from
  Solar and Heliospheric Observatory/Large Angle and Spectrometric
  Coronagraph observations (2.55 &lt; r &lt; 6.0{\text{}}{R}<SUB>⊙
  </SUB>). In the heliosphere, we compare model predictions of solar wind
  speed with velocity reconstructions from InterPlanetary Scintillation
  observations. For comparison with observations near the Earth, we use
  OMNI data. Our results show that the improved AWSoM model performs
  well in quantitative agreement with the observations between the inner
  corona and 1 au. The model now reproduces the fast solar wind speed
  in the polar regions. Near the Earth, our model shows good agreement
  with observations of solar wind velocity, proton temperature, and
  density. AWSoM offers an extensive application to study the solar
  corona and larger heliosphere in concert with current and future solar
  missions as well as being well suited for space weather predictions.

Title: Preferential Ion Heating and Particle Acceleration Downstream
    of Dispersive Shock Waves in Collisionless Multi-Ion Plasma
Authors: Zieger, B.; Toth, G.; Opher, M.
Bibcode: 2019AGUFMSH23B3396Z
Altcode:
  We briefly review the theory of dispersive shock waves in collisionless
  multi-ion plasma. In such plasma, two (or more) fast magnetosonic wave
  modes exist: the high-frequency fast mode that propagates in the ion
  component with the higher thermal speed and the low-frequency fast mode
  that propagates in the ion component with the lower thermal speed [Toida
  and Aota, 2013; Zieger et al., 2015]. Both fast modes are dispersive
  on fluid and ion scales, which results in nonlinear dispersive shock
  waves. A negative dispersive wave mode produces a trailing wave
  train downstream of the shock, while a positive dispersive wave mode
  produces a precursor wave train upstream of the shock [Biskamp, 1973;
  Hoefer, 2014]. Here we present high-resolution three-fluid simulations
  of dispersive shock waves in two-ion-species plasma. We show that
  downstream propagating nonlinear magnetosonic waves grow until they
  steepen into shocklets (thin current sheets), overturn, and start to
  propagate backward in the frame of the downstream propagating wave, as
  predicted by theory [McKenzie et al., 1993; Dubinin et al, 2006]. The
  counter-propagating nonlinear waves result in fast magnetosonic
  turbulence far downstream of the shock. Interestingly, energy is
  transferred from small scales to large scales (inverse energy cascade)
  in the high-frequency fast mode, and from large scales to small scales
  (direct energy cascade) in the low-frequency fast mode as the turbulence
  develops in time. We show that the ion species with the lower thermal
  speed is preferentially heated by the turbulence. Forward shocklets
  can efficiently accelerate both ions and electrons to high energies
  through the shock drift acceleration mechanism. We can conclude that
  fast magnetosonic turbulence in collisionless multi-ion plasma will move
  the plasma towards a state where the thermal speeds of different ion
  species are comparable. Our theoretical and numerical simulation results
  could help to explain the observed preferential heating of heavy ions
  in the solar corona, the acceleration of energetic particles downstream
  of interpanetary shocks in the multi-ion solar wind, the non-adiabatic
  cooling of solar wind ions and pickup ions in the outer heliosphere,
  and the unfolding of the anomalous cosmic ray energy spectra in the
  heliosheath, downstream of the termination shock.

Title: Validating the Space Weather Modeling Framework (SWMF)
for applications in northern Europe: Ground magnetic perturbation
    validation
Authors: Kwagala, N. K.; Hesse, M.; Tenfjord, P.; Norgren, C.; Moretto,
   T.; Toth, G.; Gombosi, T. I.
Bibcode: 2019AGUFMSM13F3373K
Altcode:
  This study evaluates the performance of the University of Michigan's
  Space Weather Modeling Framework (SWMF) in the prediction of ground
  magnetic perturbations in the northern Europe region. The SWMF
  consists of an MHD code which is a Block Adaptive Tree Solar-wind
  Roe-type Upwind Scheme (BATS-R-US), with several other models
  which can be coupled together. We use the the global magnetosphere,
  ionosphere electrodynamics and inner magnetosphere coupled SWMF. The
  SWMF is currently used for space weather forecast by the by the
  NOAA Space Weather Prediction Centre (SWPC) and at the Community
  Coordinated Modeling Centre (CCMC). The SWMF was selected to transit
  to operation after a series of community-wide validations of several
  numerical models on a global scale. In our study we further validate
  the SWMF for applications in the northern Europe region. The model
  predictions are done for selected ground magnetometer stations between
  59<SUP>o</SUP> - 78<SUP>o</SUP> magnetic latitudes spanning 5 magnetic
  local hours. The performance is quantified using the metrics-based
  analyses, normalized root-mean-square error and cross correlation
  coefficient. The different metrics are derived from contingency
  tables built for each event and station. Investigated metrics include
  the probability of detection, probability of false alarm detection,
  Heidke Skill Score and frequency bias of the model. The variation of
  the model performance is investigated from event to event, and for
  different magnetic latitudes, and magnetic local times.

Title: Impact of Non-MHD Effects on Global Magnetosphere Dynamics
    for Extreme Solar Wind Driving
Authors: Kuznetsova, M. M.; Toth, G.; Rastaetter, L.
Bibcode: 2019AGUFMSM11A..04K
Altcode:
  The presentations will address challenges in global magnetosphere
  simulations for extreme driving conditions. Strong solar wind driving
  can push the magnetopause boundary into inner magnetosphere and even
  upper atmosphere where single fluid MHD approach is not applicable. For
  extreme driving the magnetopause can move close to the earthward
  boundary of the simulation domain that can lead to increased sensitivity
  to parameters and assumptions at the inner boundary. Ionosphere
  conductance models are typically trained on observational data sets
  that do not include time periods with extreme driving. Another major
  challenge is to quantify the interaction between global evolution of the
  magnetosphere and microphysical kinetic processes in diffusion regions
  near reconnection sites. Our past studies of magnetosphere dynamics
  during moderate steady southward driving demonstrated that incorporation
  of kinetic nongyrotropic effects near reconnection sites in magnetotail
  significantly alter the global magnetosphere evolution. To study
  characteristics of loading/unloading cycle in response to extreme solar
  wind driving we utilize the global MHD component of the Space Weather
  Modeling Framework (SWMF) with incorporated kinetic corrections. We
  also discuss relative impact of kinetic effects at the reconnection
  site and conditions at the inner boundary.

Title: The Two-Lobe Structure of the Heliosphere Persists in the
    SHIELD Model, a K-MHD Model of the Outer Heliosphere
Authors: Michael, A.; Opher, M.; Toth, G.; Tenishev, V.; Borovikov, D.
Bibcode: 2019AGUFMSH51B..07M
Altcode:
  The canonical view of the shape of the heliosphere resembles a long
  comet tail, however, our research group at BU, led by Dr. Merav
  Opher, has suggested that the heliosphere is tailless with a
  two-lobe structure. This study was done with a state-of-the-art 3D
  magnetohydrodynamic (MHD) code that treats the ionized and neutral
  hydrogen atoms as fluids. Previous studies that have described the
  neutrals kinetically have claimed that this removes the two-lobe
  structure of the heliosphere. In this work, we will use the newly
  developed Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics (SHIELD) model, a self-consistent kinetic-MHD model of the
  outer heliosphere. The SHIELD model couples the Outer Heliosphere
  (OH) and Particle Tracker (PT) components within the Space Weather
  Modeling Framework (SWMF). The OH component utilizes the Block-Adaptive
  Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly
  parallel, 3D, and block-adaptive solver. The PT component is based
  on the Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct
  simulation Monte Carlo model that solves the Boltzmann equation to
  model the neutral distribution function throughout the domain. The
  SHIELD model couples the MHD solution for a single plasma fluid to the
  kinetic solution from for neutral hydrogen atoms streaming through the
  system. We use the same boundary conditions as Opher et al. (2015), the
  seminal work on the two-lobe structure, within the SHIELD model to test
  whether the two-lobe structure of the heliotail is removed. Our results
  show that despite the large difference in the neutral solution between
  the fluid and kinetic treatment of the neutral hydrogen, the two-lobe
  structure remains even when the neutral hydrogen atoms are modeled
  kinetically. These results are contrary to Izmodenov et al (2018),
  whose model maintains a perfectly ideal heliopause and does not allow
  for communication between the solar wind and interstellar medium . This
  indicates that magnetic reconnection downtail and/or instabilities
  play a crucial role for the formation of the two-lobe structure.

Title: Role of the Inductive Electric Field to the Ring Current
    Particle Energization and Trapping
Authors: Liu, J.; Ilie, R.; Toth, G.
Bibcode: 2019AGUFMSM13F3372L
Altcode:
  The dynamic nature of magnetic field within inner magnetosphere region
  plays an important role in the transport and energization process of
  ring current ion species, by altering the local gradient-curvature drift
  of trapped ring current ion population, changing the bounce path length
  of trapped particles, and inducing a global inductive electric field,
  as described by Faraday's law, that accelerates particles within a
  short period of time. Quantifying the effect brought by the dynamic
  nature of magnetic field is crucial for providing a realistic and
  accurate description of the dynamic and time-evolution of terrestrial
  ring current, especially during storm time, when the dynamic nature of
  magnetic field is prominent. <P />The motions of different particle
  population trapped within inner magnetosphere are both energy and
  pitch-angle dependent, so standard single fluid treatment of plasma
  cannot provide adequate description of the inner magnetosphere. To
  accurately simulate this closed field lines region, a kinetic model
  solving the energy and pitch-angle dependent particle drift of hot ions
  and electrons is needed. The Hot Electron Ion Drift Integrator (HEIDI)
  kinetic model is able to separate the contribution from different
  aspects of the dynamic nature of magnetic field, to particle drift,
  energization rate and pitch-angle scattering. We present here, for the
  first time, an assessment of the role the inductive electric field
  plays in trapping particles in the inner magnetosphere, and in the
  intensification of the ring current. <P />Comparison results on the
  drift, energization rate and pitch-angle change obtained from HEIDI,
  by both coupling it with BATS-R-US and running stand alone, have been
  obtained to analyze the effect of different aspects of time-changing
  magnetic field on the ring-current ion dynamics. In coupled mode,
  BATS-R-US provides HEIDI with self-consistent electric (separated by
  source) and magnetic field information, while in stand-alone mode, HEIDI
  itself is able to calculate a self-consistent inductive electric field
  generated by a time varying analytic stretching dipole magnetic field.

Title: Limitations of global MHD models of the Earth's magnetosphere
Authors: Rastaetter, L.; Moretto, T.; Hesse, M.; Kuznetsova, M. M.;
   Toth, G.; Raeder, J.; Lyon, J.; Honkonen, I. J.
Bibcode: 2019AGUFMSM12B..02R
Altcode:
  Global MHD models are an important asset in the collection of models
  that forecast and specify space weather effects in the near-Earth space
  environment. To further improve space weather forecasting accuracy, it
  is necessary to not only improve skill scores in a variety of model-data
  comparisons but also improve the models' performance by comparing
  model results with expectations derived from fundamental physics
  principles. For example, ideal MHD models are expected to have the same
  electric potential on conjugate foot points of closed magnetic field
  lines. We test the degree of non-idealness in 4 global MHD models (SWMF,
  OpenGGCM, LFM and GUMICS) at the Community Coordinated Modeling Center
  using magnetosphere-ionosphere mapping tools. Field-line resonances seen
  at ULF wave frequencies are another challenge where model responses
  can be measured. The analysis of the causes of disagreements between
  models and between models and observations can be used to improve the
  way models are run in the community (through the CCMC and elsewhere).

Title: MESSENGER observations and global simulations of highly
    compressed magnetosphere events at Mercury
Authors: Jia, X.; Slavin, J. A.; Poh, G.; DiBraccio, G. A.; Toth,
   G.; Chen, Y.; Raines, J. M.; Gombosi, T. I.
Bibcode: 2019AGUFMSM51A..03J
Altcode:
  Mercury's comparatively weak intrinsic field, lack of an appreciable
  atmosphere and its close proximity to the Sun lead to a magnetosphere
  that undergoes more direct space-weathering interactions than other
  planets. The shielding effect due to the induction currents in
  the planetary core and erosion of the dayside magnetosphere due to
  magnetopause reconnection, compete against each other for dominance in
  controlling the large-scale structure of Mercury's magnetosphere. Here
  weidentify and examine all MESSENGER crossings of Mercury's dayside
  magnetopause with magnetospheric field intensities &gt;= 300 nT. A
  total of 8 such events have been identified, all of which occurred under
  highly compressed magnetosphere (HCM) conditions. Our analysis suggests
  that the 8 HCM events represent the highest solar wind dynamic pressures
  for which the MESSENGER's orbit still passed below the magnetopause
  and provided measurements of the dayside magnetosphere. Using the
  magnetohydrodynamic model by Jia et al.(2015) that electromagnetically
  couples Mercury's interior with its magnetosphere, a series of global
  simulations are conducted to quantitatively characterize the response of
  Mercury's magnetosphere to solar wind forcing. Combining the MESSENGER
  observations with the simulations, we have obtained a consistent picture
  of how Mercury's dayside magnetospheric configuration is controlled,
  separately and in combination, by induction-driven shielding and
  reconnection-driven erosion. For solar wind pressures of ~ 40-90 nPa,
  compared with the average ~ 10-15 nPa at Mercury's orbit, the shielding
  effects of induction in Mercury's core in standing-off the solar
  wind typically exceeds the erosion of the dayside magnetosphere due to
  reconnection for these events, most of which occurred under low magnetic
  shear conditions. For high magnetic shear across the magnetopause
  our simulation predicts that reconnection would dominate. Mercury's
  effective magnetic moment as inferred from magnetopause stand-off
  distance ranges from 170 to 250 nT-R<SUB>M</SUB><SUP>3</SUP> for these
  events. These findings, presented in Jia et al. (2019), are of crucial
  importance for understanding the space weathering at Mercury and its
  contribution to the generation of Mercury's exosphere.

Title: The Structure of the Heliotail as probed by a Kinetic-MHD,
    a Multi-Ion Description of the Heliosphere and Energetic Neutral Maps
Authors: Opher, M.; Michael, A.; Kornbleuth, M. Z.; Drake, J. F.;
   Loeb, A.; Toth, G.
Bibcode: 2019AGUFMSH53A..04O
Altcode:
  A critical question regarding the heliosphere is its veryshape and the
  structure of the heliotail (whether it has a long comet-like shape,
  is bubble shaped, or "croissant"-like), prompted by observations
  and modeling (Opher et al. 2015; Pogorelov et al. 2015; Izmodenov
  &amp; Alexashov 2015; Dialynas et al. 2017; Schwadron &amp; Bzowski
  2018). Opher et al. (2015) show that the magnetic tension of the solar
  magnetic field organizes the solar wind in the heliosheath into two
  jet-like structures, giving the heliosphere a "croissant"-like shape
  where the distance to the heliopause downtail is almost the same as
  that towards the nose. <P />There have been arguments that with a
  kinetic treatment of the neutral H, the heliotail extends to large
  distances (Izmodenov et al. 2018; Pogorelov et al. 2015). We recently
  developed the Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics (SHIELD) model, a self-consistent kinetic-MHD model of the
  outer heliosphere within the SWMF framework (Toth et al. 2012). The
  SHIELD model couples the MHD solution for a single plasma fluid to
  the kinetic solution for neutral hydrogen atoms streaming through
  the system. Our results show that even when the neutral H atoms
  are treated kinetically, the two-lobe structure remains (Michael et
  al. 2019). Their results indicate that magnetic reconnection downtail
  and/or instabilities play a crucial role in the formation of the
  two-lobe structure. We will present globally distributed flux (GDF)
  ENA maps from the SHIELD model, including a latitudinal variation of
  the solar wind corresponding to the conditions in the year 2008 using
  solar wind data from Sokol et al. (2015). The GDF ENA maps replicate
  the IBEX observations for solar minima conditions. <P />We have also
  recently extended our global MHD model (Opher et al. 2019) to treat the
  pick-up ions (PUIs) created in the supersonic solar wind as a separate
  fluid from the thermal component of the solar wind. The PUIs charge
  exchange with the cold neutral H atoms of the ISM in the heliosheath
  and are quickly depleted. The depletion of PUIs cools the heliosphere
  downstream of the TS, "deflating" it and leading to a narrower HS and a
  smaller and rounder shape. With this model, we reproduce the IBEX ENA
  observations along Voyager 2, as well the magnetic field observations
  at Voyager 1 and 2 ahead of the heliosphere.

Title: Validating the Alfven Wave Solar Atmosphere (AWSoM) Model
    from the Low Corona to 1 AU
Authors: Sachdeva, N.; van der Holst, B.; Manchester, W.; Toth, G.;
   Lloveras, D. G.; Vásquez, A. M.; Lamy, P.; Jackson, B. V.; Henney,
   C. J.
Bibcode: 2019AGUFMSH51A..04S
Altcode:
  The coronal/solar wind model, the Alfven Wave Solar atmosphere Model
  (AWSoM) a component within the Space Weather Modeling Framework (SWMF)
  follows a self-consistent physics-based global description of coronal
  heating and solar wind acceleration. AWSoM includes a description
  of low-frequency forward and counter-propagating Alfven waves that
  non-linearly interact resulting in a turbulent cascade and dissipative
  heating. In addition, there are separate temperatures for electrons and
  protons with collisional and collisionless heat conduction applied only
  to electrons and radiative losses based on the Chianti model. AWSoM
  extends from the base of the transition region where the strong
  density gradient necessitates self-consistent treatment of Alfven wave
  reflection and balanced turbulence. It includes a stochastic heating
  model as well as a description of proton parallel and perpendicular
  temperatures and kinetic instabilities based on temperature anisotropy
  and plasma beta.To validate AWSoM, we model Carrington rotations
  representative of solar minimum conditions and compare the simulation
  results with a comprehensive suite of observations. In the low corona
  (r &lt; 1.25 Rs), we compare with EUV images from both STEREOA/EUVI
  and SDO/AIA and to three-dimensional tomographic reconstructions of
  the electron temperature and density based on these same data. We
  also compare the model to tomographic reconstructions of the electron
  density from SOHO/LASCO observations (2.55 &lt; r &lt; 6 Rs). In
  the heliosphere, we compare model predictions of solar wind speed
  with velocity reconstructions from Interplanetary Scintillation
  observations. For comparison with observations near the Earth, we
  use OMNI data. Our results show that the AWSoM model performs well
  in quantitative agreement with the observations between the inner
  corona and 1 AU. In the lower corona, the model and the tomographic
  reconstructions agree within 20%-30% on average. The model also
  reproduces the fast solar wind speed in the polar regions. Near the
  Earth, our model shows good agreement with observations of solar wind
  velocity, electron temperature and density. The AWSoM model provides
  a comprehensive tool to study the solar corona and larger heliosphere
  with current and future solar missions as well as being well suited
  for space weather predictions.

Title: Importance of Ambipolar Electric Field in Driving Ion Loss
From Mars: Results From a Multifluid MHD Model With the Electron
    Pressure Equation Included
Authors: Ma, Y. J.; Dong, C. F.; Toth, G.; van der Holst, B.; Nagy,
   A. F.; Russell, C. T.; Bougher, S.; Fang, Xiaohua; Halekas, J. S.;
   Espley, J. R.; Mahaffy, P. R.; Benna, M.; McFadden, J.; Jakosky, B. M.
Bibcode: 2019JGRA..124.9040M
Altcode:
  The multifluid (MF) magnetohydrodynamic model of Mars is improved
  by solving an additional electron pressure equation. Through the
  electron pressure equation, the electron temperature is calculated
  based on the effects from various electron-related heating and
  cooling processes (e.g., photoelectron heating, electron-neutral
  collision, and electron-ion collision), and thus, the improved model
  can calculate the electron temperature and the electron pressure force
  terms self-consistently. Model results of a typical case using the MF
  with electron pressure equation included model are compared in detail
  to identical cases using the MF and multispecies models to identify the
  effect of the improved physics. We find that when the electron pressure
  equation is included, the general interaction patterns are similar to
  those with no electron pressure equation. However, the MF with electron
  pressure equation included model predicts that the electron temperature
  is much larger than the ion temperature in the ionosphere, consistent
  with both Viking and Mars Atmosphere and Volatile EvolutioN (MAVEN)
  observations. Using our numerical model, we also examined in detail
  the relative importance of different forces in the plasma interaction
  region. All three models are also applied to a MAVEN event study using
  identical input conditions; overall, the improved model matches best
  with MAVEN observations. All of the simulation cases are examined in
  terms of the total ion loss, and the results show that the inclusion of
  the electron pressure equation increases the escape rates by 50-110%
  in total mass, depending on solar condition and strong crustal field
  orientation, clearly demonstrating the importance of the ambipolar
  electric field in facilitating ion escape.

Title: Studying Dawn-Dusk Asymmetries of Mercury's Magnetotail Using
    MHD-EPIC Simulations
Authors: Chen, Yuxi; Tóth, Gábor; Jia, Xianzhe; Slavin, James A.;
   Sun, Weijie; Markidis, Stefano; Gombosi, Tamas I.; Raines, Jim M.
Bibcode: 2019JGRA..124.8954C
Altcode: 2019arXiv190406753C
  MESSENGER has observed a lot of dawn-dusk asymmetries in Mercury's
  magnetotail, such as the asymmetries of the cross-tail current sheet
  thickness and the occurrence of flux ropes, dipolarization events, and
  energetic electron injections. In order to obtain a global pictures
  of Mercury's magnetotail dynamics and the relationship between these
  asymmetries, we perform global simulations with the magnetohydrodynamics
  with embedded particle-in-cell (MHD-EPIC) model, where Mercury's
  magnetotail region is covered by a PIC code. Our simulations show that
  the dawnside current sheet is thicker, the plasma density is larger,
  and the electron pressure is higher than the duskside. Under a strong
  interplanetary magnetic field driver, the simulated reconnection
  sites prefer the dawnside. We also found the dipolarization events
  and the planetward electron jets are moving dawnward while they are
  moving toward the planet, so that almost all dipolarization events and
  high-speed plasma flows concentrate in the dawn sector. The simulation
  results are consistent with MESSENGER observations.

Title: Numerical investigation of the dynamics of linear spin s fields
on a Kerr background: Late-time tails of spin s =±1 ,±2 fields
Authors: Csukás, Károly; Rácz, István; Tóth, Gábor Zsolt
Bibcode: 2019PhRvD.100j4025C
Altcode: 2019arXiv190509082C
  The time evolution of linear fields of spin s =±1 and s =±2 on Kerr
  black hole spacetimes are investigated by solving the homogeneous
  Teukolsky equation numerically. The applied numerical setup is based
  on a combination of conformal compactification and the hyperbolic
  initial value problem. The evolved basic variables are expanded in
  terms of spin-weighted spherical harmonics, which allows us to evaluate
  all angular derivatives analytically, whereas the evolution of the
  expansion coefficients in the time-radial section is determined by
  applying the method of lines implemented in a fourth order accurate
  finite differencing stencil. Concerning the initialization, in all
  of our investigations, single mode excitations—either static or
  purely dynamical-type initial data—are applied. Within this setup
  the late-time tail behavior is investigated. Because of the applied
  conformal compactification, the asymptotic decay rates are determined at
  three characteristic locations—in the domain of outer communication,
  at the event horizon, and at future null infinity—simultaneously. A
  recently introduced new type of "energy" and "angular momentum" balance
  relations are also applied in order to demonstrate the feasibility
  and robustness of the developed numerical schema and also to verify
  the proper implementation of the underlying mathematical model.

Title: Identifying Solar Flare Precursors Using Time Series of
    SDO/HMI Images and SHARP Parameters
Authors: Chen, Yang; Manchester, Ward B.; Hero, Alfred O.; Toth,
   Gabor; DuFumier, Benoit; Zhou, Tian; Wang, Xiantong; Zhu, Haonan;
   Sun, Zeyu; Gombosi, Tamas I.
Bibcode: 2019SpWea..17.1404C
Altcode: 2019arXiv190400125C
  In this paper we present several methods to identify precursors that
  show great promise for early predictions of solar flare events. A data
  preprocessing pipeline is built to extract useful data from multiple
  sources, Geostationary Operational Environmental Satellites and Solar
  Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI),
  to prepare inputs for machine learning algorithms. Two classification
  models are presented: classification of flares from quiet times
  for active regions and classification of strong versus weak flare
  events. We adopt deep learning algorithms to capture both spatial
  and temporal information from HMI magnetogram data. Effective feature
  extraction and feature selection with raw magnetogram data using deep
  learning and statistical algorithms enable us to train classification
  models to achieve almost as good performance as using active region
  parameters provided in HMI/Space-Weather HMI-Active Region Patch
  (SHARP) data files. Case studies show a significant increase in the
  prediction score around 20 hr before strong solar flare events.

Title: High Resolution Finite Volume Method for Kinetic Equations
    with Poisson Brackets
Authors: Sokolov, Igor V.; Sun, Haomin; Toth, Gabor; Huang, Zhenguang;
   Tenishev, Valeriy; Zhao, Lulu; Kota, Jozsef; Cohen, Ofer; Gombosi,
   Tamas
Bibcode: 2019arXiv191012636S
Altcode:
  Simulation of plasmas in electromagnetic fields requires numerical
  solution of a kinetic equation that describes the time evolution
  of the particle distribution function. In this paper we propose a
  finite volume scheme based on integral relation for Poisson brackets
  to solve the Liouville equation, the most fundamental kinetic
  equation. The proposed scheme conserves the number of particles,
  maintains the total-variation-diminishing (TVD) property, and provides
  high-quality numerical results. Other types of kinetic equations may
  be also formulated in terms of Poisson brackets and solved with the
  proposed method including the transport equations describing the
  acceleration and propagation of Solar Energetic Particles (SEPs),
  which is of practical importance, since the high energy SEPs produce
  radiation hazards. The proposed scheme is demonstrated to be accurate
  and efficient, which makes it applicable to global simulation systems
  analyzing space weather.

Title: Embedded Kinetic Simulation of Ganymede's Magnetosphere:
    Improvements and Inferences
Authors: Zhou, Hongyang; Tóth, Gábor; Jia, Xianzhe; Chen, Yuxi;
   Markidis, Stefano
Bibcode: 2019JGRA..124.5441Z
Altcode:
  The largest moon in the solar system, Ganymede, is also the only moon
  known to possess a strong intrinsic magnetic field and a corresponding
  magnetosphere. Using the new version of Hall magnetohydrodynamic
  with embedded particle-in-cell model with a self-consistently coupled
  resistive body representing the electrical properties of the moon's
  interior, improved inner boundary conditions, and the flexibility of
  coupling different grid geometries, we achieve better match of magnetic
  field with measurements for all six Galileo flybys. The G2 flyby
  comparisons of plasma bulk flow velocities with the Galileo Plasma
  Subsystem data support the oxygen ion assumption inside Ganymede's
  magnetosphere. Crescent shape, nongyrotropic, and nonisotropic ion
  distributions are identified from the coupled model. Furthermore, we
  have derived the energy fluxes associated with the upstream magnetopause
  reconnection of ∼10<SUP>-7</SUP>W/cm<SUP>2</SUP> based on our model
  results and found a maximum of 40% contribution to the total peak
  auroral emissions.

Title: Global MHD simulations of the Response of Jupiter's
    Magnetosphere and Ionosphere to Changes in the Solar Wind and IMF
Authors: Sarkango, Yash; Jia, Xianzhe; Toth, Gabor
Bibcode: 2019JGRA..124.5317S
Altcode:
  We have developed a new global magnetohydrodynamic (MHD) model for
  Jupiter's magnetosphere based on the BATSRUS code and an ionospheric
  electrodynamics solver. Our model includes the Io plasma torus at
  its appropriate location and couples the global magnetosphere with
  the planetary ionosphere through field-aligned currents. Through
  comparisons with available particle and field observations as well
  as empirical models, we show that the model captures the overall
  configuration of the magnetosphere reasonably well. In order to
  understand how the magnetosphere responds to different solar wind
  drivers, we have carried out time-dependent simulations using various
  kinds of upstream conditions, such as a forward shock and a rotation
  in the interplanetary magnetic field (IMF). Our model predicts that
  compression of the magnetosphere by a forward shock of typical strength
  generally weakens the corotation enforcement currents on the dayside
  and produces an enhancement on the nightside. However, the global
  response varies depending on the IMF orientation. A forward shock
  with a typical Parker-spiral IMF configuration has a larger impact
  on the magnetospheric configuration and large-scale current systems
  than with a parallel IMF configuration. Plasmoids are found to form
  in the simulation due to tail reconnection and have complex magnetic
  topology, as they evolve and propagate down tail. For a fixed mass
  input rate in the Io plasma torus, the frequency of plasmoid occurrence
  in our simulation is found to vary depending on the upstream solar
  wind driving.

Title: SPECTRUM: Synthetic Spectral Calculations for Global Space
    Plasma Modeling
Authors: Szente, J.; Landi, E.; Manchester, W. B., IV; Toth, G.;
   van der Holst, B.; Gombosi, T. I.
Bibcode: 2019ApJS..242....1S
Altcode:
  High-resolution spectroscopy is the most accurate tool for measuring
  the properties of the solar corona. However, interpreting measured
  line intensities and line profiles emitted by the optically thin solar
  corona is complicated by line-of-sight (LOS) integration, which leads to
  measuring weighted averages of the plasma properties along the LOS. LOS
  integration effects can be removed by combining CHIANTI spectral
  emissivities with a 3D global model of the solar corona to calculate
  the contribution of all structures along the LOS to the measured
  intensities. In this paper, we describe SPECTRUM, a postprocessing tool
  that can calculate the emission from the optically thin solar corona
  by combining 3D magnetohydrodynamic (MHD) space plasma simulation
  results with the CHIANTI database. Doppler-shifted, nonthermal line
  broadening due to low-frequency Alfvén waves and anisotropic proton
  and isotropic electron temperatures can be individually taken into
  account during calculations. Synthetic spectral calculations can then
  be used for model validation, for interpretation of solar observations,
  and for forward modeling purposes. SPECTRUM is implemented within the
  Space Weather Modeling Framework (SWMF) and is therefore publicly
  available. In this paper, we describe the SPECTRUM module and show
  its applications by comparing synthetic spectra using simulation data
  by the 3D MHD Alfvén Wave Solar Model with observations done by the
  Hinode/Extreme-ultraviolet Imaging Spectrometer during Carrington
  rotations 2063 and 2082.

Title: MESSENGER observations and global simulations of highly
    compressed magnetosphere events at Mercury
Authors: Jia, Xianzhe; Slavin, James; Poh, Gangkai; DiBraccio, Gina;
   Toth, Gabor; Chen, Yuxi; Raines, Jim; Gombosi, Tamas
Bibcode: 2019EGUGA..2111922J
Altcode:
  We identify and examine all MESSENGER crossings of Mercury's dayside
  magnetopause with magnetospheric field intensities &gt;= 300 nT. The 8
  such events, which occurred under highly compressed magnetosphere (HCM)
  conditions, are analyzed in the identical manner utilized by Slavin et
  al. (2014). The results suggest that the 8 HCM events represent the
  highest solar wind dynamic pressures for which the MESSENGER's orbit
  still passed below the magnetopause and provided measurements of the
  dayside magnetosphere. Using the magnetohydrodynamic model by Jia et
  al. (2015) that electromagnetically couples Mercury's interior with
  its magnetosphere, a series of global simulations are conducted to
  quantitatively characterize the response of Mercury's magnetosphere
  to solar wind forcing. Combining the MESSENGER observations with the
  simulations, we have obtained a consistent picture of how Mercury's
  dayside magnetospheric configuration is controlled, separately and in
  combination, by induction-driven shielding and reconnection-driven
  erosion. For solar wind pressures of ∼ 40-90 nPa, compared with
  the average ∼ 10-15 nPa at Mercury's orbit, the shielding events of
  induction in Mercury's core in standing-off the solar wind typically
  exceeds the erosion of the dayside magnetosphere due to reconnection
  for these events, most of which occurred under low magnetic shear
  conditions. For high magnetic shear across the magnetopause our
  simulation predicts that reconnection would dominate. Mercury's
  effective magnetic moment as inferred from magnetopause stand-off
  distance ranges from 170 to 250 nT-RM3 for these events. These findings,
  presented in Jia et al. (2019, JGR), are of crucial importance for
  understanding the space weathering at Mercury and its contribution to
  the generation of Mercury's exosphere.

Title: The Surface Distributions of the Production of the Major
    Volatile Species, H2O, CO2, CO and O2, from the Nucleus of Comet
    67P/Churyumov-Gerasimenko throughout the Rosetta Mission
Authors: Combi, Michael; Shou, Yinsi; Fougere, Nicolas; Altwegg,
   Kathrin; Rubin, Martin; Bocklee-Morvan, Dominique; Gombosi, Tamas;
   Hansen, Kenneth C.; Huang, Zhenguang; Toth, Gabor; Tenishev, Valeriy
Bibcode: 2019EGUGA..2118635C
Altcode:
  The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
  (ROSINA) suite of instruments operated throughout the just over two
  years of the Rosetta mission operations in the vicinity of comet
  67P/Churyumov-Gerasimenko. It measured gas densities and composition
  throughout the comet's atmosphere, or coma. Here we present two-years'
  worth of measurements of the four major volatile species in the coma
  of the comet, H2O, CO2, CO and O2, by one of the ROSINA sub-systems
  called the Double Focusing Mass Spectrometer (DFMS). DFMS is a very high
  mass resolution and high sensitivity mass spectrometer able to resolve
  at a tiny fraction of an atomic mass unit. We have analyzed the DFMS
  measurements using an inversion scheme based on spherical harmonics
  that solves for the distribution of potential surface activity of
  each species as the comet rotates, changing solar illumination, over
  short time intervals and as the comet changes distance from the sun
  and orientation of its spin axis over long time intervals. We also
  use the surface boundary conditions derived from the inversion scheme
  to simulate the whole coma with our fully kinetic Direct Simulation
  Monte Carlo model and calculate the production rates of the four major
  species throughout the mission. We compare the derived production rates
  with remote sensing observations by the Visible and Infrared Thermal
  Imaging Spectrometer (VIRTIS) as well as with published observations
  from the Microwave Instrument for the Rosetta Orbiter (MIRO). Finally
  we use the variation of the surface production of the major species to
  calculate the total mass loss distribution over the surface throughout
  the mission.

Title: A Predicted Small and Round Heliosphere
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
Bibcode: 2019EGUGA..2111837O
Altcode:
  The shape of the solar wind bubble within the interstellar medium, the
  so-called heliosphere, has been explored over six decades (Davis 55;
  Parker '61; Axford '72; Baranov &amp; Malama '93). As the Sun moves
  through the surrounding partially-ionized medium, neutral hydrogen
  atoms penetrate the heliosphere, and through charge-exchange with
  the supersonic solar wind, create a population of hot pick-up ions
  (PUIs). The Voyager 2 (V2) data demonstrated that the heliosheath
  pressure is dominated by PUIs. Here we use a novel magnetohydrodynamic
  model that treats the PUIs as a separate fluid from the thermal
  component of the solar wind. Unlike previous models, the new model
  reproduces the properties of the PUIs and solar wind ions based on
  the New Horizon (McComas et al. 2017) and V2 (Richardson et al. 2008)
  spacecraft observations. The model significantly changes the energy
  flow in the outer heliosphere, leading to a smaller and rounder shape
  than previously predicted, in agreement with energetic neutral atom
  observations by the Cassini spacecraft (Dialynas et al. 2017). We
  will discuss the consequences of this new shape for draping of the
  interstellar magnetic field and conditions at Voyager 1 and 2 in the
  local interstellar medium.

Title: Validating the Alfven Wave Solar Model (AWSoM) from the lower
    corona to 1 AU
Authors: Sachdeva, Nishtha; Manchester, Ward; van der Holst, Bart;
   Toth, Gabor; Vasquez, Alberto; Jackson, Bernard; Lloveras, Diego G.;
   Mac Cormack, Cecilia; Yu, Hsiu-Shan
Bibcode: 2019EGUGA..21.1465S
Altcode:
  We examine the steady state three-dimensional MHD simulations of the
  solar corona carried out with the new version of the Alfven Wave Solar
  Model (AWSoM) within the Space Weather Modeling framework (SWMF). AWSoM
  addresses the acceleration and heating of the solar corona via the
  interaction between counter-propagating Alfven waves. This non-linear
  interaction between the outward propagating low-frequency Alfven waves
  and those partially reflected by the speed gradients results in a
  turbulent energy cascade. The model uses physics-based partitioning
  of wave-dissipated heat between isotropic electron and anisotropic
  proton temperatures. To validate the AWSoM model, we select rotations
  representative of the solar minimum and maximum conditions and compare
  our simulation results with a comprehensive suite of observations. We
  use three-dimensional tomographic reconstructions of the electron
  temperature and density in the inner corona (r &lt; 1.25 Rsun) based
  on multi-wavelength extreme ultraviolet images from STEREO/EUVI
  and SDO/AIA. For comparison with observations made near the Earth,
  we compare the model with OMNI data. At different radial distances
  between 20 Rsun and 1 AU, we compare the model with reconstructions
  made with Interplanetary Scintillation (IPS) observations. Observations
  are compared with the simulated model results of plasma mass density,
  velocity, and magnetic fields, temperature anisotropy, and wave
  turbulence. Our results at solar minimum show that the improved AWSoM
  model performs well in agreement with the observations between inner
  corona and 1 AU. In the lower corona the model and the tomographic
  reconstructions match within a 20 % accuracy. Near the Earth, our model
  shows good agreement with observations of solar wind velocity, electron
  temperature and magnetic field. However, the electron density at 1 AU
  is overpredicted by the model for the solar minimum simulations. While
  this model version is already an improvement over previous predictions,
  we plan to validate our model using more Carrington rotations. The AWSoM
  model presents an extensive application to study the solar corona and
  larger heliosphere in concert with current and future solar missions.

Title: Five-moment Two-Electron Plasma Simulation for Comet
    67P/Churyumov-Gerasimenko
Authors: Huang, Zhenguang; Toth, Gabor; Gombosi, Tamas; Jia, Xianzhe;
   Combi, Michael; Hansen, Kenneth; Shou, Yinsi; Tenishev, Valeriy;
   Altwegg, Kathrin.; Rubin, Martin
Bibcode: 2019EGUGA..2118127H
Altcode:
  One of the key investigations of the Rosetta mission is to understand
  the interactions between the solar wind and the cometary magnetosphere
  of comet 67P/Churyumov-Gerasimenko (CG). Extensive numerical
  modeling work based on fluid, hybrid and fully kinetic models have
  been carried out and provided valuable context for interpreting
  various features of the cometary environment observed by different
  instruments. Fluid-type models have proven to be a useful tool for
  investigating how the solar wind interacts with comets on a global
  scale. However, in previous fluid models (e.g., MHD models), electrons
  are either treated as part of the plasma fluid or simulated with an
  additional electron pressure equation, without having their own the
  continuity and momentum equations. Such an approach cannot represent
  any of the electron kinetic features properly. Besides, previous MHD
  models could not simulate multiple electron fluids. In this study, we
  present the first five-moment two-electron plasma simulation of a comet,
  by introducing the continuity and momentum equations respectively for
  the solar wind and cometary electrons, in which case the Hall effect
  is included automatically and the electron dynamics and resulting
  electric field are simulated self-consistently. As will be shown in
  this presentation, our five-moment two-electron simulation captures
  the separate bulk motions of the solar wind electrons and the cometary
  electrons, which is consistent with the results of the Particle-In-Cell
  (PIC) simulation performed by Deca et al. (2017).

Title: End-of-Mission ROSINA/COPS observation of the innermost coma
    of comet 67P/Churyumov-Gerasimenko
Authors: Tenishev, Valeriy; Rubin, Martin; Tzou, Chia-yu; Shi, Xian;
   Combi, Michael; Altwegg, Kathrin; Gombosi, Tamas; Shou, Yinsi; Huang,
   Zhenquang; Toth, Gabor; Sierks, Holger; Hofstadter, Mark
Bibcode: 2019EGUGA..2118885T
Altcode:
  End-of-mission pressure measurements performed with ROSINA/COPS
  presented a unique chance to probe the coma of 67P/Churyumov-Gerasimenko
  in the altitude range starting from tens of kilometers down to
  the surface of the nucleus of the comet. That is an unprecedented
  opportunity to uncover effects that topology and activity of the nucleus
  have on the structure of the coma very close to the nucleus. The primary
  focus of the presented study is analyzing these measurements using the
  numerical modeling of the comet environment. At the end of the Rosetta
  mission, 67P/Churyumov-Gerasimenko was at a heliocentric distance of 3.8
  AU where the coma is collisionless. That makes it possible to apply the
  Liouville theorem to characterize the distribution of volatiles in the
  coma, as we have done in our analysis. We have used the SHAP7 nucleus
  model to account for the topology of the volatile source. Spacecraft
  trajectory and the instrument pointing relative to the comet's nucleus
  have been determined with the SPICE library. Here, we present the
  results of our analysis and discuss the effects of the surface topology
  and that of the local surface volatile injection on the distribution
  of gas in the innermost coma of comet 67P/Churyumov-Gerasimenko.

Title: The Formation and Evolution of Large Scale Magnetic Fields
    in Venus Ionosphere
Authors: Ma, Y. J.; Toth, G.; Nagy, A. F.; Russell, C. T.
Bibcode: 2019LPI....50.2903M
Altcode:
  In this study, we use a multi-species MHD model to understand the
  formation and evolution of large scale magnetic fields in Venus
  ionosphere.

Title: MESSENGER Observations and Global Simulations of Highly
    Compressed Magnetosphere Events at Mercury
Authors: Jia, Xianzhe; Slavin, James A.; Poh, Gangkai; DiBraccio,
   Gina A.; Toth, Gabor; Chen, Yuxi; Raines, Jim M.; Gombosi, Tamas I.
Bibcode: 2019JGRA..124..229J
Altcode:
  We identify and examine all MErcury Surface Space ENvironment,
  GEochemistry, and Ranging (MESSENGER) crossings of Mercury's
  dayside magnetopause with magnetospheric field intensities
  ≥300 nT. The eight such events, which occurred under
  highly compressed magnetosphere conditions, are analyzed
  in the identical manner utilized by Slavin et al. (2014, <A
  href="https://doi.org/10.1002/2014JA020319">https://doi.org/10.1002/2014JA020319</A>).
  The results suggest that the eight highly compressed magnetosphere
  events represent the highest solar wind dynamic pressures for
  which the MESSENGER's orbit still passed below the magnetopause
  and provided measurements of the dayside magnetosphere. Using
  the magnetohydrodynamic model by Jia et al. (2015, <A
  href="https://doi.org/10.1002/2015JA021143">https://doi.org/10.1002/2015JA021143</A>)
  that electromagnetically couples Mercury's interior with its
  magnetosphere, a series of global simulations are conducted to
  quantitatively characterize the response of Mercury's magnetosphere
  to solar wind forcing. Combining the MESSENGER observations with the
  simulations, we have obtained a consistent picture of how Mercury's
  dayside magnetospheric configuration is controlled, separately and
  in combination, by induction-driven shielding and reconnection-driven
  erosion. For solar wind pressures of ∼40-90 nPa, compared with the
  average ∼10-15 nPa at Mercury's orbit, the shielding effects of
  induction in Mercury's core in standing-off the solar wind typically
  exceed the erosion of the dayside magnetosphere due to reconnection
  for these events, most of which occurred under low magnetic shear
  conditions. For high magnetic shear across the magnetopause our
  simulation predicts that reconnection would dominate. Mercury's
  effective magnetic moment as inferred from magnetopause standoff
  distance ranges from 170 to 250 nT-RM3 for these events. These findings
  are of crucial importance for understanding the space weathering at
  Mercury and its contribution to the generation of Mercury's exosphere.

Title: Soft X-ray Emission Scenarios of Comet 46P/Wirtanen for its
    2018 Apparition in Accordance with HXMT Observation
Authors: Lai, I. L.; Huo, Z. X.; Huang, P. S.; Rubin, M.; Gombosi,
   T. I.; Toth, G.; Ip, W. H.
Bibcode: 2018AGUFM.P23G3514L
Altcode: 2018AGUFM.P23G3514R
  Comet 46P/Wirtanen was the original destination of the Rosetta mission
  but replaced by Comet 67P/Churyumov-Gerasimenko soon after the launch
  delay in 2003. As a result, the research work about Comet 46P has been
  very limited over the past decade. In this December, 46P will reach
  its perihelion ( 1.05 AU) making a very close approach to Earth with
  the comet-earth distance about 30 times of earth-moon distance. It is
  predicted to reach naked-eye brightness around this great apparition
  due to its hyperactivity, which provides an excellent opportunity to
  study it in detail. The Insight-HXMT (Hard X-ray Modulation Telescope)
  is the first Chinese X-ray astronomy satellite and will be used to
  observe as a target of opportunity. Models and simulation works of the
  X-ray emission of 46P as a result of solar-wind interaction during the
  close approach phase to be presented in this work would greatly assist
  the design of the HXMT observations and subsequent data analysis. The
  observational procedure and data processing pipeline established also
  will be invaluable for future mission opportunities.

Title: Impact of the September 2017 Solar Flare and ICME Events
    on Mars
Authors: Ma, Y.; Fang, X.; Pawlowski, D. J.; Halekas, J. S.; Russell,
   C. T.; Luhmann, J. G.; Xu, S.; Lillis, R. J.; Thiemann, E.; Bougher,
   S. W.; Toth, G.; Nagy, A. F.; Dong, C.; Espley, J. R.; Jakosky, B. M.;
   Lee, C. O.
Bibcode: 2018AGUFM.P51H2970M
Altcode:
  The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission observed
  a strong X-class solar flare impacting Mars on 10 September 2017,
  followed by a fast interplanetary coronal mass ejection (ICME). These
  solar events provide a great opportunity to advance our understanding of
  space weather events and their impact on Mars. In this study, the impact
  of the solar flare and ICME events on the Martian system is examined in
  detail using a sophisticated multi-species global MHD model. We found
  that the main features of the interaction can be reasonably captured by
  the model for both the solar flare and the ICME events. The results of
  the MHD model coupled with Mars Global Ionosphere-Thermosphere Model
  (MGITM) reproduce the density enhancement caused by the solar flare,
  consistent with MAVEN observations. Using derived solar wind proxy,
  our time-dependent run of the ICME event is able to reproduce some
  detailed structures observed by MAVEN. Our calculations show that the
  solar flare has an important impact on the ionosphere and the upper
  atmosphere, but has little effect at the solar wind-Mars interaction. In
  contrast, the ICME greatly disturbs the plasma enviorment of Mars,
  especially the induced magnetosphere. The ICME-driven distrubances
  include variations of various plasma boundaries and large enhancement
  of atmospheric erosion.

Title: Global dipole magnetic field: Boon or bane for the Martian
    atmospheric retention?
Authors: Dong, C.; Luhmann, J. G.; Ma, Y.; Lingam, M.; Bhattacharjee,
   A.; Lee, Y.; Bougher, S. W.; Wang, L.; Glocer, A.; Strangeway, R. J.;
   Curry, S.; Fang, X.; Toth, G.; Nagy, A. F.; Lillis, R. J.; Mitchell,
   D. L.; Brain, D.; Jakosky, B. M.
Bibcode: 2018AGUFM.P31C3736D
Altcode:
  The absence of global dipole magnetic fields at terrestrial planets
  is widely perceived as a major impediment in protecting planetary
  atmospheres from being eroded by stellar winds. In this work,
  we re-examine this idea by focusing on the rate of atmospheric
  ion escape from Mars for nominal solar wind parameters and an
  extreme ``Carrington-type'' space weather event. We carry out
  extensive numerical simulations using a sophisticated multi-fluid
  magnetohydrodynamics (MHD) model, thereby demonstrating that the escape
  rate is a non-monotonic function of the Martian dipole magnetic field
  strength, and that it varies by more than an order of magnitude in
  certain instances. Our work illustrates, for the very first time using
  the state-of-the-art global simulations, that the lack of dipole fields
  is not necessarily a disadvantage from the viewpoint of atmospheric
  losses. We are led to the conclusion that the ion escape rates from
  Mars may have actually been higher when it possessed stronger magnetic
  moment in the past. We conclude our analysis by briefly exploring the
  ensuing implications for Martian and exoplanetary habitability.

Title: Loss of the Martian atmosphere to space: Present-day loss rates
    determined from MAVEN observations and integrated loss through time
Authors: Jakosky, B. M.; Brain, D.; Chaffin, M.; Curry, S.; Deighan,
   J.; Grebowsky, J.; Halekas, J.; Leblanc, F.; Lillis, R.; Luhmann,
   J. G.; Andersson, L.; Andre, N.; Andrews, D.; Baird, D.; Baker, D.;
   Bell, J.; Benna, M.; Bhattacharyya, D.; Bougher, S.; Bowers, C.;
   Chamberlin, P.; Chaufray, J. -Y.; Clarke, J.; Collinson, G.; Combi,
   M.; Connerney, J.; Connour, K.; Correira, J.; Crabb, K.; Crary, F.;
   Cravens, T.; Crismani, M.; Delory, G.; Dewey, R.; DiBraccio, G.; Dong,
   C.; Dong, Y.; Dunn, P.; Egan, H.; Elrod, M.; England, S.; Eparvier, F.;
   Ergun, R.; Eriksson, A.; Esman, T.; Espley, J.; Evans, S.; Fallows,
   K.; Fang, X.; Fillingim, M.; Flynn, C.; Fogle, A.; Fowler, C.; Fox,
   J.; Fujimoto, M.; Garnier, P.; Girazian, Z.; Groeller, H.; Gruesbeck,
   J.; Hamil, O.; Hanley, K. G.; Hara, T.; Harada, Y.; Hermann, J.;
   Holmberg, M.; Holsclaw, G.; Houston, S.; Inui, S.; Jain, S.; Jolitz,
   R.; Kotova, A.; Kuroda, T.; Larson, D.; Lee, Y.; Lee, C.; Lefevre,
   F.; Lentz, C.; Lo, D.; Lugo, R.; Ma, Y. -J.; Mahaffy, P.; Marquette,
   M. L.; Matsumoto, Y.; Mayyasi, M.; Mazelle, C.; McClintock, W.;
   McFadden, J.; Medvedev, A.; Mendillo, M.; Meziane, K.; Milby, Z.;
   Mitchell, D.; Modolo, R.; Montmessin, F.; Nagy, A.; Nakagawa, H.;
   Narvaez, C.; Olsen, K.; Pawlowski, D.; Peterson, W.; Rahmati, A.;
   Roeten, K.; Romanelli, N.; Ruhunusiri, S.; Russell, C.; Sakai, S.;
   Schneider, N.; Seki, K.; Sharrar, R.; Shaver, S.; Siskind, D. E.;
   Slipski, M.; Soobiah, Y.; Steckiewicz, M.; Stevens, M. H.; Stewart,
   I.; Stiepen, A.; Stone, S.; Tenishev, V.; Terada, N.; Terada, K.;
   Thiemann, E.; Tolson, R.; Toth, G.; Trovato, J.; Vogt, M.; Weber,
   T.; Withers, P.; Xu, S.; Yelle, R.; Yiğit, E.; Zurek, R.
Bibcode: 2018Icar..315..146J
Altcode:
  Observations of the Mars upper atmosphere made from the Mars Atmosphere
  and Volatile Evolution (MAVEN) spacecraft have been used to determine
  the loss rates of gas from the upper atmosphere to space for a complete
  Mars year (16 Nov 2014 - 3 Oct 2016). Loss rates for H and O are
  sufficient to remove ∼2-3 kg/s to space. By itself, this loss would
  be significant over the history of the planet. In addition, loss rates
  would have been greater early in history due to the enhanced solar
  EUV and more-active Sun. Integrated loss, based on current processes
  whose escape rates in the past are adjusted according to expected
  solar evolution, would have been as much as 0.8 bar CO<SUB>2</SUB>
  or 23 m global equivalent layer of H<SUB>2</SUB>O; these losses are
  likely to be lower limits due to the nature of the extrapolation of
  loss rates to the earliest times. Combined with the lack of surface
  or subsurface reservoirs for CO<SUB>2</SUB> that could hold remnants
  of an early, thick atmosphere, these results suggest that loss of
  gas to space has been the dominant process responsible for changing
  the climate of Mars from an early, warmer environment to the cold,
  dry one that we see today.

Title: Specification of the near-Earth space environment with SHIELDS
Authors: Jordanova, V. K.; Delzanno, G. L.; Henderson, M. G.; Godinez,
   H. C.; Jeffery, C. A.; Lawrence, E. C.; Morley, S. K.; Moulton,
   J. D.; Vernon, L. J.; Woodroffe, J. R.; Brito, T. V.; Engel, M. A.;
   Meierbachtol, C. S.; Svyatsky, D.; Yu, Y.; Tóth, G.; Welling, D. T.;
   Chen, Y.; Haiducek, J.; Markidis, S.; Albert, J. M.; Birn, J.; Denton,
   M. H.; Horne, R. B.
Bibcode: 2018JASTP.177..148J
Altcode:
  Predicting variations in the near-Earth space environment that can lead
  to spacecraft damage and failure is one example of "space weather" and
  a big space physics challenge. A project recently funded through the
  Los Alamos National Laboratory (LANL) Directed Research and Development
  (LDRD) program aims at developing a new capability to understand, model,
  and predict Space Hazards Induced near Earth by Large Dynamic Storms,
  the SHIELDS framework. The project goals are to understand the dynamics
  of the surface charging environment (SCE), the hot (keV) electrons
  representing the source and seed populations for the radiation belts,
  on both macro- and micro-scale. Important physics questions related
  to particle injection and acceleration associated with magnetospheric
  storms and substorms, as well as plasma waves, are investigated. These
  challenging problems are addressed using a team of world-class experts
  in the fields of space science and computational plasma physics, and
  state-of-the-art models and computational facilities. A full two-way
  coupling of physics-based models across multiple scales, including
  a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D)
  and an inner magnetosphere (RAM-SCB) codes, is achieved. New data
  assimilation techniques employing in situ satellite data are developed;
  these provide an order of magnitude improvement in the accuracy in the
  simulation of the SCE. SHIELDS also includes a post-processing tool
  designed to calculate the surface charging for specific spacecraft
  geometry using the Curvilinear Particle-In-Cell (CPIC) code that can
  be used for reanalysis of satellite failures or for satellite design.

Title: Modeling Martian Atmospheric Losses over Time: Implications
    for (Exo)Planetary Climate Evolution and Habitability
Authors: Dong, Chuanfei; Lee, Yuni; Ma, Yingjuan; Lingam, Manasvi;
   Bougher, Stephen; Luhmann, Janet; Curry, Shannon; Toth, Gabor; Nagy,
   Andrew; Tenishev, Valeriy; Fang, Xiaohua; Mitchell, David; Brain,
   Dave; Jakosky, Bruce
Bibcode: 2018DPS....5030311D
Altcode:
  Mars has always represented an important target from the standpoint
  of planetary science, especially on account of its long-term climate
  evolution. One of the most striking differences between ancient and
  current Mars is that the former had a thicker atmosphere compared
  to the present-day value, thereby making Noachian Mars potentially
  more conducive to hosting life. This discrepancy immediately raises
  the question of how and when the majority of the Martian atmosphere
  was lost, as well as the channels through which it occurred. There
  are compelling observational and theoretical reasons to believe that
  the majority of atmospheric escape must have occurred early in the
  planet's geological history, when the extreme ultraviolet (EUV) flux
  and the solar wind from the Sun were much stronger than today. Our
  understanding of present-day Martian atmospheric escape has improved
  greatly thanks to observations undertaken by, e.g., the MAVEN in
  conjunction with detailed theoretical modeling. In this study, we
  adopted the one-way coupled framework, which has been employed to study
  the ion and photochemical losses at the current epoch. We adopted the
  3-D Mars thermosphere from the Mars Global Ionosphere Thermosphere Model
  (M-GITM) and the hot atomic oxygen density from the Mars exosphere Monte
  Carlo model Adaptive Mesh Particle Simulator (AMPS) as the input for
  the 3-D BATS-RUS Mars multi-fluid MHD (MF-MHD) model. The Mars AMPS hot
  oxygen corona and the associated photochemical loss rate were calculated
  based on the thermospheric/ionospheric background from M-GITM. Our
  simulations indicate that the total photochemical and ion atmospheric
  losses over the span 0-4 Ga are approximately equal to each other, and
  their sum amounts to 0.1 bar being lost over this duration. If we assume
  that the oxygen lost through a combination of ion and photochemical
  escape mechanisms was originally derived from surface water, we find
  3.8 × 10^17 kg of water has been lost from Mars between 0 and 4 Ga;
  this mass corresponds to a global surface depth of 2.6 m. This study
  offers fresh insights concerning the long-term climate evolution and
  habitability of the increasing number of exoplanets discovered yearly
  due to atmospheric losses.

Title: Integration of RAM-SCB into the Space Weather Modeling
    Framework
Authors: Welling, Daniel T.; Toth, Gabor; Jordanova, Vania K.;
   Yu, Yiqun
Bibcode: 2018JASTP.177..160W
Altcode:
  Numerical simulations of the ring current are a challenging
  endeavor. They require a large set of inputs, including electric and
  magnetic fields and plasma sheet fluxes. Because the ring current
  broadly affects the magnetosphere-ionosphere system, the input set is
  dependent on the ring current region itself. This makes obtaining a set
  of inputs that are self-consistent with the ring current difficult. To
  overcome this challenge, researchers have begun coupling ring current
  models to global models of the magnetosphere-ionosphere system. This
  paper describes the coupling between the Ring current Atmosphere
  interaction Model with Self-Consistent Magnetic field (RAM-SCB)
  to the models within the Space Weather Modeling Framework. Full
  details on both previously introduced and new coupling mechanisms are
  defined. The impact of self-consistently including the ring current
  on the magnetosphere-ionosphere system is illustrated via a set of
  example simulations.

Title: Roadmap for Reliable Ensemble Forecasting of the Sun-Earth
    System
Authors: Nita, Gelu; Angryk, Rafal; Aydin, Berkay; Banda, Juan;
   Bastian, Tim; Berger, Tom; Bindi, Veronica; Boucheron, Laura; Cao,
   Wenda; Christian, Eric; de Nolfo, Georgia; DeLuca, Edward; DeRosa,
   Marc; Downs, Cooper; Fleishman, Gregory; Fuentes, Olac; Gary, Dale;
   Hill, Frank; Hoeksema, Todd; Hu, Qiang; Ilie, Raluca; Ireland,
   Jack; Kamalabadi, Farzad; Korreck, Kelly; Kosovichev, Alexander;
   Lin, Jessica; Lugaz, Noe; Mannucci, Anthony; Mansour, Nagi; Martens,
   Petrus; Mays, Leila; McAteer, James; McIntosh, Scott W.; Oria, Vincent;
   Pan, David; Panesi, Marco; Pesnell, W. Dean; Pevtsov, Alexei; Pillet,
   Valentin; Rachmeler, Laurel; Ridley, Aaron; Scherliess, Ludger; Toth,
   Gabor; Velli, Marco; White, Stephen; Zhang, Jie; Zou, Shasha
Bibcode: 2018arXiv181008728N
Altcode:
  The authors of this report met on 28-30 March 2018 at the New Jersey
  Institute of Technology, Newark, New Jersey, for a 3-day workshop
  that brought together a group of data providers, expert modelers, and
  computer and data scientists, in the solar discipline. Their objective
  was to identify challenges in the path towards building an effective
  framework to achieve transformative advances in the understanding
  and forecasting of the Sun-Earth system from the upper convection
  zone of the Sun to the Earth's magnetosphere. The workshop aimed to
  develop a research roadmap that targets the scientific challenge
  of coupling observations and modeling with emerging data-science
  research to extract knowledge from the large volumes of data (observed
  and simulated) while stimulating computer science with new research
  applications. The desire among the attendees was to promote future
  trans-disciplinary collaborations and identify areas of convergence
  across disciplines. The workshop combined a set of plenary sessions
  featuring invited introductory talks and workshop progress reports,
  interleaved with a set of breakout sessions focused on specific topics
  of interest. Each breakout group generated short documents, listing
  the challenges identified during their discussions in addition to
  possible ways of attacking them collectively. These documents were
  combined into this report-wherein a list of prioritized activities
  have been collated, shared and endorsed.

Title: Noether currents for the Teukolsky master equation
Authors: Tóth, Gábor Zsolt
Bibcode: 2018CQGra..35r5009T
Altcode: 2018arXiv180104710T
  Conserved currents associated with the time translation and axial
  symmetries of the Kerr spacetime and with scaling symmetry are
  constructed for the Teukolsky master equation (TME). Three partly
  different approaches are taken, of which the third one applies
  only to the spacetime symmetries. The results yielded by the three
  approaches, which correspond to three variants of Noether’s theorem,
  are essentially the same, nevertheless. The construction includes
  the embedding of the TME into a larger system of equations, which
  admits a Lagrangian and turns out to consist of two TMEs with opposite
  spin weight. The currents thus involve two independent solutions of
  the TME with opposite spin weights. The first approach provides an
  example of the application of an extension of Noether’s theorem to
  nonvariational differential equations. This extension is also reviewed
  in general form. The variant of Noether’s theorem applied in the
  third approach is a generalization of the standard construction of
  conserved currents associated with spacetime symmetries in general
  relativity, in which the currents are obtained by the contraction
  of the symmetric energy-momentum tensor with the relevant Killing
  vector fields. Symmetries and conserved currents related to boundary
  conditions are introduced as well, and Noether’s theorem and
  its variant for nonvariational differential equations are extended
  to them. The extension of the latter variant is used to construct
  conserved currents related to the Sommerfeld boundary condition.

Title: Modeling Martian Atmospheric Losses Over Time: Implications
    for (Exo)Planetary Climate Evolution and Habitability
Authors: Dong, C. F.; Lee, Y.; Ma, Y. J.; Lingam, M.; Bougher, S. W.;
   Luhmann, J. G.; Curry, S. M.; Toth, G.; Nagy, A. F.; Tenishev, V.;
   Fang, X.; Mitchell, D. L.; Brain, D. A.; Jakosky, B. M.
Bibcode: 2018LPICo2065.2052D
Altcode:
  We make use of the one-way coupled framework (linking our GCM, DSMC,
  and MHD models), known to accurately reproduce MAVEN observations,
  for studying the atmospheric ion and photochemical escape rates and
  climate evolution over the history of Mars.

Title: Solar Wind Interaction With the Martian Upper Atmosphere:
    Roles of the Cold Thermosphere and Hot Oxygen Corona
Authors: Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Lee,
   Yuni; Toth, Gabor; Nagy, Andrew F.; Fang, Xiaohua; Luhmann, Janet;
   Liemohn, Michael W.; Halekas, Jasper S.; Tenishev, Valeriy; Pawlowski,
   David J.; Combi, Michael R.
Bibcode: 2018JGRA..123.6639D
Altcode: 2018arXiv180400937D
  We study roles of the thermosphere and exosphere on the Martian
  ionospheric structure and ion escape rates in the process of the
  solar wind-Mars interaction. We employ a four-species multifluid
  magnetohydrodynamic model to simulate the Martian ionosphere
  and magnetosphere. The cold thermosphere background is taken
  from the Mars Global Ionosphere Thermosphere Model, and the hot
  oxygen exosphere is adopted from the Mars exosphere Monte Carlo
  model—Adaptive Mesh Particle Simulator. A total of four cases with
  the combination of 1-D (globally averaged) and 3-D thermospheres
  and exospheres are studied. The ion escape rates calculated by
  adopting 1-D and 3-D atmospheres are similar; however, the latter
  are required to adequately reproduce the ionospheric observations by
  the Mars Atmosphere and Volatile EvolutioN mission. In addition, our
  simulations show that the 3-D hot oxygen corona plays an important role
  in preventing planetary molecular ions (O&lt;mrow&gt;&lt;/mrow&gt;2+
  and CO&lt;mrow&gt;&lt;/mrow&gt;2+) escaping from Mars, mainly resulting
  from the mass loading of the high-altitude exospheric O<SUP>+</SUP>
  ions. The cold thermospheric oxygen atom, however, is demonstrated to
  be the primary neutral source for O<SUP>+</SUP> ion escape during the
  relatively weak solar cycle 24.

Title: A Predicted Small and Round Heliosphere
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
Bibcode: 2018arXiv180806611O
Altcode:
  The shape of the solar wind bubble within the interstellar medium,
  the so-called heliosphere, has been explored over six decades. As the
  Sun moves through the surrounding partially-ionized medium, neutral
  hydrogen atoms penetrate the heliosphere, and through charge-exchange
  with the supersonic solar wind, create a population of hot pick-up
  ions (PUIs). The Termination Shock (TS) crossing by Voyager 2 (V2)
  data demonstrated that the heliosheath (HS) (the region of shocked
  solar wind) pressure is dominated by suprathermal particles. Here we
  use a novel magnetohydrodynamic model that treats the freshly ionized
  PUIs as a separate fluid from the thermal component of the solar
  wind. Unlike previous models, the new model reproduces the properties of
  the PUIs and solar wind ions based on the New Horizon and V2 spacecraft
  observations. The PUIs charge exchange with the cold neutral H atoms of
  the ISM in the HS and are quickly depleted. The depletion of PUIs cools
  the heliosphere downstream of the TS, "deflating" it and leading to a
  narrower HS and a smaller and rounder shape, in agreement with energetic
  neutral atom observations by the Cassini spacecraft. The new model, with
  interstellar magnetic field orientation constrained by the IBEX ribbon,
  reproduces the magnetic field data outside the HP at Voyager 1(V1). We
  present the predictions for the magnetic field outside the HP at V2.

Title: The Impact and Solar Wind Proxy of the 2017 September ICME
    Event at Mars
Authors: Ma, Yingjuan; Fang, Xiaohua; Halekas, Jasper S.; Xu, Shaosui;
   Russell, Christopher T.; Luhmann, Janet G.; Nagy, Andrew F.; Toth,
   Gabor; Lee, Christina O.; Dong, Chuanfei; Espley, Jared R.; McFadden,
   James P.; Mitchell, David L.; Jakosky, Bruce M.
Bibcode: 2018GeoRL..45.7248M
Altcode:
  We study a large interplanetary coronal mass ejection event impacting
  Mars in mid-September 2017 numerically. During this time period,
  MAVEN remained inside the Martian bow shock and therefore could not
  measure the solar wind directly. We first simulate the event using three
  steady state cases with estimated solar wind conditions and find that
  these cases were able to reproduce the general features observed by
  MAVEN. However, these time-stationary runs cannot capture the response
  of the system to large variations in the solar wind associated with
  the event. To address this problem, we derive a solar wind proxy based
  on MAVEN observations in the sheath region and their comparison with
  steady state magnetohydrodynamic model results. The derived solar
  wind proxy is then used to drive a time-dependent magnetohydrodynamic
  model, and we find that the data-model comparison is greatly improved,
  especially in the magnetosheath. We are able to reproduce some detailed
  structures observed by MAVEN during the period, despite the lack of a
  direct measurement of the solar wind, indicating that the derived solar
  wind conditions are reliable. Finally, we examine in detail the impact
  of the event on the Martian system: including variations of the three
  typical plasma boundaries and the ion loss rates. Our results show that
  these plasma boundary locations varied drastically during the event, and
  the total ion loss rate was enhanced by more than an order of magnitude.

Title: The Astrosphere and Mass-Loss Ratio of Proxima Centauri
Authors: Opher, Merav; Toth, Gabor; Loeb, Abraham
Bibcode: 2018cosp...42E2514O
Altcode:
  Our understanding about the heliosphere dramatically evolved from
  the results from Voyager, Cassini and Interstellar Boundary Explorer
  (IBEX). With the rapid discovery of exoplanets in other stellar systems
  it is important to understand how this new acquired knowledge affects
  the astrospheres around other stars. In particular, recently the shape
  of the Heliosphere is being challenged by theoretical and observation
  work (Opher et al. 2015; Diyalinas et al. 2017). The nearest star to the
  Sun, Proxima Centauri, is particularly interesting as it was recently
  discovered to host an Earth-size planet in its "habitable zone", Proxima
  b. Here we investigate the astrosphere around Proxima Centauri. As the
  star moves through the surrounding partially-ionized medium, neutral
  hydrogen atoms penetrate the astrospheres and through charge-exchange
  with the supersonic stellar wind creating a population of hot pick-up
  ions (PUIs). We present global magnetohydrodynamic simulations that
  treats the PUIs as a separate fluid. Most global models treat the PUI
  and thermal component as a single fluid. Planetary atmospheres are
  affected by particle fluxes from their host stars. The only means
  by which coronal winds of Sun-like stars have ever been probed is
  by the circumstellar H Lyman-alpha absorption fin the interaction
  region between the wind and the interstellar medium, namely the
  "astrospheres". The Lyman-alpha constrains on the stellar wind based
  on Hubble Space Telescope measurements rely on prior hydrodynamical
  models. Here we revisit the constraints on the mass-loss of Proxima
  Centauri (Wood et al. 2011) with improved theoretical predictions and
  discuss the implications for Space Weather effects on Proxima b.

Title: NOAA SWPC's Operational Geospace Model Performance during
    Earth-Affecting Events
Authors: Cash, Michele; Singer, . Howard; Millward, George; Toth,
   Gabor; Welling, Daniel; Balch, Christopher
Bibcode: 2018cosp...42E.524C
Altcode:
  The Geospace model was first transitioned into real-time operations at
  the NOAA Space Weather Prediction Center (SWPC) in October 2016 and
  has been upgraded once since going operational. The Geospace model
  is a part of the Space Weather Modeling Framework (SWMF) developed
  at the University of Michigan, and the model simulates the full
  time-dependent 3D Geospace environment (Earth's magnetosphere, ring
  current and ionosphere) and predicts global and local space weather
  parameters such as induced magnetic perturbations in space and on
  Earth's surface. The current version of the Geospace model uses three
  coupled components of SWMF: the BATS-R-US global magnetosphere model,
  the Rice Convection Model (RCM) of the inner magnetosphere, and the
  Ridley Ionosphere electrodynamics Model (RIM). In the operational mode,
  SWMF/Geospace runs continually using real-time solar wind data from a
  satellite at L1, either DSCOVR or ACE. We present an analysis of the
  overall performance of the Geospace model during the Earth-affecting
  events that occurred since the Geospace model went operational. We
  also use past large Earth-affecting events to evaluate how well the
  current operational version of the model would have performed during
  enhanced storm periods.

Title: The effects of Pick-up Ions on the Shape of The Heliosphere
Authors: Opher, Merav; Toth, Gabor; Loeb, Abraham
Bibcode: 2018cosp...42E2513O
Altcode:
  As the Sun moves through the surrounding partially-ionized medium,
  neutrals hydrogen atom penetrate the heliosphere and through
  charge-exchange with the supersonic solar wind create a population of
  hot pick-up ions (PUIs). With the crossing of the termination shock by
  Voyager 2 it became clear that the heliosheath pressure is dominated
  by the PUIs while the bulk thermal solar wind is much colder. Recently
  the shape of the Heliosphere is being challenged by theoretical and
  observation work (Opher et al. 2015; Diyalinas et al. 2017). Previously
  we had explored the effects of PUIs in the termination shock crossing
  (Zieger et al. 2015). In this work, we explore the effects of PUIs on
  the shape of the heliosphere. We present global magnetohydrodynamic
  simulations that treats the PUIs a separate fluid. Most global models
  treat the PUI and thermal component as a single fluid. We comment
  on the effect of the global structure as well as the properties of
  the heliosheath.

Title: Quantifying the access of Jupiter's magnetospheric plasma to
    Europa's surface through a multi-fluid MHD model
Authors: Harris, Camilla; Toth, Gabor; Rubin, Martin; Jia, Xianzhe;
   Slavin, A. James
Bibcode: 2018cosp...42E1383H
Altcode:
  Europa's space environment is controlled by the wobbling of Jupiter's
  magnetic field, the magnetic response to this wobbling induced in
  the conducting subsurface ocean, and the interaction of Jupiter's
  magnetosphere with Europa's ionosphere and extended exosphere. We have
  developed a multi-fluid MHD model for Europa's plasma interaction which
  self-consistently solves for the bulk properties of 3 ion fluids and
  the electromagnetic fields in the vicinity of the moon. To validate our
  model, we have simulated the Galileo E4 Flyby using the observed plasma
  and magnetic field conditions. Our model has accurately reproduced
  Galileo magnetometer observations along the flyby trajectory, and
  provides full 3D density and velocity fields for O^+ and O_2^+ ionized
  from Europa's neutral O_2 exosphere, and the thermal, corotating O^+
  from Jupiter's magnetosphere. Based on the three-ion-fluid MHD model,
  we have mapped the distribution of the magnetospheric plasma that was
  able to penetrate the plasma interaction to reach Europa's surface. We
  find that while the majority of downward flux impinges on the upstream
  hemisphere, the surface impact by the ambient magnetospheric O^+ ions
  exhibits a slight preference towards the anti-jovian hemisphere due to
  the influence of the convectional electric field. Under the E4 flyby
  conditions, we estimate that about 13% of the available upstream O^+
  ions precipitate to Europa's surface. Most of the ambient plasma is
  instead diverted around the moon due to the plasma interaction with the
  ionosphere. This precipitation represents the contribution of thermal
  plasma to the sputtering interaction with Europa's icy surface which
  replenishes the O_2 exosphere.

Title: MHD Simulations of the Impact of the September 2017 Major
    Solar Flare and ICME Events on Mars
Authors: Ma, Yingjuan; Luhmann, Janet G.; Russell, C. T.; Bougher,
   Stephen; Nagy, Andrew; Toth, Gabor; Lee, Christina O.; Pawlowski,
   David; Lillis, Robert; Fang, Xiaohua; Jakosky, Bruce; Halekas, Jasper;
   Espley, Jared; Thiemann, Edward; Connerney, John; Xu, Shaosui; Dong,
   Chuanfei
Bibcode: 2018cosp...42E2103M
Altcode:
  We study the impact of the September 2017 extreme solar flare
  and interplanetary coronal mass ejection events on Mars using a
  sophisticated multi-species MHD model. The flare impact is examined by
  coupling with the Mars Global Ionosphere-Thermosphere Model. A great
  challenge of the study is that MAVEN was mostly inside the Martian
  bow shock during the events, and thus no direct solar wind measurement
  was available. To carry out reasonable simulations, we first simulate
  the events using steady-state assumptions with rough solar wind
  estimates. Although these simplistic time-stationary runs are able to
  capture the general features observed by MAVEN, they cannot represent
  the details of the large perturbations associated with the events. To
  describe the time variation during the space weather events, we estimate
  upstream solar wind conditions by fitting steady-state MHD model results
  to MAVEN observations in the sheath region. The obtained solar wind
  proxies are then used to drive a time-dependent MHD simulation. It is
  found that the data-model comparison is greatly improved, especially
  in the magnetosheath region. We are able to reproduce many detailed
  structures observed by MAVEN during the period despite the fact
  that no direct measurement of the solar wind is available. This
  model-data agreement confirms the validity of the derived upstream
  solar wind conditions. Using the time-dependent results, we examine
  in detail the impact of the events on the Martian system, including
  three plasma boundaries (Bow Shock, induced magnetosphere and ion
  composition boundaries) and ion loss rates. It is found that these
  plasma boundaries vary dramatically during the ICME and total planetary
  ion loss rates are enhanced by more than an order of magnitude.

Title: Consequences of Treating the Solar Magnetic Field as a Dipole
    on the Global Structure of the Heliosphere and Heliosheath
Authors: Michael, A. T.; Opher, M.; Tóth, G.
Bibcode: 2018ApJ...860..171M
Altcode:
  We investigate the effect of including the heliospheric current sheet
  on global modeling of the heliosphere. Due to inherent numerical
  dissipation in the current handling of the heliospheric current sheet,
  models have chosen to remove it to avoid numerical problems. We compare
  a model where the polarity of the Parker spiral is the same in both
  hemispheres (unipolar) to a dipole description of the solar magnetic
  field, with the magnetic and rotational axes aligned forming a flat
  heliospheric current sheet. The flat current sheet is pulled into the
  northern hemisphere, which reduces the magnetic field strength at the
  Voyager 1 trajectory over the last 22% of the heliosheath. The decrease
  in magnetic field intensity is transferred into the thermal energy of
  the plasma causing the dipole model to predict an entirely thermally
  dominated heliosheath; this is a stark contrast to the magnetically
  dominated region ahead of the heliopause in the unipole model. We
  find that the two-lobe structure of the solar wind magnetic field
  persists within the dipole model, with the flat current sheet not
  able to fully erode the magnetic tension force. However, there is a
  large amount of magnetic dissipation in the tail between the lobes,
  which affects the structure of the plasma in the region. Furthermore,
  the draped interstellar magnetic field in the dipole model is strongly
  affected by reconnection at the nose of the heliosphere, yielding a
  distinctly different draping pattern than that observed at Voyager 1.

Title: Reconnection in the Martian Magnetotail: Hall-MHD With Embedded
    Particle-in-Cell Simulations
Authors: Ma, Yingjuan; Russell, Christopher T.; Toth, Gabor; Chen,
   Yuxi; Nagy, Andrew F.; Harada, Yuki; McFadden, James; Halekas, Jasper
   S.; Lillis, Rob; Connerney, John E. P.; Espley, Jared; DiBraccio, Gina
   A.; Markidis, Stefano; Peng, Ivy Bo; Fang, Xiaohua; Jakosky, Bruce M.
Bibcode: 2018JGRA..123.3742M
Altcode:
  Mars Atmosphere and Volatile EvolutioN (MAVEN) mission observations show
  clear evidence of the occurrence of the magnetic reconnection process in
  the Martian plasma tail. In this study, we use sophisticated numerical
  models to help us understand the effects of magnetic reconnection
  in the plasma tail. The numerical models used in this study are
  (a) a multispecies global Hall-magnetohydrodynamic (HMHD) model and
  (b) a global HMHD model two-way coupled to an embedded fully kinetic
  particle-in-cell code. Comparison with MAVEN observations clearly shows
  that the general interaction pattern is well reproduced by the global
  HMHD model. The coupled model takes advantage of both the efficiency
  of the MHD model and the ability to incorporate kinetic processes of
  the particle-in-cell model, making it feasible to conduct kinetic
  simulations for Mars under realistic solar wind conditions for the
  first time. Results from the coupled model show that the Martian
  magnetotail is highly dynamic due to magnetic reconnection, and the
  resulting Mars-ward plasma flow velocities are significantly higher
  for the lighter ion fluid, which are quantitatively consistent with
  MAVEN observations. The HMHD with Embedded Particle-in-Cell model
  predicts that the ion loss rates are more variable but with similar
  mean values as compared with HMHD model results.

Title: An Integrated Modeling Suite for Simulating the Core Induction
    and Kinetic Effects in Mercury's Magnetosphere
Authors: Jia, X.; Slavin, J.; Chen, Y.; Poh, G.; Toth, G.; Gombosi, T.
Bibcode: 2018LPICo2047.6082J
Altcode:
  We present results from state-of-the-art global models of Mercury's
  space environment capable of self-consistently simulating the induction
  effect at the core and resolving kinetic physics important for magnetic
  reconnection.

Title: Modeling Martian Atmospheric Losses over Time: Implications
    for Exoplanetary Climate Evolution and Habitability
Authors: Dong, Chuanfei; Lee, Yuni; Ma, Yingjuan; Lingam, Manasvi;
   Bougher, Stephen; Luhmann, Janet; Curry, Shannon; Toth, Gabor; Nagy,
   Andrew; Tenishev, Valeriy; Fang, Xiaohua; Mitchell, David; Brain,
   David; Jakosky, Bruce
Bibcode: 2018ApJ...859L..14D
Altcode: 2018arXiv180505016D
  In this Letter, we make use of sophisticated 3D numerical simulations
  to assess the extent of atmospheric ion and photochemical losses from
  Mars over time. We demonstrate that the atmospheric ion escape rates
  were significantly higher (by more than two orders of magnitude) in the
  past at ∼4 Ga compared to the present-day value owing to the stronger
  solar wind and higher ultraviolet fluxes from the young Sun. We found
  that the photochemical loss of atomic hot oxygen dominates over the
  total ion loss at the current epoch, while the atmospheric ion loss
  is likely much more important at ancient times. We briefly discuss the
  ensuing implications of high atmospheric ion escape rates in the context
  of ancient Mars, and exoplanets with similar atmospheric compositions
  around young solar-type stars and M-dwarfs.

Title: Including Kinetic Ion Effects in the Coupled Global Ionospheric
    Outflow Solution
Authors: Glocer, A.; Toth, G.; Fok, M. -C.
Bibcode: 2018JGRA..123.2851G
Altcode:
  We present a new expansion of the Polar Wind Outflow Model to include
  kinetic ions using the particle-in-cell (PIC) approach with Monte Carlo
  collisions. This implementation uses the original hydrodynamic solution
  at low altitudes for efficiency and couples to the kinetic solution
  at higher altitudes to account for kinetic effects important for
  ionospheric outflow. The modeling approach also includes wave-particle
  interactions, suprathermal electrons, and a hybrid parallel computing
  approach combining shared and distributed memory paralellization. The
  resulting model is thus a comprehensive, global, model of ionospheric
  outflow that can be run efficiently on large supercomputing clusters. We
  demonstrate the model's capability to study a range of problems
  starting with the comparison of kinetic and hydrodynamic solutions
  along a single field line in the sunlit polar cap, and progressing
  to the altitude evolution of the ion conic distribution in the cusp
  region. The interplay between convection and the cusp on the global
  outflow solution is also examined. Finally, we demonstrate the impact
  of these new model features on the magnetosphere by presenting the
  first two-way coupled ionospheric outflow-magnetosphere calculation
  including kinetic ion effects.

Title: Hall effect in the coma of 67P/Churyumov-Gerasimenko
Authors: Huang, Z.; Tóth, G.; Gombosi, T. I.; Jia, X.; Combi, M. R.;
   Hansen, K. C.; Fougere, N.; Shou, Y.; Tenishev, V.; Altwegg, K.;
   Rubin, M.
Bibcode: 2018MNRAS.475.2835H
Altcode: 2018arXiv180103991H
  Magnetohydrodynamics simulations have been carried out in studying the
  solar wind and cometary plasma interactions for decades. Various plasma
  boundaries have been simulated and compared well with observations
  for comet 1P/Halley. The Rosetta mission, which studies comet
  67P/Churyumov-Gerasimenko, challenges our understanding of the
  solar wind and comet interactions. The Rosetta Plasma Consortium
  observed regions of very weak magnetic field outside the predicted
  diamagnetic cavity. In this paper, we simulate the inner coma with the
  Hall magnetohydrodynamics equations and show that the Hall effect is
  important in the inner coma environment. The magnetic field topology
  becomes complex and magnetic reconnection occurs on the dayside when
  the Hall effect is taken into account. The magnetic reconnection on the
  dayside can generate weak magnetic field regions outside the global
  diamagnetic cavity, which may explain the Rosetta Plasma Consortium
  observations. We conclude that the substantial change in the inner coma
  environment is due to the fact that the ion inertial length (or gyro
  radius) is not much smaller than the size of the diamagnetic cavity.

Title: A Spectroscopic Study of the Energy Deposition in the Low
Corona: Connecting Global Modeling to Observations
Authors: Szente, J.; Landi, E.; Toth, G.; Manchester, W.; van der
   Holst, B.; Gombosi, T. I.
Bibcode: 2017AGUFMSH41C..06S
Altcode:
  We are looking for signatures of coronal heating process using a
  physically consistent 3D MHD model of the global corona. Our approach is
  based on the Alfvén Wave Solar atmosphere Model (AWSoM), with a domain
  ranging from the upper chromosphere (50,000K) to the outer corona,
  and the solar wind is self-consistently heated and accelerated by the
  dissipation of low-frequency Alfvén waves. Taking into account separate
  electron and anisotropic proton heating, we model the coronal plasma
  at the same time and location as observed by Hinode/EIS, and calculate
  the synthetic spectra that we compare with the observations. With
  the obtained synthetic spectra, we are able to directly calculate
  line intensities, line width, thermal and nonthermal motions, line
  centroids, Doppler shift distributions and compare our predictions
  to real measurements. Our results directly test the extent to which
  Alfvénic heating is present in the low corona.

Title: Gas Production at Comet 67P/Churyumov-Gerasimenko as Measured
by the ROSINA Instrument: Long Term Trends and Correlations with
    H<SUB>2</SUB>O and CO<SUB>2</SUB>
Authors: Hansen, K. C.; Altwegg, K.; Berthelier, J. J.; Combi, M. R.;
   De Keyser, J.; Fiethe, B.; Fougere, N.; Fuselier, S. A.; Gombosi,
   T. I.; Huang, Z.; Rubin, M.; Tenishev, V.; Toth, G.; Tzou, C. Y.
Bibcode: 2017AGUFM.P54D..03H
Altcode:
  The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)
  instrument onboard the Rosetta spacecraft measured the in situ gas
  density of comet 67P/Churyumov-Gerasimenko during the full perihelion
  passage of the comet within 3.5au. During this time, ROSINA sampled the
  neutral coma, measuring the broad range of cometary species including
  both the major constituents such as H2O, CO2, CO as well as many other
  species that are interesting to the general astrophysical community,
  such as O2, Xe, Si and even amino acids. Many of these species are hard
  to detect and therefore measurements are limited to when the spacecraft
  was close to the comet or the production rate was high. In contrast,
  in this work we will consider species that are most easily measured due
  to either their higher production rates or the ease with which their
  mass peaks are located (H2O, CO2, CO, O2, 18OH, HDO, OCS, SO2, H2S, CN,
  HCN, NH3, CH4, C2H2, C2H3, CH3OH and F). The advantage of examining
  these species is that we are able to present measurements over the
  entire perihelion passage at reasonably high time resolution. In this
  work we will present two important results. First, we will examine the
  long-term trend and heliocentric distance dependence of the production
  of these species over the entire perihelion passage of 67P. Second we
  will consider the correlation of the production of each species with
  the production of H2O and CO2. The study will consider both the long
  term correspondence between production of different species as well
  as the shorter term correlation.

Title: Influence of the solar wind and IMF on Jupiter's magnetosphere:
    Results from global MHD simulations
Authors: Sarkango, Y.; Jia, X.; Toth, G.; Hansen, K. C.
Bibcode: 2017AGUFMSM33C2679S
Altcode:
  Due to its large size, rapid rotation and presence of substantial
  internal plasma sources, Jupiter's magnetosphere is fundamentally
  different from that of the Earth. How and to what extent do the external
  factors, such as the solar wind and interplanetary magnetic field (IMF),
  influence the internally-driven magnetosphere is an open question. In
  this work, we solve the 3D semi-relativistic magnetohydrodynamic (MHD)
  equations using a well-established code, BATSRUS, to model the Jovian
  magnetosphere and study its interaction with the solar wind. Our
  global model adopts a non-uniform mesh covering the region from 200
  RJ upstream to 1800 RJ downstream with the inner boundary placed at a
  radial distance of 2.5 RJ. The Io plasma torus centered around 6 RJ is
  generated in our model through appropriate mass-loading terms added to
  the set of MHD equations. We perform systematic numerical experiments
  in which we vary the upstream solar wind properties to investigate
  the impact of solar wind events, such as interplanetary shock and
  IMF rotation, on the global magnetosphere. From our simulations,
  we extract the location of the magnetopause boundary, the bow shock
  and the open-closed field line boundary (OCB), and determine their
  dependence on the solar wind properties and the IMF orientation. For
  validation, we compare our simulation results, such as density,
  temperature and magnetic field, to published empirical models based
  on in-situ measurements.

Title: Space Weather Forecasting at NOAA with Michigan's Geospace
Model: Results from the First Year in Real-Time Operations
Authors: Cash, M. D.; Singer, H. J.; Millward, G. H.; Balch, C. C.;
   Toth, G.; Welling, D. T.
Bibcode: 2017AGUFMSM11E..07C
Altcode:
  In October 2016, the first version of the Geospace model was
  transitioned into real-time operations at NOAA Space Weather Prediction
  Center (SWPC). The Geospace model is a part of the Space Weather
  Modeling Framework (SWMF) developed at the University of Michigan,
  and the model simulates the full time-dependent 3D Geospace environment
  (Earth's magnetosphere, ring current and ionosphere) and predicts global
  space weather parameters such as induced magnetic perturbations in space
  and on Earth's surface. The current version of the Geospace model uses
  three coupled components of SWMF: the BATS-R-US global magnetosphere
  model, the Rice Convection Model (RCM) of the inner magnetosphere, and
  the Ridley Ionosphere electrodynamics Model (RIM). In the operational
  mode, SWMF/Geospace runs continually in real-time as long as there is
  new solar wind data arriving from a satellite at L1, either DSCOVR or
  ACE. We present an analysis of the overall performance of the Geospace
  model during the first year of real-time operations. Evaluation metrics
  include Kp, Dst, as well as regional magnetometer stations. We will
  also present initial results from new products, such as the AE index,
  available with the recent upgrade to the Geospace model.

Title: The contribution of inductive electric fields to particle
    energization in the inner magnetosphere
Authors: Ilie, R.; Toth, G.; Liemohn, M. W.; Chan, A. A.
Bibcode: 2017AGUFMSM23A2586I
Altcode:
  Assessing the relative contribution of potential versus inductive
  electric fields at the energization of the hot ion population in the
  inner magnetosphere is only possible by thorough examination of the
  time varying magnetic field and current systems using global modeling of
  the entire system. We present here a method to calculate the inductive
  and potential components of electric field in the entire magnetosphere
  region. This method is based on the Helmholtz vector decomposition of
  the motional electric field as calculated by the BATS-R-US model, and is
  subject to boundary conditions. This approach removes the need to trace
  independent field lines and lifts the assumption that the magnetic field
  lines can be treated as frozen in a stationary ionosphere. In order to
  quantify the relative contributions of potential and inductive electric
  fields at driving plasma sheet ions into the inner magnetosphere,
  we apply this method for the March 17th, 2013 geomagnetic storm. We
  present here the consequences of slow continuous changes in the
  geomagnetic field as well as the strong tail dipolarizations on the
  distortion of the near-Earth magnetic field and current systems. Our
  findings indicate that the inductive component of the electric field
  is comparable, and even higher at times than the potential component,
  suggesting that the electric field induced by the time varying magnetic
  field plays a crucial role in the overall particle energization in
  the inner magnetosphere.

Title: Are "Habitable" Exoplanets Really Habitable? -A perspective
    from atmospheric loss
Authors: Dong, C.; Huang, Z.; Jin, M.; Lingam, M.; Ma, Y. J.; Toth,
   G.; van der Holst, B.; Airapetian, V.; Cohen, O.; Gombosi, T. I.
Bibcode: 2017AGUFM.P42B..02D
Altcode:
  In the last two decades, the field of exoplanets has witnessed a
  tremendous creative surge. Research in exoplanets now encompasses
  a wide range of fields ranging from astrophysics to heliophysics
  and atmospheric science. One of the primary objectives of studying
  exoplanets is to determine the criteria for habitability, and whether
  certain exoplanets meet these requirements. The classical definition
  of the Habitable Zone (HZ) is the region around a star where liquid
  water can exist on the planetary surface given sufficient atmospheric
  pressure. However, this definition largely ignores the impact of
  the stellar wind and stellar magnetic activity on the erosion of
  an exoplanet's atmosphere. Amongst the many factors that determine
  habitability, understanding the mechanisms of atmospheric loss is
  of paramount importance. We will discuss the impact of exoplanetary
  space weather on climate and habitability, which offers fresh insights
  concerning the habitability of exoplanets, especially those orbiting
  M-dwarfs, such as Proxima b and the TRAPPIST-1 system. For each case,
  we will demonstrate the importance of the exoplanetary space weather
  on atmospheric ion loss and habitability.

Title: Solar Atmosphere to Earth's Surface: Long Lead Time dB/dt
    Predictions with the Space Weather Modeling Framework
Authors: Welling, D. T.; Manchester, W.; Savani, N.; Sokolov, I.;
   van der Holst, B.; Jin, M.; Toth, G.; Liemohn, M. W.; Gombosi, T. I.
Bibcode: 2017AGUFMSH34B..05W
Altcode:
  The future of space weather prediction depends on the community's
  ability to predict L1 values from observations of the solar
  atmosphere, which can yield hours of lead time. While both
  empirical and physics-based L1 forecast methods exist, it is not
  yet known if this nascent capability can translate to skilled
  dB/dt forecasts at the Earth's surface. This paper shows results
  for the first forecast-quality, solar-atmosphere-to-Earth's-surface
  dB/dt predictions. Two methods are used to predict solar wind and
  IMF conditions at L1 for several real-world coronal mass ejection
  events. The first method is an empirical and observationally based
  system to estimate the plasma characteristics. The magnetic field
  predictions are based on the Bz4Cast system which assumes that the
  CME has a cylindrical flux rope geometry locally around Earth's
  trajectory. The remaining plasma parameters of density, temperature
  and velocity are estimated from white-light coronagraphs via a variety
  of triangulation methods and forward based modelling. The second is
  a first-principles-based approach that combines the Eruptive Event
  Generator using Gibson-Low configuration (EEGGL) model with the Alfven
  Wave Solar Model (AWSoM). EEGGL specifies parameters for the Gibson-Low
  flux rope such that it erupts, driving a CME in the coronal model
  that reproduces coronagraph observations and propagates to 1AU. The
  resulting solar wind predictions are used to drive the operational
  Space Weather Modeling Framework (SWMF) for geospace. Following the
  configuration used by NOAA's Space Weather Prediction Center, this
  setup couples the BATS-R-US global magnetohydromagnetic model to the
  Rice Convection Model (RCM) ring current model and a height-integrated
  ionosphere electrodynamics model. The long lead time predictions
  of dB/dt are compared to model results that are driven by L1 solar
  wind observations. Both are compared to real-world observations from
  surface magnetometers at a variety of geomagnetic latitudes. Metrics
  are calculated to examine how the simulated solar wind drivers
  impact forecast skill. These results illustrate the current state
  of long-lead-time forecasting and the promise of this technology for
  operational use.

Title: End-of-mission ROSINA/COPS measurements as a probe of the
    innermost coma of comet 67P/Churyumov-Gerasimenko
Authors: Tenishev, V.; Fougere, N.; Rubin, M.; Tzou, C. Y.; Combi,
   M. R.; Altwegg, K.; Gombosi, T. I.; Shou, Y.; Huang, Z.; Hansen,
   K. C.; Toth, G.
Bibcode: 2017AGUFM.P51D2634T
Altcode:
  A cometary coma is a unique phenomenon in the Solar system that
  represents an example of a planetary atmosphere influenced by little
  or no gravity. Due to the negligible gravity of a comet's nucleus, a
  coma has a characteristic size that exceeds that of the nucleus itself
  by many orders of magnitude. An extended dusty gas cloud that forms
  a coma is affected mainly by molecular collisions, radiative cooling,
  and photolytic, charge-exchange, and impact-ionization reactions. Such
  an environment has been extensively observed during the recent Rosetta
  mission, which was the first mission that escorts a comet along its way
  through the Solar system for an extended amount of time with the main
  scientific objectives of characterizing comet's nucleus, determining the
  surface composition, and studying the comet's activity development. The
  ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis)
  Comet Pressure Sensor (COPS) onboard the Rosetta spacecraft has
  performed one of the most exciting observations of the innermost coma
  during the spacecraft descend maneuver during the last ten hours of
  the mission when the random and outflow directed pressures in the coma
  have been measured all the way down to the comet's surface. Performed
  at such close proximity to the nucleus, these observations can help
  to characterize effects due to topological features and/or the gas
  local conditions at the surface of the nucleus. The major focus
  of the presented study is analyzing of the end-of-mission pressure
  measurements by the ROSINA/COPS instrument. Because the coma at a
  heliocentric distance of 3.8 AU was in a collisionless regime, it
  can be described by solving the Liouville equation, as we have done
  in our analysis. We have used the SHAP5 nucleus model to account for
  the topology of the volatile source. Spacecraft trajectory and the
  instrument pointing with respect to the comet's nucleus have been
  obtained with the SPICE library. Here, we present results of our
  analysis and discuss the effects of the surface topology and that of
  the local surface volatile injection on the distribution of gas in
  the innermost coma of comet 67P/Churyumov-Gerasimenko.

Title: Global Magnetosphere Modeling With Kinetic Treatment of
    Magnetic Reconnection
Authors: Toth, G.; Chen, Y.; Gombosi, T. I.; Cassak, P.; Markidis,
   S.; Peng, B.; Henderson, M. G.
Bibcode: 2017AGUFMSM22B..04T
Altcode:
  Global magnetosphere simulations with a kinetic treatment of magnetic
  reconnection are very challenging because of the large separation of
  global and kinetic scales. We have developed two algorithms that can
  overcome these difficulties: 1) the two-way coupling of the global
  magnetohydrodynamic code with an embedded particle-in-cell model
  (MHD-EPIC) and 2) the artificial increase of the ion and electron
  kinetic scales. Both of these techniques improve the efficiency
  of the simulations by many orders of magnitude. We will describe
  the techniques and show that they provide correct and meaningful
  results. Using the coupled model and the increased kinetic scales,
  we will present global magnetosphere simulations with the PIC domains
  covering the dayside and/or tail reconnection sites. The simulation
  results will be compared to and validated with MMS observations.

Title: Five-moment multi-fluid plasma simulation for comet
    67P/Churyumov-Gerasimenko
Authors: Huang, Z.; Toth, G.; Gombosi, T. I.; Jia, X.; Hansen,
   K. C.; Combi, M. R.; Tenishev, V.; Shou, Y.; Fougere, N.; Rubin, M.;
   Altwegg, K.
Bibcode: 2017AGUFM.P51D2629H
Altcode:
  Understanding the interactions between the solar wind and
  cometary magnetosphere was one of the key topics in the Rosetta
  mission. Numerical simulations have been widely carried out to
  investigate these interactions and the results agree well with
  observations. There are three different kinds of models: fluid models
  (in which both the ions and electrons are treated as fluids), hybrid
  models (in which the ions are considered as particles while the
  electrons are considered as a fluid) and fully kinetic models (in
  which both the ions and electrons are treated as particles). Fluid
  models can well simulate the large-scale boundaries of the solar
  wind-comet interaction, such as the bow shock position and the size of
  the diamagnetic cavity, and typically have much lower computational
  cost than hybrid and fully kinetic models. In previous fluid models,
  electrons are usually simulated with an electron pressure equation,
  without specifying the continuity and momentum equations. Such
  an approach cannot represent any of the electron kinetic features
  properly. In this study, we present the first five-moment multi-fluid
  plasma simulation of a comet, by introducing the continuity and
  momentum equations for the electrons, in which case the electrons
  and electric field are simulated more self-consistently than the
  classical multi-fluid MHD simulations and the Hall effect is included
  automatically. We compare the five-moment multi-fluid simulation
  results with those of a multi-fluid Hall MHD simulation and discuss
  the new features observed in the five-moment multi-fluid model.

Title: The Structure of the Heliosphere with Solar Cycle and Its
    Effect on the Conditions in the Local ISM
Authors: Opher, M.; Drake, J. F.; Toth, G.; Swisdak, M.; Michael,
   A.; Kornbleuth, M. Z.; Zieger, B.
Bibcode: 2017AGUFMSH54B..04O
Altcode:
  We argued (Opher et al. 2015, Drake et al. 2015) that the magnetic
  tension of the solar magnetic field plays a crucial role in
  organizing the solar wind in the heliosheath into two jet-like
  structures. The heliosphere then has a "croissant"-like shape where
  the distance to the heliopause downtail is almost the same as towards
  the nose. Regardless of whether the heliospheric tail is split in two
  or has a long comet shape there is consensus that the magnetic field
  in the heliosheath behaves differently than previously expected -
  it has a "slinky" structure and is turbulent. In this presentation,
  we will discuss several aspects related with this new model. We will
  show that this structure persists when the solar magnetic field is
  treated as a dipole. We show how the heliosphere, with its "Croissant"
  shape, evolves when the solar wind with solar cycle conditions are
  included and when the neutrals are treated kinetically (with our new
  MHD-Kinetic code). Due to reconnection (and turbulence of the jets)
  there is a substantial amount of heliosheath material sitting on open
  field lines. We will discuss the impact of artificial dissipation
  of the magnetic field in driving mixing and how it evolves with the
  solar cycle. We will discuss as well the development of turbulence
  in the jets and its role in mixing the plasma in the heliosheath and
  LISM and controlling the global structure of the heliosphere. We will
  discuss how the conditions upstream of the heliosphere, in the local
  interstellar medium are affected by reconnection in the tail and how it
  evolves with solar cycle. Recently we established (Opher et al. 2017)
  that reconnection in the eastern flank of the heliosphere is responsible
  for the twist of the interstellar magnetic field (BISM) acquiring a
  strong east-west component as it approaches the Heliopause. Reconnection
  drives a rotational discontinuity (RD) that twists the BISM into the
  -T direction and propagates upstream in the interstellar medium toward
  the nose. The consequence is that the N component of BISM is reduced in
  a band upstream of the HP. We show how the location of the RD upstream
  of the heliopause is affected by the solar cycle.

Title: A New Global Multi-fluid MHD Model of the Solar Corona
Authors: van der Holst, B.; Chandran, B. D. G.; Alterman, B. L.;
   Kasper, J. C.; Toth, G.
Bibcode: 2017AGUFMSH32A..09V
Altcode:
  We present a multi-fluid generalization of the AWSoM model, a global
  magnetohydrodynamic (MHD) solar corona model with low-frequency Alfven
  wave turbulence (van der Holst et al., 2014). This new extended
  model includes electron and multi-ion temperatures and velocities
  (protons and alpha particles). The coronal heating and acceleration
  is addressed via outward propagating low-frequency Alfven waves that
  are partially reflected by Alfven speed gradients. The nonlinear
  interaction of these counter-propagating waves results in turbulent
  energy cascade. To apportion the wave dissipation to the electron and
  ion temperatures, we employ the results of the theories of linear wave
  damping and nonlinear stochastic heating as described by Chandran et
  al. (2011, 2013). This heat partitioning results in a more than mass
  proportional heating among ions.

Title: Multi-fluid MHD simulations of Europa's interaction with
    Jupiter's magnetosphere
Authors: Harris, C. D. K.; Jia, X.; Slavin, J. A.; Rubin, M.; Toth, G.
Bibcode: 2017AGUFMSM41C..04H
Altcode:
  Several distinct physical processes generate the interaction between
  Europa, the smallest of Jupiter's Galilean moons, and Jupiter's
  magnetosphere. The 10˚ tilt of Jupiter's dipole causes time varying
  magnetic fields at Europa's orbit which interact with Europa's
  subsurface conducting ocean to induce magnetic perturbations around the
  moon. Jovian plasma interacts with Europa's icy surface to sputter off
  neutral particles, forming a tenuous exosphere which is then ionized
  by impact and photo-ionization to form an ionosphere. As jovian plasma
  flows towards the moon, mass-loading and interaction with the ionosphere
  slow the flow, producing magnetic perturbations that propagate along
  the field lines to form an Alfvén wing current system, which connects
  Europa to its bright footprint in Jupiter's ionosphere. The Galileo
  mission has shown that the plasma interaction generates significant
  magnetic perturbations that obscure signatures of the induced field
  from the subsurface ocean. Modeling the plasma-related perturbations
  is critical to interpreting the magnetic signatures of Europa's
  induction field, and therefore to magnetic sounding of its interior,
  a central goal of the upcoming Europa Clipper mission. Here we model
  the Europa-Jupiter interaction with multi-fluid magnetohydrodynamic
  simulations to understand quantitatively how these physical processes
  affect the plasma and magnetic environment around the moon. Our
  model separately tracks the bulk motion of three different ion fluids
  (exospheric O2+, O+, and magnetospheric O+), and includes sources and
  losses of mass, momentum and energy to each of the ion fluids due to
  ionization, charge-exchange and recombination. We include calculations
  of the electron temperature allowing for field-aligned electron
  heat conduction, and Hall effects due to differential ion-electron
  motion. Compared to previous simulations, this multi-fluid model allows
  us to more accurately determine the precipitation flux of jovian plasma
  to Europa's surface, which has significant implications for space
  weathering at the moon. Including the Hall effect in our simulations
  enables us to determine the effects of separate ion-electron bulk
  motion throughout the interaction, and our simulations reveal noticeable
  asymmetries and small-scale features in the Alfvén wings.

Title: Impacts of Extreme Space Weather Events on Power Grid
Infrastructure: Physics-Based Modelling of Geomagnetically-Induced
    Currents (GICs) During Carrington-Class Geomagnetic Storms
Authors: Henderson, M. G.; Bent, R.; Chen, Y.; Delzanno, G. L.;
   Jeffery, C. A.; Jordanova, V. K.; Morley, S.; Rivera, M. K.; Toth,
   G.; Welling, D. T.; Woodroffe, J. R.; Engel, M.
Bibcode: 2017AGUFMSA22A..01H
Altcode:
  Large geomagnetic storms can have devastating effects on power
  grids. The largest geomagnetic storm ever recorded - called the
  Carrington Event - occurred in 1859 and produced Geomagnetically Induced
  Currents (GICs) strong enough to set fires in telegraph offices. It
  has been estimated that if such a storm occurred today, it would
  have devastating, long-lasting effects on the North American power
  transmission infrastructure. Acutely aware of this imminent threat,
  the North American Electric Reliability Corporation (NERC) was recently
  instructed to establish requirements for transmission system performance
  during geomagnetic disturbance (GMD) events and, although the benchmarks
  adopted were based on the best available data at the time, they suffer
  from a severely limited physical understanding of the behavior of GMDs
  and the resulting GICs for strong events. To rectify these deficiencies,
  we are developing a first-of-its-kind data-informed modelling capability
  that will provide transformational understanding of the underlying
  physical mechanisms responsible for the most harmful intense localized
  GMDs and their impacts on real power transmission networks. This work
  is being conducted in two separate modes of operation: (1) using
  historical, well-observed large storm intervals for which robust
  data-assimilation can be performed, and (2) extending the modelling
  into a predictive realm in order to assess impacts of poorly and/or
  never-before observed Carrington-class events. Results of this work
  are expected to include a potential replacement for the current NERC
  benchmarking methodology and the development of mitigation strategies
  in real power grid networks. We report on progress to date and show
  some preliminary results of modeling large (but not yet extreme) events.

Title: Numerical simulation of the kinetic effects in the solar wind
Authors: Sokolov, I.; Toth, G.; Gombosi, T. I.
Bibcode: 2017AGUFMSH14B..07S
Altcode:
  Global numerical simulations of the solar wind are usually based on
  the ideal or resistive MagnetoHydroDynamics (MHD) equations. Within
  a framework of MHD the electric field is assumed to vanish in
  the co-moving frame of reference (ideal MHD) or to obey a simple
  and non-physical scalar Ohm's law (resistive MHD). The Maxwellian
  distribution functions are assumed, the electron and ion temperatures
  may be different. Non-disversive MHD waves can be present in this
  numerical model. The averaged equations for MHD turbulence may be
  included as well as the energy and momentum exchange between the
  turbulent and regular motion. With the use of explicit numerical
  scheme, the time step is controlled by the MHD wave propagtion time
  across the numerical cell (the CFL condition) More refined approach
  includes the Hall effect vie the generalized Ohm's law. The Lorentz
  force acting on light electrons is assumed to vanish, which gives the
  expression for local electric field in terms of the total electric
  current, the ion current as well as the electron pressure gradient
  and magnetic field. The waves (whistlers, ion-cyclotron waves etc)
  aquire dispersion and the short-wavelength perturbations propagate with
  elevated speed thus strengthening the CFL condition. If the grid size
  is sufficiently small to resolve ion skindepth scale, then the timestep
  is much shorter than the ion gyration period. The next natural step
  is to use hybrid code to resolve the ion kinetic effects. The hybrid
  numerical scheme employs the same generalized Ohm's law as Hall MHD
  and suffers from the same constraint on the time step while solving
  evolution of the electromagnetic field. The important distiction,
  however, is that by sloving particle motion for ions we can achieve
  more detailed description of the kinetic effect without significant
  degrade in the computational efficiency, because the time-step is
  sufficient to resolve the particle gyration. We present the fisrt
  numerical results from coupled BATS-R-US+ALTOR code as applied to
  kinetic simulations of the solar wind.

Title: Global Three-dimensional Simulation of the Solar
    Wind-Magnetosphere Interaction Using a Two-way Coupled
    Magnetohydrodynamics with Embedded Particle-in-Cell Model
Authors: Chen, Y.; Toth, G.; Cassak, P.; Jia, X.; Gombosi, T. I.;
   Slavin, J. A.; Welling, D. T.; Markidis, S.; Peng, I. B.; Jordanova,
   V. K.; Henderson, M. G.
Bibcode: 2017AGUFMSM24A..05C
Altcode:
  We perform a three-dimensional (3D) global simulation of Earth's
  magnetosphere with kinetic reconnection physics to study the interaction
  between the solar wind and Earth's magnetosphere. In this global
  simulation with magnetohydrodynamics with embedded particle-in-cell
  model (MHD-EPIC), both the dayside magnetopause reconnection region
  and the magnetotail reconnection region are covered with a kinetic
  particle-in-cell code iPIC3D, which is two-way coupled with the global
  MHD model BATS-R-US. We will describe the dayside reconnection related
  phenomena, such as the lower hybrid drift instability (LHDI) and the
  evolution of the flux transfer events (FTEs) along the magnetopause,
  and compare the simulation results with observations. We will also
  discuss the response of the magnetotail to the southward IMF. The
  onset of the tail reconnection and the properties of the magnetotail
  flux ropes will be discussed.

Title: 3D Hall MHD-EPIC Simulations of Ganymede's Magnetosphere
Authors: Zhou, H.; Toth, G.; Jia, X.
Bibcode: 2017AGUFMSM33D2700Z
Altcode:
  Fully kinetic modeling of a complete 3D magnetosphere is still
  computationally expensive and not feasible on current computers. While
  magnetohydrodynamic (MHD) models have been successfully applied to a
  wide range of plasma simulation, they cannot capture some important
  kinetic effects. We have recently developed a new modeling tool
  to embed the implicit particle-in-cell (PIC) model iPIC3D into
  the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme (BATS-R-US)
  magnetohydrodynamic model. This results in a kinetic model of the
  regions where kinetic effects are important. In addition to the
  MHD-EPIC modeling of the magnetosphere, the improved model presented
  here is now able to represent the moon as a resistive body. We use
  a stretched spherical grid with adaptive mesh refinement (AMR) to
  capture the resistive body and its boundary. A semi-implicit scheme is
  employed for solving the magnetic induction equation to allow time steps
  that are not limited by the resistivity. We have applied the model to
  Ganymede, the only moon in the solar system known to possess a strong
  intrinsic magnetic field, and included finite resistivity beneath the
  moon`s surface to model the electrical properties of the interior in
  a self-consistent manner. The kinetic effects of electrons and ions
  on the dayside magnetopause and tail current sheet are captured with
  iPIC3D. Magnetic reconnections under different upstream background
  conditions of several Galileo flybys are simulated to study the global
  reconnection rate and the magnetospheric dynamics

Title: A new hybrid particle/fluid model for cometary dust
Authors: Shou, Y.; Combi, M. R.; Tenishev, V.; Toth, G.; Hansen,
   K. C.; Huang, Z.; Gombosi, T. I.; Fougere, N.; Rubin, M.
Bibcode: 2017AGUFM.P51D2641S
Altcode:
  Cometary dust grains, which originate from comets, are believed to
  contain clues to the formation and the evolution of comets. They
  also play an important role in shaping the cometary environment,
  as they are able to decelerate and heat the gas through collisions,
  carry charges and interact with the plasma environment, and possibly
  sublimate gases. Therefore, the loss rate and behavior of dust
  grains are of interest to scientists. Currently, mainly two types of
  numerical dust models exist: particle models and fluid models have
  been developed. Particle models, which keep track of the positions
  and velocities of all gas and dust particles, allow crossing dust
  trajectories and a more accurate description of returning dust grains
  than the fluid model. However, in order to compute the gas drag
  force, the particle model needs to follow more gas particles than dust
  particles. A fluid model is usually more computationally efficient and
  is often used to provide simulations on larger spatial and temporal
  scales. In this work, a new hybrid model is developed to combine the
  advantages of both particle and fluid models. In the new approach a
  fluid model based on the University of Michigan BATSRUS code computes
  the gas properties, and feeds the gas drag force to the particle
  model, which is based on the Adaptive Mesh Particle Simulator (AMPS)
  code, to calculate the motion of dust grains. The coupling is done
  via the Space Weather Modeling Framework (SWMF). In addition to the
  capability of simulating the long-term dust phenomena, the model can
  also designate small active regions on the nucleus for comparison with
  the temporary fine dust features in observations. With the assistance
  of the newly developed model, the effect of viewing angles on observed
  dust jet shapes and the transportation of heavy dust grains from the
  southern to the northern hemisphere of comet 67P/Churyumov-Gerasimenko
  will be studied and compared with Rosetta mission images. Preliminary
  results will be presented. Support from contracts JPL #1266314 and
  #1266313 from the US Rosetta Project and grant NNX14AG84G from the
  NASA Planetary Atmospheres Program are gratefully acknowledged.

Title: Surface Activity Distributions of Comet
    67P/Churyumov-Gerasimenko Derived from VIRTIS Images
Authors: Fougere, N.; Combi, M. R.; Tenishev, V.; Migliorini,
   A.; Bockelée-Morvan, D.; Fink, U.; Filacchione, G.; Rinaldi, G.;
   Capaccioni, F.; Toth, G.; Gombosi, T. I.; Hansen, K. C.; Huang, Z.;
   Shou, Y.
Bibcode: 2017AGUFM.P51D2642F
Altcode:
  The outgassing mechanism of comets still remains a critical question to
  better understand these objects. The Rosetta mission gave some insight
  regarding the potential activity distribution from the surface of
  the nucleus of comet 67P/Churyumov-Gerasimenko, Fougere et al. (2016)
  used a spherical harmonics inversion scheme with in-situ measurements
  from the ROSINA instrument to derive mapping of the broad distribution
  of potential activity at the surface of the nucleus. Marschall et
  al. (2017) based on the appearance of dust active areas suggested
  that the so-called "neck" region and regions with fractured cliffs
  and locally steep slopes show more activity than the rest of comet
  67P's nucleus. Using in situ ROSINA measurements from a distance makes
  it difficult to distinguish between these two scenarios because the
  fast expansion of the gas and large molecular mean free paths prevents
  distinguishing small outgassing features even when the spacecraft was in
  bound orbits within 10 km from the nucleus. In this paper, we present a
  similar numerical inversion approach using VIRTIS images, which should
  better probe the very inner coma of comet 67P and give more detailed
  information about the outgassing activity. Support from contracts JPL
  #1266314 and #1266313 from the US Rosetta Project and grant NNX14AG84G
  from the NASA Planetary Atmospheres Program are gratefully acknowledged.

Title: Importance of Ambipolar Electric Field in the Ion Loss from
    Mars- Results from a Multi-fluid MHD Model with the Electron Pressure
    Equation Included
Authors: Ma, Y.; Dong, C.; van der Holst, B.; Nagy, A. F.; Bougher,
   S. W.; Toth, G.; Cravens, T.; Yelle, R. V.; Jakosky, B. M.
Bibcode: 2017AGUFM.P11B2509M
Altcode:
  The multi-fluid (MF) magnetohydrodynamic (MHD) model of Mars is further
  improved by solving an additional electron pressure equation. Through
  the electron pressure equation, the electron temperature is calculated
  based on the effects from various electrons related heating and cooling
  processes (e.g. photo-electron heating, electron-neutral collision
  and electron-ion collision), and thus the improved model is able to
  calculate the electron temperature and the electron pressure force
  self-consistently. Electron thermal conductivity is also considered in
  the calculation. Model results of a normal case with electron pressure
  equation included (MFPe) are compared in detail to an identical case
  using the regular MF model to identify the effect of the improved
  physics. We found that when the electron pressure equation is included,
  the general interaction patterns are similar to that of the case
  with no electron pressure equation. The model with electron pressure
  equation predicts that electron temperature is much larger than the ion
  temperature in the ionosphere, consistent with both Viking and MAVEN
  observations. The inclusion of electron pressure equation significantly
  increases the total escape fluxes predicted by the model, indicating the
  importance of the ambipolar electric field(electron pressure gradient)
  in driving the ion loss from Mars.

Title: Results from the OH-PT model: a Kinetic-MHD Model of the
    Outer Heliosphere within SWMF
Authors: Michael, A.; Opher, M.; Tenishev, V.; Borovikov, D.; Toth, G.
Bibcode: 2017AGUFMSH23C2676M
Altcode:
  We present an update of the OH-PT model, a kinetic-MHD model of the
  outer heliosphere. The OH-PT model couples the Outer Heliosphere (OH)
  and Particle Tracker (PT) components within the Space Weather Modeling
  Framework (SWMF). The OH component utilizes the Block-Adaptive Tree
  Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly
  parallel, 3D, and block-adaptive solver. As a stand-alone model,
  the OH component solves the ideal MHD equations for the plasma and
  a separate set of Euler's equations for the different populations of
  neutral atoms. The neutrals and plasma in the outer heliosphere are
  coupled through charge-exchange. While this provides an accurate
  solution for the plasma, it is an inaccurate description of the
  neutrals. The charge-exchange mean free path is on the order of the
  size of the heliosphere; therefore the neutrals cannot be described
  as a fluid. The PT component is based on the Adaptive Mesh Particle
  Simulator (AMPS) model, a 3D, direct simulation Monte Carlo model
  that solves the Boltzmann equation for the motion and interaction of
  multi-species plasma and is used to model the neutral distribution
  functions throughout the domain. The charge-exchange process occurs
  within AMPS, which handles each event on a particle-by-particle basis
  and calculates the resulting source terms to the MHD equations. The
  OH-PT model combines the MHD solution for the plasma with the kinetic
  solution for the neutrals to form a self-consistent model of the
  heliosphere. In this work, we present verification and validation of
  the model as well as demonstrate the codes capabilities. Furthermore we
  provide a comparison of the OH-PT model to our multi-fluid approximation
  and detail the differences between the models in both the plasma
  solution and neutral distribution functions.

Title: Modeling of Ion and Photochemical Losses to Space Over the
Martian History: Implications for Exoplanetary Climate Evolution
    and Habitability
Authors: Dong, C. F.; Lee, Y.; Ma, Y. J.; Bougher, S. W.; Luhmann,
   J. G.; Jakosky, B. M.; Curry, S. M.; Brain, D. A.; Toth, G.; Nagy,
   A. F.
Bibcode: 2017LPICo2042.4023D
Altcode:
  This study informs our understanding of the long-term evolution of the
  Martian climate due to atmospheric losses to space, and has implications
  for analogous change on exoplanets. Thus, it offers fresh insights
  concerning the habitability of exoplanets.

Title: Are "Habitable" Exoplanets Really Habitable? A Perspective
    from Atmospheric Loss
Authors: Dong, C. F.; Huang, Z. G.; Jin, M.; Lingam, M.; Ma, Y. J.;
   Toth, G.; van der Holst, B.; Airapetian, V.; Cohen, O.; Gombosi, T.
Bibcode: 2017LPICo2042.4021D
Altcode:
  We will discuss the impact of exoplanetary space weather on the
  climate and habitability, which offers fresh insights concerning the
  habitability of exoplanets, especially those orbiting M-dwarfs, such
  as Proxima b and the TRAPPIST-1 system.

Title: A New 3D Multi-fluid Dust Model: A Study of the Effects
    of Activity and Nucleus Rotation on Dust Grain Behavior at Comet
    67P/Churyumov-Gerasimenko
Authors: Shou, Y.; Combi, M.; Toth, G.; Tenishev, V.; Fougere, N.;
   Jia, X.; Rubin, M.; Huang, Z.; Hansen, K.; Gombosi, T.
Bibcode: 2017ApJ...850...72S
Altcode:
  Improving our capability to interpret observations of cometary dust
  is necessary to deepen our understanding of the role of dust in the
  formation of comets and in altering the cometary environments. Models
  including dust grains are in demand to interpret observations and
  test hypotheses. Several existing models have taken into account the
  gas-dust interaction, varying sizes of dust grains and the cometary
  gravitational force. In this work, we develop a multi-fluid dust
  model based on the BATS-R-US code. This model not only incorporates
  key features of previous dust models, but also has the capability
  of simulating time-dependent phenomena. Since the model is run in
  the rotating comet reference frame, the centrifugal and Coriolis
  forces are included. The boundary conditions on the nucleus surface
  can be set according to the distribution of activity and the solar
  illumination. The Sun revolves around the comet in this frame. A newly
  developed numerical mesh is also used to resolve the real-shaped
  nucleus in the center and to facilitate prescription of the outer
  boundary conditions that accommodate the rotating frame. The inner
  part of the mesh is a box composed of Cartesian cells and the outer
  surface is a smooth sphere, with stretched cells filled in between the
  box and the sphere. Our model achieved comparable results to the Direct
  Simulation Monte Carlo method and the Rosetta/OSIRIS observations. It
  is also applied to study the effects of the rotating nucleus and the
  cometary activity and offers interpretations of some dust observations
  of comet 67P/Churyumov-Gerasimenko.

Title: Venus Ionosphere and Induced Magnetosphere Responses to Solar
    Wind Dynamic Pressure and IMF Direction
Authors: Ma, Yingjuan; Toth, Gabor; Nagy, Andew; Russell, Chris
Bibcode: 2017DPS....4950501M
Altcode:
  In this study, we focus on the responses of the ionosphere and the
  induced magnetosphere of Venus to two typical changes in the solar wind:
  solar wind dynamic pressure changes and the interplanetary magnetic
  field (IMF) direction changes. Often regarded as the Earth’s ‘sister
  planet’, Venus has similar size and mass as Earth. But it is also
  remarkably different from Earth in many respects. Even though we have
  some basic knowledge of the solar wind interaction with Venus based on
  spacecraft observations, little is known about how the interaction
  and the resulting plasma escape rates vary in response to solar
  wind variations due to the lack of coordinated observations of both
  upstream solar wind conditions and simultaneous plasma properties in
  the Venus ionosphere. Furthermore, recent observations suggest that
  plasma escape rates are significantly enhanced during stormy space
  weather in response to solar wind pressure pulses (Edberg et al.,
  2011). Thus it is important to understand the plasma interaction under
  varying solar wind conditions. We use a sophisticated multi-species
  MHD model that has been recently developed for Venus (Ma et al.,
  2013) to characterize the changes of the ionosphere and the induced
  magnetosphere for varying solar wind conditions. Based on model results,
  we discuss the perturbations of the magnetic field in the ionosphere
  and its variation with altitude; the variation of the total plasma
  escape-rate; and the time scale of the Venus ionosphere and induced
  magnetosphere in responding to both types of changes in the solar wind.

Title: Global Three-Dimensional Simulation of Earth's Dayside
    Reconnection Using a Two-Way Coupled Magnetohydrodynamics With
Embedded Particle-in-Cell Model: Initial Results
Authors: Chen, Yuxi; Tóth, Gábor; Cassak, Paul; Jia, Xianzhe;
   Gombosi, Tamas I.; Slavin, James A.; Markidis, Stefano; Peng, Ivy Bo;
   Jordanova, Vania K.; Henderson, Michael G.
Bibcode: 2017JGRA..12210318C
Altcode: 2017arXiv170403803C
  We perform a three-dimensional (3-D) global simulation of Earth's
  magnetosphere with kinetic reconnection physics to study the
  flux transfer events (FTEs) and dayside magnetic reconnection
  with the recently developed magnetohydrodynamics with embedded
  particle-in-cell model. During the 1 h long simulation, the FTEs are
  generated quasi-periodically near the subsolar point and move toward the
  poles. We find that the magnetic field signature of FTEs at their early
  formation stage is similar to a "crater FTE," which is characterized
  by a magnetic field strength dip at the FTE center. After the FTE core
  field grows to a significant value, it becomes an FTE with typical
  flux rope structure. When an FTE moves across the cusp, reconnection
  between the FTE field lines and the cusp field lines can dissipate the
  FTE. The kinetic features are also captured by our model. A crescent
  electron phase space distribution is found near the reconnection
  site. A similar distribution is found for ions at the location where
  the Larmor electric field appears. The lower hybrid drift instability
  (LHDI) along the current sheet direction also arises at the interface of
  magnetosheath and magnetosphere plasma. The LHDI electric field is about
  8 mV/m, and its dominant wavelength relative to the electron gyroradius
  agrees reasonably with Magnetospheric Multiscale (MMS) observations.

Title: Analysis of the ROSINA/COPS end-of-mission measurements of
    the coma of comet 67P/Churyumov-Gerasimenko
Authors: Tenishev, Valeriy; Combi, Michael R.; Fougere, Nicolas;
   Rubin, Martin; Tzou, Chia-Yu; Shou, Yinsi; Gombosi, T. I.; Altwegg,
   Kathrin; Huang, Zhenguang; Toth, Gabor; Hansen, Kenneth C.
Bibcode: 2017DPS....4950905T
Altcode:
  A cometary coma is a unique phenomenon in the Solar system that
  represents an example of a planetary atmosphere influenced by little
  or no gravity. Due to the negligible gravity of a comet’s nucleus, a
  coma has a characteristic size that exceeds that of the nucleus itself
  by many orders of magnitude. An extended dusty gas cloud that forms
  a coma is affected mainly by molecular collisions, radiative cooling,
  and photolytic, charge-exchange, and impact-ionization reactions.Such
  an environment has been extensively observed during the recent Rosetta
  mission, which was the first mission that escorts a comet along its
  way through the Solar system for an extended amount of time with
  the main scientific objectives of characterizing comet’s nucleus,
  determining the surface composition, and studying the comet’s activity
  development.The ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral
  Analysis) Comet Pressure Sensor (COPS) onboard the Rosetta spacecraft
  has performed one of the most exciting observations of the innermost
  coma during the spacecraft descend maneuver during the last ten hours of
  the mission when the random and outflow directed pressures in the coma
  have been measured all the way down to the comet’s surface. Performed
  at such close proximity to the nucleus, these observations can help
  to characterize effects due to topological features and/or the gas
  local conditions at the surface of the nucleus.The major focus of
  the presented study is analyzing of the end-of-mission pressure
  measurements by the ROSINA/COPS instrument. Because the coma at a
  heliocentric distance of 3.8 AU was in a collisionless regime, it
  can be described by solving the Liouville equation, as we have done
  in our analysis. We have used the SHAP5 nucleus model to account
  for the topology of the volatile source. Spacecraft trajectory and
  the instrument pointing with respect to the comet’s nucleus have
  been obtained with the SPICE library. Here, we present results of our
  analysis and discuss the effects of the surface topology and that of
  the local surface volatile injection on the distribution of gas in
  the innermost coma of comet 67P/Churyumov-Gerasimenko.

Title: Surface Activity Distributions of Comet
    67P/Churyumov-Gerasimenko Derived from VIRTIS Images
Authors: Fougere, Nicolas; Combi, Michael R.; Tenishev, Valeriy;
   Migliorini, Alessandra; Bockelee-Morvan, Dominique; Fink, Uwe;
   Filacchione, Gianrico; Rinaldi, Giovanna; Capaccioni, Fabrizio; Toth,
   Gabor; Gombosi, T. I.; Hansen, Kenneth C.; Huang, Zhenguang; Shou,
   Yinsi; VIRTIS Team
Bibcode: 2017DPS....4941501F
Altcode:
  The outgassing mechanism of comets still remains a critical question
  to better understand these objects. The Rosetta mission gave some
  insight regarding the potential activity distribution from the
  surface of the nucleus of comet 67P/Churyumov-Gerasimenko, Fougere
  et al. (2016, Astronomy &amp; Astrophysics, Volume 588, id.A134, 11
  pp and Monthly Notices of the Royal Astronomical Society, Volume 462,
  Issue Suppl_1, p.S156-S169) used a spherical harmonics inversion scheme
  with in-situ measurements from the ROSINA instrument to derive mapping
  of the broad distribution of potential activity at the surface of the
  nucleus. Marschall et al. (2016, Astronomy &amp; Astrophysics, doi:
  10.1051/0004-6361/201730849) based on the appearance of dust active
  areas suggested that the so-called “neck” region and regions with
  fractured cliffs and locally steep slopes show more activity than the
  rest of comet 67P’s nucleus. Using in situ ROSINA measurements from a
  distance makes it difficult to distinguish between these two scenarios
  because the fast expansion of the gas and large molecular mean free
  paths prevents distinguishing small outgassing features even when the
  spacecraft was in bound orbits within 10 km from the nucleus. In this
  paper, we present a similar numerical inversion approach using VIRTIS
  images, which should better probe the very inner coma of comet 67P and
  give more detailed information about the outgassing activity. Support
  from contracts JPL #1266314 and #1266313 from the US Rosetta Project
  and grant NNX14AG84G from the NASA Planetary Atmospheres Program are
  gratefully acknowledged.

Title: Scaling the Ion Inertial Length and Its Implications for
    Modeling Reconnection in Global Simulations
Authors: Tóth, Gábor; Chen, Yuxi; Gombosi, Tamas I.; Cassak, Paul;
   Markidis, Stefano; Peng, Ivy Bo
Bibcode: 2017JGRA..12210336T
Altcode:
  We investigate the use of artificially increased ion and electron
  kinetic scales in global plasma simulations. We argue that as long
  as the global and ion inertial scales remain well separated, (1) the
  overall global solution is not strongly sensitive to the value of the
  ion inertial scale, while (2) the ion inertial scale dynamics will also
  be similar to the original system, but it occurs at a larger spatial
  scale, and (3) structures at intermediate scales, such as magnetic
  islands, grow in a self-similar manner. To investigate the validity and
  limitations of our scaling hypotheses, we carry out many simulations
  of a two-dimensional magnetosphere with the magnetohydrodynamics with
  embedded particle-in-cell (MHD-EPIC) model. The PIC model covers
  the dayside reconnection site. The simulation results confirm that
  the hypotheses are true as long as the increased ion inertial length
  remains less than about 5% of the magnetopause standoff distance. Since
  the theoretical arguments are general, we expect these results to
  carry over to three dimensions. The computational cost is reduced
  by the third and fourth powers of the scaling factor in two- and
  three-dimensional simulations, respectively, which can be many orders
  of magnitude. The present results suggest that global simulations
  that resolve kinetic scales for reconnection are feasible. This is a
  crucial step for applications to the magnetospheres of Earth, Saturn,
  and Jupiter and to the solar corona.

Title: The Dehydration of Water Worlds via Atmospheric Losses
Authors: Dong, Chuanfei; Huang, Zhenguang; Lingam, Manasvi; Tóth,
   Gábor; Gombosi, Tamas; Bhattacharjee, Amitava
Bibcode: 2017ApJ...847L...4D
Altcode: 2017arXiv170901219D
  We present a three-species multi-fluid magnetohydrodynamic model
  (H<SUP>+</SUP>, H<SUB>2</SUB>O<SUP>+</SUP>, and e <SUP>-</SUP>),
  endowed with the requisite atmospheric chemistry, that is capable
  of accurately quantifying the magnitude of water ion losses from
  exoplanets. We apply this model to a water world with Earth-like
  parameters orbiting a Sun-like star for three cases: (I) current normal
  solar wind conditions, (II) ancient normal solar wind conditions,
  and (III) one extreme “Carrington-type” space weather event. We
  demonstrate that the ion escape rate for (II), with a value of 6.0 ×
  10<SUP>26</SUP> s<SUP>-1</SUP>, is about an order of magnitude higher
  than the corresponding value of 6.7 × 10<SUP>25</SUP> s<SUP>-1</SUP>
  for (I). Studies of ion losses induced by space weather events, where
  the ion escape rates can reach ∼10<SUP>28</SUP> s<SUP>-1</SUP>,
  are crucial for understanding how an active, early solar-type star
  (e.g., with frequent coronal mass ejections) could have accelerated
  the depletion of the exoplanet’s atmosphere. We briefly explore
  the ramifications arising from the loss of water ions, especially
  for planets orbiting M-dwarfs where such effects are likely to be
  significant.

Title: Noether's theorems and conserved currents in gauge theories
    in the presence of fixed fields
Authors: Tóth, Gábor Zsolt
Bibcode: 2017PhRvD..96b5018T
Altcode: 2016arXiv161003281T
  We extend the standard construction of conserved currents for
  matter fields in general relativity to general gauge theories. In
  the original construction, the conserved current associated with
  a spacetime symmetry generated by a Killing field h<SUP>μ</SUP>
  is given by √{-g }T<SUP>μ ν</SUP>h<SUB>ν</SUB> , where T<SUP>μ
  ν</SUP> is the energy-momentum tensor of the matter. We show that if
  in a Lagrangian field theory that has gauge symmetry in the general
  Noetherian sense some of the elementary fields are fixed and are
  invariant under a particular infinitesimal gauge transformation, then
  there is a current B<SUP>μ</SUP> that is analogous to √{-g }T<SUP>μ
  ν</SUP>h<SUB>ν</SUB> and is conserved if the nonfixed fields satisfy
  their Euler-Lagrange equations. The conservation of B<SUP>μ</SUP>
  can be seen as a consequence of an identity that is a generalization of
  ∇<SUB>μ</SUB>T<SUP>μ ν</SUP>=0 and is a consequence of the gauge
  symmetry of the Lagrangian. This identity holds in any configuration of
  the fixed fields if the nonfixed fields satisfy their Euler-Lagrange
  equations. We also show that B<SUP>μ</SUP> differs from the relevant
  canonical Noether current by the sum of an identically conserved current
  and a term that vanishes if the nonfixed fields are on shell. For an
  example, we discuss the case of general, possibly fermionic, matter
  fields propagating in fixed gravitational and Yang-Mills background. We
  find that in this case the generalization of ∇<SUB>μ</SUB>T<SUP>μ
  ν</SUP>=0 is the Lorentz law ∇<SUB>μ</SUB>T<SUP>μ ν</SUP>-F<SUP>a
  ν λ</SUP>J<SUB>a λ</SUB>=0 , which holds as a consequence of the
  diffeomorphism, local Lorentz and Yang-Mills gauge symmetry of the
  matter Lagrangian. For a second simple example, we consider the case
  of general fields propagating in a background that consists of a
  gravitational and a real scalar field.

Title: Spectral Analysis of Heating Processes in the Alfvén Wave
    Driven Global Corona Model
Authors: Szente, Judit; Toth, Gabor; Landi, Enrico; Manchester, Ward;
   van der Holst, Bart; Gombosi, Tamas
Bibcode: 2017shin.confE..78S
Altcode:
  Among numerous theories explaining the existence of the hot solar
  corona and continuous solar wind, one of the most successful one is
  based on wave heating. This approach describes Alfvén waves traveling
  along the magnetic field lines carrying sufficient energy to heat the
  corona and accelerate the solar wind. The wave energy is deposited
  through turbulent dissipation, which leaves identifiable traces in the
  plasma. Spectral observations have suggested the existence of wave
  heating: via the decrease of non-thermal spectral line broadening,
  and via charge state ratios of specific minor-ions reflecting the
  heating history of the solar wind plasma. We determine the extent
  to which Alfvén-waves drive the solar corona using a combination of
  spectral modeling and observational techniques. <P />In this study,
  we reevaluate observational evidence of the coronal heating process:
  we simulate observations of the global corona and its spectral line
  emission with the Alfvén Wave Solar Model (AWSoM) and compare the
  synthetic data with observations.

Title: Consequences of treating the solar magnetic field as a dipole
    on the global structure of the heliosphere and an update on the
    OH-PT model
Authors: Michael, Adam Thomas; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Borovikov, Dmitry
Bibcode: 2017shin.confE.168M
Altcode:
  Through the use of numerical models, we have begun to realize the
  importance the solar magnetic field has on the heliosphere. The aim
  of all outer heliosphere simulations is to accurately model the solar
  magnetic field, including a self-consistent approach to the heliospheric
  current sheet. We investigate the effect that including the heliospheric
  current sheet has on our global 3D MHD model of the heliosphere. We
  compare the unipolar model, where the polarity of the Parker spiral
  is the same in both hemispheres, to the dipole description of the
  solar magnetic field with the magnetic and rotational axes aligned
  forming a flat heliospheric current sheet, defined as a discontinuity
  between polarities. The flat current sheet is pulled into the northern
  hemisphere, avoiding the stagnation region, and reduces the magnetic
  field strength at the Voyager 1 trajectory over the last 22.5% of the
  heliosheath. The decrease in magnetic field intensity is transferred
  into the thermal energy of the plasma causing the dipole model to
  predict an entirely thermally dominated heliosheath, a stark contrast
  to the magnetically dominated region ahead of the heliopause in the
  unipole model. The jet that forms within the current sheet increases
  the radial velocity and ram pressure just downstream of the heliopause
  causing the heliopause to be asymmetric and located further in the
  northern hemisphere. We find that the two-lobe structure of the solar
  wind magnetic field persists within the dipole model with the flat
  current sheet not able to fully erode the magnetic tension force. We
  also present an update of the OH-PT model within SWMF. The OH-PT model
  is a kinetic-MHD model that couples the BATS-R-US MHD solver to AMPS,
  a DSMC code used to solve the Boltzmann equation for the distribution
  function of the neutrals and energetic neutral atoms streaming through
  the heliosphere.

Title: Calculating the inductive electric field in the terrestrial
    magnetosphere
Authors: Ilie, Raluca; Daldorff, Lars K. S.; Liemohn, Michael W.;
   Toth, Gabor; Chan, Anthony A.
Bibcode: 2017JGRA..122.5391I
Altcode:
  This study presents a theoretical approach to calculate the inductive
  electric field, and it is further applied to global MHD simulations
  of the magnetosphere. The contribution of the inductive component to
  the total electric field is found by decomposing the motional electric
  field into a superposition of an irrotational and a solenoidal vector
  and assuming that the time-varying magnetic field vanishes on the
  boundary. We find that a localized change in the magnetic field
  generates an inductive electric field whose effect extends over all
  space, meaning that the effect of the inductive electric field is global
  even if the changes in the magnetic field are localized. Application
  of this formalism to disturbed times provides strong evidence that
  during periods of increased activity the electric field induced
  by the localized change in magnetic field can be comparable to (or
  larger than) the potential electric fields in certain regions. This
  induced field exhibits significant spatial and temporal variations,
  which means that particles that drift into different regions of space
  are being exposed to different means of acceleration. These results
  suggest that the inductive electric field could have a substantial
  contribution to particle energization in the near-Earth region even
  though the changes in the magnetic fields occur at distances of several
  tens of Earth radii. This finding is particularly important for ring
  current modeling which in many cases excludes inductive contributions
  to the total particle drift.

Title: Effects of electric field methods on modeling the midlatitude
    ionospheric electrodynamics and inner magnetosphere dynamics
Authors: Yu, Yiqun; Jordanova, Vania K.; Ridley, Aaron J.; Toth,
   Gabor; Heelis, Roderick
Bibcode: 2017JGRA..122.5321Y
Altcode:
  We report a self-consistent electric field coupling between the
  midlatitude ionospheric electrodynamics and inner magnetosphere dynamics
  represented in a kinetic ring current model. This implementation in
  the model features another self-consistency in addition to its already
  existing self-consistent magnetic field coupling with plasma. The
  model is therefore named as Ring current-Atmosphere interaction
  Model with Self-Consistent magnetic (B) and electric (E) fields,
  or RAM-SCB-E. With this new model, we explore, by comparing with
  previously employed empirical Weimer potential, the impact of using
  self-consistent electric fields on the modeling of storm time global
  electric potential distribution, plasma sheet particle injection,
  and the subauroral polarization streams (SAPS) which heavily rely on
  the coupled interplay between the inner magnetosphere and midlatitude
  ionosphere. We find the following phenomena in the self-consistent
  model: (1) The spatially localized enhancement of electric field is
  produced within 2.5 &lt; L &lt; 4 during geomagnetic active time in the
  dusk-premidnight sector, with a similar dynamic penetration as found in
  statistical observations. (2) The electric potential contours show more
  substantial skewing toward the postmidnight than the Weimer potential,
  suggesting the resistance on the particles from directly injecting
  toward the low-L region. (3) The proton flux indeed indicates that the
  plasma sheet inner boundary at the dusk-premidnight sector is located
  further away from the Earth than in the Weimer potential, and a "tongue"
  of low-energy protons extends eastward toward the dawn, leading to
  the Harang reversal. (4) SAPS are reproduced in the subauroral region,
  and their magnitude and latitudinal width are in reasonable agreement
  with data.

Title: Variability of Jupiter's IR H<SUB>3</SUB><SUP>+</SUP> aurorae
    during Juno approach
Authors: Moore, L.; O'Donoghue, J.; Melin, H.; Stallard, T.; Tao,
   C.; Zieger, B.; Clarke, J.; Vogt, M. F.; Bhakyapaibul, T.; Opher,
   M.; Tóth, G.; Connerney, J. E. P.; Levin, S.; Bolton, S.
Bibcode: 2017GeoRL..44.4513M
Altcode:
  We present ground-based observations of Jupiter's
  H<SUB>3</SUB><SUP>+</SUP> aurorae over four nights in April 2016
  while the Juno spacecraft was monitoring the upstream interplanetary
  magnetic field. High-precision maps of auroral H<SUB>3</SUB><SUP>+</SUP>
  densities, temperatures, and radiances reveal significant variabilities
  in those parameters, with regions of enhanced density and emission
  accompanied by reduced temperature. Juno magnetometer data,
  combined with solar wind propagation models, suggest that a shock
  may have impacted Jupiter in the days preceding the observation
  interval but that the solar wind was quiescent thereafter. Auroral
  H<SUB>3</SUB><SUP>+</SUP> temperatures reveal a downward temporal trend,
  consistent with a slowly cooling upper atmosphere, such as might follow
  a period of shock recovery. The brightest H<SUB>3</SUB><SUP>+</SUP>
  emissions are from the end of the period, 23 April. A lack of
  definitive signatures in the upstream interplanetary magnetic field
  lends supporting evidence to the possibility that this brightening
  event may have been driven by internal magnetospheric processes.

Title: MHD Coupling with PIC to Study the Magnetic Reconnection
    Process in the Martian Plasma Tail
Authors: Ma, Yingjuan; Russell, Christopher; Toth, Gabor; Chen,
   Yuki; Nagy, Andrew; Harada, Yuki; McFadden, James; Halekas, Jasper;
   Connerney, Jack; Jakosky, Bruce; Markidis, Stefano; Peng, Ive
Bibcode: 2017EGUGA..1910180M
Altcode:
  Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) observations
  showed clear evidence that magnetic reconnection happens in the Martian
  plasma tail. We use both the HALL MHD model and the two-way coupled
  MHD-PIC model to study a MAVEN magnetotail reconnection event based
  on the observed solar wind conditions to understand the reconnection
  process and quantify its global consequences. The coupled approach takes
  advantage of both MHD and PIC models, making it feasible to conduct
  kinetic simulations under realistic solar wind conditions. Model results
  show that the Martian magnetotail is highly dynamic and the Marsward
  plasma flow velocities due to magnetic reconnection are higher for
  the lighter ion fluid, which are quantatively consistent with MAVEN
  observations. The effect of the magnetic reconnection on the total
  ion loss rate will also be discussed based on model results.

Title: The Twist of the Draped Interstellar Magnetic Field Ahead
of the Heliopause: A Magnetic Reconnection Driven Rotational
    Discontinuity
Authors: Opher, M.; Drake, J. F.; Swisdak, M.; Zieger, B.; Toth, G.
Bibcode: 2017ApJ...839L..12O
Altcode: 2017arXiv170206178O
  Based on the difference between the orientation of the interstellar B
  <SUB>ISM</SUB> and the solar magnetic fields, there was an expectation
  that the magnetic field direction would rotate dramatically across
  the heliopause (HP). However, the Voyager 1 spacecraft measured
  very little rotation across the HP. Previously, we showed that the B
  <SUB>ISM</SUB> twists as it approaches the HP and acquires a strong
  T component (east-west). Here, we establish that reconnection in the
  eastern flank of the heliosphere is responsible for the twist. On the
  eastern flank the solar magnetic field has twisted into the positive N
  direction and reconnects with the southward pointing component of the
  B <SUB>ISM</SUB>. Reconnection drives a rotational discontinuity (RD)
  that twists the B <SUB>ISM</SUB> into the -T direction and propagates
  upstream in the interstellar medium toward the nose. The consequence is
  that the N component of B <SUB>ISM</SUB> is reduced in a finite width
  band upstream of the HP. Voyager 1 currently measures angles (δ ={\sin
  }<SUP>-1</SUP>({B}<SUB>N</SUB>/B)) close to solar values. We present MHD
  simulations to support this scenario, suppressing reconnection in the
  nose region while allowing it in the flanks, consistent with recent
  ideas about reconnection suppression from diamagnetic drifts. The
  jump in plasma β (the plasma to magnetic pressure) across the nose
  of HP is much greater than in the flanks because the heliosheath β is
  greater there than in the flanks. Large-scale reconnection is therefore
  suppressed in the nose but not at the flanks. Simulation data suggest
  that B <SUB>ISM</SUB> will return to its pristine value 10-15 au past
  the HP.

Title: Variations of the Martian plasma environment during the ICME
passage on 8 March 2015: A time-dependent MHD study
Authors: Ma, Y. J.; Russell, C. T.; Fang, X.; Dong, C. F.; Nagy,
   A. F.; Toth, G.; Halekas, J. S.; Connerney, J. E. P.; Espley, J. R.;
   Mahaffy, P. R.; Benna, M.; McFadden, J.; Mitchell, D. L.; Andersson,
   L.; Jakosky, B. M.
Bibcode: 2017JGRA..122.1714M
Altcode:
  The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft observed
  a strong interplanetary coronal mass ejection (ICME) impacting Mars on
  8 March 2015. We use a time-dependent global MHD model to investigate
  the response of the Martian ionosphere and induced magnetosphere to the
  large solar wind disturbance associated with the ICME. Taking observed
  upstream solar wind conditions from MAVEN as inputs to the MHD model,
  the variations of the Martian plasma environments are simulated
  realistically in a time period from 2.5 h prior to the arrival of
  the ICME shock to about 12 h after the impact. Detailed comparisons
  between the model results and the relevant MAVEN plasma measurements
  are presented, which clearly show that the time-dependent multispecies
  single-fluid MHD model is able to reproduce the main features observed
  by the spacecraft during the ICME passage. Model results suggest
  that the induced magnetosphere responds to solar wind variation on
  a very short time scale (approximately minutes). The variations of
  the plasma boundaries' distances from the planet along the subsolar
  line are examined in detail, which show a clear anticorrelation with
  the magnetosonic Mach number. Plasma properties in the ionosphere
  (especially the induced magnetic field) varied rapidly with solar
  wind changes. Model results also show that ion escape rates could be
  enhanced by an order of magnitude in response to the high solar wind
  dynamic pressure during the ICME event.

Title: Coronal Jets Simulated with the Global Alfvén Wave Solar Model
Authors: Szente, J.; Toth, G.; Manchester, W. B., IV; van der Holst,
   B.; Landi, E.; Gombosi, T. I.; DeVore, C. R.; Antiochos, S. K.
Bibcode: 2017ApJ...834..123S
Altcode:
  This paper describes a numerical modeling study of coronal jets to
  understand their effects on the global corona and their contribution
  to the solar wind. We implement jets into a well-established
  three-dimensional, two-temperature magnetohydrodynamic (MHD) solar
  corona model employing Alfvén-wave dissipation to produce a realistic
  solar-wind background. The jets are produced by positioning a compact
  magnetic dipole under the solar surface and rotating the boundary plasma
  around the dipole's magnetic axis. The moving plasma drags the magnetic
  field lines along with it, ultimately leading to a reconnection-driven
  jet similar to that described by Pariat et al. We compare line-of-sight
  synthetic images to multiple jet observations at EUV and X-ray
  bands, and find very close matches in terms of physical structure,
  dynamics, and emission. Key contributors to this agreement are the
  greatly enhanced plasma density and temperature in our jets compared
  to previous models. These enhancements arise from the comprehensive
  thermodynamic model that we use and, also, our inclusion of a dense
  chromosphere at the base of our jet-generating regions. We further
  find that the large-scale corona is affected significantly by the
  outwardly propagating torsional Alfvén waves generated by our polar
  jet, across 40° in latitude and out to 24 R<SUB>⊙</SUB>. We estimate
  that polar jets contribute only a few percent to the steady-state
  solar-wind energy outflow.

Title: Chromosphere to 1 AU Simulation of the 2011 March 7th Event:
    A Comprehensive Study of Coronal Mass Ejection Propagation
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
   Tóth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
Bibcode: 2017ApJ...834..172J
Altcode: 2016arXiv161108897J
  We perform and analyze the results of a global magnetohydrodynamic
  simulation of the fast coronal mass ejection (CME) that occurred
  on 2011 March 7. The simulation is made using the newly developed
  Alfvén Wave Solar Model (AWSoM), which describes the background
  solar wind starting from the upper chromosphere and extends to
  24 R<SUB>⊙</SUB>. Coupling AWSoM to an inner heliosphere model
  with the Space Weather Modeling Framework extends the total domain
  beyond the orbit of Earth. Physical processes included in the model
  are multi-species thermodynamics, electron heat conduction (both
  collisional and collisionless formulations), optically thin radiative
  cooling, and Alfvén-wave turbulence that accelerates and heats the
  solar wind. The Alfvén-wave description is physically self-consistent,
  including non-Wentzel-Kramers-Brillouin reflection and physics-based
  apportioning of turbulent dissipative heating to both electrons and
  protons. Within this model, we initiate the CME by using the Gibson-Low
  analytical flux rope model and follow its evolution for days, in which
  time it propagates beyond STEREO A. A detailed comparison study is
  performed using remote as well as in situ observations. Although the
  flux rope structure is not compared directly due to lack of relevant
  ejecta observation at 1 au in this event, our results show that the
  new model can reproduce many of the observed features near the Sun
  (e.g., CME-driven extreme ultraviolet [EUV] waves, deflection of the
  flux rope from the coronal hole, “double-front” in the white light
  images) and in the heliosphere (e.g., shock propagation direction,
  shock properties at STEREO A).

Title: Data-constrained Coronal Mass Ejections in a Global
    Magnetohydrodynamics Model
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
   Tóth, G.; Mullinix, R. E.; Taktakishvili, A.; Chulaki, A.; Gombosi,
   T. I.
Bibcode: 2017ApJ...834..173J
Altcode: 2016arXiv160505360J
  We present a first-principles-based coronal mass ejection (CME)
  model suitable for both scientific and operational purposes by
  combining a global magnetohydrodynamics (MHD) solar wind model with
  a flux-rope-driven CME model. Realistic CME events are simulated
  self-consistently with high fidelity and forecasting capability by
  constraining initial flux rope parameters with observational data from
  GONG, SOHO/LASCO, and STEREO/COR. We automate this process so that
  minimum manual intervention is required in specifying the CME initial
  state. With the newly developed data-driven Eruptive Event Generator
  using Gibson-Low configuration, we present a method to derive Gibson-Low
  flux rope parameters through a handful of observational quantities so
  that the modeled CMEs can propagate with the desired CME speeds near
  the Sun. A test result with CMEs launched with different Carrington
  rotation magnetograms is shown. Our study shows a promising result
  for using the first-principles-based MHD global model as a forecasting
  tool, which is capable of predicting the CME direction of propagation,
  arrival time, and ICME magnetic field at 1 au (see the companion paper
  by Jin et al. 2016a).

Title: A new 3D multi-fluid dust model: a study of the effects of
    activity and nucleus rotation on the dust grains' behavior in the
    cometary environment
Authors: Shou, Y.; Combi, M. R.; Toth, G.; Fougere, N.; Tenishev,
   V.; Huang, Z.; Jia, X.; Hansen, K. C.; Gombosi, T. I.; Bieler, A. M.;
   Rubin, M.
Bibcode: 2016AGUFM.P43A2099S
Altcode:
  Cometary dust observations may deepen our understanding of the role
  of dust in the formation of comets and in altering the cometary
  environment. Models including dust grains are in demand to interpret
  observations and test hypotheses. Several existing models have taken
  into account the gas-dust interaction, varying sizes of dust grains and
  the cometary gravitational force. In this work, we develop a multi-fluid
  dust model based on BATS-R-US in the University of Michigan's Space
  Weather Modeling Framework (SWMF). This model not only incorporates
  key features of previous dust models, but also has the capability
  of simulating time-dependent phenomena. Since the model is running
  in the rotating comet reference frame with a real shaped nucleus in
  the computational domain, the fictitious centrifugal and Coriolis
  forces are included. The boundary condition on the nucleus surface
  can be set according to the distribution of activity and the solar
  illumination. The Sun, which drives sublimation and the radiation
  pressure force, revolves around the comet in this frame. A newly
  developed numerical mesh is also used to resolve the real shaped nucleus
  in the center and to facilitate prescription of the outer boundary
  conditions that accommodate the rotating frame. The inner part of the
  grid is a box composed of Cartesian cells and the outer surface is a
  smooth sphere, with stretched cells filled in between the box and the
  sphere. The effects of the rotating nucleus and the activity region on
  the surface are discussed and preliminary results are presented. This
  work has been partially supported by grant NNX14AG84G from the NASA
  Planetary Atmospheres Program, and US Rosetta contracts JPL #1266313,
  JPL #1266314 and JPL #1286489.

Title: Increased electron pressure as possible origin of magnetic
    field dropouts observed by RPC-MAG of comet 67P/Churyumov-Gerasimenko
Authors: Huang, Z.; Toth, G.; Gombosi, T. I.; Bieler, A. M.; Combi,
   M. R.; Hansen, K. C.; Jia, X.; Fougere, N.; Shou, Y.; Cravens, T.;
   Tenishev, V.; Altwegg, K.; Rubin, M.
Bibcode: 2016AGUFM.P43A2091H
Altcode:
  The Rosetta Plasma Consortium MAGnetometer (RPC-MAG) has observed
  signatures of magnetic field dropouts in the inner coma region of comet
  67P/Churyumov-Gerasimenko at distances from 30km to 400km, which is
  larger than what has been predicted by numerical simulations of the
  cometary plasma environment. It is still unclear how these magnetic
  field dropouts form in the inner coma region. In the present work, we
  use our newly developed multi-fluid plasma-neutral interaction model
  (Huang et al. 2016) to investigate this problem. The model solves the
  governing multi-ion MHD equations for the cometary and solar wind ions
  and electrons, and the Euler equations for the neutral gas fluid. We
  show that a strong local increase of electron pressure is capable
  to generate the features of the magnetic field dropouts observed by
  RPC-MAG: the simulation results show that a low magnetic field region
  is formed and the recovery phase of the magnetic field magnitude is
  faster than the declining phase, which suggests that the mechanism
  proposed here based on localized enhancement of electron pressure may
  provide a possible explanation for the unusually large distance of
  the observed magnetic field dropouts.

Title: How Numerical Magnetic Dissipation at the Heliospheric
    Current Sheet Affects Model Predictions at Voyager 1 and Results
    from a Kinetic-MHD Model of the Heliosphere within SWMF
Authors: Michael, A.; Opher, M.; Toth, G.; Borovikov, D.; Tenishev,
   V.; Provornikova, E.
Bibcode: 2016AGUFMSH41C2544M
Altcode:
  Several studies suggest that there is a need to move beyond ideal MHD
  in order to explain the Voyager 1 and 2 observations (Richardson et
  al. 2013; Michael et al. 2015). In the numerical simulations there
  is inherent and unavoidable numerical dissipation in the heliospheric
  current sheet that greatly exceeds the realistic dissipation rates. The
  magnetic dissipation inherent in modeling the heliospheric current
  sheet offers us a chance to explore non-ideal MHD effects in the
  heliosphere and heliosheath. In this work we investigate the role
  magnetic dissipation has on the overall structure of the heliosheath
  by comparing models describing the solar magnetic field both as a
  unipole and a dipole. We show that magnetic dissipation reduces the
  solar wind magnetic field strength over a significant fraction of
  the heliosheath. The region affected by the dissipation is increased
  when 11-year solar cycle variations in the solar wind are included
  and we discuss how this alters our prediction for Voyager 1 and 2
  observations. We also present a new kinetic-MHD model of the outer
  heliosphere, which couples the Outer Heliosphere (OH) and Particle
  Tracker (PT) components within the Space Weather Modeling Framework
  (SWMF). The OH component uses the BATS-R-US MHD solver, a highly
  parallel, 3D, and block-adaptive code. The PT component is based on the
  Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct simulation
  Monte Carlo model that solves the Boltzmann equation for the motion and
  interaction of a multi-species gas within a plasma. The neutrals and
  plasma in the outer heliosphere are coupled through charge-exchange;
  the OH-PT model combines the MHD solution for the plasma with the
  kinetic solution for the neutrals to form a self-consistent model
  of the heliosphere. We present preliminary results of this model and
  discuss the implications on the structure of the heliosphere.

Title: Multi-fluid MHD study of the solar wind interaction with Pluto
Authors: Dong, C.; Ma, Y.; McComas, D. J.; Bhattacharjee, A.;
   Zirnstein, E.; Toth, G.; Luhmann, J. G.; Wang, L.
Bibcode: 2016AGUFMSM51E2558D
Altcode:
  The study of the solar wind interaction with Pluto's upper atmosphere
  has triggered a great of interest in recent years. The Solar Wind
  Around Pluto (SWAP) instrument onboard New Horizon (NH) spacecraft
  has provided a wealth of detailed and quantitative information about
  Pluto and its interaction with the tenuous solar wind out at 33 AU. The
  SWAP data reveals Pluto's unique interaction with the solar wind as a
  hybrid of comet-like and the Venus/Mars-like interactions. While SWAP
  data has provided many of the key results, a lot of details are still
  missing merely based on NH flyby observations. In order to further
  investigate the solar wind-Pluto interaction from a global point of
  view, we develop a 3-D multi-fluid MHD (MF-MHD) model. The MF-MHD
  model solves separate continuity, momentum and energy equations for
  each ion species. We adopt the 1-D modeled neutral atmosphere, which
  is based on NH observations, as the MF-MHD input. Photoionization,
  charge exchange and electron impact ionization are all included in
  the MF-MHD model. We will study the ion escape rate, and Pluto's
  magnetosphere and heavy ion tail structure. We will also do some
  data-model comparisons. This work has the potential to improve our
  understanding of present day Pluto's unique solar wind interaction
  and thus enhance the science returned from the NH mission.

Title: Probing the nature of pick-up ions (and kappa distribution)
    in the heliosheath through global ENA measurements and in-situ
    measurements
Authors: Opher, M.; Zieger, B.; Drake, J. F.; Kornbleuth, M. Z.;
   Toth, G.
Bibcode: 2016AGUFMSH13D..01O
Altcode:
  Both Voyager and IBEX are providing us with an un-precedent view of
  the nature of the heliosheath through in situ and global ENA maps. Both
  their measurements indicated that the thermodynamic of the heliosheath
  is dominated by the presence of pick-up ions (PUIs). Kappa distributions
  are routinely used to capture the presence of PUIs. Recently we
  investigated the nature of the crossing of the termination shock
  by the presence of the pick-up ions (Zieger et al. 2015). We were
  able to constrain the properties of the PUI in the heliosheath by
  matching the Voyager observations to the properties of the non-linear
  structures created by the multi-fluid nature of the solar wind called
  "oscilliton". Here we will review these results as well as our recent
  effort on understanding the nature of the turbulence of the heliosheath
  by the presence of pick-up ions. We will review as well our recent
  proposed scenario where that the structure of the heliosphere might be
  very different than we previously thought (Opher et al. 2015). We showed
  (Opher et al. 2015, Drake et al. 2015) that the magnetic tension of the
  solar magnetic field plays a crucial role on organizing the solar wind
  in the heliosheath into two jet-like structures. The global ENA maps
  provide another window in constraining the pick-up ions and heating
  in the heliosheath (Opher et al. 2013). We will discuss the resultant
  maps from the "heliosphere with jets" and the constrains on the nature
  of the pick-up ions in the heliosheath.

Title: Validation of 2D and 3D MHD with embedded PIC (MHD-EPIC)
    simulations against MMS observations
Authors: Chen, Y.; Toth, G.; Gombosi, T. I.; Markidis, S.; Peng,
   I. B.; Cassak, P.; Hietala, H.
Bibcode: 2016AGUFMSM14B..06C
Altcode:
  We carry out 2D and 3D global simulations of Earth's magnetosphere with
  the recently developed MHD-EPIC model, which is a two-way coupling of
  the extended magnetohydrodynamic (XMHD) code BATS-R-US with the implicit
  Particle-in-Cell (PIC) model iPIC3D. The PIC model covers both the
  dayside and tail reconnection regions, while the global Hall MHD code
  handles the rest of the computational domain. We use several 2D global
  simulations to demonstrate that the size and dynamics of flux ropes
  at the dayside do not depend on either ion mass or grid resolution as
  long as the MHD quantities are fixed. Increasing the ion mass allows
  the kinetic physics to be resolved with reasonable computational
  resources. Similar to the MMS observations, the crescent-shape electron
  phase space distribution is found near the reconnection site in the
  global 2D simulations. The tail reconnection site is also covered
  by PIC model for these 2D cases. The difference between the dayside
  reconnection and the tail reconnection is compared. We also carry out
  3D MHD-EPIC global simulations for MMS events with varying solar wind
  conditions. Since MHD-EPIC simulations provide both electron and ion
  information, we can compare the kinetic property of particles with
  MMS observation besides electromagnetic fields.

Title: Effects of Induction and Magnetopause Reconnection on Mercury's
Magnetosphere: MESSENGER Observations and Global MHD Simulations
    with Coupled Planetary Interior
Authors: Jia, X.; Slavin, J. A.; Poh, G.; Toth, G.; Gombosi, T. I.
Bibcode: 2016AGUFMSM41C2455J
Altcode:
  It has long been suggested that two processes, i.e., erosion of the
  dayside magnetosphere due to strong magnetopause reconnection and the
  shielding effect of the induction currents at the planetary core,
  compete against each other in governing the structure of Mercury's
  magnetosphere. We have combined analysis of MESSENGER data during
  extreme solar wind conditions with global MHD simulations to assess
  the relative importance of the two processes. Following the study of
  Slavin et al. (2014), we have analyzed an additional set of MESSENGER
  magnetopause crossings to determine the dependence of the magnetopause
  standoff distance on solar wind parameters. We have also employed
  the global MHD model of Jia et al. (2015) that electromagnetically
  couples Mercury's interior to the surrounding space environment
  to simulate the response of the system to solar wind forcing for a
  wide range of solar wind and IMF conditions. We find that while the
  magnetopause standoff distance decreases with increasing solar wind
  pressure, just as expected, its dependence on the external pressure
  follows closely a power-law relationship with an index of -1/6,
  rather than a steeper power-law falling-off expected for the case
  with only induction present. Our results suggest that for the external
  conditions examined, induction and magnetopause reconnection appear to
  play equally important roles in determining the global configuration
  of Mercury's magnetosphere, consistent with the finding obtained by
  Slavin et al. (2014). We also find that the magnetospheric current
  systems produce magnetic perturbations that are spatially non-uniform in
  nature, resulting in induced magnetic field at the core that contains
  significant power in both the dipole and high order moments. Based
  on the simulation results, we determine how the induced field varies
  with the solar wind conditions, and provide quantitative constraints
  on the ability of Mercury's core to shield the planetary surface from
  direct solar wind impact.

Title: MHD Modeling of Jupiter's Magnetosphere using the Space
Weather Modeling Framework (SWMF): Preliminary Results
Authors: Sarkango, Y.; Jia, X.; Toth, G.; Hansen, K. C.
Bibcode: 2016AGUFMSM51E2532S
Altcode:
  Jupiter's magnetosphere is driven predominantly by its rapid
  rotation and high rate of internal plasma loading arising from the
  moon, Io. Modeling this system using magnetohydrodynamics (MHD)
  provides a means to understand magnetospheric dynamics from a global
  perspective. However, MHD modeling of Jupiter's magnetosphere is
  computationally challenging mainly due to the system size and the
  large wave speeds close to the planet. Using the Space Weather Modeling
  Framework, we have modeled the Jovian magnetosphere with a single-fluid
  approach and a combined explicit and implicit scheme that enables large
  time steps making it feasible to simulate the magnetosphere for long
  periods of time at acceptable computational cost. Unlike previous MHD
  models that assume the magnetic dipole to be aligned with the spin axis,
  our model includes the 10° tilt of Jupiter's dipole in order to capture
  the periodic modulations driven by this non-axisymmetric internal
  field, one of the fundamental features of the Jovian magnetosphere. Our
  simulation also includes effects of mass loading based on an empirical
  neutral gas distribution peaked around Io's orbit, which is ionized and
  added as source terms in the MHD equations. As a first step, we drive
  our simulation with steady solar wind conditions in order to establish
  a physical picture of the global configuration of the magnetosphere,
  such as the global convection pattern and large-scale current systems
  present in the magnetosphere. We observe that the magnetosphere consists
  of distinguishable regions with varying degrees of corotation. Moreover,
  the central plasma sheet is found to exhibit oscillatory behavior due to
  the tilt of the dipole axis. We compare the model output with Galileo
  particle and field measurements, such as plasma density, velocity,
  and magnetic field, in order to validate our model.

Title: Collisionless Asymmetric Magnetic Reconnection in 3D MHD-EPIC
    Global Simulations
Authors: Markidis, S.; Peng, I. B.; Chen, Y.; Toth, G.; Gombosi,
   T. I.; Erkisson, E.; Johlander, A.; Khotyaintsev, Y. V.; Vaivads,
   A.; Laure, E.
Bibcode: 2016AGUFMSM21A2413M
Altcode:
  Kinetic simulations that are embedded in global MHD simulations
  (MHD-EPIC) enable the study of collisionless magnetic reconnection
  in realistic configurations. The MHD simulation solves the global
  interaction of solar wind with the planet magnetosphere over the whole
  domain while the kinetic simulations are performed only in the selected
  regions where kinetic physics plays a critical role. The coupling
  between MHD and kinetic simulations is two-way as the MHD simulation
  provides boundary conditions to the kinetic simulations while the
  results of the kinetic simulations overwrite the results of the MHD
  simulations. One of the main applications of this simulation technique
  is the study of magnetic reconnection with local kinetic simulations
  only in the magnetopause and the magnetotail regions. We carry out 3D
  local iPIC3D Particle-in-Cell (PIC) simulations in global BATS-R-US Hall
  MHD simulations using the SWMF coupling framework to study the kinetic
  features of driven asymmetric magnetic reconnection. Because the PIC
  simulations are initialized and coupled with Hall MHD simulations,
  the PIC simulations of asymmetric reconnection are carried out
  in a realistic initial configuration of the electric and magnetic
  fields and with a realistic driver from the boundaries. The 3D PIC
  simulations resolve the electron inertial length of the system to
  accurately describe the physics in the electron diffusion region
  during asymmetric reconnection. The 3D PIC simulations show the
  development of flux ropes as results of magnetic reconnection and the
  presence of instabilities and strong wave activities in proximity of
  the current sheet. In particular, electron outflow jets are unstable
  against Kelvin-Helmholtz instability and lower-hybrid drift waves are
  present in proximity of the current sheet. The PIC simulations also
  allow us to study the electron distribution functions in the electron
  diffusion region and to identify crescent-shaped electron distribution
  functions as recently observed by the MMS spacecrafts. The results
  of the embedded 3D PIC simulations provide a realistic picture of
  collisionless asymmetric magnetic reconnection that can be used for
  further understanding the observations from MMS.

Title: A New 3D Multi-fluid Model: A Study of Kinetic Effects and
    Variations of Physical Conditions in the Cometary Coma
Authors: Shou, Y.; Combi, M.; Toth, G.; Tenishev, V.; Fougere, N.;
   Jia, X.; Rubin, M.; Huang, Z.; Hansen, K.; Gombosi, T.; Bieler, A.
Bibcode: 2016ApJ...833..160S
Altcode:
  Physics-based numerical coma models are desirable whether to interpret
  the spacecraft observations of the inner coma or to compare with the
  ground-based observations of the outer coma. In this work, we develop a
  multi-neutral-fluid model based on the BATS-R-US code of the University
  of Michigan, which is capable of computing both the inner and outer
  coma and simulating time-variable phenomena. It treats H<SUB>2</SUB>O,
  OH, H<SUB>2</SUB>, O, and H as separate fluids and each fluid has
  its own velocity and temperature, with collisions coupling all fluids
  together. The self-consistent collisional interactions decrease the
  velocity differences, re-distribute the excess energy deposited by
  chemical reactions among all species, and account for the varying
  heating efficiency under various physical conditions. Recognizing
  that the fluid approach has limitations in capturing all of the
  correct physics for certain applications, especially for very
  low density environment, we applied our multi-fluid coma model to
  comet 67P/Churyumov-Gerasimenko at various heliocentric distances
  and demonstrated that it yields comparable results to the Direct
  Simulation Monte Carlo (DSMC) model, which is based on a kinetic
  approach that is valid under these conditions. Therefore, our model may
  be a powerful alternative to the particle-based model, especially for
  some computationally intensive simulations. In addition, by running the
  model with several combinations of production rates and heliocentric
  distances, we characterize the cometary H<SUB>2</SUB>O expansion
  speeds and demonstrate the nonlinear dependencies of production rate
  and heliocentric distance. Our results are also compared to previous
  modeling work and remote observations, which serve as further validation
  of our model.

Title: Studying the thermodynamics of coronal jets through modeling-
    and observational diagnostics techniques
Authors: Szente, J.; Manchester, W.; Landi, E.; Toth, G.; van der
   Holst, B.; Gombosi, T. I.; DeVore, C. R.; Antiochos, S. K.
Bibcode: 2016AGUFMSH21E2577S
Altcode:
  We present a comprehensive study of simulated and observed coronal jets
  using EUV and soft X-ray narrow-band images and EUV high resolution
  spectra. The goal of our study is to understand the thermodynamics
  and time evolution of jets and their impact on the coronal plasma. We
  simulate jets with a full 3D MHD coronal model with separate electron
  and proton temperatures and heating due to Alfvén wave turbulence. Due
  to the fast dynamics of the small-scale eruptive reconnections at the
  footpoint of the jet, it is essential to undertake this effort with a
  model with separate electron and proton temperatures to interpret the
  observed signatures in EUV and soft X-ray bands. The obtained synthetic
  images are compared to observations done by the instrumentations of
  SDO, STEREO and Hinode space crafts. The turbulence in this model is
  ideally suited to analyze the spectroscopic signatures, such as line
  broadening. The 3-hour long simulation of jets interacting with the
  global solar corona shows plasma responses potentially being observed
  with the upcoming Solar Probe Plus mission.

Title: Dispersive Magnetosonic Waves and Turbulence in the
Heliosheath: Multi-Fluid MHD Reconstruction of Voyager 2 Observations
Authors: Zieger, B.; Opher, M.; Toth, G.
Bibcode: 2016AGUFMSH41C2542Z
Altcode:
  Recently we demonstrated that our three-fluid MHD model of the solar
  wind plasma (where cold thermal solar wind ions, hot pickup ions, and
  electrons are treated as separate fluids) is able to reconstruct the
  microstructure of the termination shock observed by Voyager 2 [Zieger
  et al., 2015]. We constrained the unknown pickup ion abundance and
  temperature and confirmed the presence of a hot electron population at
  the termination shock, which has been predicted by a number of previous
  theoretical studies [e.g. Chasei and Fahr, 2014; Fahr et al., 2014]. We
  showed that a significant part of the upstream hydrodynamic energy is
  transferred to the heating of pickup ions and "massless" electrons. As
  shown in Zieger et al., [2015], three-fluid MHD theory predicts two
  fast magnetosonic modes, a low-frequency fast mode or solar wind ion
  (SW) mode and a high-frequency fast mode or pickup ion (PUI) mode. The
  coupling of the two ion populations results in a quasi-stationary
  nonlinear mode or oscilliton, which appears as a trailing wave
  train downstream of the termination shock. In single-fluid plasma,
  dispersive effects appear on the scale of the Debye length. However,
  in a non-equilibrium plasma like the solar wind, where solar wind
  ions and PUIs have different temperatures, dispersive effects become
  important on fluid scales [see Zieger et al., 2015]. Here we show that
  the dispersive effects of fast magnetosonic waves are expected on the
  scale of astronomical units (AU), and dispersion plays an important
  role producing compressional turbulence in the heliosheath. The
  trailing wave train of the termination shock (the SW-mode oscilliton)
  does not extend to infinity. Downstream propagating PUI-mode waves
  grow until they steepen into PUI shocklets and overturn starting to
  propagate backward. The upstream propagating PUI-mode waves result
  in fast magnetosonic turbulence and limit the downstream extension of
  the oscilliton. The overturning distance of the PUI-mode, where these
  waves start to propagate backward, depends on the maximum growth rate
  of the PUI-mode. We discuss our simulations in light of the Voyager
  2 observations in the heliosheath.

Title: Resolving the Kinetic Reconnection Length Scale in Global
    Magnetospheric Simulations with MHD-EPIC
Authors: Toth, G.; Chen, Y.; Cassak, P.; Jordanova, V.; Peng, B.;
   Markidis, S.; Gombosi, T. I.
Bibcode: 2016AGUFMSM23C..03T
Altcode:
  We have recently developed a new modeling capability: the
  Magnetohydrodynamics with Embedded Particle-in-Cell (MHD-EPIC) algorithm
  with support from Los Alamos SHIELDS and NSF INSPIRE grants. We have
  implemented MHD-EPIC into the Space Weather Modeling Framework (SWMF)
  using the implicit Particle-in-Cell (iPIC3D) and the BATS-R-US extended
  magnetohydrodynamic codes. The MHD-EPIC model allows two-way coupled
  simulations in two and three dimensions with multiple embedded PIC
  regions. Both BATS-R-US and iPIC3D are massively parallel codes. The
  MHD-EPIC approach allows global magnetosphere simulations with embedded
  kinetic simulations. For small magnetospheres, like Ganymede or
  Mercury, we can easily resolve the ion scales around the reconnection
  sites. Modeling the Earth magnetosphere is very challenging even with
  our efficient MHD-EPIC model due to the large separation between the
  global and ion scales. On the other hand the large separation of
  scales may be exploited: the solution may not be sensitive to the
  ion inertial length as long as it is small relative to the global
  scales. The ion inertial length can be varied by changing the ion mass
  while keeping the MHD mass density, the velocity, and pressure the same
  for the initial and boundary conditions. Our two-dimensional MHD-EPIC
  simulations for the dayside reconnection region show in fact, that the
  overall solution is not sensitive to ion inertial length. The shape,
  size and frequency of flux transfer events are very similar for a wide
  range of ion masses. Our results mean that 3D MHD-EPIC simulations for
  the Earth and other large magnetospheres can be made computationally
  affordable by artificially increasing the ion mass: the required grid
  resolution and time step in the PIC model are proportional to the ion
  inertial length. Changing the ion mass by a factor of 4, for example,
  speeds up the PIC code by a factor of 256. In fact, this approach
  allowed us to perform an hour-long 3D MHD-EPIC simulations for the
  Earth magnetosphere.

Title: Multi-ion Multi-fluid Simulations of the Effects of Pick-up
    Ions on the Global Structure of the Heliosphere
Authors: Bambic, C. J.; Opher, M.; Zieger, B.; Michael, A.; Kornbleuth,
   M. Z.; Toth, G.
Bibcode: 2016AGUFMSH41C2543B
Altcode:
  We present the first 3D MHD multi-ion, multi-fluid simulations
  including pick-up ions as a separate fluid on the global structure of
  the heliosphere. Pick-up ions, formed by charge exchange between the
  solar wind and local interstellar medium, are thought to account for
  the missing thermal energy measured by Voyager 2 at the crossing of the
  Termination Shock. By treating the pick-up ions as a separate fluid
  (with an isotropic distribution) from the solar wind thermal plasma,
  we are able to isolate the properties of the suprathermal pick-up
  ion plasma from that of the thermal solar wind. In addition to the
  two charged ion fluids, we include four neutral fluids which interact
  via charge exchange with the pick-up ion plasma. We show that pick-up
  ions are dynamically important in the outer heliosphere, thinning and
  heating the heliosheath. Since the neutral fluids are imprinted with the
  properties of the plasma they are born from, this work has implications
  for the Energetic Neutral Atom (ENA) maps of the global heliosphere. We
  discuss briefly the effects on the global ENA maps of the heliosphere
  in addition to measurements along the Voyager 1 and 2 trajectories.

Title: Operationalizing the Space Weather Modeling Framework:
    Challenges and Resolutions
Authors: Welling, D. T.; Gombosi, T. I.; Toth, G.; Singer, H. J.;
   Millward, G. H.; Balch, C. C.; Cash, M. D.
Bibcode: 2016AGUFMSM23C..06W
Altcode:
  Predicting ground-based magnetic perturbations is a critical step
  towards specifying and predicting geomagnetically induced currents
  (GICs) in high voltage transmission lines. Currently, the Space
  Weather Modeling Framework (SWMF), a flexible modeling framework for
  simulating the multi-scale space environment, is being transitioned from
  research to operational use (R2O) by NOAA's Space Weather Prediction
  Center. Upon completion of this transition, the SWMF will provide
  localized time-varying magnetic field (dB/dt) predictions using
  real-time solar wind observations from L1 and the F10.7 proxy for EUV
  as model input. This presentation chronicles the challenges encountered
  during the R2O transition of the SWMF. Because operations relies on
  frequent calculations of global surface dB/dt, new optimizations were
  required to keep the model running faster than real time. Additionally,
  several singular situations arose during the 30-day robustness test that
  required immediate attention. Solutions and strategies for overcoming
  these issues will be presented. This includes new failsafe options for
  code execution, new physics and coupling parameters, and the development
  of an automated validation suite that allows us to monitor performance
  with code evolution. Finally, the operations-to-research (O2R) impact
  on SWMF-related research is presented. The lessons learned from this
  work are valuable and instructive for the space weather community as
  further R2O progress is made.

Title: The role of inductive electric fields in the ring current
    enhancement during the March 17<SUP>th</SUP>, 2013 geomagnetic storm
Authors: Ilie, R.; Toth, G.; Liemohn, M. W.; Chan, A. A.
Bibcode: 2016AGUFMSM11A2128I
Altcode:
  The terrestrial magnetosphere has the capability to rapidly accelerate
  charged particles up to very high energies over relatively short
  times and distances. These energetic particles are injected
  from the magnetotail into the inner magnetosphere through two
  primary mechanisms. One transport method is the potential-driven
  convection during periods of southward IMF, which allows part of the
  dawn-to-dusk solar wind electric field to effectively map down to
  the polar ionosphere. The second transport process involves a sudden
  reconfiguration of the magnetic field and the creation of transient
  induced electric fields. However, it is not possible to distinguish
  the two terms by only measuring the electric field. Assessing the
  relative contribution of potential versus inductive electric fields at
  the energization of the hot ion population in the inner magnetosphere
  is only possible by thorough examination of the time varying magnetic
  field and current systems using global modeling of the entire system. We
  developed a novel method to calculate the inductive and potential
  components of electric field in the entire magnetosphere domain. This
  approach removes the need to trace independent field lines and lifts
  the assumption that the magnetic field lines can be treated as frozen
  in a stationary ionosphere. We quantify the relative contributions of
  potential and inductive electric fields at driving plasma sheet ions
  into the inner magnetosphere during the March 17th, 2103 geomagnetic
  storm. The consequence of these injections on the distortion of
  the near-Earth magnetic field and current systems have been rarely
  separated in order to determine their relative effectiveness from a
  global perspective.

Title: New Space Weather Forecasting at NOAA with Michigan's
    Geospace Model
Authors: Singer, H. J.; Millward, G. H.; Balch, C. C.; Cash, M. D.;
   Onsager, T. G.; Toth, G.; Welling, D. T.; Gombosi, T. I.
Bibcode: 2016AGUFMSH11C2259S
Altcode:
  We will present first results from the University of Michigan's Geospace
  model that is transitioning, during 2016, from a research capability
  into operations at the NOAA Space Weather Prediction Center. The
  first generation of space weather products from this model will be
  described. These initial products will support power grid operators,
  as well as other users, with both global and regional, short-term
  predictions of geomagnetic activity. The Geospace model is a coupled
  system including three components: the BATS-R-US magnetohydrodynamic
  (MHD) model of the magnetosphere; the Ridley ionosphere electrodynamics
  model (RIM); and the Rice Convection Model (RCM), an inner magnetosphere
  ring-current model developed at Rice University. The model is driven by
  solar wind data from a satellite at L1 (now NOAA's DSCOVR satellite)
  and F10.7, a proxy for solar extreme ultra-violet radiation. The
  Geospace model runs continuously, driven by the 1-minute cadence
  real-time L1 data that is propagated to the inflow boundary of the
  MHD code. The model steps back to an earlier time and then continues
  forward if high-speed solar wind overtakes slower solar wind. This
  mode of operation is unique among the models at NOAA's National
  Center for Environment Prediction's Central Operations (NCO), and it
  is also different from the typical scientific simulation mode. All
  of this work has involved 3D graphical model displays and validation
  tools that are being developed to support forecasters and web-based
  external users. Lessons learned during the transition process will
  be described, as well as the iterative process that occurs between
  Research and Operations and the scientific challenges for future model
  and product improvements.

Title: Specification of the Surface Charging Environment with SHIELDS
Authors: Jordanova, V.; Delzanno, G. L.; Henderson, M. G.; Godinez,
   H. C.; Jeffery, C. A.; Lawrence, E. C.; Meierbachtol, C.; Moulton,
   J. D.; Vernon, L.; Woodroffe, J. R.; Brito, T.; Toth, G.; Welling,
   D. T.; Yu, Y.; Albert, J.; Birn, J.; Borovsky, J.; Denton, M.; Horne,
   R. B.; Lemon, C.; Markidis, S.; Thomsen, M. F.; Young, S. L.
Bibcode: 2016AGUFMSM23C..02J
Altcode:
  Predicting variations in the near-Earth space environment that can
  lead to spacecraft damage and failure, i.e. "space weather", remains
  a big space physics challenge. A recently funded project through the
  Los Alamos National Laboratory (LANL) Directed Research and Development
  (LDRD) program aims at developing a new capability to understand, model,
  and predict Space Hazards Induced near Earth by Large Dynamic Storms,
  the SHIELDS framework. The project goals are to understand the dynamics
  of the surface charging environment (SCE), the hot (keV) electrons
  representing the source and seed populations for the radiation belts,
  on both macro- and microscale. Important physics questions related to
  rapid particle injection and acceleration associated with magnetospheric
  storms and substorms as well as plasma waves are investigated. These
  challenging problems are addressed using a team of world-class experts
  in the fields of space science and computational plasma physics, and
  state-of-the-art models and computational facilities. In addition to
  physics-based models (like RAM-SCB, BATS-R-US, and iPIC3D), new data
  assimilation techniques employing data from LANL instruments on the Van
  Allen Probes and geosynchronous satellites are developed. Simulations
  with the SHIELDS framework of the near-Earth space environment where
  operational satellites reside are presented. Further model development
  and the organization of a "Spacecraft Charging Environment Challenge"
  by the SHIELDS project at LANL in collaboration with the NSF Geospace
  Environment Modeling (GEM) Workshop and the multi-agency Community
  Coordinated Modeling Center (CCMC) to assess the accuracy of SCE
  predictions are discussed.

Title: Real-time SWMF-Geospace at CCMC: assessing the quality of
    output from continuous operational simulations
Authors: Liemohn, M. W.; Welling, D. T.; De Zeeuw, D.; Kuznetsova,
   M. M.; Rastaetter, L.; Ganushkina, N. Y.; Ilie, R.; Toth, G.; Gombosi,
   T. I.; van der Holst, B.
Bibcode: 2016AGUFMSH31C..03L
Altcode:
  The ground-based magnetometer index Dst is a decent measure of the
  near-Earth current systems, in particular those in the storm-time
  inner magnetosphere. The ability of a large-scale, physics-based
  model to reproduce, or even predict, this index is therefore a
  tangible measure of the overall validity of the code for space
  weather research and space weather operational usage. Experimental
  real-time simulations of the Space Weather Modeling Framework (SWMF)
  are conducted at the Community Coordinated Modeling Center (CCMC),
  with results available there (http://ccmc.gsfc.nasa.gov/realtime.php),
  through the CCMC Integrated Space Weather Analysis (iSWA) site
  (http://iswa.ccmc.gsfc.nasa.gov/IswaSystemWebApp/), and the Michigan
  SWMF site (http://csem.engin.umich.edu/realtime). Presently,
  two configurations of the SWMF are running in real time at
  CCMC, both focusing on the geospace modules, using the BATS-R-US
  magnetohydrodynamic model, the Ridley Ionosphere Model, and with and
  without the Rice Convection Model for inner magnetospheric drift
  physics. While both have been running for several years, nearly
  continuous results are available since July 2015. Dst from the model
  output is compared against the Kyoto real-time Dst. Various quantitative
  measures are presented to assess the goodness of fit between the models
  and observations. In particular, correlation coefficients, RMSE and
  prediction efficiency are calculated and discussed. In addition,
  contingency tables are presented, demonstrating the ability of the
  model to predict "disturbed times" as defined by Dst values below
  some critical threshold. It is shown that the SWMF run with the inner
  magnetosphere model is significantly better at reproducing storm-time
  values, with prediction efficiencies above 0.25 and Heidke skill
  scores above 0.5. This work was funded by NASA and NSF grants, and
  the European Union's Horizon 2020 research and innovation programme
  under grant agreement 637302 PROGRESS.

Title: Forecasting CMEs at 1AU with a Flux Rope-Driven Model
Authors: Manchester, W.; Jin, M.; van der Holst, B.; Toth, G.;
   Mullinix, R.; Taktakishvili, A.; Chulaki, A.; Gombosi, T. I.
Bibcode: 2016AGUFMSH11C2249M
Altcode:
  Until recently, operational models of coronal mass ejection (CME)
  propagation omitted magnetic drivers and imposed CMEs with field-free
  flows. While capable of predicting the arrival times of solar wind
  disturbances, such models are incapable of predicting the magnetic
  ejecta of a CME, which is the fundamental driver of large geomagnetic
  storms. Here, we report on a significant advancement in the development
  and delivery of a magnetic flux rope-driven operational CME model
  Eruptive Event Generator Gibson-Low EEGGL that was recently installed
  at the Community Coordinated Modeling Center (CCMC). This new model
  simulates the propagation of CMEs from Sun to 1AU by combining the
  analytical Gibson &amp; Low (GL) flux rope model with the state-of-art
  Alfven Wave Solar Model. Using synoptic magnetcogram and coronagraph
  observations, the model can predict the long-term evolution of the CME
  magnetic fields in interplanetary space. Following the work of Jin et
  al. (2016), we examine case studies of CMEs at 1 AU to illustrate the
  capabilities and limitations of this space weather forecasting tool.

Title: The Heliosphere with Jets and its implications for the global
    Energetic Neutral Atoms Maps throughout the Solar Cycle and its
    impact on the large-scale draping of the interstellar magnetic field
Authors: Opher, M.; Drake, J. F.; Kornbleuth, M. Z.; Michael, A.;
   Zieger, B.; Swisdak, M.; Toth, G.
Bibcode: 2016AGUFMSH23A..05O
Altcode:
  Recently we proposed a scenario (Opher et al. 2015) that the
  structure of the heliosphere might be very different than we previously
  thought. The standard picture of the heliosphere is a comet-shape like
  structure with the tail extending for 1000's of AUs. This standard
  picture stems from a view where magnetic forces are negligible and the
  solar magnetic field is convected passively down the tail. We showed
  (Opher et al. 2015, Drake et al. 2015) that the magnetic tension
  of the solar magnetic field plays a crucial role on organizing the
  solar wind in the heliosheath into two jet-like structures. The two
  heliospheric jets are separated by the interstellar medium that
  flows between them. The heliosphere then has a ``croissant"-like
  shape where the distance to the heliopause downtail is almost the
  same as towards the nose. Here we present the implications of this
  "croissant-like structure" for the global Energetic Neutral Atoms
  maps as measured by IBEX in the heliotail and its variation with
  solar cycle. We include solar cycle variations of the solar wind
  (density and speed and magnetic intensity) while keeping a unipolar
  configuration to minimize spurious magnetic dissipation that erodes
  the solar magnetic field. We discuss as well the consequences on the
  draping and reconnection of the interstellar magnetic field across the
  heliopause. We show that reconnection in the flanks and tail control the
  draping and the orientation of the interstellar magnetic field (BISM)
  ahead of the heliopause and can explain the Voyager 1 observations. The
  BISM twists as it approaches the HP and acquires a strong T component
  (East-West) as shown in Opher &amp; Drake (2013). Only after some
  significant distance outside the HP is the direction of the interstellar
  field distinguishably different from that of the Parker spiral.

Title: Direct Simulation Monte Carlo modelling of the major species
    in the coma of comet 67P/Churyumov-Gerasimenko
Authors: Fougere, Nicolas; Altwegg, K.; Berthelier, J. -J.; Bieler,
   A.; Bockelée-Morvan, D.; Calmonte, U.; Capaccioni, F.; Combi, M. R.;
   De Keyser, J.; Debout, V.; Erard, S.; Fiethe, B.; Filacchione, G.;
   Fink, U.; Fuselier, S. A.; Gombosi, T. I.; Hansen, K. C.; Hässig,
   M.; Huang, Z.; Le Roy, L.; Leyrat, C.; Migliorini, A.; Piccioni, G.;
   Rinaldi, G.; Rubin, M.; Shou, Y.; Tenishev, V.; Toth, G.; Tzou, C. -Y.
Bibcode: 2016MNRAS.462S.156F
Altcode:
  We analyse the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
  (ROSINA) - the Double Focusing Mass Spectrometer data between 2014
  August and 2016 February to examine the effect of seasonal variations
  on the four major species within the coma of 67P/Churyumov-Gerasimenko
  (H<SUB>2</SUB>O, CO<SUB>2</SUB>, CO, and O<SUB>2</SUB>), resulting from
  the tilt in the orientation of the comet's spin axis. Using a numerical
  data inversion, we derive the non-uniform activity distribution at the
  surface of the nucleus for these species, suggesting that the activity
  distribution at the surface of the nucleus has not significantly been
  changed and that the differences observed in the coma are solely due to
  the variations in illumination conditions. A three-dimensional Direct
  Simulation Monte Carlo model is applied where the boundary conditions
  are computed with a coupling of the surface activity distributions and
  the local illumination. The model is able to reproduce the evolution
  of the densities observed by ROSINA including the changes happening at
  equinox. While O<SUB>2</SUB> stays correlated with H<SUB>2</SUB>O as it
  was before equinox, CO<SUB>2</SUB> and CO, which had a poor correlation
  with respect to H<SUB>2</SUB>O pre-equinox, also became well correlated
  with H<SUB>2</SUB>O post-equinox. The integration of the densities
  from the model along the line of sight results in column densities
  directly comparable to the VIRTIS-H observations. Also, the evolution
  of the volatiles' production rates is derived from the coma model
  showing a steepening in the production rate curves after equinox. The
  model/data comparison suggests that the seasonal effects result in the
  Northern hemisphere of 67P's nucleus being more processed with a layered
  structure while the Southern hemisphere constantly exposes new material.

Title: Evolution of water production of 67P/Churyumov-Gerasimenko:
    An empirical model and a multi-instrument study
Authors: Hansen, Kenneth C.; Altwegg, K.; Berthelier, J. -J.; Bieler,
   A.; Biver, N.; Bockelée-Morvan, D.; Calmonte, U.; Capaccioni, F.;
   Combi, M. R.; de Keyser, J.; Fiethe, B.; Fougere, N.; Fuselier, S. A.;
   Gasc, S.; Gombosi, T. I.; Huang, Z.; Le Roy, L.; Lee, S.; Nilsson,
   H.; Rubin, M.; Shou, Y.; Snodgrass, C.; Tenishev, V.; Toth, G.; Tzou,
   C. -Y.; Simon Wedlund, C.; Rosina Team
Bibcode: 2016MNRAS.462S.491H
Altcode:
  We examine the evolution of the water production of comet
  67P/Churyumov-Gerasimenko during the Rosetta mission (2014 June-2016
  May) based on in situ and remote sensing measurements made by Rosetta
  instruments, Earth-based telescopes and through the development of an
  empirical coma model. The derivation of the empirical model is described
  and the model is then applied to detrend spacecraft position effects
  from the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
  (ROSINA) data. The inter-comparison of the instrument data sets shows
  a high level of consistency and provides insights into the water and
  dust production. We examine different phases of the orbit, including
  the early mission (beyond 3.5 au) where the ROSINA water production does
  not show the expected increase with decreasing heliocentric distance. A
  second important phase is the period around the inbound equinox, where
  the peak water production makes a dramatic transition from northern to
  southern latitudes. During this transition, the water distribution is
  complex, but is driven by rotation and active areas in the north and
  south. Finally, we consider the perihelion period, where there may be
  evidence of time dependence in the water production rate. The peak water
  production, as measured by ROSINA, occurs 18-22 d after perihelion at
  3.5 ± 0.5 × 10<SUP>28</SUP> water molecules s<SUP>-1</SUP>. We show
  that the water production is highly correlated with ground-based dust
  measurements, possibly indicating that several dust parameters are
  constant during the observed period. Using estimates of the dust/gas
  ratio, we use our measured water production rate to calculate a uniform
  surface loss of 2-4 m during the current perihelion passage.

Title: A possible mechanism for the formation of magnetic field
    dropouts in the coma of 67P/Churyumov-Gerasimenko
Authors: Huang, Z.; Tóth, G.; Gombosi, T. I.; Bieler, A.; Combi,
   M. R.; Hansen, K. C.; Jia, X.; Fougere, N.; Shou, Y.; Cravens, T. E.;
   Tenishev, V.; Altwegg, K.; Rubin, M.
Bibcode: 2016MNRAS.462S.468H
Altcode:
  The Rosetta Plasma Consortium MAGnetometer (RPC-MAG) has
  detected signatures of diamagnetic regions associated with comet
  67P/Churyumov-Gerasimenko at distances from 30 to 400 km at different
  heliocentric distances, which is larger than what has been predicted by
  numerical simulations of the cometary plasam environment. The physical
  mechanism behind these diamagnetic regions is still unknown. In
  this work, we use our newly developed multifluid plasma-neutral
  model to explore a possible physical mechanism that might create such
  regions. The model solves the governing multifluid magnetohydrodynamic
  equations for cometary and solar wind ions and electrons, and the Euler
  equations for the neutral gas fluid. We find that a local increase
  of electron thermal pressure is capable of generating many of the
  observed features of the diamagnetic regions observed by RPC-MAG. The
  simulation results show that a magnetic field-free region is formed
  and the recovery phase of the magnetic field magnitude is faster than
  the declining phase.

Title: A new 3D multi-fluid model: a study of kinetic effects and
    variations of physical conditions in the cometary coma
Authors: Shou, Yinsi; Combi, Michael R.; Toth, Gabor; Huang, Zhenguang;
   Jia, Xianzhe; Fougere, Nicolas; Tenishev, Valeriy; Gombosi, T. I.;
   Hansen, Kenneth C.; Bieler, Andre
Bibcode: 2016DPS....4821705S
Altcode:
  Physics-based numerical coma models are desirable whether to interpret
  the spacecraft observations of the inner coma or to compare with
  the ground-based observations of the outer coma. In this work,
  we develop a multi-neutral-fluid model based on BATS-R-US in the
  University of Michigan's SWMF (Space Weather Modeling Framework),
  which is capable of computing both the inner and the outer coma and
  simulating time-variable phenomena. It treats H<SUB>2</SUB>O, OH,
  H<SUB>2</SUB>, O, and H as separate fluids and each fluid has its
  own velocity and temperature, with collisions coupling all fluids
  together. The self-consistent collisional interactions decrease the
  velocity differences, re-distribute the excess energy deposited by
  chemical reactions among all species, and account for the varying
  heating efficiency under various physical conditions. Recognizing
  that the fluid approach has limitations in capturing all of the
  correct physics for certain applications, especially for very low
  density environment, we applied our multi-fluid coma model to comet
  67P/Churyumov-Gerasimenko (CG) at various heliocentric distances
  and demonstrated that it is able to yield comparable results as
  the Direct Simulation Monte Carlo (DSMC) model, which is based on
  a kinetic approach that is valid under these conditions. Therefore,
  our model may be a powerful alternative to the particle-based model,
  especially for some computationally intensive simulations. In addition,
  by running the model with several combinations of production rates and
  heliocentric distances, we can characterize the cometary H<SUB>2</SUB>O
  expansion speeds and demonstrate the nonlinear effect of production
  rates or photochemical heating. Our results are also compared to
  previous modeling work (e.g., Bockelee-Morvan &amp; Crovisier 1987) and
  remote observations (e.g., Tseng et al. 2007), which serve as further
  validation of our model. This work has been partially supported by
  grant NNX14AG84G from the NASA Planetary Atmospheres Program, and US
  Rosetta contracts JPL #1266313, JPL #1266314 and JPL #1286489.

Title: Data Constrained Coronal Mass Ejections in A Global
    Magnetohydrodynamics Model
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Sokolov, I.;
   Toth, G.; Mullinix, R. E.; Taktakishvili, A.; Chulaki, A.; Gombosi,
   T. I.
Bibcode: 2016usc..confE.120J
Altcode:
  We present a first-principles-based coronal mass ejection (CME)
  model suitable for both scientific and operational purposes by
  combining a global magnetohydrodynamics (MHD) solar wind model with
  a flux rope-driven CME model. Realistic CME events are simulated
  self-consistently with high fidelity and forecasting capability by
  constraining initial flux rope parameters with observational data from
  GONG, SDO/HMI, SOHO/LASCO, and STEREO/COR. We automate this process
  so that minimum manual intervention is required in specifying the CME
  initial state. With the newly developed data-driven Eruptive Event
  Generator Gibson-Low (EEGGL), we present a method to derive Gibson-Low
  (GL) flux rope parameters through a handful of observational quantities
  so that the modeled CMEs can propagate with the desired CME speeds near
  the Sun. A test result with CMEs launched with different Carrington
  rotation magnetograms are shown. Our study shows a promising result
  for using the first-principles-based MHD global model as a forecasting
  tool, which is capable of predicting the CME direction of propagation,
  arrival time, and ICME magnetic field at 1 AU.

Title: Direct Simulation Monte-Carlo Modeling of the Major Volatile
    Species of Comet 67P/Churyumov-Gerasimenko observed by ROSINA
    and VIRTIS
Authors: Fougere, Nicolas; altwegg, kathrin; Berthelier, Jean-Jacques;
   Bieler, Andre; Bockelee-Morvan, Dominique; Calmonte, Ursina;
   Capaccioni, Fabrizio; Combi, Michael R.; De Keyser, Johan; Debout,
   Vincent; Erard, Stéphane; Fiethe, Björn; Filacchione, Gianrico;
   Fink, Uwe; Fuselier, Stephen; Gombosi, T. I.; Hansen, Kenneth C.;
   Hässig, Myrtha; Huang, Zhenguang; Le Roy, Léna; Migliorini,
   Alessandra; Piccioni, Giuseppe; Rinaldi, Giovanna; Rubin, Martin;
   Shou, Yinsi; Tenishev, Valeriy; Toth, Gabor; Tzou, Chia-Yu; VIRTIS
   Team and ROSINA Team
Bibcode: 2016DPS....4811610F
Altcode:
  During the past few decades, modeling of cometary coma has known
  tremendous improvements notably with the increase of computer
  capacity. While the Haser model is still widely used for interpretation
  of cometary observations, its rather simplistic assumptions such as
  spherical symmetry and constant outflow velocity prevent it to explain
  some of the coma observations. Hence, more complex coma models have
  emerged taking full advantage of the numerical approach. The only method
  that can resolve all the flow regimes encountered in the coma due to the
  drastic changes of Knudsen numbers is the Direct Simulation Monte-Carlo
  (DSMC) approach.The data acquired by the instruments on board of the
  Rosetta spacecraft provides a large amount of observations regarding the
  spatial and temporal variations of comet 67P/Churyumov-Gerasimenko's
  coma. These measurements provide constraints that can be applied to
  the coma model in order to describe best the rarefied atmosphere of
  67P. We present the last results of our 3D multi-species DSMC model
  using the Adaptive Mesh Particle Simulator (Tenishev et al. 2008 and
  2011, Fougere 2014). The model uses a realistic nucleus shape model from
  the OSIRIS team and takes into account the self-shadowing created by
  its concavities. The gas flux at the surface of the nucleus is deduced
  from the relative orientation with respect to the Sun and an activity
  distribution that enables to simulate both the non-uniformity of the
  surface activity and the heterogeneities of the outgassing.The model
  results are compared to the ROSINA and VIRTIS observations. Progress
  in incorporating Rosetta measurements from the last half of the mission
  into our models will be presented. The good agreement between the model
  and these measurements from two very different techniques reinforces
  our understanding of the physical processes taking place in the coma.

Title: An empirical model of H<SUB>2</SUB>O, CO<SUB>2</SUB>
    and CO coma distributions and production rates for comet
    67P/Churyumov-Gerasimenko based on ROSINA/DFMS measurements and
    AMPS-DSMC simulations
Authors: Hansen, Kenneth C.; Altwegg, Kathrin; Bieler, Andre;
   Berthelier, Jean-Jacques; Calmonte, Ursina; Combi, Michael R.; De
   Keyser, Johan; Fiethe, Björn; Fougere, Nicolas; Fuselier, Stephen;
   Gombosi, T. I.; Hässig, Myrtha; Huang, Zhenguang; Le Roy, Léna;
   Rubin, Martin; Tenishev, Valeriy; Toth, Gabor; Tzou, Chia-Yu;
   ROSINA Team
Bibcode: 2016DPS....4811623H
Altcode:
  We have previously used results from the AMPS DSMC (Adaptive Mesh
  Particle Simulator Direct Simulation Monte Carlo) model to create an
  empirical model of the near comet water (H<SUB>2</SUB>O) coma of comet
  67P/Churyumov-Gerasimenko. In this work we create additional empirical
  models for the coma distributions of CO<SUB>2</SUB> and CO. The AMPS
  simulations are based on ROSINA DFMS (Rosetta Orbiter Spectrometer
  for Ion and Neutral Analysis, Double Focusing Mass Spectrometer)
  data taken over the entire timespan of the Rosetta mission. The
  empirical model is created using AMPS DSMC results which are extracted
  from simulations at a range of radial distances, rotation phases and
  heliocentric distances. The simulation results are then averaged over
  a comet rotation and fitted to an empirical model distribution. Model
  coefficients are then fitted to piecewise-linear functions of
  heliocentric distance. The final product is an empirical model of
  the coma distribution which is a function of heliocentric distance,
  radial distance, and sun-fixed longitude and latitude angles. The model
  clearly mimics the behavior of water shifting production from North to
  South across the inbound equinox while the CO<SUB>2</SUB> production
  is always in the South.The empirical model can be used to de-trend
  the spacecraft motion from the ROSINA COPS and DFMS data. The ROSINA
  instrument measures the neutral coma density at a single point and the
  measured value is influenced by the location of the spacecraft relative
  to the comet and the comet-sun line. Using the empirical coma model
  we can correct for the position of the spacecraft and compute a total
  production rate based on single point measurements. In this presentation
  we will present the coma production rates as a function of heliocentric
  distance for the entire Rosetta mission.This work was supported by
  contracts JPL#1266313 and JPL#1266314 from the US Rosetta Project and
  NASA grant NNX14AG84G from the Planetary Atmospheres Program.

Title: Coronal response to EUV jets modeled with the Alfvén Wave
    Solar Model
Authors: Szente, Judith; Toth, Gabor; Manchester, Ward B., IV; van der
   Holst, Bartholomeus; Landi, Enrico; Gombosi, Tamas; DeVore, Carl R.;
   Antiochos, Spiro K.
Bibcode: 2016usc..confE..72S
Altcode:
  We study the thermodynamics of jet phenomena with the use of multiple
  wavelength SDO-AIA observations [e.g. Adams (2014) and Moore (2015)]
  combined with advanced numerical simulations made with AWSoM coronal
  model [van der Holst (2014)]. AWSoM provides a fully three-dimensional,
  magnetohydrodynamic description of the solar atmosphere heated by the
  dissipation of kinetic Alfvén waves in a self-consistent manner. In
  addition, the model's multi-species thermodynamics with electron
  heat conduction provides for the accurate construction of synthetic
  line-of-sight images of phenomena. We implement our jets in the solar
  wind with a magnetic dipole twisted about axis, resulting in EUV jets
  similar in topology and dynamics as being observed. We show that the
  coronal atmosphere responds at a large-scale as torsional Alfvén waves
  propagate into the outer corona (up to 24 solar radii and 40 degrees in
  latitude), introduced by the small-scale eruptive reconnection events
  at the footpoint of the jet.

Title: A Possible Mechanism for the Formation of Magnetic
    Field Dropouts Observed by RPC-MAG in the Inner Coma of Comet
    67P/Churyumov-Gerasimenko
Authors: Huang, Zhenguang; Toth, Gabor; Gombosi, T. I.; Bieler,
   Andre; Combi, Michael R.; Hansen, Kenneth C.; Jia, Xianzhe; Fougere,
   Nicolas; Shou, Yinsi; Cravens, Thomas; Tenishev, Valeriy; Rubin,
   Martin; altwegg, kathrin
Bibcode: 2016DPS....4811620H
Altcode:
  The Rosetta Plasma Consortium MAGnetometer (RPC-MAG) has detected
  signatures of a diamagnetic cavity associated with the comet
  67P/Churyumov-Gerasimenko at a distance of 170 km, which is two to three
  times larger than what has been predicted by numerical simulations of
  the cometary plasma environment. It remains unclear how this extended
  diamagnetic cavity forms. In the present work, we investigate this
  problem with our newly developed multi-fluid plasma-neutral interaction
  model (Huang et al., 2016). The multi-fluid model solves the governing
  multifluid MHD equations (for the cometary ions, the solar wind protons
  and the electrons) and the Euler equations for the neutral gas fluid. We
  find that a strong increase of electron pressure along a magnetic flux
  tube is capable of generating similar features of the diamagnetic
  cavity as those observed by the RPC-MAG. Direct comparison of our
  model results with the RPC observations shows reasonable agreement
  in terms of key characteristics of the cavity crossings, such as
  the duration and the magnetic field variations, suggesting that the
  mechanism proposed here based on localized enhancement of electron
  pressure may provide a possible explanation for the unusually large
  distance of the observed cavity.This work was supported by contracts
  JPL#1266313 and JPL#1266314 from the US Rosetta Project and NASA grant
  NNX14AG84G from the Planetary Atmospheres Program.

Title: Threaded-Field-Lines Model for the Low Solar Corona Powered
    by the Alfven Wave Turbulence
Authors: Sokolov, Igor V.; van der Holst, Bart; Manchester, Ward B.;
   Ozturk, Doga Can Su; Szente, Judit; Taktakishvili, Aleksandre; Tóth,
   Gabor; Jin, Meng; Gombosi, Tamas I.
Bibcode: 2016arXiv160904379S
Altcode:
  We present an updated global model of the solar corona, including
  the transition region. We simulate the realistic tree-dimensional
  (3D) magnetic field using the data from the photospheric magnetic
  field measurements and assume the magnetohydrodynamic (MHD) Alfvén
  wave turbulence and its non-linear dissipation to be the only source
  for heating the coronal plasma and driving the solar wind. In closed
  field regions the dissipation efficiency in a balanced turbulence
  is enhanced. In the coronal holes we account for a reflection of
  the outward propagating waves, which is accompanied by generation of
  weaker counter-propagating waves. The non-linear cascade rate degrades
  in strongly imbalanced turbulence, thus resulting in colder coronal
  holes. The distinctive feature of the presented model is the description
  of the low corona as almost-steady-state low-beta plasma motion and
  heat flux transfer along the magnetic field lines. We trace the magnetic
  field lines through each grid point of the lower boundary of the global
  corona model, chosen at some heliocentric distance, $R=R_{b}\sim1.1\
  R_\odot$ well above the transition region. One can readily solve the
  plasma parameters along the magnetic field line from 1D equations for
  the plasma motion and heat transport together with the Alfvén wave
  propagation, which adequately describe physics within the heliocentric
  distances range, $R_{\odot}&lt;R&lt;R_{b}$, in the low solar corona. By
  interfacing this threaded-field-lines model with the full MHD global
  corona model at $r=R_{b}$, we find the global solution and achieve a
  faster-than-real-time performance of the model on $\sim200$ cores.

Title: Effects of Numerical Magnetic Dissipation on the
    Characteristics of the Heliosphere
Authors: Michael, Adam Thomas; Opher, Merav; Provornikova, Elena;
   Toth, Gabor
Bibcode: 2016shin.confE.125M
Altcode:
  Through the use of numerical models, we have recently begun to
  realize the importance the solar wind"s magnetic field has on the
  location of the termination shock (Izmodenov and Alexashov 2015)
  as well as the shape of the heliosphere (Opher et al. 2015) and
  thickness of the heliosheath (Drake et al. 2015). Several studies
  suggest that there should be a need to move beyond ideal MHD in order
  to explain the Voyager 1 and 2 observations (Richardson et al. 2013;
  Michael et al. 2015). In the numerical simulations there is inherent
  numerical dissipation in the helispheric current sheet that an ideal
  MHD model cannot control. In a sense the dissipated magnetic energy
  can be transferred to thermal heating or to ram pressure. The magnetic
  dissipation inherent in modeling the heliospheric current sheet offers
  us a chance to explore non-ideal MHD effects in the heliosphere
  and heliosheath. Solar cycle models that include the reversal of
  the magnetic field have inherently a large fraction of magnetic
  dissipation. In this work we investigate the role magnetic dissipation
  has on the overall structure of the heliosheath. We describe the solar
  magnetic field both as a dipole, with the magnetic and rotational axes
  aligned, as well as a unipole. We have seen in Opher et al. 2016 that
  the use of a dipole magnetic field, in the case without any motion
  through the ISM, reduces the confinement of the plasma at the current
  sheet. We investigate how the magnetic dissipation affects the shape and
  thickness of the heliosheath and heliosphere. Furthermore, we explore
  how these effects are altered when 11-year solar cycle variations in
  the solar wind are included and comment on how magnetic dissipation
  alters the prediction for Voyager 1 and 2 observations.

Title: Validating Physics-based Space Weather Models for Operational
    Use
Authors: Gombosi, Tamas; Singer, Howard; Millward, George; Toth,
   Gabor; Welling, Daniel
Bibcode: 2016cosp...41E.696G
Altcode:
  The Geospace components of the Space Weather Modeling Framework
  developed at the University of Michigan is presently transitioned to
  operational use by the NOAA Space Weather Prediction Center. This talk
  will discuss the various ways the model is validated and skill scores
  are calculated.

Title: Do we know the actual magnetopause position for typical solar
    wind conditions?
Authors: Samsonov, A. A.; Gordeev, E.; Tsyganenko, N. A.; Å
   afránková, J.; Němeček, Z.; Å imÅ¯nek, J.; Sibeck, D. G.;
   Tóth, G.; Merkin, V. G.; Raeder, J.
Bibcode: 2016JGRA..121.6493S
Altcode:
  We compare predicted magnetopause positions at the subsolar point and
  four reference points in the terminator plane obtained from several
  empirical and numerical MHD models. Empirical models using various
  sets of magnetopause crossings and making different assumptions about
  the magnetopause shape predict significantly different magnetopause
  positions (with a scatter &gt;1 R<SUB>E</SUB>) even at the subsolar
  point. Axisymmetric magnetopause models cannot reproduce the cusp
  indentations or the changes related to the dipole tilt effect,
  and most of them predict the magnetopause closer to the Earth than
  nonaxisymmetric models for typical solar wind conditions and zero
  tilt angle. Predictions of two global nonaxisymmetric models do not
  match each other, and the models need additional verification. MHD
  models often predict the magnetopause closer to the Earth than the
  nonaxisymmetric empirical models, but the predictions of MHD simulations
  may need corrections for the ring current effect and decreases of the
  solar wind pressure that occur in the foreshock. Comparing MHD models
  in which the ring current magnetic field is taken into account with
  the empirical Lin et al. model, we find that the differences in the
  reference point positions predicted by these models are relatively
  small for B<SUB>z</SUB>=0. Therefore, we assume that these predictions
  indicate the actual magnetopause position, but future investigations
  are still needed.

Title: The interaction between the solar wind and the heterogeneous
    neutral gas coma of comet 67P/Churyumov-Gerasimenko
Authors: Rubin, Martin; Toth, Gabor; Tenishev, Valeriy; Fougere,
   Nicolas; Huang, Zhenguang
Bibcode: 2016cosp...41E1660R
Altcode:
  Comets are surrounded by an extended gas and dust coma. Neutral
  particles are continuously ionized by solar irradiation and then
  picked-up by the solar wind. This leads to a complex interaction between
  the neutral gas coma and the solar wind, which changes over the course
  of the comet's orbit around the Sun. The European Space Agency's Rosetta
  spacecraft has been in orbit around comet 67P/Churyumov-Gerasimenko
  since August 2014. Rosetta carries several instruments to investigate
  the comet's nucleus and surrounding neutral gas coma and plasma. Part
  of the payload is the Rosetta Orbiter Spectrometer for Ion and Neutral
  Analysis (ROSINA) that consists of two mass spectrometers and a pressure
  sensor. ROSINA was designed to measure the neutral gas abundance and
  composition and low energy ions in the coma in situ. ROSINA observations
  have shown that the coma is very heterogeneous both in total density and
  composition of the neutral gas. This heterogeneity is driven in large
  part by the complex shape of the nucleus and the varying illumination
  conditions associated with the comet's rotation. In this presentation
  we will show the time-dependent distribution of the major volatiles
  around the comet constrained by ROSINA observations. Furthermore we
  will investigate the impact of the highly non-symmetric neutral gas
  coma on the interaction of the solar wind with the comet.

Title: FDIPS: Finite Difference Iterative Potential-field Solver
Authors: Toth, Gabor; van der Holst, Bartholomeus; Huang, Zhenguang
Bibcode: 2016ascl.soft06011T
Altcode:
  FDIPS is a finite difference iterative potential-field solver that
  can generate the 3D potential magnetic field solution based on a
  magnetogram. It is offered as an alternative to the spherical harmonics
  approach, as when the number of spherical harmonics is increased, using
  the raw magnetogram data given on a grid that is uniform in the sine
  of the latitude coordinate can result in inaccurate and unreliable
  results, especially in the polar regions close to the Sun. FDIPS is
  written in Fortran 90 and uses the MPI library for parallel execution.

Title: Four-fluid MHD simulations of the plasma and neutral gas
    environment of comet 67P/Churyumov-Gerasimenko near perihelion
Authors: Huang, Zhenguang; Tóth, Gábor; Gombosi, Tamas I.; Jia,
   Xianzhe; Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi,
   Michael R.; Bieler, Andre; Hansen, Kenneth C.; Shou, Yinsi; Altwegg,
   Kathrin
Bibcode: 2016JGRA..121.4247H
Altcode:
  The neutral and plasma environment is critical in understanding the
  interaction of the solar wind and comet 67P/Churyumov-Gerasimenko
  (CG), the target of the European Space Agency's Rosetta mission. To
  serve this need and support the Rosetta mission, we have developed a
  3-D four-fluid model, which is based on BATS-R-US (Block-Adaptive Tree
  Solarwind Roe-type Upwind Scheme) within SWMF (Space Weather Modeling
  Framework) that solves the governing multifluid MHD equations and the
  Euler equations for the neutral gas fluid. These equations describe the
  behavior and interactions of the cometary heavy ions, the solar wind
  protons, the electrons, and the neutrals. This model incorporates
  different mass loading processes, including photoionization and
  electron impact ionization, charge exchange, dissociative ion-electron
  recombination, and collisional interactions between different fluids. We
  simulated the plasma and neutral gas environment near perihelion
  in three different cases: an idealized comet with a spherical body
  and uniform neutral gas outflow, an idealized comet with a spherical
  body and illumination-driven neutral gas outflow, and comet CG with a
  realistic shape model and illumination-driven neutral gas outflow. We
  compared the results of the three cases and showed that the simulations
  with illumination-driven neutral gas outflow have magnetic reconnection,
  a magnetic pileup region and nucleus directed plasma flow inside
  the nightside reconnection region, which have not been reported in
  the literature.

Title: The Coma of Comet 67P/Churyumov-Gerasimenko Pre- and Post-
    Equinox
Authors: Fougere, Nicolas; Altwegg, Kathrin; Berthelier, Jean-Jacques;
   Bieler, Andre; Bockelee-Morvan, Dominique; Calmonte, Ursina;
   Capaccioni, Fabrizio; Combi, Mike; Dekeyser, Johan; Debout, Vincent;
   Erard, Stephane; Fiethe, Bjorn; Fillacchione, Gianrico; Fink, Uwe;
   Fuselier, Stephen; Gombosi, Tamas; Hansen, Kenneth; Hassig, Myrtha;
   Huang, Zhenguang; Leroy, Lena; Leyrat, Cedric; Migliorini, Alessandra;
   Piccioni, Giuseppe; Rinaldi, Giovanna; Rubin, Martin; Tenishev,
   Valeriy; Toth, Gabor; Tzou, Chia-Yu; Shou, Yinsi
Bibcode: 2016EGUGA..1817897F
Altcode:
  As the Rosetta spacecraft escorts comet 67P/Churyumov-Gerasimenko
  (67P) during its journey in the Solar System, it monitors the
  evolution of the neutrals' distribution in the coma of 67P. Indeed,
  while the comet orbits around the Sun, the energy input received
  by the different regions of the nucleus varies, directly impacting
  67P's outgassing pattern. We model the H2O, CO2, and CO coma of Comet
  67P/Churyumov-Gerasimenko (67P) pre- and post- equinox using a 3D Direct
  Monte-Carlo Simulation approach. The use of a kinetic method enables
  us to model the coma from the nucleus' surface to a few hundreds of
  kilometers even in the regions where collisions cannot maintain a
  fluid regime. The activity at the surface of the nucleus is described
  using a spherical harmonic expansion with 25 terms constrained by
  ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis)
  observations. The model outputs contain information about numerous
  macroscopic parameters such as number densities, velocities, and
  temperatures of each species. Then, the results from the simulations
  are integrated along the line of sight to be compared with the remote
  sensing observations from the VIRTIS (Visible and Infrared Thermal
  Imaging Spectrometer) instrument. The model shows a good agreement
  with the data, giving a clear evidence of our understanding of the
  physics of the coma of comet 67P.

Title: Four-fluid MHD Simulations of the Plasma and Neutral Gas
    Environment of Comet 67P/Churyumov-Gerasimenko Near Perihelion
Authors: Huang, Zhenguang; Toth, Gabor; Gombosi, Tamas; Jia, Xianzhe;
   Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi, Michael;
   Bieler, Andre; Hansen, Kenneth; Shou, Yinsi; Altwegg, Kathrin
Bibcode: 2016EGUGA..18.2214H
Altcode:
  The neutral and plasma environment is critical in understanding the
  interaction of the solar wind and comet 67P/Churyumov-Gerasimenko
  (CG), the target of the European Space Agency's Rosetta mission. In
  this study, we have developed a 3-D four-fluid model, which is based
  on BATS-R-US (Block-Adaptive Tree Solarwind Roe-type Upwind Scheme)
  within SWMF (Space Weather Modeling Framework) that solves the governing
  multi-fluid MHD equations and the Euler equations for the neutral
  gas fluid. These equations describe the behavior and interactions
  of the cometary heavy ions, the solar wind protons, the electrons,
  and the neutrals. We simulated the plasma and neutral gas environment
  of comet CG with SHAP5 model near perihelion and we showed that the
  plasma environment in the inner coma region have some new features:
  magnetic reconnection in the tail region, a magnetic pile-up region on
  the nightside, and nucleus directed plasma flow inside the nightside
  reconnection region.

Title: Pre- and Post-equinox ROSINA production rates calculated using
    a realistic empirical coma model derived from AMPS-DSMC simulations
    of comet 67P/Churyumov-Gerasimenko
Authors: Hansen, Kenneth; Altwegg, Kathrin; Berthelier, Jean-Jacques;
   Bieler, Andre; Calmonte, Ursina; Combi, Michael; De Keyser, Johan;
   Fiethe, Björn; Fougere, Nicolas; Fuselier, Stephen; Gombosi, Tamas;
   Hässig, Myrtha; Huang, Zhenguang; Le Roy, Lena; Rubin, Martin;
   Tenishev, Valeriy; Toth, Gabor; Tzou, Chia-Yu
Bibcode: 2016EGUGA..1817905H
Altcode:
  We have previously used results from the AMPS DSMC (Adaptive Mesh
  Particle Simulator Direct Simulation Monte Carlo) model to create an
  empirical model of the near comet coma (&lt;400 km) of comet 67P for
  the pre-equinox orbit of comet 67P/Churyumov-Gerasimenko. In this work
  we extend the empirical model to the post-equinox, post-perihelion
  time period. In addition, we extend the coma model to significantly
  further from the comet (~100,000-1,000,000 km). The empirical model
  characterizes the neutral coma in a comet centered, sun fixed reference
  frame as a function of heliocentric distance, radial distance from the
  comet, local time and declination. Furthermore, we have generalized
  the model beyond application to 67P by replacing the heliocentric
  distance parameterizations and mapping them to production rates. Using
  this method, the model become significantly more general and can be
  applied to any comet. The model is a significant improvement over
  simpler empirical models, such as the Haser model. For 67P, the
  DSMC results are, of course, a more accurate representation of the
  coma at any given time, but the advantage of a mean state, empirical
  model is the ease and speed of use. One application of the empirical
  model is to de-trend the spacecraft motion from the ROSINA COPS and
  DFMS data (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis,
  Comet Pressure Sensor, Double Focusing Mass Spectrometer). The ROSINA
  instrument measures the neutral coma density at a single point and
  the measured value is influenced by the location of the spacecraft
  relative to the comet and the comet-sun line. Using the empirical coma
  model we can correct for the position of the spacecraft and compute a
  total production rate based on the single point measurement. In this
  presentation we will present the coma production rate as a function
  of heliocentric distance both pre- and post-equinox and perihelion.

Title: Three-dimensional direct simulation Monte-Carlo modeling of
    the coma of comet 67P/Churyumov-Gerasimenko observed by the VIRTIS
    and ROSINA instruments on board Rosetta
Authors: Fougere, N.; Altwegg, K.; Berthelier, J. -J.; Bieler, A.;
   Bockelée-Morvan, D.; Calmonte, U.; Capaccioni, F.; Combi, M. R.;
   De Keyser, J.; Debout, V.; Erard, S.; Fiethe, B.; Filacchione, G.;
   Fink, U.; Fuselier, S. A.; Gombosi, T. I.; Hansen, K. C.; Hässig,
   M.; Huang, Z.; Le Roy, L.; Leyrat, C.; Migliorini, A.; Piccioni, G.;
   Rinaldi, G.; Rubin, M.; Shou, Y.; Tenishev, V.; Toth, G.; Tzou, C. -Y.
Bibcode: 2016A&A...588A.134F
Altcode:
  Context. Since its rendezvous with comet 67P/Churyumov-Gerasimenko
  (67P), the Rosetta spacecraft has provided invaluable information
  contributing to our understanding of the cometary environment. On
  board, the VIRTIS and ROSINA instruments can both measure gas
  parameters in the rarefied cometary atmosphere, the so-called coma,
  and provide complementary results with remote sensing and in situ
  measurement techniques, respectively. The data from both ROSINA and
  VIRTIS instruments suggest that the source regions of H<SUB>2</SUB>O
  and CO<SUB>2</SUB> are not uniformly distributed over the surface of
  the nucleus even after accounting for the changing solar illumination
  of the irregularly shaped rotating nucleus. The source regions of
  H<SUB>2</SUB>O and CO<SUB>2</SUB> are also relatively different
  from one another. <BR /> Aims: The use of a combination of a formal
  numerical data inversion method with a fully kinetic coma model is a
  way to correlate and interpret the information provided by these two
  instruments to fully understand the volatile environment and activity
  of comet 67P. <BR /> Methods: In this work, the nonuniformity of the
  outgassing activity at the surface of the nucleus is described by
  spherical harmonics and constrained by ROSINA-DFMS data. This activity
  distribution is coupled with the local illumination to describe
  the inner boundary conditions of a 3D direct simulation Monte-Carlo
  (DSMC) approach using the Adaptive Mesh Particle Simulator (AMPS)
  code applied to the H<SUB>2</SUB>O and CO<SUB>2</SUB> coma of comet
  67P. <BR /> Results: We obtain activity distribution of H<SUB>2</SUB>O
  and CO<SUB>2</SUB> showing a dominant source of H<SUB>2</SUB>O in the
  Hapi region, while more CO<SUB>2</SUB> is produced in the southern
  hemisphere. The resulting model outputs are analyzed and compared with
  VIRTIS-M/-H and ROSINA-DFMS measurements, showing much better agreement
  between model and data than a simpler model assuming a uniform surface
  activity. The evolution of the H<SUB>2</SUB>O and CO<SUB>2</SUB>
  production rates with heliocentric distance are derived accurately
  from the coma model showing agreement between the observations from
  the different instruments and ground-based observations. <BR />
  Conclusions: We derive the activity distributions for H<SUB>2</SUB>O
  and CO<SUB>2</SUB> at the surface of the nucleus described in
  spherical harmonics, which we couple to the local solar illumination
  to constitute the boundary conditions of our coma model. The model
  presented reproduces the coma observations made by the ROSINA and VIRTIS
  instruments on board the Rosetta spacecraft showing our understanding
  of the physics of 67P's coma. This model can be used for further data
  analyses, such as dust modeling, in a future work.

Title: Response of Mercury's Magnetosphere to Solar Wind Forcing:
    Results of Global MHD Simulations with Coupled Planetary Interior
Authors: Jia, Xianzhe; Slavin, James; Poh, Gangkai; Toth, Gabor;
   Gombosi, Tamas
Bibcode: 2016EGUGA..18.5291J
Altcode:
  As the innermost planet, Mercury arguably undergoes the most direct
  space weathering interactions due to its weak intrinsic magnetic field
  and its close proximity to the Sun. It has long been suggested that two
  processes, i.e., erosion of the dayside magnetosphere due to intense
  magnetopause reconnection and the shielding effect of the induction
  currents generated at the conducting core, compete against each other
  in governing the large-scale structure of Mercury's magnetosphere. An
  outstanding question concerning Mercury's space weather is which
  of the two processes is more important. To address this question,
  we have developed a global MHD model in which Mercury's interior is
  electromagnetically coupled to the surrounding space environment. As
  demonstrated in Jia et al. (2015), the new modeling capability allows
  for self-consistently characterizing the dynamical response of the
  Mercury system to time-varying external conditions. To assess the
  relative importance of induction and magnetopause reconnection in
  controlling the magnetospheric configuration, especially under
  strong solar driving conditions, we have carried out multiple
  global simulations that adopt a wide range of solar wind dynamic
  pressure and IMF conditions. We find that, while the magnetopause
  standoff distance decreases with increasing solar wind pressure,
  just as expected, its dependence on the solar wind pressure follows
  closely a power-law relationship with an index of ~ -1/6, rather
  than a steeper power-law falling-off expected for the case with only
  induction present. This result suggests that for the range of solar wind
  conditions examined, the two competing processes, namely induction and
  reconnection, appear to play equally important roles in determining
  the global configuration of Mercury's magnetosphere, consistent
  with the finding obtained by Slavin et al. (2014) based on MESSENGER
  observations. We also find that the magnetic perturbations produced by
  the magnetospheric current systems are spatially non-uniform in nature,
  and consequently they result in an induced magnetic field at the core
  that contains significant power in not only the dipole but also high
  order moments. Based on the simulation results, we determine how the
  induced magnetic field varies with the external solar wind conditions,
  and provide quantitative constraints on the ability of Mercury's core
  to shield the planetary surface from direct solar wind impact.

Title: Extended Magnetohydrodynamics with Embedded Particle-in-Cell
    (XMHD-EPIC) Simulations of Magnetospheric Reconnection
Authors: Toth, Gabor; Gombosi, Tamas; Jia, Xianzhe; Welling, Daniel;
   Chen, Yuxi; Haiducek, John; Jordanova, Vania; Peng, Ivy Bo; Markidis,
   Stefano; Lapenta, Giovanni
Bibcode: 2016EGUGA..18.2344T
Altcode:
  We have recently developed a new modeling capability to embed the
  implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US
  extended magnetohydrodynamic model. The PIC domain can cover the
  regions where kinetic effects are most important, such as reconnection
  sites. The BATS-R-US code with its block-adaptive grid can efficiently
  handle the rest of the computational domain where the MHD or Hall MHD
  description is sufficient. The current implementation of the MHD-EPIC
  model allows two-way coupled simulations in two and three dimensions
  with multiple embedded PIC regions. The MHD and PIC grids can have
  different grid resolutions and grid structures. The MHD variables
  and the moments of the PIC distribution functions are interpolated
  and message passed in an efficient manner through the Space Weather
  Modeling Framework (SWMF). Both BATS-R-US and iPIC3D are massively
  parallel codes fully integrated into, run by and coupled through
  the SWMF. We have successfully applied the MHD-EPIC code to model
  Ganymede's and Mercury's magnetospheres. We compared our results with
  Galileo and MESSENGER magnetic observations, respectively, and found
  good overall agreement. We will report our progress on modeling the
  Earth magnetosphere with MHD-EPIC with the goal of providing direct
  comparison with and global context for the MMS observations.

Title: Responses of Venus Ionosphere and Induced Magnetosphere to
    Solar Wind Pressure Variations
Authors: Ma, Yingjuan; Toth, Gabor; Nagy, Andrew F.; Russell,
   Christopher T.
Bibcode: 2016EGUGA..18.9743M
Altcode:
  Often regarded as the Earth's 'sister planet', Venus has similar size
  and mass as Earth. But it is also remarkably different from Earth in
  many respects. Even though we have some basic knowledge of the solar
  wind interaction with Venus based on spacecraft observations, little
  is known about how the interaction and the resulting plasma escape
  rates vary in response to solar wind variations due to the lack of
  coordinated observations of both upstream solar wind conditions and
  simultaneous plasma properties in the Venus ionosphere. Furthermore,
  recent observations suggest that plasma escape rates are significantly
  enhanced during stormy space weather in response to solar wind pressure
  pulses (Edberg et al., 2011). Thus it is important to understand the
  plasma interaction under varying solar wind conditions. In this study,
  we use a sophisticated multi-species MHD model that has been recently
  developed for Venus (Ma et al., 2013) to characterize the responses
  of the ionosphere and the induced magnetosphere of Venus to a typical
  variation of the solar wind: dynamic pressure change. We will examine
  the response of the ionosphere and the induced magnetosphere to both
  pressure enhancements and decreases. We will quantify the total plasma
  escape-rate change in response to such variations and to identify the
  underlying driver for changes in escape rate. We will also quantify
  the time scale of the Venus ionosphere and induced magnetosphere in
  responding to the pressure change of the external solar wind driver.

Title: Extended magnetohydrodynamics with embedded particle-in-cell
    simulation of Ganymede's magnetosphere
Authors: Tóth, Gábor; Jia, Xianzhe; Markidis, Stefano; Peng, Ivy Bo;
   Chen, Yuxi; Daldorff, Lars K. S.; Tenishev, Valeriy M.; Borovikov,
   Dmitry; Haiducek, John D.; Gombosi, Tamas I.; Glocer, Alex; Dorelli,
   John C.
Bibcode: 2016JGRA..121.1273T
Altcode:
  We have recently developed a new modeling capability to embed
  the implicit particle-in-cell (PIC) model iPIC3D into the
  Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme magnetohydrodynamic
  (MHD) model. The MHD with embedded PIC domains (MHD-EPIC) algorithm
  is a two-way coupled kinetic-fluid model. As one of the very first
  applications of the MHD-EPIC algorithm, we simulate the interaction
  between Jupiter's magnetospheric plasma and Ganymede's magnetosphere. We
  compare the MHD-EPIC simulations with pure Hall MHD simulations
  and compare both model results with Galileo observations to assess
  the importance of kinetic effects in controlling the configuration
  and dynamics of Ganymede's magnetosphere. We find that the Hall
  MHD and MHD-EPIC solutions are qualitatively similar, but there are
  significant quantitative differences. In particular, the density and
  pressure inside the magnetosphere show different distributions. For our
  baseline grid resolution the PIC solution is more dynamic than the Hall
  MHD simulation and it compares significantly better with the Galileo
  magnetic measurements than the Hall MHD solution. The power spectra of
  the observed and simulated magnetic field fluctuations agree extremely
  well for the MHD-EPIC model. The MHD-EPIC simulation also produced a
  few flux transfer events (FTEs) that have magnetic signatures very
  similar to an observed event. The simulation shows that the FTEs
  often exhibit complex 3-D structures with their orientations changing
  substantially between the equatorial plane and the Galileo trajectory,
  which explains the magnetic signatures observed during the magnetopause
  crossings. The computational cost of the MHD-EPIC simulation was only
  about 4 times more than that of the Hall MHD simulation.

Title: What Controls the Structure and Dynamics of Earth's
    Magnetosphere?
Authors: Eastwood, J. P.; Hietala, H.; Toth, G.; Phan, T. D.;
   Fujimoto, M.
Bibcode: 2016mssf.book..271E
Altcode:
  No abstract at ADS

Title: Separator reconnection at the magnetopause for predominantly
northward and southward IMF: Techniques and results
Authors: Glocer, A.; Dorelli, J.; Toth, G.; Komar, C. M.; Cassak, P. A.
Bibcode: 2016JGRA..121..140G
Altcode:
  In this work, we demonstrate how to track magnetic separators
  in three-dimensional simulated magnetic fields with or without
  magnetic nulls, apply these techniques to enhance our understanding
  of reconnection at the magnetopause. We present three methods for
  locating magnetic separators and apply them to 3-D resistive MHD
  simulations of the Earth's magnetosphere using the Block-Adaptive-Tree
  Solar-wind Roe-type Upwind Scheme code. The techniques for finding
  separators and determining the reconnection rate are insensitive to
  interplanetary magnetic field (IMF) clock angle and can in principle
  be applied to any magnetospheric model. Moreover, the techniques
  have a number of advantages over prior separator finding techniques
  applied to the magnetosphere. The present work examines cases of high
  and low resistivity for two clock angles. We go beyond previous work
  examine the separator during Flux Transfer Events (FTEs). Our analysis
  of reconnection on the magnetopause yields a number of interesting
  conclusions: Reconnection occurs all along the separator even during
  predominately northward IMF cases. Multiple separators form in
  low-resistivity conditions, and in the region of an FTE the separator
  splits into distinct branches. Moreover, the local contribution to the
  reconnection rate, as determined by the local parallel electric field,
  drops in the vicinity of the FTE with respect to the value when there
  are none.

Title: Multi-fluid MHD Study of the Solar Wind Interaction with Mars'
    Upper Atmosphere during the 2015 March 8th ICME Event
Authors: Dong, C.; Ma, Y.; Bougher, S. W.; Toth, G.; Nagy, A. F.;
   Halekas, J. S.; Dong, Y.; Curry, S.; Luhmann, J. G.; Brain, D. A.;
   Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.; Benna, M.;
   McFadden, J. P.; Mitchell, D. L.; DiBraccio, G. A.; Lillis, R. J.;
   Jakosky, B. M.; Grebowsky, J. M.
Bibcode: 2015AGUFM.P21A2083D
Altcode:
  The 3-D Mars multi-fluid BATS-R-US MHD code is used to study the solar
  wind interaction with the Martian upper atmosphere during the 2015
  March 8th interplanetary coronal mass ejection (ICME). We studied
  four steady-state cases, corresponding to three major ICME phases:
  pre-ICME phase (Case 1), sheath phase (Cases 2--3), and ejecta
  phase (Case 4). Detailed data-model comparisons demonstrate that
  the simulation results are in good agreement with Mars Atmosphere
  and Volatile EvolutioN (MAVEN) measurements, indicating that the
  multi-fluid MHD model can reproduce most of the features observed by
  MAVEN, thus providing confidence in the estimate of ion escape rates
  from its calculation. The total ion escape rate is increased by an
  order of magnitude, from 2.05×1024 s-1 (pre-ICME phase) to 2.25×1025
  s-1 (ICME sheath phase), during this time period. The calculated ion
  escape rates were used to examine the relative importance of the two
  major ion loss channels from the planet: energetic pickup ion loss
  through the dayside plume and cold ionospheric ion loss through the
  nightside plasma wake region. We found that the energetic pickup ions
  escaping from the dayside plume could be as much as ~23% of the total
  ion loss prior to the ICME arrival. Interestingly, the tailward ion
  escape rate is significantly increased at the ejecta phase, leading
  to a reduction of the dayside ion escape to ~5% of the total ion
  loss. Under such circumstance, the cold ionospheric ions escaping
  from the plasma wake comprise the majority of the ion loss from the
  planet. Furthermore, by comparing four simulation results along the
  same MAVEN orbit, we note that there is no significant variation in
  the Martian lower ionosphere. Finally, both bow shock and magnetic
  pileup boundary (BS, MPB) locations are decreased from (1.2 RMars, 1.57
  RMars) at the pre-ICME phase to (1.16 RMars, 1.47 RMars) respectively
  during the sheath phase along the dayside Sun-Mars line. MAVEN has
  provided a great opportunity to study the evolution of the Martian
  atmosphere and climate over its history. A large quantity of useful
  data has been returned for future studies. These kinds of data-model
  comparisons can help the community to better understand the Martian
  upper atmosphere response to the (extreme) variation in the solar wind
  and its interplanetary environment from a global perspective.

Title: Four-fluid MHD Simulations of the Plasma and Neutral Gas
    Environment of Comet Churyumov-Gerasimenko Near Perihelio
Authors: Huang, Z.; Toth, G.; Gombosi, T. I.; Jia, X.; Rubin, M.;
   Hansen, K. C.; Fougere, N.; Bieler, A. M.; Shou, Y.; Altwegg, K.;
   Combi, M. R.; Tenishev, V.
Bibcode: 2015AGUFM.P31E2116H
Altcode:
  The neutral and plasma environment is critical in understanding the
  interaction of comet Churyumov-Gerasimenko (CG), the target of the
  Rosetta mission, and the solar wind. To serve this need and support
  the Rosetta mission, we develop a 3-D four fluid model, which is
  based on BATS-R-US within the SWMF (Space Weather Modeling Framework)
  that solves the governing multi-fluid MHD equations and the Euler
  equations for the neutral gas fluid. These equations describe the
  behavior and interactions of the cometary heavy ions, the solar wind
  protons, the electrons, and the neutrals. This model incorporates
  different mass loading processes, including photo and electron impact
  ionization, charge exchange, dissociative ion-electron recombination,
  and collisional interactions between different fluids. We simulate the
  near nucleus plasma and neutral gas environment near perihelion with
  a realistic shape model of CG and compare our simulation results with
  Rosetta observations.

Title: Solar Wind Prediction at Pluto During the New Horizons Flyby:
    Results From a Two-Dimensional Multi-fluid MHD Model of the Outer
    Heliosphere
Authors: Zieger, B.; Toth, G.; Opher, M.; Gombosi, T. I.
Bibcode: 2015AGUFMSM31D2539Z
Altcode:
  We adapted the outer heliosphere (OH) component of the Space Weather
  Modeling Framework, which is a 3-D global multi-fluid MHD model of the
  outer heliosphere with one ion fluid and four neutral populations, for
  time-dependent 2-D multi-fluid MHD simulations of solar wind propagation
  from a heliocentric distance of 1 AU up to 50 AU. We used this model to
  predict the solar wind plasma parameters as well as the interplanetary
  magnetic field components at Pluto and along the New Horizons trajectory
  during the whole calendar year of 2015 including the closest approach
  on July 14. The simulation is run in the solar equatorial plane in the
  heliographic inertial frame (HGI). The inner boundary conditions along
  a circle of 1 AU radius are set by near-Earth solar wind observations
  (hourly OMNI data), assuming that the global solar wind distribution
  does not change much during a Carrington rotation (27.2753 days). Our
  2-D multi-fluid MHD code evolves one ion fluid and two neutral fluids,
  which are the primary interstellar neutral atoms and the interstellar
  neutral atoms deflected in the outer heliosheath between the slow bow
  shock and the heliopause. Spherical expansion effects are properly
  taken into account for the ions and the solar magnetic field. The
  inflow parameters of the two neutral fluids (density, temperature,
  and velocity components) are set at the negative X (HGI) boundary at 50
  AU distance, which are taken from previous 3-D global multi-fluid MHD
  simulations of the heliospheric interface in a much larger simulation
  box (1500x1500x1500 AU). The inflow velocity vectors of the two neutral
  fluids define the so-called hydrogen deflection plane. The solar wind
  ions and the interstellar neutrals interact through charge exchange
  source terms included in the multi-fluid MHD equations, so the two
  neutral populations are evolved self-consistently. We validate our
  model with the available plasma data from New Horizons as well as
  with Voyager 2 plasma and magnetic field observations within the
  heliocentric distance of 50 AU. Our new time-dependent 2-D multi-fluid
  MHD model is generally applicable for solar wind predictions at any
  outer planet (Jupiter, Saturn, Uranus, Neptune) or spacecraft in the
  outer heliosphere where charge exchange between solar wind ions and
  interstellar neutrals play an important role.

Title: Modeling AWSoM CMEs with EEGGL: A New Approach for Space
    Weather Forecasting
Authors: Jin, M.; Manchester, W.; van der Holst, B.; Sokolov, I.;
   Toth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
Bibcode: 2015AGUFMSH43C..02J
Altcode:
  The major source of destructive space weather is coronal mass ejections
  (CMEs). However, our understanding of CMEs and their propagation in the
  heliosphere is limited by the insufficient observations. Therefore,
  the development of first-principals numerical models plays a vital
  role in both theoretical investigation and providing space weather
  forecasts. Here, we present results of the simulation of CME propagation
  from the Sun to 1AU by combining the analytical Gibson &amp; Low (GL)
  flux rope model with the state-of-art solar wind model AWSoM. We also
  provide an approach for transferring this research model to a space
  weather forecasting tool by demonstrating how the free parameters of
  the GL flux rope can be prescribed based on remote observations via
  the new Eruptive Event Generator by Gibson-Low (EEGGL) toolkit. This
  capability allows us to predict the long-term evolution of the CME
  in interplanetary space. We perform proof-of-concept case studies to
  show the capability of the model to capture physical processes that
  determine CME evolution while also reproducing many observed features
  both in the corona and at 1 AU. We discuss the potential and limitations
  of this model as a future space weather forecasting tool.

Title: Combining DSMC Simulations and ROSINA/COPS Data of Comet
    67P/Churyumov-Gerasimenko to Develop a Realistic Empirical Coma
    Model and to Determine Accurate Production Rates
Authors: Hansen, K. C.; Fougere, N.; Bieler, A. M.; Altwegg, K.;
   Combi, M. R.; Gombosi, T. I.; Huang, Z.; Rubin, M.; Tenishev, V.;
   Toth, G.; Tzou, C. Y.
Bibcode: 2015AGUFM.P31E2104H
Altcode:
  We have previously published results from the AMPS DSMC (Adaptive
  Mesh Particle Simulator Direct Simulation Monte Carlo) model and its
  characterization of the neutral coma of comet 67P/Churyumov-Gerasimenko
  through detailed comparison with data collected by the ROSINA/COPS
  (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/COmet
  Pressure Sensor) instrument aboard the Rosetta spacecraft [Bieler,
  2015]. Results from these DSMC models have been used to create an
  empirical model of the near comet coma (&lt;200 km) of comet 67P. The
  empirical model characterizes the neutral coma in a comet centered,
  sun fixed reference frame as a function of heliocentric distance,
  radial distance from the comet, local time and declination. The
  model is a significant improvement over more simple empirical models,
  such as the Haser model. While the DSMC results are a more accurate
  representation of the coma at any given time, the advantage of a mean
  state, empirical model is the ease and speed of use. One use of such
  an empirical model is in the calculation of a total cometary coma
  production rate from the ROSINA/COPS data. The COPS data are in situ
  measurements of gas density and velocity along the ROSETTA spacecraft
  track. Converting the measured neutral density into a production rate
  requires knowledge of the neutral gas distribution in the coma. Our
  empirical model provides this information and therefore allows us to
  correct for the spacecraft location to calculate a production rate as
  a function of heliocentric distance. We will present the full empirical
  model as well as the calculated neutral production rate for the period
  of August 2014 - August 2015 (perihelion).

Title: A multifluid magnetohydrodynamic simulation of the interaction
    between Jupiter's magnetosphere and its moon Europa
Authors: Rubin, M.; Jia, X.; Altwegg, K.; Combi, M. R.; Daldorff,
   L. K. S.; Gombosi, T. I.; Khurana, K. K.; Kivelson, M.; Tenishev,
   V.; Toth, G.; van der Holst, B.; Wurz, P.
Bibcode: 2015AGUFM.P21B..01R
Altcode:
  Jupiter's moon Europa is believed to contain a subsurface water
  ocean whose finite electrical conductance imposes clear induction
  signatures on the magnetic field in its surroundings. The evidence
  rests heavily on measurements performed by the magnetometer on board
  the Galileo spacecraft during multiple flybys of the moon. Europa's
  interaction with the Jovian magnetosphere has become a major target
  of research in planetary science, partly because of the potential
  of a salty ocean to harbor life outside our own planet. Thus it is
  of considerable interest to develop numerical simulations of the
  Europa-Jupiter interaction that can be compared with data in order
  to refine our knowledge of Europa's subsurface structure. In this
  presentation we show aspects of Europa's interaction with the Jovian
  magnetosphere extracted from a multifluid magnetohydrodynamics (MHD)
  code BATS-R-US recently developed at the University of Michigan. The
  model dynamically separates magnetospheric and pick-up ions and is
  capable of capturing some of the physics previously accessible only to
  kinetic approaches. The model utilizes an adaptive grid to maintain the
  high spatial resolution on the surface required to resolve the portion
  of Europa's neutral atmosphere with a scale height of a few tens of
  kilometers that is in thermal equilibrium. The model also derives the
  electron temperature, which is crucial to obtain the local electron
  impact ionization rates and hence the plasma mass loading in Europa's
  atmosphere. We compare our results with observations made by the plasma
  particles and fields instruments on the Galileo spacecraft to validate
  our model. We will show that multifluid MHD is able to reproduce the
  basic features of the plasma moments and magnetic field observations
  obtained during the Galileo E4 and E26 flybys at Europa.

Title: Using the 11-year Solar Cycle to Predict the Heliosheath
    Environment at Voyager 1 and 2
Authors: Michael, A.; Opher, M.; Provornikova, E.; Richardson, J. D.;
   Toth, G.
Bibcode: 2015AGUFMSH41A2373M
Altcode:
  As Voyager 2 moves further into the heliosheath, the region of subsonic
  solar wind plasma in between the termination shock and the heliopause,
  it has observed an increase of the magnetic field strength to large
  values, all while maintaining magnetic flux conservation. Dr. Burlaga
  will present these observations in the 2015 AGU Fall meeting
  (abstract ID: 59200). The increase in magnetic field strength could
  be a signature of Voyager 2 approaching the heliopause or, possibly,
  due to solar cycle effects. In this work we investigate the role the
  11-year solar cycle variations as well as magnetic dissipation effects
  have on the heliosheath environments observed at Voyager 1 and 2 using
  a global 3D magnetohydrodynamic model of the heliosphere. We use time
  and latitude-dependent solar wind velocity and density inferred from
  SOHO/SWAN and IPS data and solar cycle variations of the magnetic
  field derived from 27-day averages of the field magnitude average
  of the magnetic field at 1 AU from the OMNI database as presented in
  Michael et al. (2015). Since the model has already accurately matched
  the flows and magnetic field strength at Voyager 2 until 93 AU,
  we extend the boundary conditions to model the heliosheath up until
  Voyager 2 reaches the heliopause. This work will help clarify if the
  magnetic field observed at Voyager 2 should increase or decrease
  due to the solar cycle. We describe the solar magnetic field both
  as a dipole, with the magnetic and rotational axes aligned, and as
  a monopole, with magnetic field aligned with the interstellar medium
  to reduce numerical reconnection within the heliosheath, due to the
  removal of the heliospheric surrent sheet, and at the solar wind -
  interstellar medium interface. A comparison of the models allows for
  a crude estimation of the role that magnetic dissipation plays in the
  system and whether it allows for a better understanding of the Voyager
  2 location in the heliosheath.

Title: Overview of the SHIELDS Project at LANL
Authors: Jordanova, V.; Delzanno, G. L.; Henderson, M. G.; Godinez,
   H. C.; Jeffery, C. A.; Lawrence, E. C.; Meierbachtol, C.; Moulton,
   D.; Vernon, L.; Woodroffe, J. R.; Toth, G.; Welling, D. T.; Yu, Y.;
   Birn, J.; Thomsen, M. F.; Borovsky, J.; Denton, M.; Albert, J.; Horne,
   R. B.; Lemon, C. L.; Markidis, S.; Young, S. L.
Bibcode: 2015AGUFMSM31E..04J
Altcode:
  The near-Earth space environment is a highly dynamic and coupled
  system through a complex set of physical processes over a large range
  of scales, which responds nonlinearly to driving by the time-varying
  solar wind. Predicting variations in this environment that can affect
  technologies in space and on Earth, i.e. "space weather", remains
  a big space physics challenge. We present a recently funded project
  through the Los Alamos National Laboratory (LANL) Directed Research
  and Development (LDRD) program that is developing a new capability to
  understand, model, and predict Space Hazards Induced near Earth by Large
  Dynamic Storms, the SHIELDS framework. The project goals are to specify
  the dynamics of the hot (keV) particles (the seed population for the
  radiation belts) on both macro- and micro-scale, including important
  physics of rapid particle injection and acceleration associated with
  magnetospheric storms/substorms and plasma waves. This challenging
  problem is addressed using a team of world-class experts in the fields
  of space science and computational plasma physics and state-of-the-art
  models and computational facilities. New data assimilation techniques
  employing data from LANL instruments on the Van Allen Probes and
  geosynchronous satellites are developed in addition to physics-based
  models. This research will provide a framework for understanding of key
  radiation belt drivers that may accelerate particles to relativistic
  energies and lead to spacecraft damage and failure. The ability to
  reliably distinguish between various modes of failure is critically
  important in anomaly resolution and forensics. SHIELDS will enhance
  our capability to accurately specify and predict the near-Earth space
  environment where operational satellites reside.

Title: Initial Predictions of Outflow Rates from Jupiter's Ionosphere
Authors: Garcia-Sage, K.; Glocer, A.; Bell, J. M.; Toth, G.; Khazanov,
   G. V.
Bibcode: 2015AGUFMSM31C2518G
Altcode:
  Although Voyager 2 observations of H3+ in Jupiter's magnetosphere
  indicate an ionospheric source of plasma, very little work has been
  done to predict outflow rates from Jupiter's ionosphere. We use the
  Polar Wind Outflow Model (PWOM), originally developed for Saturn and
  Earth, to model outflow at Jupiter. We use a neutral atmosphere and
  atmosphere-ionosphere chemistry from the Jupiter-Global Ionosphere
  and Thermosphere Model (J-GITM) model and solve the field-aligned
  gyrotropic transport equations along open flux tubes. The model includes
  the effects of topside electron heat flux, collisional heating, and
  photoionization. We describe a new modeling approach that includes
  a kinetic description of superthermal photoelectrons and secondary
  electron production. We show the preliminary results for vertical
  transport and outflow of ionospheric H+, H2+, and H3+. These results
  provide initial predictions for ion populations that Juno may observe
  over Jupiter's polar regions.

Title: Modeling of the Inner Coma of Comet 67P/Churyumov-Gerasimenko
    Constrained by VIRTIS and ROSINA Observations
Authors: Fougere, N.; Combi, M. R.; Tenishev, V.; Bieler, A. M.;
   Migliorini, A.; Bockelée-Morvan, D.; Toth, G.; Huang, Z.; Gombosi,
   T. I.; Hansen, K. C.; Capaccioni, F.; Filacchione, G.; Piccioni, G.;
   Debout, V.; Erard, S.; Leyrat, C.; Fink, U.; Rubin, M.; Altwegg, K.;
   Tzou, C. Y.; Le Roy, L.; Calmonte, U.; Berthelier, J. J.; Rème, H.;
   Hässig, M.; Fuselier, S. A.; Fiethe, B.; De Keyser, J.
Bibcode: 2015AGUFM.P31E2105F
Altcode:
  As it orbits around comet 67P/Churyumov-Gerasimenko (CG), the Rosetta
  spacecraft acquires more information about its main target. The
  numerous observations made at various geometries and at different
  times enable a good spatial and temporal coverage of the evolution of
  CG's cometary coma. However, the question regarding the link between
  the coma measurements and the nucleus activity remains relatively open
  notably due to gas expansion and strong kinetic effects in the comet's
  rarefied atmosphere. In this work, we use coma observations made by
  the ROSINA-DFMS instrument to constrain the activity at the surface
  of the nucleus. The distribution of the H2O and CO2 outgassing is
  described with the use of spherical harmonics. The coordinates in the
  orthogonal system represented by the spherical harmonics are computed
  using a least squared method, minimizing the sum of the square residuals
  between an analytical coma model and the DFMS data. Then, the previously
  deduced activity distributions are used in a Direct Simulation Monte
  Carlo (DSMC) model to compute a full description of the H2O and CO2
  coma of comet CG from the nucleus' surface up to several hundreds of
  kilometers. The DSMC outputs are used to create synthetic images,
  which can be directly compared with VIRTIS measurements. The good
  agreement between the VIRTIS observations and the DSMC model, itself
  constrained with ROSINA data, provides a compelling juxtaposition of
  the measurements from these two instruments. Acknowledgements Work at
  UofM was supported by contracts JPL#1266313, JPL#1266314 and NASA grant
  NNX09AB59G. Work at UoB was funded by the State of Bern, the Swiss
  National Science Foundation and by the ESA PRODEX Program. Work at
  Southwest Research institute was supported by subcontract #1496541 from
  the JPL. Work at BIRA-IASB was supported by the Belgian Science Policy
  Office via PRODEX/ROSINA PEA 90020. The authors would like to thank ASI,
  CNES, DLR, NASA for supporting this research. VIRTIS was built by a
  consortium formed by Italy, France and Germany, under the scientific
  responsibility of the IAPS of INAF, which guides also the scientific
  operations. The consortium includes also the LESIA of the Observatoire
  de Paris, and the Institut für Planetenforschung of DLR. The authors
  wish to thank the RSGS and the RMOC for their continuous support.

Title: MHD Model Results of Solar Wind Interaction with Mars and
    Comparison with MAVEN Plasma Observations
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Fang, X.; Dong, Y.;
   Toth, G.; Halekas, J. S.; Connerney, J. E. P.; Espley, J. R.; Mahaffy,
   P. R.; Benna, M.; McFadden, J. P.; Mitchell, D. L.; Jakosky, B. M.
Bibcode: 2015AGUFM.P13D..06M
Altcode:
  The Mars Atmosphere and Volatile Evolution mission (MAVEN), launched on
  November 18, 2013, is now in its primary science phase. The mission was
  designed to study the upper atmosphere, ionosphere, and magnetosphere
  of Mars, the response to solar and solar-wind input, and the ability
  of atmospheric molecules and atoms to escape to space. In this study,
  we use a time-dependent MHD model to interpret plasma observations
  made by MAVEN particle and field instruments. Detailed comparisons
  between the model and the relevant plasma observations from MAVEN
  are presented for an entire Mars rotation under relatively quiet
  solar wind conditions. Through comparison along MAVEN orbits, we
  find that the time-dependent multi-species single-fluid MHD model is
  able to reproduce the main features of the plasma environment around
  Mars. Using the model results, we find that photoionization beyond
  the terminator is the dominant ion source as compared with day-night
  transport in maintaining the nightside ionosphere. Model results
  also show that both the time-varying solar wind conditions and the
  continuously rotating crustal field work together to control the ion
  escape variation with time.

Title: Modeled Interaction of Comet 67P/Churyumov-Gerasimenko with
    the Solar Wind Inside 2 AU
Authors: Rubin, M.; Gombosi, T. I.; Hansen, K. C.; Ip, W. -H.;
   Kartalev, M. D.; Koenders, C.; Tóth, G.
Bibcode: 2015EM&P..116..141R
Altcode: 2015EM&P..tmp...20R
  Periodic comets move around the Sun on elliptical orbits. As such
  comet 67P/Churyumov-Gerasimenko (hereafter 67P) spends a portion of
  time in the inner solar system where it is exposed to increased solar
  insolation. Therefore given the change in heliocentric distance, in
  case of 67P from aphelion at 5.68 AU to perihelion at ~1.24 AU, the
  comet's activity—the production of neutral gas and dust—undergoes
  significant variations. As a consequence, during the inbound portion,
  the mass loading of the solar wind increases and extends to larger
  spatial scales. This paper investigates how this interaction changes
  the character of the plasma environment of the comet by means of
  multifluid MHD simulations. The multifluid MHD model is capable of
  separating the dynamics of the solar wind ions and the pick-up ions
  created through photoionization and electron impact ionization in the
  coma of the comet. We show how two of the major boundaries, the bow
  shock and the diamagnetic cavity, form and develop as the comet moves
  through the inner solar system. Likewise for 67P, although most likely
  shifted back in time with respect to perihelion passage, this process
  is reversed on the outbound portion of the orbit. The presented model
  herein is able to reproduce some of the key features previously only
  accessible to particle-based models that take full account of the ions'
  gyration. The results shown herein are in decent agreement to these
  hybrid-type kinetic simulations.

Title: Magnetospheric Simulations With the Three-Dimensional
    Magnetohydrodynamics With Embedded Particle-in-Cell Model
Authors: Toth, G.; Jia, X.; Chen, Y.; Markidis, S.; Peng, B.;
   Daldorff, L. K. S.; Tenishev, V.; Borovikov, D.; Haiducek, J. D.;
   Gombosi, T. I.; Glocer, A.; Dorelli, J.; Lapenta, G.
Bibcode: 2015AGUFMSM54A..07T
Altcode:
  We have recently developed a new modeling capability to embed the
  implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US
  magnetohydrodynamic model. The PIC domain can cover the regions where
  kinetic effects are most important, such as reconnection sites. The
  BATS-R-US code, on the other hand, can efficiently handle the rest
  of the computational domain where the MHD or Hall MHD description is
  sufficient with its block-adaptive grid. The current implementation
  of the MHD-EPIC model allows two-way coupled simulations in two and
  three dimensions with multiple embedded PIC regions. The MHD and
  PIC grids can have different grid resolutions. The MHD variables
  and the moments of the PIC distribution functions are interpolated
  and message passed in an efficient manner through the Space Weather
  Modeling Framework (SWMF). Both BATS-R-US and iPIC3D are massively
  parallel codes fully integrated into, run by and coupled through
  the SWMF. We have successfully applied the MHD-EPIC code to model
  Ganymede's magnetosphere. Using four PIC regions we have in effect
  performed a fully kinetic simulation of the moon's mini-magnetosphere
  with a grid resolution that is about 5 times finer than the ion inertial
  length. The Hall MHD model provides proper boundary conditions for the
  four PIC regions and connects them with each other and with the inner
  and outer outer boundary conditions of the much larger MHD domain. We
  compare our results with Galileo magnetic observations and find good
  overall agreement with both Hall MHD and MHD-EPIC simulations. The
  power spectrum for the small scale fluctuations, however, agrees with
  the data much better for the MHD-EPIC simulation than for Hall MHD. In
  the MHD-EPIC simulation, unlike in the pure Hall MHD results, we also
  find signatures of flux transfer events (FTEs) that agree very well with
  the observed FTE signatures both in terms of shape and amplitudes. We
  will also highlight our ongoing efforts to model the magnetospheres
  of Mercury and Earth with the MHD-EPIC model.

Title: Magnetohydrodynamics with Embedded Particle-in-Cell Simulation
    of Mercury's Magnetosphere
Authors: Chen, Y.; Toth, G.; Jia, X.; Gombosi, T. I.; Markidis, S.
Bibcode: 2015AGUFMSM31A2474C
Altcode:
  Mercury's magnetosphere is much more dynamic than other planetary
  magnetospheres because of Mercury's weak intrinsic magnetic field and
  its proximity to the Sun. Magnetic reconnection and Kelvin-Helmholtz
  phenomena occur in Mercury's magnetopause and magnetotail at higher
  frequencies than in other planetary magnetosphere. For instance,
  chains of flux transfer events (FTEs) on the magnetopause, have been
  frequentlyobserved by the the MErcury Surface, Space ENvironment,
  GEochemistry and Ranging (MESSENGER) spacecraft (Slavin et al.,
  2012). Because ion Larmor radius is comparable to typical spatial
  scales in Mercury's magnetosphere, finite Larmor radius effects need
  to be accounted for. In addition, it is important to take in account
  non-ideal dissipation mechanisms to accurately describe magnetic
  reconnection. A kinetic approach allows us to model these phenomena
  accurately. However, kinetic global simulations, even for small-size
  magnetospheres like Mercury's, are currently unfeasible because of the
  high computational cost. In this work, we carry out global simulations
  of Mercury's magnetosphere with the recently developed MHD-EPIC model,
  which is a two-way coupling of the extended magnetohydrodynamic
  (XMHD) code BATS-R-US with the implicit Particle-in-Cell (PIC) model
  iPIC3D. The PIC model can cover the regions where kinetic effects are
  most important, such as reconnection sites. The BATS-R-US code, on the
  other hand, can efficiently handle the rest of the computational domain
  where the MHD or Hall MHD description is sufficient. We will present
  our preliminary results and comparison with MESSENGER observations.

Title: Nowcasting Ground Magnetic Perturbations with the Space
    Weather Modeling Framework
Authors: Welling, D. T.; Toth, G.; Singer, H. J.; Millward, G. H.;
   Gombosi, T. I.
Bibcode: 2015AGUFMSM13F..07W
Altcode:
  Predicting ground-based magnetic perturbations is a critical step
  towards specifying and predicting geomagnetically induced currents
  (GICs) in high voltage transmission lines. Currently, the Space Weather
  Modeling Framework (SWMF), a flexible modeling framework for simulating
  the multi-scale space environment, is being transitioned from research
  to operational use (R2O) by NOAA's Space Weather Prediction Center. Upon
  completion of this transition, the SWMF will provide localized B/t
  predictions using real-time solar wind observations from L1 and the
  F10.7 proxy for EUV as model input. This presentation describes the
  operational SWMF setup and summarizes the changes made to the code
  to enable R2O progress. The framework's algorithm for calculating
  ground-based magnetometer observations will be reviewed. Metrics
  from data-model comparisons will be reviewed to illustrate predictive
  capabilities. Early data products, such as regional-K index and grids
  of virtual magnetometer stations, will be presented. Finally, early
  successes will be shared, including the code's ability to reproduce
  the recent March 2015 St. Patrick's Day Storm.

Title: The impact of exospheric neutral dynamics on ring current decay
Authors: Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.;
   Gruntman, M.; Bailey, J. J.; Toth, G.
Bibcode: 2015AGUFMSA32A..01I
Altcode:
  The geocorona plays an important role in the energy budget of the
  Earth's inner magnetosphere since charge exchange of energetic ions
  with exospheric neutrals makes the exosphere act as an energy sink
  for ring current particles. Long-term ring current decay following a
  magnetic storm is mainly due to these electron transfer reactions,
  leading to the formation energetic neutral atoms (ENAs) that leave
  the ring current system on ballistic trajectories. The number of ENAs
  emitted from a given region of space depends on several factors,
  such as the energy and species of the energetic ion population
  in that region and the density of the neutral gas with which the
  ions undergo charge exchange. However, the density and structure
  of the exosphere are strongly dependent on changes in atmospheric
  temperature and density as well as charge exchange with the ions
  of plasmaspheric origin, which depletes the geocorona (by having a
  neutral removed from the system). Moreover, the radiation pressure
  exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen
  away from the Earth in an anti-sunward direction to form a tail of
  neutral hydrogen. TWINS ENA images provide a direct measurement of
  these ENA losses and therefore insight into the dynamics of the ring
  current decay through interactions with the geocorona. We assess the
  influence of geocoronal neutrals on ring current formation and decay by
  analysis of the predicted ENA emissions using 6 different geocoronal
  models and simulations from the HEIDI ring current model during storm
  time. Comparison with TWINS ENA images shows that the location of
  the peak ENA enhancements is highly dependent on the distribution of
  geocoronal hydrogen density. We show that the neutral dynamics has a
  strong influence on the time evolution of the ring current populations
  as well as on the formation of energetic neutral atoms.

Title: Global Multi-fluid Solar Corona Model with Temperature
    Anisotropy
Authors: van der Holst, B.; Chandran, B. D. G.; Kasper, J. C.; Szente,
   J.; Sokolov, I.; Toth, G.; Gombosi, T. I.
Bibcode: 2015AGUFMSH13C2448V
Altcode:
  The mechanisms that heat and accelerate the fast and slow wind have
  not yet been conclusively identified. Plasma properties of Helium
  in the solar wind are critical tracers for both processes so that
  understanding them is key towards gaining insight in the solar wind
  phenomenon, and being able to model it and predict its properties. We
  present a generalization of the AWSoM model, a global solar corona model
  with low-frequency Alfvén wave turbulence (van der Holst et al., 2014)
  to include alpha-particle dynamics. To apportion the wave dissipation
  to the isotropic electron temperature, parallel and perpendicular ion
  temperatures, we employ the results of the theories of linear wave
  damping and nonlinear stochastic heating as described by Chandran
  et al. (2011, 2013). We account for the instabilities due to the
  developing temperature anisotropies for the protons (Meng et al.,
  2012) and alpha particles (Verscharen et al., 2013). We discuss the
  feasibility for Alfvén wave turbulence to simultaneously address the
  coronal heating and alpha-proton differential streaming.

Title: A study of the variation of physical conditions in the cometary
    coma based on a 3D multi-fluid model
Authors: Shou, Y.; Combi, M. R.; Fougere, N.; Tenishev, V.; Toth,
   G.; Gombosi, T. I.; Huang, Z.; Jia, X.; Bieler, A. M.; Hansen, K. C.
Bibcode: 2015AGUFM.P31E2114S
Altcode:
  Physics-based numerical coma models are desirable whether to
  interpret the spacecraft observations of the inner coma or to
  compare with the ground-based observations of the outer coma. One
  example is Direct Simulation Monte Carlo (DSMC) method, which has
  been successfully adopted to simulate the coma under various complex
  conditions. However, for bright comets with large production rates,
  the time step in DSMC model has to be tiny to accommodate the small
  mean free path and the high collision frequency. In addition a truly
  time-variable 3D DSMC model would still be computationally difficult
  or even impossible under most circumstances. In this work, we develop
  a multi-neutral-fluid model based on BATS-R-US in the University of
  Michigan's SWMF (Space Weather Modeling Framework), which can serve
  as a useful alternative to DSMC methods to compute both the inner
  and the outer coma and to treat time-variable phenomena. This model
  treats H2O, OH, H2, O, H and CO2 as separate fluids and each fluid
  has its own velocity and temperature. But collisional interactions
  can also couple all fluids together. Collisional interactions tend to
  decrease the velocity differences and are also able to re-distribute
  the excess energy deposited by chemical reactions among all species. To
  compute the momentum and energy transfer caused by such interactions
  self-consistently, collisions between fluids, whose efficiency is
  proportional to the densities, are included as well as heating from
  various chemical reactions. By applying the model to comets with
  different production rates (i.e. 67P/Churyumov-Gerasimenko, 1P/Halley,
  etc.), we are able to study how the heating efficiency varies with
  cometocentric distances and production rates. The preliminary results
  and comparison are presented and discussed. This work has been partially
  supported by grant NNX14AG84G from the NASA Planetary Atmospheres
  Program, and US Rosetta contracts JPL #1266313, JPL #1266314 and
  JPL #1286489.

Title: Dynamics of Polar Jets from the Chromosphere to the Corona:
    Mass, Momentum and Energy Transfer
Authors: Szente, J.; Toth, G.; Manchester, W.; van der Holst, B.;
   Landi, E.; DeVore, C. R.; Gombosi, T. I.
Bibcode: 2015AGUFMSH23D..05S
Altcode:
  Coronal jets, routinely observed by multiple instruments at
  multiple wavelengths, provide a unique opportunity to understand
  the relationships between magnetic field topology, reconnection, and
  solar wind heating and acceleration. We simulate coronal jets with the
  Alfvén Wave Solar Model (AWSoM) [van der Holst (2014)] and focus our
  study on the thermodynamical evolution of the plasma. AWSoM solves
  the two-temperature MHD equations with electron heat conduction,
  which not only addresses the thermodynamics of individual species,
  but also allows for the construction of synthetic images from the EUV
  and soft X-ray wavelength range. Our jet model takes the form of a
  slowly rotating bipole field imbedded in the open magnetic field of
  a coronal hole; a topology suggested by observations. We follow the
  formation and evolution of polar jets starting from the chromosphere
  and extending into the outer corona. The simulations show small-scale
  eruptive reconnection events that self-consistently heat and accelerate
  the solar wind. Our results provide a quantitative comparison to
  observations made in the EUV and X-ray spectrum.

Title: Magnetized Jets Driven by the Sun, the Structure of the
Heliosphere Revisited: Consequences for Draping of BISM ahead of
    the HP and Time Variability of ENAs
Authors: Opher, M.; Drake, J. F.; Zieger, B.; Michael, A.; Toth, G.;
   Swisdak, M.; Gombosi, T. I.
Bibcode: 2015AGUFMSH41A2371O
Altcode:
  Recently we proposed (Opher et al. 2015) that the structure of the
  heliosphere might be very different than we previously thought. The
  classic accepted view of the heliosphere is a quiescent, comet-like
  shape aligned in the direction of the Sun's travel through the
  interstellar medium (ISM) extending for thousands of astronomical
  units. We have shown, based on magnetohydrodynamic (MHD) simulations,
  that the tension force of the twisted magnetic field of the Sun
  confines the solar wind plasma beyond the termination shock and drives
  jets to the north and south very much like astrophysical jets. These
  heliospheric jets are deflected into the tail region by the motion of
  the Sun through the ISM. As in some astrophysical jets the interstellar
  wind blows the two jets into the tail but is not strong enough to force
  the lobes into a single comet-like tail. Instead, the interstellar wind
  flows around the heliosphere and into the equatorial region between
  the two jets. We show that the heliospheric jets are turbulent (due
  to large-scale MHD instabilities and reconnection) and strongly mix
  the solar wind with the ISM. The resulting turbulence has important
  implications for particle acceleration in the heliosphere. The two-lobe
  structure is consistent with the energetic neutral atom (ENA) images of
  the heliotail from IBEX where two lobes are visible in the north and
  south and the suggestion from the Cassini ENAs that the heliosphere
  is "tailless." The new structure of the heliosphere is supported by
  recent analytic work (Drake et al. 2015) that shows that even in high
  β heliosheath the magnetic field plays a crucial role in funneling the
  solar wind in two jets. Here we present these recent results and show
  that the heliospheric jets mediate the draping of the magnetic field
  and the conditions ahead of the heliopause. We show that reconnection
  between the interstellar and solar magnetic field both at the flanks of
  the jets and in between them twist the interstellar magnetic field in a
  small layer ahead of the HP in agreement with Voyager 1 observations (as
  seen in Opher &amp; Drake 2013). We present results of the heliospheric
  jets for a weaker magnetic field, representative of the 2010-2012
  period and what is expected to be seen in the ENA maps with solar cycle.

Title: Testing the magnetotail configuration based on observations
    of low-altitude isotropic boundaries during quiet times
Authors: Ilie, R.; Ganushkina, N.; Toth, G.; Dubyagin, S.; Liemohn,
   M. W.
Bibcode: 2015JGRA..12010557I
Altcode:
  We investigate the configuration of the geomagnetic field on the
  nightside magnetosphere during a quiet time interval based on National
  Oceanic and Atmospheric Administration Polar Orbiting Environment
  Satellites Medium Energy Proton and Electron Detector (NOAA/POES
  MEPED) measurements in combination with numerical simulations of the
  global terrestrial magnetosphere using the Space Weather Modeling
  Framework. Measurements from the NOAA/POES MEPED low-altitude data
  sets provide the locations of isotropic boundaries; those are used to
  extract information regarding the field structure in the source regions
  in the magnetosphere. In order to evaluate adiabaticity and mapping
  accuracy, which is mainly controlled by the ratio between the radius
  of curvature and the particle's Larmor radius, we tested the threshold
  condition for strong pitch angle scattering based on the MHD magnetic
  field solution. The magnetic field configuration is represented by
  the model with high accuracy, as suggested by the high correlation
  coefficients and very low normalized root-mean-square errors between
  the observed and the modeled magnetic field. The scattering criterion,
  based on the values of k=&lt;mfrac&gt;Rcρ&lt;/mfrac&gt; ratio at
  the crossings of magnetic field lines, associated with isotropic
  boundaries, with the minimum B surface, predicts a critical value of
  k<SUB>CR</SUB>∼33. This means that, in the absence of other scattering
  mechanisms, the strong pitch angle scattering takes place whenever the
  Larmor radius is ∼33 times smaller than the radius of curvature of the
  magnetic field, as predicted by the Space Weather Modeling Framework.

Title: New Publicly Available EEGGL Tool for Simulating Coronal
    Mass Ejections.
Authors: Sokolov, I.; Manchester, W.; van der Holst, B.; Gombosi,
   T. I.; Jin, M.; Mullinix, R.; Taktakishvili, A.; Chulaki, A.; Toth, G.
Bibcode: 2015AGUFMSH21B2403S
Altcode:
  We present and demonstrate a new tool, EEGGL (Eruptive Event Generator
  using Gibson-Low configuration) for simulating CMEs (Coronal Mass
  Ejections). CMEs are among the most significant space weather events,
  producing the radiation hazards (via the diffuse shock acceleration
  of the Solar Energetic Particles - SEPs), the interplanetary shock
  waves as well as the geomagnetic activity due to the drastic changes of
  the interplanetary magnetic field within the "magnetic clouds" ("flux
  ropes"). Some of this effects may be efficiently simulated using the
  "cone model", which is employed in the real-time simulations of the
  ongoing CMEs at the NASA-Goddard Space Flight Center. The cone model
  provides a capability to predict the location, time, width and shape of
  the hydrodynamic perturbation in the upper solar corona (at ~0.1 AU),
  which can be used to drive the heliospheric simulation (with the ENLIL
  code, for example). At the same time the magnetic field orientation
  in this perturbation is uncertain within the cone model, which limits
  the capability of the geomagnetic activity forecast. The new EEGGL
  tool http://ccmc.gsfc.nasa.gov/analysis/EEGGL/recently developed at
  the Goddard Space Flight Center in collaboration with the University
  of Michigan provides a new capability for both evaluating the magnetic
  field configuration resulting from the CME and tracing the CME through
  the solar corona. In this way not only the capability to simulate the
  magnetic field evolution at 1 AU may be achieved, but also the more
  extensive comparison with the CME observations in the solar corona may
  be achieved. Based on the magnetogram and evaluation of the CME initial
  location and speed, the user may choose the active region from which
  the CME originates and then the EEGGL tools provides the parameters
  of the Gibson-Low magnetic configuration to parameterize the CME. The
  recommended parameters may be used then to drive the simulation of CME
  propagation from the low solar corona to 1 AU using the global code
  for simulating the solar corona and inner heliosphere. The Community
  Coordinated Modeling Center (CCMC) provides the capability for CME
  runs-on-request, to the heliophysics community.

Title: Alfvén wave solar model (AWSoM): proton temperature anisotropy
    and solar wind acceleration
Authors: Meng, X.; van der Holst, B.; Tóth, G.; Gombosi, T. I.
Bibcode: 2015MNRAS.454.3697M
Altcode:
  Temperature anisotropy has been frequently observed in the solar corona
  and the solar wind, yet poorly represented in computational models
  of the solar wind. Therefore, we have included proton temperature
  anisotropy in our Alfvén wave solar model (AWSoM). This model solves
  the magnetohydrodynamic equations augmented with low-frequency Alfvén
  wave turbulence. The wave reflection due to Alfvén speed gradient
  and field-aligned vorticity results in turbulent cascade. At the
  gyroradius scales, the apportioning of the turbulence dissipation into
  coronal heating of the protons and electrons is through stochastic
  heating. This paper focuses on the impacts of the proton temperature
  anisotropy on the solar wind. We apply AWSoM to simulate the steady
  solar wind from the corona to 1 AU using synoptic magnetograms. The
  Alfvén wave energy density at the inner boundary is prescribed with
  a uniform Poynting flux per field strength. We present the proton
  temperature anisotropy distribution, and investigate the firehose
  instability in the heliosphere from our simulations. In particular, the
  comparisons between the simulated and observed solar wind properties
  at 1 AU during the ramping-up phase and the maximum of solar cycle 24
  imply the importance of addressing the proton temperature anisotropy
  in solar wind modelling to capture the fast solar wind speed.

Title: Ganymede as a Laboratory for Multiscale Physics
Authors: Glocer, A.; Dorelli, J.; Toth, G.; Daughton, W. S.; Le, A.
Bibcode: 2015AGUFMSM54A..03G
Altcode:
  There are multiple scales on which the local physics of collisionless
  magnetic reconnection operate. These include the ion scale and
  electron scales defined by the associated inertial lengths. In
  Earth's magnetosphere, even the ion scale is inaccessible to even
  very large-scale numerical simulations, as it is just a tiny fraction
  of the total system size. Therefore we primarily rely on resistive
  MHD simulations when studying Earth's magnetosphere. In contrast,
  Ganymede's magnetosphere is much smaller, and the ion inertial
  length is much larger compared to the system's size. The relatively
  large scales make it possible to model Ganymede's magnetosphere with
  more sophisticated approaches while adequately resolving the relevant
  physical scales. Ganymede is therefore an ideal laboratory for studying
  both the multiple scales involved in collisionless reconnection as
  well as the consequences for the global magnetosphere; it is a real
  magnetosphere with available in situ data that is also accessible to
  multiple modeling approaches. We present recent Hall MHD simulations
  with the BATSRUS code, and comparisons to Galileo observations, of this
  small magnetosphere and demonstrate the global importance of ion scale
  effects. We further extract magnetic separators and compare the results
  with resistive MHD, Hybrid and PIC results. As with the GEM reconnection
  challenge, we find that including ion scale physics is the minimum
  extension of MHD to capture most basic features of the magnetosphere.

Title: Modeling of the VIRTIS-M Observations of the Coma of Comet
    67P/Churyumov-Gerasimenko
Authors: Fougere, Nicolas; Combi, Michael R.; Tenishev, Valeriy;
   Bieler, Andre; Migliorini, Alessandra; Piccioni, Giuseppe; Capaccioni,
   Fabrizio; Filacchione, Gianrico; Toth, Gabor; Huang, Zhenguang;
   Gombosi, Tamas; Hansen, Kenneth; Bockelee-Morvan, Dominique; Debout,
   Vincent; Erard, Stephane; Leyrat, Cedric; Fink, Uwe; Rubin, Martin;
   Altwegg, Kathrin; Tzou, Chia-Yu; Le Roy, Lena; Calmonte, Ursina;
   Berthelier, Jean-Jacques; Reme, Henri; Hassig, Myrtha; Fuselier,
   Stephen; Fiethe, Bjorn; De Keyser, Johan
Bibcode: 2015DPS....4741306F
Altcode:
  The recent images of the inner coma of 67P/Churyumov-Gerasimenko (CG)
  made by the infrared channel of the VIRTIS-M instrument on board the
  Rosetta spacecraft show the gas distribution as it expands in the
  coma (Migliorini et al. 2015, DPS abstract).Since VIRTIS is a remote
  sensing instrument, a proper modeling of these observations requires
  the computation of the full coma of comet CG, which necessitates the
  use of a kinetic approach due to the rather low gas densities. Hence,
  we apply a Direct Simulation Monde Carlo (DSMC) method to solve the
  Boltzmann equation and describe CG’s coma from the nucleus surface
  up to a few hundreds of kilometers. The model uses the SHAP5 nucleus
  shape model from the OSIRIS team. The gas flux distribution takes into
  account solar illumination, including self-shadowing. The local activity
  at the surface of the nucleus is given by spherical harmonics expansion
  reproducing best the ROSINA-DFMS data. The densities from the DSMC model
  outputs are then integrated along the line-of-sight to create synthetic
  images that are directly comparable with the VIRTIS-M column density
  measurements.The good agreement between the observations and the model
  illustrates our continuously improving understanding of the physics
  of the coma of comet CG.AcknowledgementsWork at UofM was supported by
  contracts JPL#1266313, JPL#1266314 and NASA grant NNX09AB59G. Work
  at UoB was funded by the State of Bern, the Swiss National Science
  Foundation and by the European Space Agency PRODEX Program. Work at
  Southwest Research institute was supported by subcontract #1496541 from
  the JPL. Work at BIRA-IASB was supported by the Belgian Science Policy
  Office via PRODEX/ROSINA PEA 90020. The authors would like to thank ASI,
  CNES, DLR, NASA for supporting this research. VIRTIS was built by a
  consortium formed by Italy, France and Germany, under the scientific
  responsibility of the IAPS of INAF, which guides also the scientific
  operations. The consortium includes also the LESIA of the Observatoire
  de Paris, and the Institut für Planetenforschung of DLR. The authors
  wish to thank the RSGS and the RMOC for their continuous support.

Title: The Plasma Environment in Comets Over a Wide Range of
Heliocentric Distances: Application to Coment C/2006 P1 (McNaught)
Authors: Shou, Yinsi; Combi, Michael; Jia, Yingdong; Gombosi, Tamas;
   Toth, Gabor; Rubin, Martin
Bibcode: 2015DPS....4741519S
Altcode:
  On 2007 January 12, comet C/2006 P1 (McNaught) passed its perihelion at
  0.17 AU. Abundant remote observations offer plenty of information on the
  neutral composition and neutral velocities within 1 million kilometers
  of the comet nucleus. In early February, the Ulysses spacecraft made
  an in situ measurement of the ion composition, plasma velocity, and
  magnetic field when passing through the distant ion tail and the ambient
  solar wind. The measurement by Ulysses was made when the comet was
  at around 0.8 AU. With the constraints provided by remote and in situ
  observations, we simulated the plasma environment of Comet C/2006 P1
  (McNaught) using a multi-species comet MHD model over a wide range of
  heliocentric distances from 0.17 to 1.75 AU. The solar wind interaction
  of the comet at various locations is characterized and typical subsolar
  standoff distances of the bow shock and contact surface are presented
  and compared to analytic solutions. We find the variation in the bow
  shock standoff distances at different heliocentric distances is smaller
  than the contact surface. In addition, we modified the multi-species
  model for the case when the comet was at 0.7 AU and achieved comparable
  water group ion abundances, proton densities, plasma velocities, and
  plasma temperatures to the Ulysses/SWICS and SWOOPS observations. We
  discuss the dominating chemical reactions throughout the comet-solar
  wind interaction region and demonstrate the link between the ion
  composition near the comet and in the distant tail as measured by
  Ulysses. The work at the University of Michigan was supported by the
  NASA Planetary Atmospheres grant NNX14AG84G.

Title: Solar wind Mars interaction during the MAVEN Deep Dip
campaigns: multi-fluid MHD simulations based upon the SWIA, NGIMS
    and MAG measurements
Authors: Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth,
   Gabor; Curry, Shannon M.; Nagy, Andrew F.; Halekas, Jasper S.; Luhmann,
   Janet G.; Mahaffy, Paul; Benna, Mehdi; Connerney, Jack E. P.; Espley,
   Jared; Mitchell, David L.; Brain, David A.; Jakosky, Bruce M.
Bibcode: 2015DPS....4741913D
Altcode:
  The 3-D Mars multi-fluid Block Adaptive Tree Solar-wind Roe
  Upwind Scheme (BATS-R-US) MHD code is used to study the solar wind
  interaction with the Martian upper atmosphere during the MAVEN Deep Dip
  campaigns. MAVEN made the first comprehensive measurements of Martian
  thermosphere and ionosphere composition, structure, and variability at
  altitudes down to ~130 km in the subsolar region during the second of
  its Deep Dip campaigns. MAVEN will start its fourth Deep Dip campaign
  this September and a large quantity of useful data will be returned
  for this study as well. In this study we adopt the MAVEN measurements
  as the multi-fluid MHD inputs. The estimated solar wind density and
  velocity, the estimated interplanetary magnetic field (IMF), and the
  exactly measured neutral atmosphere profile are taken from the SWIA,
  MAG and NGIMS instruments, respectively. We will compare the calculated
  ionosphere ion profiles with the NGIMS measurements. In the meantime,
  we will show the calculations of the global ion escape rates based
  upon actual measured neutral atmosphere profiles during the MAVEN Deep
  Dip campaigns.

Title: Comparison of 3D kinetic and hydrodynamic models to ROSINA-COPS
    measurements of the neutral coma of 67P/Churyumov-Gerasimenko
Authors: Bieler, Andre; Altwegg, Kathrin; Balsiger, Hans; Berthelier,
   Jean-Jacques; Calmonte, Ursina; Combi, Michael; De Keyser, Johan;
   Fiethe, Björn; Fougere, Nicolas; Fuselier, Stephen; Gasc, Sébastien;
   Gombosi, Tamas; Hansen, Kenneth; Hässig, Myrtha; Huang, Zhenguang;
   Jäckel, Annette; Jia, Xianzhe; Le Roy, Lena; Mall, Urs A.; Rème,
   Henri; Rubin, Martin; Tenishev, Valeriy; Tóth, Gábor; Tzou, Chia-Yu;
   Wurz, Peter
Bibcode: 2015A&A...583A...7B
Altcode:
  67P/Churyumov-Gerasimenko (67P) is a Jupiter-family comet and the object
  of investigation of the European Space Agency mission Rosetta. This
  report presents the first full 3D simulation results of 67P's neutral
  gas coma. In this study we include results from a direct simulation
  Monte Carlo method, a hydrodynamic code, and a purely geometric
  calculation which computes the total illuminated surface area on the
  nucleus. All models include the triangulated 3D shape model of 67P as
  well as realistic illumination and shadowing conditions. The basic
  concept is the assumption that these illumination conditions on the
  nucleus are the main driver for the gas activity of the comet. As a
  consequence, the total production rate of 67P varies as a function of
  solar insolation. The best agreement between the model and the data
  is achieved when gas fluxes on the night side are in the range of 7%
  to 10% of the maximum flux, accounting for contributions from the
  most volatile components. To validate the output of our numerical
  simulations we compare the results of all three models to in situ gas
  number density measurements from the ROSINA COPS instrument. We are
  able to reproduce the overall features of these local neutral number
  density measurements of ROSINA COPS for the time period between early
  August 2014 and January 1 2015 with all three models. Some details in
  the measurements are not reproduced and warrant further investigation
  and refinement of the models. However, the overall assumption that
  illumination conditions on the nucleus are at least an important
  driver of the gas activity is validated by the models. According to
  our simulation results we find the total production rate of 67P to be
  constant between August and November 2014 with a value of about 1 ×
  10<SUP>26</SUP> molecules s<SUP>-1</SUP>.

Title: MHD model results of solar wind interaction with Mars and
    comparison with MAVEN plasma observations
Authors: Ma, Y. J.; Russell, C. T.; Fang, X.; Dong, Y.; Nagy, A. F.;
   Toth, G.; Halekas, J. S.; Connerney, J. E. P.; Espley, J. R.; Mahaffy,
   P. R.; Benna, M.; McFadden, J. P.; Mitchell, D. L.; Jakosky, B. M.
Bibcode: 2015GeoRL..42.9113M
Altcode:
  The Mars Atmosphere and Volatile EvolutioN mission (MAVEN), launched
  on 18 November 2013, is now in its primary science phase, orbiting
  Mars with a 4.5 h period. In this study, we use a time-dependent MHD
  model to interpret plasma observations made by MAVEN particle and
  field instruments. Detailed comparisons between the model and the
  relevant plasma observations from MAVEN are presented for an entire
  Mars rotation under relatively quiet solar wind conditions. Through
  comparison along MAVEN orbits, we find that the time-dependent
  multispecies single-fluid MHD model is able to reproduce the main
  features of the plasma environment around Mars. Using the model results,
  we find that photoionization beyond the terminator is the dominant
  ion source as compared with day-night transport in maintaining the
  nightside ionosphere. Model results also show that both the time-varying
  solar wind conditions and the continuously rotating crustal field work
  together to control the ion escape variation with time.

Title: Three-dimensional kinetic modeling of the neutral and charged
    dust in the coma of Rosetta’s target comet 67P/Churyumov-Gerasimenko
Authors: Tenishev, Valeriy; Borovikov, Dmitry; Combi, Michael R.;
   Fougere, Nicolas; Huang, Zhenguang; Bieler, Andre; Hansen, Kenneth;
   Toth, Gabor; Jia, Xianzhe; Shou, Yinsi; Gombosi, Tamas; Rubin, Martin;
   Rotundi, Alessandra; Della Corte, Vincenzo
Bibcode: 2015DPS....4750309T
Altcode:
  Rosetta is the first mission that escorts a comet along its way
  through the Solar System for an extended amount of time. As a result,
  the target of the mission, comet 67P/Churyumov-Gerasimenko, is an
  object of great scientific interest.Dust ejected from the nucleus
  is entrained into the coma by the escaping gas. Interacting with the
  ambient plasma the dust particles are charged by the electron and ion
  collection currents. The photo and secondary emission currents can also
  change the particle charge. The resulting Lorentz force together with
  the gas drag, gravity, and radiation pressure define the dust particle
  trajectories.At altitudes comparable to those of the Rosetta trajectory,
  direction of a dust particle velocity can be significantly different
  from that in the innermost vicinity of the coma near the nucleus. At
  such altitudes the angular distribution of the dust grains velocity has
  a pronounced tail-like structure. This is consistent with Rosetta’s
  GIADA dust observations showing dust grains moving in the anti-sunward
  direction.Here, we present results of our model study of the neutral
  and charged dust in the coma of comet 67P/Churyumov-Gerasimenko,
  combining the University of Michigan AMPS kinetic particle model and the
  BATSRUS MHD model. Trajectories of dust particles within the observable
  size range of Rosetta’s GIADA dust instrument have been calculated
  accounting for the radiation pressure, gas drag, the nucleus gravity,
  the Lorentz force, and the effect of the nucleus rotation. The dust
  grain electric charge is calculated by balancing the collection currents
  at the grain’s location. We present angular velocity distribution
  maps of these charged dust grains for a few locations representative
  of Rosetta's trajectory around the comet.This work was supported by
  US Rosetta project contracts JPL-1266313 and JPL-1266314 and NASA
  Planetary Atmospheres grant NNX14AG84G

Title: Multifluid MHD study of the solar wind interaction with Mars'
    upper atmosphere during the 2015 March 8th ICME event
Authors: Dong, Chuanfei; Ma, Yingjuan; Bougher, Stephen W.; Toth,
   Gabor; Nagy, Andrew F.; Halekas, Jasper S.; Dong, Yaxue; Curry, Shannon
   M.; Luhmann, Janet G.; Brain, David; Connerney, Jack E. P.; Espley,
   Jared; Mahaffy, Paul; Benna, Mehdi; McFadden, James P.; Mitchell,
   David L.; DiBraccio, Gina A.; Lillis, Robert J.; Jakosky, Bruce M.;
   Grebowsky, Joseph M.
Bibcode: 2015GeoRL..42.9103D
Altcode:
  We study the solar wind interaction with the Martian upper atmosphere
  during the 8 March 2015 interplanetary coronal mass ejection (ICME)
  by using a global multifluid MHD model. Comparison of the simulation
  results with observations from Mars Atmosphere and Volatile EvolutioN
  (MAVEN) spacecraft shows good agreement. The total ion escape rate
  is increased by an order of magnitude, from 2.05 × 10<SUP>24</SUP>
  s<SUP>-1</SUP> (pre-ICME phase) to 2.25 × 10<SUP>25</SUP>
  s<SUP>-1</SUP> (ICME sheath phase), during this time period. Two major
  ion escape channels are illustrated: accelerated pickup ion loss through
  the dayside plume and ionospheric ion loss through the nightside plasma
  wake region. Interestingly, the tailward ion loss is significantly
  increased at the ejecta phase. Both bow shock and magnetic pileup
  boundary (BS and MPB) locations are decreased from (1.2R<SUB>M</SUB>,
  1.57R<SUB>M</SUB>) at the pre-ICME phase to (1.16R<SUB>M</SUB>,
  1.47R<SUB>M</SUB>), respectively, during the sheath phase along the
  dayside Mars-Sun line. Furthermore, both simulation and observational
  results indicate that there is no significant variation in the Martian
  ionosphere (at altitudes ≲ 200 km, i.e., the photochemical region)
  during this event.

Title: 3D DSMC Modeling of the Coma of Comet 67P/Churyumov-Gerasimenko
    Observed by the VIRTIS and ROSINA instruments
Authors: Fougere, N.; Combi, M. R.; Tenishev, V.; Bieler, A.; Toth, G.;
   Huang, Z.; Gombosi, T. I.; Hansen, K. C.; Capaccioni, F.; Filacchione,
   G.; Migliorini, A.; Bockelée-Morvan, D.; Debout, V.; Erard, S.;
   Leyrat, C.; Fink, U.; Rubin, M.; Altwegg, K.; Tzou, C. -Y.; Le Roy, L.
Bibcode: 2015EPSC...10..344F
Altcode:
  Since its rendez-vous with comet 67P/Chruryumov- Gerasimenko (CG),
  the Rosetta spacecraft has provided invaluable information contributing
  to our understanding of the cometary environment. On board, the VIRTIS
  and ROSINA instruments can both measure gas parameters in the rarefied
  cometary atmosphere, the coma, and provide complementary results with
  remote sensing and in-situ measurements, respectively. The use of
  a numerical model is a way to correlate the information provided by
  both VIRTIS and ROSINA to fully understand the volatile environment
  of comet CG. To describe the entire coma including the regions where
  collisions cannot maintain the flow in a fluid regime, the use of a
  kinetic method is necessary. Here, the Direct Simulation Monte-Carlo
  (DSMC) approach is applied to the cometary coma to solve the Boltzmann
  equation [1] using the Adaptive Mesh Particle Simulator (AMPS) code [2],
  [3], [4], [5], and then compared with VIRTIS and ROSINA data.

Title: Four-fluid MHD Simulations of the Plasma and Neutral Gas
    Environment of Comet Churyumov-Gerasimenko Near Perihelion
Authors: Huang, Z.; Toth, G.; Gombosi, T.; Jia, X.; Rubin, M.;
   Fougere, N.; Tenishev, V.; Combi, M.; Bieler, A.; Hansen, K.; Shou,
   Y.; Altwegg, K.
Bibcode: 2015EPSC...10..406H
Altcode:
  We develop a 3-D four fluid model to study the plasma environment of
  comet Churyumov- Gerasimenko (CG), which is the target of the Rosetta
  mission. Our model is based on BATS-R-US within the SWMF (Space Weather
  Modeling Framework) that solves the governing multifluid MHD equations
  and and the Euler equations for the neutral gas fluid. These equations
  describe the behavior and interactions of the cometary heavy ions,
  the solar wind protons, the electrons, and the neutrals. This model
  incorporates mass loading processes, including photo and electron
  impact ionization, furthermore taken into account are charge exchange,
  dissociative ion-electron recombination, as well as collisional
  interactions between different fluids. We simulate the near nucleus
  plasma and neutral gas environment with a realistic shape model of
  CG near perihelion and compare our simulation results with Rosetta
  observations.

Title: MHD Model Results of Solar Wind Plasma Interaction with
    Mars and Comparison with MAVEN Observations during Quiet Solar
    Wind Conditions
Authors: Ma, Y.; Russell, C.; Nagy, A. F.; Toth, G.; Halekas, J. S.;
   Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.; Benna, Mhedi;
   McFadden, James
Bibcode: 2015EPSC...10..316M
Altcode:
  The Mars Atmosphere and Volatile Evolution mission (MAVEN), launched
  on November 18, 2013, is now in its primary science phase, orbiting
  Mars with a 4.5 hour period. In this presentation, we show detailed
  comparisons between the MHD model results and the relevant plasma
  observations from MAVEN during quiet solar wind conditions. Through
  comparison with relevant observation along MAVEN orbits, we find that
  in general, the time-dependent multi-species MHD model reproduces very
  well the plasma interaction process around Mars.

Title: Constraining the pickup ion abundance and temperature through
    the multifluid reconstruction of the Voyager 2 termination shock
    crossing
Authors: Zieger, Bertalan; Opher, Merav; Tóth, Gábor; Decker,
   Robert B.; Richardson, John D.
Bibcode: 2015JGRA..120.7130Z
Altcode:
  Voyager 2 observations revealed that the hot solar wind ions (the
  so-called pickup ions) play a dominant role in the thermodynamics
  of the termination shock and the heliosheath. The number density and
  temperature of this hot population, however, have remained unknown,
  since the plasma instrument on board Voyager 2 can only detect the
  colder thermal ion component. Here we show that due to the multifluid
  nature of the plasma, the fast magnetosonic mode splits into a
  low-frequency fast mode and a high-frequency fast mode. The coupling
  between the two fast modes results in a quasi-stationary nonlinear
  wave mode, the "oscilliton," which creates a large-amplitude trailing
  wave train downstream of the thermal ion shock. By fitting multifluid
  shock wave solutions to the shock structure observed by Voyager 2,
  we are able to constrain both the abundance and the temperature of
  the undetected pickup ions. In our three-fluid model, we take into
  account the nonnegligible partial pressure of suprathermal energetic
  electrons (0.022-1.5 MeV) observed by the Low-Energy Charged Particle
  Experiment instrument on board Voyager 2. The best fitting simulation
  suggests a pickup ion abundance of 20 ± 3%, an upstream pickup ion
  temperature of 13.4 ± 2 MK, and a hot electron population with an
  apparent temperature of ~0.83 MK. We conclude that the actual shock
  transition is a subcritical dispersive shock wave with low Mach number
  and high plasma β.

Title: Solar wind interaction with the Martian upper atmosphere:
    Crustal field orientation, solar cycle, and seasonal variations
Authors: Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth,
   Gabor; Lee, Yuni; Nagy, Andrew F.; Tenishev, Valeriy; Pawlowski,
   Dave J.; Combi, Michael R.; Najib, Dalal
Bibcode: 2015JGRA..120.7857D
Altcode:
  A comprehensive study of the solar wind interaction with the Martian
  upper atmosphere is presented. Three global models: the 3-D Mars
  multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme MHD
  code (MF-MHD), the 3-D Mars Global Ionosphere Thermosphere Model
  (M-GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh
  Particle Simulator (M-AMPS) were used in this study. These models
  are one-way coupled; i.e., the MF-MHD model uses the 3-D neutral
  inputs from M-GITM and the 3-D hot oxygen corona distribution from
  M-AMPS. By adopting this one-way coupling approach, the Martian
  upper atmosphere ion escape rates are investigated in detail with
  the combined variations of crustal field orientation, solar cycle,
  and Martian seasonal conditions. The calculated ion escape rates are
  compared with Mars Express observational data and show reasonable
  agreement. The variations in solar cycles and seasons can affect the
  ion loss by a factor of ∼3.3 and ∼1.3, respectively. The crustal
  magnetic field has a shielding effect to protect Mars from solar wind
  interaction, and this effect is the strongest for perihelion conditions,
  with the crustal field facing the Sun. Furthermore, the fraction of cold
  escaping heavy ionospheric molecular ions [(O<SUB>2</SUB><SUP>+</SUP>
  and/or O<SUB>2</SUB><SUP>+</SUP>)/Total] are inversely proportional
  to the fraction of the escaping (ionospheric and corona) atomic
  ion [O<SUP>+</SUP>/Total], whereas O<SUB>2</SUB><SUP>+</SUP> and
  O<SUB>2</SUB><SUP>+</SUP> ion escape fractions show a positive linear
  correlation since both ion species are ionospheric ions that follow
  the same escaping path.

Title: The Plasma Environment in Comets over a Wide Range of
Heliocentric Distances: Application to Comet C/2006 P1 (McNaught)
Authors: Shou, Y.; Combi, M.; Jia, Y. -D.; Gombosi, T.; Toth, G.;
   Rubin, M.
Bibcode: 2015ApJ...809..156S
Altcode:
  On 2007 January 12, comet C/2006 P1 (McNaught) passed its perihelion
  at 0.17 AU. Abundant remote observations offer plenty of information
  on the neutral composition and neutral velocities within 1 million
  kilometers of the comet nucleus. In early February, the Ulysses
  spacecraft made an in situ measurement of the ion composition, plasma
  velocity, and magnetic field when passing through the distant ion
  tail and the ambient solar wind. The measurement by Ulysses was made
  when the comet was at around 0.8 AU. With the constraints provided by
  remote and in situ observations, we simulated the plasma environment of
  Comet C/2006 P1 (McNaught) using a multi-species comet MHD model over
  a wide range of heliocentric distances from 0.17 to 1.75 AU. The solar
  wind interaction of the comet at various locations is characterized
  and typical subsolar standoff distances of the bow shock and contact
  surface are presented and compared to analytic solutions. We find the
  variation in the bow shock standoff distances at different heliocentric
  distances is smaller than the contact surface. In addition, we modified
  the multi-species model for the case when the comet was at 0.7 AU
  and achieved comparable water group ion abundances, proton densities,
  plasma velocities, and plasma temperatures to the Ulysses/SWICS and
  SWOOPS observations. We discuss the dominating chemical reactions
  throughout the comet-solar wind interaction region and demonstrate
  the link between the ion composition near the comet and in the distant
  tail as measured by Ulysses.

Title: Solar Cycle Variation of the Magnetic Field Strength and
    Magnetic Dissipation Effects in the Heliosheath
Authors: Michael, Adam Thomas; Opher, Merav; Provornikova, Elena;
   Richardson, John; Toth, Gabor
Bibcode: 2015shin.confE..81M
Altcode:
  We investigate the role the 11-year solar cycle variation of the
  magnetic field strength as well as magnetic dissipation effects have on
  the flows within the heliosheath using a global 3D magnetohydrodynamic
  model of the heliosphere. We use time and latitude-dependent solar
  wind velocity and density inferred from SOHO/SWAN and IPS data and
  implemented solar cycle variations of the magnetic field derived from
  27-day averages of the field magnitude average of the magnetic field at
  1 AU from the OMNI database. This model predicts Voyager 1 (V1) and 2
  (V2) will observe similar plasma parameters within the HS. While this
  model accurately predicts the observations at V2, it does not reproduce
  the decrease in radial velocity or drop in magnetic flux observed by
  V1. This implies that the solar cycle variations in solar wind magnetic
  field observed at 1 AU do not cause the order of magnitude decrease
  in magnetic flux observed in the V1 data. We describe the solar wind
  magnetic field as a monopole, to remove the heliospheric current sheet
  (HCS), with the magnetic field aligned with that of the interstellar
  medium. This diminishes any numerical reconnection at the ISM - solar
  wind interface as well as within the heliosheath itself. We compare
  our model to the same model describing the solar wind magnetic field
  as a dipole. In the dipole case, there is an intrinsic loss of magnetic
  energy near the HCS due to reconnection. This reconnection is numerical
  since we do not include real resistivity in the model. The comparison of
  the two models allows for an estimation of the effects of reconnection
  in the HS. We compare both models to observations along V1 and V2 and
  discuss whether magnetic dissipation is a significant process affecting
  the flows within the heliosheath.

Title: The role of the Hall effect in the global structure and
dynamics of planetary magnetospheres: Ganymede as a case study
Authors: Dorelli, J. C.; Glocer, Alex; Collinson, Glyn; Tóth, Gábor
Bibcode: 2015JGRA..120.5377D
Altcode: 2015arXiv150100501D
  We present high-resolution Hall MHD simulations of Ganymede's
  magnetosphere demonstrating that Hall electric fields in ion-scale
  magnetic reconnection layers have significant global effects not
  captured in resistive MHD simulations. Consistent with local kinetic
  simulations of magnetic reconnection, our global simulations show
  the development of intense field-aligned currents along the magnetic
  separatrices. These currents extend all the way down to the moon's
  surface, where they may contribute to Ganymede's aurora. Within the
  magnetopause and magnetotail current sheets, Hall J × B forces
  accelerate ions to the local Alfvén speed in the out-of-plane
  direction, producing a global system of ion drift belts that
  circulates Jovian magnetospheric plasma throughout Ganymede's
  magnetosphere. We discuss some observable consequences of these
  Hall-induced currents and ion drifts: the appearance of a sub-Jovian
  "double magnetopause" structure, an Alfvénic ion jet extending across
  the upstream magnetopause, and an asymmetric pattern of magnetopause
  Kelvin-Helmholtz waves.

Title: Polar Jet Simulation with the Alfvén Wave Solar Model (AWSoM)
Authors: Szente, Judit; Toth, Gabor; van der Holst, Bart; DeVore,
   C. Richard; Gombosi, Tamas
Bibcode: 2015shin.confE..87S
Altcode:
  Coronal jets are being observed by multiple instruments at multiple
  wavelengths (SOHO, Yohkoh, STEREO, Hinode [Paraschiv (2010,
  2015)]). Studying polar jets can lead to an improved understanding
  of the relations between magnetic field topology and reconnection
  as well as solar wind heating and acceleration.The thermodynamical
  evolution of the plasma is the focus of our work. We introduce a
  slowly accelerated rotating bipole field in the open region of the
  background magnetic field. Similar magnetic topology is also implied in
  observations. Our aim is to implement the formation and evolution of
  polar jets in the coronal hole region starting from the chromosphere
  up to the outer corona. The simulations show small-scale eruptive
  reconnection events. The self-consistent heating and acceleration of
  the solar wind in the AWSoM model [van der Holst (2014)] provides the
  opportunity to study the energetics of the jet phenomena. This study
  leads to the possibility of quantitative comparison of the simulation
  results to X-ray, EUV or white light observations.

Title: The two-way relationship between ionospheric outflow and the
    ring current
Authors: Welling, D. T.; Jordanova, V. K.; Glocer, A.; Toth, G.;
   Liemohn, M. W.; Weimer, D. R.
Bibcode: 2015JGRA..120.4338W
Altcode:
  It is now well established that the ionosphere, because it acts as a
  significant source of plasma, plays a critical role in ring current
  dynamics. However, because the ring current deposits energy into the
  ionosphere, the inverse may also be true: the ring current can play a
  critical role in the dynamics of ionospheric outflow. This study uses
  a set of coupled, first-principles-based numerical models to test
  the dependence of ionospheric outflow on ring current-driven region
  2 field-aligned currents (FACs). A moderate magnetospheric storm
  event is modeled with the Space Weather Modeling Framework using
  a global MHD code (Block Adaptive Tree Solar wind Roe-type Upwind
  Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model),
  and a bounce-averaged kinetic ring current model (ring current
  atmosphere interaction model with self-consistent magnetic field,
  RAM-SCB). Initially, each code is two-way coupled to all others except
  for RAM-SCB, which receives inputs from the other models but is not
  allowed to feed back pressure into the MHD model. The simulation
  is repeated with pressure coupling activated, which drives strong
  pressure gradients and region 2 FACs in BATS-R-US. It is found that
  the region 2 FACs increase heavy ion outflow by up to 6 times over
  the noncoupled results. The additional outflow further energizes the
  ring current, establishing an ionosphere-magnetosphere mass feedback
  loop. This study further demonstrates that ionospheric outflow is not
  merely a plasma source for the magnetosphere but an integral part in
  the nonlinear ionosphere-magnetosphere-ring current system.

Title: Global MHD simulations of Mercury's magnetosphere with coupled
planetary interior: Induction effect of the planetary conducting
    core on the global interaction
Authors: Jia, Xianzhe; Slavin, James A.; Gombosi, Tamas I.; Daldorff,
   Lars K. S.; Toth, Gabor; Holst, Bart
Bibcode: 2015JGRA..120.4763J
Altcode:
  Mercury's comparatively weak intrinsic magnetic field and its close
  proximity to the Sun lead to a magnetosphere that undergoes more direct
  space-weathering interactions than other planets. A unique aspect of
  Mercury's interaction system arises from the large ratio of the scale
  of the planet to the scale of the magnetosphere and the presence of a
  large-size core composed of highly conducting material. Consequently,
  there is strong feedback between the planetary interior and the
  magnetosphere, especially under conditions of strong external
  forcing. Understanding the coupled solar wind-magnetosphere-interior
  interaction at Mercury requires not only analysis of observations but
  also a modeling framework that is both comprehensive and inclusive. We
  have developed a new global MHD model for Mercury in which the
  planetary interior is modeled as layers of different electrical
  conductivities that electromagnetically couple to the surrounding plasma
  environment. This new modeling capability allows us to characterize
  the dynamical response of Mercury to time-varying external conditions
  in a self-consistent manner. Comparison of our model results with
  observations by the MErcury Surface, Space ENvironment, GEochemistry,
  and Ranging (MESSENGER) spacecraft shows that the model provides
  a reasonably good representation of the global magnetosphere. To
  demonstrate the capability to model induction effects, we have performed
  idealized simulations in which Mercury's magnetosphere is impacted by
  a solar wind pressure enhancement. Our results show that due to the
  induction effect, Mercury's core exerts strong global influences on the
  way Mercury responds to changes in the external environment, including
  modifying the global magnetospheric structure and affecting the extent
  to which the solar wind directly impacts the surface. The global MHD
  model presented here represents a crucial step toward establishing a
  modeling framework that enables self-consistent characterization of
  Mercury's tightly coupled planetary interior-magnetosphere system.

Title: Assessing the role of oxygen on ring current formation and
    evolution through numerical experiments
Authors: Ilie, R.; Liemohn, M. W.; Toth, G.; Yu Ganushkina, N.;
   Daldorff, L. K. S.
Bibcode: 2015JGRA..120.4656I
Altcode:
  We address the effect of ionospheric outflow and magnetospheric ion
  composition on the physical processes that control the development
  of the 5 August 2011 magnetic storm. Simulations with the Space
  Weather Modeling Framework are used to investigate the global
  dynamics and energization of ions throughout the magnetosphere
  during storm time, with a focus on the formation and evolution of
  the ring current. Simulations involving multifluid (with variable
  H<SUP>+</SUP>/O<SUP>+</SUP> ratio in the inner magnetosphere) and
  single-fluid (with constant H<SUP>+</SUP>/O<SUP>+</SUP> ratio in
  the inner magnetosphere) MHD for the global magnetosphere with inner
  boundary conditions set either by specifying a constant ion density or
  by physics-based calculations of the ion fluxes reveal that dynamical
  changes of the ion composition in the inner magnetosphere alter the
  total energy density of the magnetosphere, leading to variations in
  the magnetic field as well as particle drifts throughout the simulated
  domain. A low oxygen to hydrogen ratio and outflow resulting from a
  constant ion density boundary produced the most disturbed magnetosphere,
  leading to a stronger ring current but misses the timing of the storm
  development. Conversely, including a physics-based solution for the
  ionospheric outflow to the magnetosphere system leads to a reduction
  in the cross-polar cap potential (CPCP). The increased presence of
  oxygen in the inner magnetosphere affects the global magnetospheric
  structure and dynamics and brings the nightside reconnection point
  closer to the Earth. The combination of reduced CPCP together with
  the formation of the reconnection line closer to the Earth yields
  less adiabatic heating in the magnetotail and reduces the amount of
  energetic plasma that has access to the inner magnetosphere.

Title: Stellar winds on the main-sequence. I. Wind model
Authors: Johnstone, C. P.; Güdel, M.; Lüftinger, T.; Toth, G.;
   Brott, I.
Bibcode: 2015A&A...577A..27J
Altcode: 2015arXiv150306669J
  <BR /> Aims: We develop a method for estimating the properties of
  stellar winds for low-mass main-sequence stars between masses of 0.4
  M<SUB>⊙</SUB> and 1.1 M<SUB>⊙</SUB> at a range of distances from the
  star. <BR /> Methods: We use 1D thermal pressure driven hydrodynamic
  wind models run using the Versatile Advection Code. Using in situ
  measurements of the solar wind, we produce models for the slow and
  fast components of the solar wind. We consider two radically different
  methods for scaling the base temperature of the wind to other stars:
  in Model A, we assume that wind temperatures are fundamentally linked
  to coronal temperatures, and in Model B, we assume that the sound speed
  at the base of the wind is a fixed fraction of the escape velocity. In
  Paper II of this series, we use observationally constrained rotational
  evolution models to derive wind mass loss rates. <BR /> Results: Our
  model for the solar wind provides an excellent description of the real
  solar wind far from the solar surface, but is unrealistic within the
  solar corona. We run a grid of 1200 wind models to derive relations
  for the wind properties as a function of stellar mass, radius, and
  wind temperature. Using these results, we explore how wind properties
  depend on stellar mass and rotation. <BR /> Conclusions: Based on our
  two assumptions about the scaling of the wind temperature, we argue that
  there is still significant uncertainty in how these properties should
  be determined. Resolution of this uncertainty will probably require
  both the application of solar wind physics to other stars and detailed
  observational constraints on the properties of stellar winds. In the
  final section of this paper, we give step by step instructions for how
  to apply our results to calculate the stellar wind conditions far from
  the stellar surface.

Title: Self-consistent multifluid MHD simulations of Europa's
    exospheric interaction with Jupiter's magnetosphere
Authors: Rubin, M.; Jia, X.; Altwegg, K.; Combi, M. R.; Daldorff,
   L. K. S.; Gombosi, T. I.; Khurana, K.; Kivelson, M. G.; Tenishev,
   V. M.; Tóth, G.; Holst, B.; Wurz, P.
Bibcode: 2015JGRA..120.3503R
Altcode:
  The Jovian moon, Europa, hosts a thin neutral gas atmosphere, which
  is tightly coupled to Jupiter's magnetosphere. Magnetospheric ions
  impacting the surface sputter off neutral atoms, which, upon ionization,
  carry currents that modify the magnetic field around the moon. The
  magnetic field in the plasma is also affected by Europa's induced
  magnetic field. In this paper we investigate the environment of Europa
  using our multifluid MHD model and focus on the effects introduced
  by both the magnetospheric and the pickup ion populations. The model
  self-consistently derives the electron temperature that governs
  the electron impact ionization process, which is the major source
  of ionization in this environment. The resulting magnetic field is
  compared to measurements performed by the Galileo magnetometer, the
  bulk properties of the modeled thermal plasma population is compared
  to the Galileo Plasma Subsystem observations, and the modeled surface
  precipitation fluxes are compared to Galileo Ultraviolet Spectrometer
  observations. The model shows good agreement with the measured magnetic
  field and reproduces the basic features of the plasma interaction
  observed at the moon for both the E4 and the E26 flybys of the Galileo
  spacecraft. The simulation also produces perturbations asymmetric
  about the flow direction that account for observed asymmetries.

Title: What Controls the Structure and Dynamics of Earth's
    Magnetosphere?
Authors: Eastwood, J. P.; Hietala, H.; Toth, G.; Phan, T. D.;
   Fujimoto, M.
Bibcode: 2015SSRv..188..251E
Altcode: 2014SSRv..tmp...20E
  Unlike most cosmic plasma structures, planetary magnetospheres
  can be extensively studied in situ. In particular, studies of the
  Earth's magnetosphere over the past few decades have resulted in
  a relatively good experimental understanding of both its basic
  structural properties and its response to changes in the impinging
  solar wind. In this article we provide a broad overview, designed
  for researchers unfamiliar with magnetospheric physics, of the main
  processes and parameters that control the structure and dynamics of
  planetary magnetospheres, especially the Earth's. In particular, we
  concentrate on the structure and dynamics of three important regions:
  the bow shock, the magnetopause and the magnetotail. In the final part
  of this review we describe the current status of global magnetospheric
  modelling, which is crucial to placing in situ observations in the
  proper context and providing a better understanding of magnetospheric
  structure and dynamics under all possible input conditions. Although
  the parameter regime experienced in the solar system is limited, the
  plasma physics that is learned by studying planetary magnetospheres
  can, in principle, be translated to more general studies of cosmic
  plasma structures. Conversely, studies of cosmic plasma under a wide
  range of conditions should be used to understand Earth's magnetosphere
  under extreme conditions. We conclude the review by discussing this
  and summarizing some general properties and principles that may be
  applied to studies of other cosmic plasma structures.

Title: Plasma and wave properties downstream of Martian bow shock:
    Hybrid simulations and MAVEN observations
Authors: Dong, Chuanfei; Winske, Dan; Cowee, Misa; Bougher, Stephen
   W.; Andersson, Laila; Connerney, Jack; Epley, Jared; Ergun, Robert;
   McFadden, James P.; Ma, Yingjuan; Toth, Gabor; Curry, Shannon; Nagy,
   Andrew; Jakosky, Bruce
Bibcode: 2015TESS....130502D
Altcode:
  Two-dimensional hybrid simulation codes are employed to investigate
  the kinetic properties of plasmas and waves downstream of the Martian
  bow shock. The simulations are two-dimensional in space but three
  dimensional in field and velocity components. Simulations show that
  ion cyclotron waves are generated by temperature anisotropy resulting
  from the reflected protons around the Martian bow shock. These proton
  cyclotron waves could propagate downward into the Martian ionosphere
  and are expected to heat the O<SUP>+</SUP> layer peaked from 250 to
  300 km due to the wave-particle interaction. The proton cyclotron wave
  heating is anticipated to be a significant source of energy into the
  thermosphere, which impacts atmospheric escape rates. The simulation
  results show that the specific dayside heating altitude depends on the
  Martian crustal field orientations, solar cycles and seasonal variations
  since both the cyclotron resonance condition and the non/sub-resonant
  stochastic heating threshold depend on the ambient magnetic field
  strength. The dayside magnetic field profiles for different crustal
  field orientation, solar cycle and seasonal variations are adopted
  from the BATS-R-US Mars multi-fluid MHD model. The simulation results,
  however, show that the heating of O<SUP>+</SUP> via proton cyclotron
  wave resonant interaction is not likely in the relatively weak crustal
  field region, based on our simplified model. This indicates that
  either the drift motion resulted from the transport of ionospheric
  O<SUP>+</SUP>, or the non/sub-resonant stochastic heating mechanism are
  important to explain the heating of Martian O<SUP>+</SUP> layer. We
  will investigate this further by comparing the simulation results
  with the available MAVEN data. These simulated ion cyclotron waves
  are important to explain the heating of Martian O<SUP>+</SUP> layer
  and have significant implications for future observations.

Title: Lifetime of the Fossil Field in Titan's Ionosphere
Authors: Ma, Yingjuan; Russell, Christopher T.; Wei, Hanying; Nagy,
   Andrew F.; Toth, Gabor; Dougherty, Michele K.; Coates, Andrew J.;
   Wahlund, Jan-Erik; Edberg, Niklas J. T.
Bibcode: 2015EGUGA..17.6940M
Altcode:
  Cassini spacecraft has made more than 100 Titan flybys since October
  2004. Among these flybys, there are a few special ones (T32, T42, T85,
  T96). During or shortly before periapsis on these encounters, Titan was
  found to be outside the Saturnian magnetosphere, in the magnetosheath
  region or directly exposed in the solar wind. During the T32 flyby,
  the first magnetosheath encounter, simulation results and observations
  clearly demonstrated the existence of fossil field, because the magnetic
  field direction in the magnetosheath region was opposite to the field
  orientation surrounding Titan when it had been inside the Saturnian
  magnetosphere. However, because Cassini passed by Titan shortly after
  the magnetopause crossing, this flyby only provides a lower limit of
  the lifetime of the fossil field. Quantifying the lifetime of the fossil
  field has important implications for understanding the magnetic field of
  other Titan flybys. Since the plasma is highly dynamic in Saturn's outer
  magnetosphere, even though the ambient plasma condition is not changing
  as dramatically as discussed in the presented flyby, Titan's ionosphere
  could still record some of those changes so that the observed field in
  the deep ionosphere might have very complicated signatures. The same
  behavior could also occur at Venus and Mars (in the weak crustal field
  region), which would help us to understand the complicated magnetic
  signatures in un-magnetized planetary ionospheres. In this paper,
  we present observations and simulation results for the other three
  Titan flybys to provide a better constraint on the lifetime of the
  fossil field in Titan's ionosphere.

Title: Magnetic Flux Conservation in the Heliosheath Including Solar
    Cycle Variations of Magnetic Field Intensity
Authors: Michael, A. T.; Opher, M.; Provornikova, E.; Richardson,
   J. D.; Tóth, G.
Bibcode: 2015ApJ...803L...6M
Altcode:
  In the heliosheath (HS), Voyager 2 has observed a flow with constant
  radial velocity and magnetic flux conservation. Voyager 1, however,
  has observed a decrease in the flow’s radial velocity and an order of
  magnitude decrease in magnetic flux. We investigate the role of the 11
  yr solar cycle variation of the magnetic field strength on the magnetic
  flux within the HS using a global 3D magnetohydrodynamic model of the
  heliosphere. We use time and latitude-dependent solar wind velocity
  and density inferred from Solar and Heliospheric Observatory/SWAN
  and interplanetary scintillations data and implemented solar cycle
  variations of the magnetic field derived from 27 day averages of
  the field magnitude average of the magnetic field at 1 AU from the
  OMNI database. With the inclusion of the solar cycle time-dependent
  magnetic field intensity, the model matches the observed intensity
  of the magnetic field in the HS along both Voyager 1 and 2. This is
  a significant improvement from the same model without magnetic field
  solar cycle variations, which was over a factor of two larger. The
  model accurately predicts the radial velocity observed by Voyager 2;
  however, the model predicts a flow speed ∼100 km s<SUP>-1</SUP>
  larger than that derived from LECP measurements at Voyager 1. In the
  model, magnetic flux is conserved along both Voyager trajectories,
  contrary to observations. This implies that the solar cycle variations
  in solar wind magnetic field observed at 1 AU does not cause the order
  of magnitude decrease in magnetic flux observed in the Voyager 1 data.

Title: Real-time SWMF-Geospace: A New Website Enabling Community Use
Authors: Liemohn, Michael; De Zeeuw, Darren; Kopmanis, Jeff;
   Ganushkina, Natalia; Welling, Daniel; Toth, Gabor; Ridley, Aaron;
   Ilie, Raluca; Gombosi, Tamas; Kuznetsova, Maria M.; Maddox, Marlo;
   Rastaetter, Lutz
Bibcode: 2015TESS....120005L
Altcode:
  An experimental real-time simulation of the Space Weather Modeling
  Framework (SWMF) is conducted at the Community Coordinated Modeling
  Center (CCMC), (http://ccmc.gsfc.nasa.gov/realtime.php) and also
  through the CCMC's Integrated Space Weather Analysis (iSWA) site
  (http://iswa.ccmc.gsfc.nasa.gov/IswaSystemWebApp/). Presently,
  two configurations of the SWMF are running in real time at
  CCMC, both focusing on the geospace modules, using the BATS-R-US
  magnetohydrodynamic model, the Ridley Ionosphere Model, and with
  and without the Rice Convection Model for inner magnetospheric
  drift physics. The model output includes result extractions along
  satellite trajectories as well as magnetic perturbation vectors
  at ground-based station locations. Here we unveil a new website
  (http://csem.engin.umich.edu/realtime) to highlight these real-time
  model results conducted by the CCMC, present some basic data-model
  comparisons with real-time observations, and archive the accuracy of
  this continuously-available simulation.

Title: Instantaneous configuration of the geomagnetic field inferred
from the low-altitude isotropic boundaries: modeling and observations
Authors: Ilie, Raluca; Ganushkina, Natalia; Toth, Gabor; Liemohn,
   Michael
Bibcode: 2015TESS....120601I
Altcode:
  Understanding the interplay between ionospheric, auroral and
  magnetospheric phenomena requires detailed knowledge of Earth’s
  magnetic field geometry under various solar wind conditions. This
  geometry is directly relevant to the magnetic field mapping between
  different regions of near-Earth space.To evaluate the instantaneous
  geomagnetic field configuration we probe the isotropic boundaries (IB)
  of energetic particles measured at low altitudes. Those are interpreted
  as the boundary between the regions of adiabatic and stochastic particle
  motion in the equatorial magnetotail and provide information regarding
  the degree of magnetic field stretching.We investigate the topology and
  dynamics of the magnetotail current during active and quiet times as
  de- pendent on solar wind and IMF parameters based on NOAA/POES MEPED
  and DMSP SSJ/4 measurements in combination with global magnetospheric
  simulations using the Space Weather Modeling Framework (SWMF).The
  extensive NOAA/POES MEPED low-altitude data sets give the locations of
  isotropic boundaries, which are used to extract information regarding
  particle distributions and field structure in the source regions in
  the magnetosphere.We present a comparison between the magnetic field
  lines with the observed IB latitude and those com- puted from the SWMF
  using the theoretical relation for IB locations in the magnetotail,
  i.e. where the ratio between curvature radius and Larmor radius is
  close to 8. This investigation assesses the accuracy of the model
  magnetic field and the structure of the magnetotail. The results are
  examined in relation to the solar wind and IMF conditions to determine
  the corresponding configuration and dynamics of the magnetotail.

Title: The Heterogeneous Coma of Comet 67P/Churyumov-Gerasimenko
    from Rosetta Observations
Authors: Fougere, Nicolas; Tenishev, Valeriy; Bieler, Andre; Combi,
   Michael; Gombosi, Tamas; Toth, Gabor; Hansen, Kenneth; Shou, Yinsi;
   Huang, Zhenguang; Jia, Xianzhe; Rubin, Martin; Altwegg, Kathrin; Wurz,
   Peter; Balsiger, Hans; Jaeckel, Annette; Le Roy, Lena; Gasc, Sebastien;
   Calmonte, Ursina; Tzou, Chia-Yu; Hässig, Myrtha; Fuselier, Stephen;
   De Keyser, Johan; Berthelier, Jean-Jacques; Mall, Urs; Rème, Henri;
   Fiethe, Bjorn
Bibcode: 2015EGUGA..17.4695F
Altcode:
  Since its orbit insertion around comet 67P/Churyumov-Gerasimenko (CG),
  the Rosetta spacecraft has revealed invaluable information regarding
  the cometary coma environment. The prolonged period of observation
  enabled a relatively extensive spatial coverage of comet CG's coma,
  which showed distinct spatial distributions for different species. We
  introduce a fully 3D kinetic model performed with the Direct Simulation
  Monte-Carlo approach of the H2O, CO, and CO2 coma of comet CG using
  the Adaptive Mesh Particle Simulator code with the shape model of the
  Rosetta nucleus. The model allows the description of the full coma of
  comet CG including the regions where collisions cannot maintain a flow
  that can be described by a fluid. The model is constrained by Rosetta
  observations giving clues regarding the gas release of the different
  species. This constitutes the most advanced coma model of comet CG,
  which is critical to interpret instrument data and for further mission
  planning.

Title: MHD Model Results of Solar Wind Plasma Interaction with Mars
    and Comparison with MAVEN Observations
Authors: Ma, Y. J.; Russell, C. T.; Nagy, A. F.; Toth, G.; Halekas,
   J. S.; Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.
Bibcode: 2015LPI....46.1202M
Altcode: 2015LPICo1832.1202M
  This study investigates in detail how plasma properties in Mars
  ionosphere are influenced locally by the crustal field and its rotation.

Title: A 3D Description of the Coma of Comet 67P/Churyumov-Gerasimenko
    Constrained by Rosetta Observations
Authors: Fougere, N.; Tenishev, V.; Bieler, A. M.; Combi, M. R.;
   Gombosi, T. I.; Hansen, K. C.; Jia, X.; Shou, Y.; Huang, Z.; Toth, G.;
   Altwegg, K.; Wurz, P.; Balsiger, H.; Jäckel, A.; Le Roy, L.; Gasc,
   S.; Calmonte, U.; Rubin, M.; Tzou, C. Y.; Hässig, M.; Fuselier, S.;
   De Keyser, J.; Berthelier, J. J.; Mall, U. A.; Rème, H.; Fiethe, B.
Bibcode: 2014AGUFM.P41C3930F
Altcode:
  For the first time, the Rosetta spacecraft stays with a comet over an
  extended period of time during its journey in the inner the solar
  system. The data provided by the suite of instruments on board
  the Rosetta spacecraft, notably the ROSINA mass spectrometers and
  the pressure sensor, provides critical information concerning comet
  67P/Churyumov-Gerasimenko (CG) and its environment. These measurements
  reinforce our knowledge of comet CG and enable us to describe the
  nucleus and the sources with more details. The observations allow us
  to better constrain and accordingly develop much more realistic models
  of the comet's coma. We show a 3D simulation of the gas and dust coma
  of comet CG using a Direct Simulation Monte-Carlo model performed with
  the Adaptive Mesh Particle Simulator (Tenishev et al. 2008, 2011). The
  coma model presented includes a realistic nucleus shape, with a gas
  flux distribution and a surface temperature that takes into account
  irregularities and concavities of the nucleus. Along with the gas drag,
  the gravity field drives the dust dynamics and is therefore accurately
  computed around the irregular nucleus shape. This constitutes the
  state-of-the-art of cometary coma models, which are crucial to interpret
  instrument data and for further mission planning. Acknowledgement:This
  work was supported by contracts JPL#1266313 and JPL#1266314 from
  the US Rosetta Project and NASA grant NNX09AB59G from the Planetary
  Atmospheres Program. References:Tenishev et al. 2008 ApJ 685:659,
  and 2011 ApJ 732:104

Title: Counter-streaming alpha proton plasmas in an eroding magnetic
cloud: new insights into space plasma evolution from Wind
Authors: Szente, J.; Toth, G.; Manchester, W.; van der Holst, B.;
   Landi, E.; DeVore, C. R.; Gombosi, T. I.
Bibcode: 2014AGUFMSH23D..05S
Altcode:
  Coronal jets, routinely observed by multiple instruments at
  multiple wavelengths, provide a unique opportunity to understand
  the relationships between magnetic field topology, reconnection, and
  solar wind heating and acceleration. We simulate coronal jets with the
  Alfvén Wave Solar Model (AWSoM) [van der Holst (2014)] and focus our
  study on the thermodynamical evolution of the plasma. AWSoM solves
  the two-temperature MHD equations with electron heat conduction,
  which not only addresses the thermodynamics of individual species,
  but also allows for the construction of synthetic images from the EUV
  and soft X-ray wavelength range. Our jet model takes the form of a
  slowly rotating bipole field imbedded in the open magnetic field of
  a coronal hole; a topology suggested by observations. We follow the
  formation and evolution of polar jets starting from the chromosphere
  and extending into the outer corona. The simulations show small-scale
  eruptive reconnection events that self-consistently heat and accelerate
  the solar wind. Our results provide a quantitative comparison to
  observations made in the EUV and X-ray spectrum.

Title: 3D Direct Simulation Monte Carlo Modeling of the Spacecraft
    Environment of Rosetta
Authors: Bieler, A. M.; Tenishev, V.; Fougere, N.; Gombosi, T. I.;
   Hansen, K. C.; Combi, M. R.; Huang, Z.; Jia, X.; Toth, G.; Altwegg,
   K.; Wurz, P.; Jäckel, A.; Le Roy, L.; Gasc, S.; Calmonte, U.; Rubin,
   M.; Tzou, C. Y.; Hässig, M.; Fuselier, S.; De Keyser, J.; Berthelier,
   J. J.; Mall, U. A.; Rème, H.; Fiethe, B.; Balsiger, H.
Bibcode: 2014AGUFM.P41C3931B
Altcode:
  The European Space Agency's Rosetta mission is the first to escort
  a comet over an extended time as the comet makes its way through the
  inner solar system. The ROSINA instrument suite consisting of a double
  focusing mass spectrometer, a time of flight mass spectrometer and a
  pressure sensor, will provide temporally and spatially resolved data on
  the comet's volatile inventory. The effect of spacecraft outgassing is
  well known and has been measured with the ROSINA instruments onboard
  Rosetta throughout the cruise phase. The flux of released neutral
  gas originating from the spacecraft cannot be distinguished from the
  cometary signal by the mass spectrometers and varies significantly
  with solar illumination conditions. For accurate interpretation of
  the instrument data, a good understanding of spacecraft outgassing is
  necessary. In this talk we present results simulating the spacecraft
  environment with the Adaptive Mesh Particle Simulator (AMPS) code. AMPS
  is a direct simulation monte carlo code that includes multiple species
  in a 3D adaptive mesh to describe a full scale model of the spacecraft
  environment. We use the triangulated surface model of the spacecraft
  to implement realistic outgassing rates for different areas on the
  surface and take shadowing effects in consideration. The resulting
  particle fluxes are compared to the measurements of the ROSINA
  experiment and implications for ROSINA measurements and data analysis
  are discussed. Spacecraft outgassing has implications for future space
  missions to rarefied atmospheres as it imposes a limit on the detection
  of various species.

Title: The Mars Magnetosphere in the Tail of Comet C/2013 A1(Siding
    Spring)
Authors: Ma, Y.; Jia, Y. D.; Russell, C. T.; Nagy, A. F.; Toth, G.;
   Combi, M. R.; Yelle, R. V.; Dong, C.; Bougher, S. W.
Bibcode: 2014AGUFM.P43A3971M
Altcode:
  Comet C/2013 A1 (Siding Spring) is an Oort cloud comet with an open
  path. In October 2014, comet Siding Spring passes about 12 Mars radii
  from the center of the planet. Carrying multiple active spacecraft,
  Mars is expected to enter the plasma tail of the comet, providing a
  unique opportunity to study the response of the Mars magnetosphere
  to the supersonic cometary tail. We use our multi-fluid MHD model,
  which has been successfully applied to various comets, to simulate the
  composition of plasma trailing the comet. We include the effects of the
  decomposition, ionization, and charge exchange of major ion species
  around the comet in the model. The model result is then extracted
  along Mars orbit into a time dependent plasma distribution. Second,
  we simulate the real-time response of the Mars magnetosphere in
  the comet tail using a multi-fluid model of Mars. The comet tail
  plasma distribution is used as the upstream boundary conditions for
  the Mars model. The simulation results will be used to quantify the
  perturbations of the plasma environment around Mars and provide a
  baseline for interpreting plasma observations along the MAVEN orbit
  during the comet passage.

Title: Global Multi-Fluid Solar Corona and Inner Heliosphere Model
    for Solar Probe Plus and Solar Orbite
Authors: van der Holst, B.; Sokolov, I.; Toth, G.; Gombosi, T. I.
Bibcode: 2014AGUFMSH21B4095V
Altcode:
  The mechanisms that heat and accelerate the fast and slow wind have
  not yet been conclusively identified, and their understanding is one of
  the major science goals of the Solar Orbiter (SO) and Solar Probe Plus
  (SPP) missions. Helium abundance and properties in the solar wind are
  critical tracers for both processes so that understanding them is key
  towards gaining insight in the solar wind phenomenon, and being able
  to model it and predict its properties. SO and SPP will carry critical
  instrumentation to measure the properties of Helium in the solar wind
  at distances between within 10 solar radii up to 1 AU. We present
  a generalization of the recently developed global solar corona and
  inner heliosphere model with low-frequency Alfvenic turbulence [van
  der Holst et al. (2014)] to include alpha-particle dynamics. This new
  multi-fluid model uses the stochastic heating mechanism to partition
  the turbulence dissipation into coronal heating of the electrons and
  ions. The momentum and energy exchange rates due to Coulomb collisions
  are accounted for. We discuss the feasibility for Alfvenic turbulence
  to simultaneously address the coronal heating and proton-alpha particle
  differential streaming.

Title: Solar Wind Interaction with the Martian Upper Atmosphere at
    Early Mars/Extreme Solar Conditions
Authors: Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy,
   A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.
Bibcode: 2014AGUFM.P53C4032D
Altcode:
  The investigation of ion escape fluxes from Mars, resulting from
  the solar wind interaction with its upper atmosphere/ionosphere, is
  important due to its potential impact on the long-term evolution of
  Mars atmosphere (e.g., loss of water) over its history. In the present
  work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~
  300 km) from the newly developed and validated Mars Global Ionosphere
  Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km
  ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle
  Simulator (AMPS). We apply these 3-D model output fields into the 3-D
  BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can
  simulate the interplay between Mars upper atmosphere and solar wind by
  considering the dynamics of individual ion species. The multi-fluid MHD
  model solves separate continuity, momentum and energy equations for
  each ion species (H+, O+, O2+, CO2+). The M-GITM model together with
  the AMPS exosphere model take into account the effects of solar cycle
  and seasonal variations on both cold and hot neutral atmospheres. This
  feature allows us to investigate the corresponding effects on the Mars
  upper atmosphere ion escape by using a one-way coupling approach, i.e.,
  both the M-GITM and AMPS model output fields are used as the input for
  the multi-fluid MHD model and the M-GITM is used as input into the AMPS
  exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD
  calculations (1-way coupled) for 2.5 GYA conditions and/or extreme
  solar conditions for present day Mars (high solar wind velocities,
  high solar wind dynamic pressure, and high solar irradiance conditions,
  etc.). Present day extreme conditions may result in MF-MHD outputs that
  are similar to 2.5 GYA cases. The crustal field orientations are also
  considered in this study. By comparing estimates of past ion escape
  rates with the current ion loss rates to be returned by the MAVEN
  spacecraft (2013-2016), we can better constrain the total ion loss to
  space over Mars history, and thus enhance the science returned from
  the MAVEN mission.

Title: MHD-Epic: Embedded Particle-in-Cell Simulations of Reconnection
    in Global 3D Extended MHD Simulations
Authors: Daldorff, L. K. S.; Toth, G.; Borovikov, D.; Gombosi, T. I.;
   Lapenta, G.
Bibcode: 2014AGUFMSM13B4161D
Altcode:
  With the new modeling capability in the Space Weather Modeling Framework
  (SWMF) of embedding an implicit Particle-in-Cell (PIC) model iPIC3D
  into the BATS-R-US magnetohydrodynamics model (Daldorff et al. 2014,
  JCP, 268, 236) we are ready to locally handle the full physics of the
  reconnection and its implications on the full system where globally,
  away from the reconnection region, a magnetohydrodynamic description is
  satisfactory. As magnetic reconnection is one of the main drivers in
  magnetospheric and heliospheric plasma dynamics, the self-consistent
  description of the electron dynamics in the coupled MHD-EPIC model is
  well suited for investigating the nature of these systems. We will
  compare the new embedded MHD-EPIC model with pure MHD and Hall MHD
  simulations of the Earth's magnetosphere.

Title: The Multi-fluid Nature of the Termination Shock
Authors: Zieger, B.; Opher, M.; Toth, G.
Bibcode: 2014AGUFMSH21D..05Z
Altcode:
  After the crossing of the termination shock by the Voyager spacecraft,
  it became clear that pickup ions (PUIs) dominate the thermodynamics
  of the heliosheath. Particle-in-cell simulations by Wu et al. [2010]
  have shown that the sum of the thermal solar wind and non-thermal PUI
  distributions downstream of the termination shock can be approximated
  with a 2-Maxwellian distribution. Therefore the heliosheath can be
  described as multi-fluid plasma comprising of cold thermal solar
  wind ions, hot pickup ions (PUI) and electrons. The abundance of
  the hot pickup ion population has remained unknown, since the plasma
  instrument on board Voyager 2 can only detect the colder thermal ion
  component. Upstream of the termination shock, where the solar wind bulk
  flow is quasi-perpendicular to the Parker spiral-like heliospheric
  magnetic field, the two ion fluids are fully coupled. However, in
  the heliosheath, where the ion flows start to divert from the radial
  direction, PUIs and thermal solar wind ions become decoupled in the
  parallel direction, resulting in differential ion flow velocities. This
  multi-fluid nature of the heliosheath cannot be captured in current
  single-fluid MHD models of the heliosphere. Here we present our new
  multi-ion Hall MHD model of the termination shock, which is able to
  resolve finite gyroradius effects [Zieger et al., 2014]. The addition
  of hot PUIs to the mixture of thermal solar wind protons and cold
  electrons results in the mode splitting of fast magnetosonic waves
  into a high-frequency fast mode (or PUI mode) and a low-frequency fast
  mode (or thermal proton mode). We show that the multi-fluid nature of
  the solar wind predicts two termination shocks, one in the thermal
  and the other in the pickup ion component. We demonstrate that the
  thermal ion shock is a dispersive shock wave, with a trailing wave
  train, which is a quasi-stationary nonlinear wave mode, also known
  as oscilliton. We constrain the previously unknown PUI abundance and
  the PUI temperature by fitting simulated multi-fluid termination shock
  profiles to Voyager 2 observations. Our model provides self-consistent
  energy partitioning between the ion species across the termination shock
  and predicts the preferential heating of the thermal ion component. The
  nonlinear oscilliton mode can be a source of compressional turbulence
  in the heliosheath.

Title: Global impact of collisionless magnetic reconnection on the
    structure of planetary magnetospheres
Authors: Dorelli, J.; Glocer, A.; Collinson, G.; Toth, G.
Bibcode: 2014AGUFMSM13B4159D
Altcode:
  While the local physics of collisionless magnetic reconnection
  has been well studied, the consequences for global magnetospheric
  structure remain largely unexplored. It is well known, for example,
  that Hall electric fields generate a new system of field-aligned
  currents propagating from the reconnection site along the magnetic
  separatrices; but it is not known how these currents contribute to the
  global region 1 and region 2 current systems or to auroral substorm
  features. In this presentation, we show that collisionless reconnection
  has a significant impact on the large scale structure of planetary
  magnetospheres. Using global Hall MHD simulations, we demonstrate
  that field-aligned currents generated at the reconnection sites (and
  carried by whistler or kinetic Alfven waves) extend all the way down
  to the surface of the magnetized body and must therefore be included
  in the magnetosphere-ionosphere coupling physics (e.g., Harang-like
  discontinuities in the ionospheric convection pattern -- absent in
  MHD -- are introduced, and the current densities are large enough to
  produce auroral emission). More surprisingly, ions and electrons pick up
  magnetic drifts (due to JxB forces in the ion diffusion regions) that
  significantly alter the global magnetospheric convection pattern. Ions
  in the plasma sheet drift duskward while electrons drift dawnward,
  producing large asymmetries in the plasma sheet structure even in the
  absense of solar wind asymmetry, asymmetric ionospheric conductance
  or co-rotation. We discuss the implications of these effects for the
  reconnection-driven magnetospheres of Ganymede, Mercury and Earth.

Title: Global MHD Simulation of the Coronal Mass Ejection on 2011
March 7: from Chromosphere to 1 AU
Authors: Jin, M.; Manchester, W.; van der Holst, B.; Sokolov, I.;
   Toth, G.; Vourlidas, A.; de Koning, C. A.; Gombosi, T. I.
Bibcode: 2014AGUFMSH43A4176J
Altcode:
  Performing realistic simulations of solar eruptions and validating
  those simulations with observations are important goals in order
  to achieve accurate space weather forecasts. Here, we perform and
  analyze results of a global magnetohydrodyanmic (MHD) simulation of the
  fast coronal mass ejection (CME) that occurred on 2011 March 7. The
  simulation is made using the newly developed Alfven Wave Solar Model
  (AWSoM), which describes the background solar wind starting from the
  upper chromosphere and expands to 24 Rs. Coupling of AWSoM to an inner
  heliosphere (IH) model with the Space Weather Modeling Framework (SWMF)
  extends the total domain beyond the orbit of Earth. Physical processes
  included in the model are multi-species thermodynamics, electron heat
  conduction (both collisional and collisionless formulations), optically
  thin radiative cooling, and Alfven-wave pressure that accelerates
  the solar wind. The Alfven-wave description is physically consistent,
  including non-WKB reflection and physics-based apportioning of turbulent
  dissipative heating to both electrons and protons. Within this model,
  we initiate the CME by using the Gibson-Low (GL) analytical flux rope
  model and follow its evolution for days, in which time it propagates
  beyond 1 AU. A comprehensive validation study is performed using
  remote as well as in-situ observations from SDO, SOHO, STEREOA/B,
  and OMNI. Our results show that the new model can reproduce many
  of the observed features near the Sun (e.g., CME-driven EUV waves,
  deflection of the flux rope from the coronal hole, "double-front"
  in the white light images) and in the heliosphere (e.g., CME-CIR
  interaction, shock properties at 1 AU). The CME-driven shock arrival
  time is within 1 hour of the observed arrival time, and nearly all the
  in-situ parameters are correctly simulated, which suggests the global
  MHD model as a powerful tool for the space weather forecasting.

Title: Time-dependent MHD modeling of Titan's plasma interaction
    during T32, T85 and T96 and comparison to Cassini data
Authors: Ma, Y.; Nagy, A. F.; Toth, G.; Bertucci, C.; Dougherty,
   M. K.; Coates, A. J.; Wahlund, J. E.
Bibcode: 2014AGUFMSM33A..07M
Altcode:
  The Cassini Spacecraft flew past Titan on June 13, 2007 and found
  Titan was outside Saturn's magnetopause. During this pass (T32),
  observations showed dramatic changes of magnetic field orientation as
  well as plasma flow parameters during inbound and outbound segments. We
  have studied Titan's ionospheric responses to such a sudden change in
  the upstream plasma conditions, using a sophisticated multi-species
  global MHD model. Simulation results of three different cases (steady
  state; simple current sheet crossing and magnetopause crossing) are
  presented and compared against Cassini Magnetometer (MAG), Langmuir
  Probe (LP) and Cassini Plasma Spectrometer (CAPS) observations. The
  simulation results provide clear evidence of the existence of fossil
  field. The MAG data can be well reproduced with a simple current sheet
  crossing. The Cassini plasma observations can only be reproduced by the
  magnetopause crossing case using plasma conditions constrained by CAPS
  observations. Real-time simulation also reveals how the fossil field
  formed during the interaction and shows the coexistence of two pile-up
  regions with opposite magnetic orientation, the formation of a pair of
  new Alfven wings and tail disconnection during magnetopause crossing
  process. During two recent Titan flybys T85 and T96, Titan was found
  to be in the magnetosheath region of Saturn and in the solar wind,
  respectively. We present simulation results for those two flybys and
  compare features of Titan's plasma interaction in different plasma
  environments.

Title: High Order Schemes in Bats-R-US for Faster and More Accurate
    Predictions
Authors: Chen, Y.; Toth, G.; Gombosi, T. I.
Bibcode: 2014AGUFMSM31A4161C
Altcode:
  BATS-R-US is a widely used global magnetohydrodynamics model that
  originally employed second order accurate TVD schemes combined with
  block based Adaptive Mesh Refinement (AMR) to achieve high resolution
  in the regions of interest. In the last years we have implemented
  fifth order accurate finite difference schemes CWENO5 and MP5 for
  uniform Cartesian grids. Now the high order schemes have been extended
  to generalized coordinates, including spherical grids and also to
  the non-uniform AMR grids including dynamic regridding. We present
  numerical tests that verify the preservation of free-stream solution and
  high-order accuracy as well as robust oscillation-free behavior near
  discontinuities. We apply the new high order accurate schemes to both
  heliospheric and magnetospheric simulations and show that it is robust
  and can achieve the same accuracy as the second order scheme with much
  less computational resources. This is especially important for space
  weather prediction that requires faster than real time code execution.

Title: The role of superthermal electrons in high latitude ionospheric
    outflows
Authors: Glocer, A.; Khazanov, G. V.; Liemohn, M. W.; Toth, G.;
   Gombosi, T. I.
Bibcode: 2014AGUFMSM44A..06G
Altcode:
  It is well accepted that the ionosphere is a critical source of plasma
  for the magnetosphere, providing O+, H+, and He+ which can have wide
  ranging consequences for the space environment system. Changing ion
  composition affects magnetic reconnection in the magnetosphere, the ring
  current, and the wave environment which is important for high energy
  radiation belt electrons. Of the myriad of mechanisms that are important
  in determining the ionospheric outflow solution at high latitudes,
  we focus on the role of superthermal electron populations. It has
  been demonstrated in multiple studies that even small concentrations
  of superthermal electrons can have a dramatic effect on the outflow
  solution. In this presentation, we present simulation results using
  our Polar Wind Outflow Model (PWOM) and our SuperThermal Electron
  Transport (STET) code. We describe recent results on superthermal
  electrons role in defining the quiet time solar wind solution with
  comparisons to observations. We also discuss preliminary results that
  combine the PWOM and STET codes for a more comprehensive treatment of
  the impact of superthermal electrons.

Title: Magnetic Dissipation Effects on the Flows within the
    Heliosheath
Authors: Michael, A.; Opher, M.; Provornikova, E.; Toth, G.
Bibcode: 2014AGUFMSH11B4041M
Altcode:
  We investigate the effect that magnetic dissipation has on the
  flows within the heliosheath (HS), the subsonic plasma in between
  the termination shock (TS) and the heliopause (HP). We use a global
  3D multi-fluid magnetohydrodynamic (MHD) model of the heliosphere,
  which has a grid resolution of 0.5 AU within the heliosphere along
  both Voyager 1 and Voyager 2 trajectories. We describe the solar
  wind magnetic field as a monopole, to remove the heliospheric current
  sheet, with the magnetic field aligned with that of the interstellar
  medium (ISM) to diminish any numerical reconnection at the ISM -
  solar wind interface. This configuration of the solar wind magnetic
  field also reduces any numerical magnetic dissipation effects in the
  HS. We compare our model to the same model describing the solar wind
  magnetic field as a dipole. In the dipole case, there is an intrinsic
  loss of magnetic energy near the heliospheric current sheet (HCS)
  due to reconnection. This reconnection is numerical since we do not
  include real resistivity in the model. The comparison of the two models
  will allow for an estimation of the effects of reconnection in the HS
  since there is no numerical dissipation of the magnetic field in the
  monopole model. We compare steady state solutions and the role magnetic
  dissipation has on the global characteristics of the heliosphere. We
  find that the monopole model of the solar wind magnetic field removes
  the asymmetry observed in the TS and predicted for the HP. Furthermore,
  the TS is considerably closer to the Sun in the monopole model due
  to the build up of magnetic filed at the HP. We also investigate
  magnetic dissipation effects in the 11-year solar cycle variations
  of the solar wind in a 3D time-dependent model. This model includes
  3D latitudinal and temporal variations of the solar wind density
  and velocity taken from SOHO/SWAN and IPS data from 1990 to 2012 as
  described in Provornikova et al. 2014. We additionally include a time
  varying magnetic field obtained from the OMNI database. We compare
  both models to observations along Voyager 1 and Voyager 2 and discuss
  whether magnetic dissipation is a significant process affecting the
  flows within the HS.

Title: Storm time plasma transport in a unified and inter-coupled
    global magnetosphere model
Authors: Ilie, R.; Liemohn, M. W.; Toth, G.
Bibcode: 2014AGUFMSM14A..03I
Altcode:
  We present results from the two-way self-consistent coupling between
  the kinetic Hot Electron and Ion Drift Integrator (HEIDI) model and
  the Space Weather Modeling Framework (SWMF). HEIDI solves the time
  dependent, gyration and bounced averaged kinetic equation for the phase
  space density of different ring current species and computes full pitch
  angle distributions for all local times and radial distances. During
  geomagnetic times the dipole approximation becomes unsuitable even in
  the inner magnetosphere. Therefore the HEIDI model was generalized
  to accommodate an arbitrary magnetic field and through the coupling
  with SWMF it obtains a magnetic field description throughout the
  HEIDI domain along with a plasma distribution at the model outer
  boundary from the Block Adaptive Tree Solar Wind Roe Upwind Scheme
  (BATS-R-US) magnetohydrodynamics (MHD) model within SWMF. Electric field
  self-consistency is assured by the passing of convection potentials
  from the Ridley Ionosphere Model (RIM) within SWMF. In this study we
  test the various levels of coupling between the 3 physics based models,
  highlighting the role that the magnetic field, plasma sheet conditions
  and the cross polar cap potential play in the formation and evolution
  of the ring current. We show that the dynamically changing geospace
  environment itself plays a key role in determining the geoeffectiveness
  of the driver. The results of the self-consistent coupling between
  HEIDI, BATS-R-US and RIM during disturbed conditions emphasize the
  importance of a kinetic self-consistent approach to the description
  of geospace.

Title: MHD-EPIC: Extended Magnetohydrodynamics with Embedded
    Particle-in-Cell Simulation of Ganymede's Magnetosphere.
Authors: Toth, G.; Daldorff, L. K. S.; Jia, X.; Gombosi, T. I.;
   Lapenta, G.
Bibcode: 2014AGUFMSM23D..03T
Altcode:
  We have recently developed a new modeling capability to
  embed theimplicit Particle-in-Cell (PIC) model iPIC3D into the
  BATS-R-USmagnetohydrodynamic model. The PIC domain can cover the
  regions wherekinetic effects are most important, such as reconnection
  sites. TheBATS-R-US code, on the other hand, can efficiently
  handle the rest ofthe computational domain where the MHD or Hall
  MHD description issufficient. As one of the very first applications
  of the MHD-EPICalgorithm (Daldorff et al. 2014, JCP, 268, 236) we
  simulate theinteraction between Jupiter's magnetospheric plasma with
  Ganymede'smagnetosphere, where the separation of kinetic and global
  scalesappears less severe than for the Earth's magnetosphere. Because
  theexternal Jovian magnetic field remains in an anti-parallel
  orientationwith respect to Ganymede's intrinsic magnetic field,
  magneticreconnection is believed to be the major process that
  couples the twomagnetospheres. As the PIC model is able to describe
  self-consistentlythe electron behavior, our coupled MHD-EPIC model
  is well suited forinvestigating the nature of magnetic reconnection
  in thisreconnection-driven mini-magnetosphere. We will compare the
  MHD-EPICsimulations with pure Hall MHD simulations and compare both
  modelresults with Galileo plasma and magnetic field measurements
  to assess therelative importance of ion and electron kinetics in
  controlling theconfiguration and dynamics of Ganymede's magnetosphere.

Title: A Multi-neutral-fluid model of comet 67P/Churyumov-Gerasimenko
Authors: Shou, Y.; Combi, M. R.; Gombosi, T. I.; Jia, X.; Toth, G.;
   Hansen, K. C.; Tenishev, V.; Fougere, N.
Bibcode: 2014AGUFM.P41C3924S
Altcode:
  As comet 67P/Churyumov-Gerasimenko, the Rosetta mission target, is
  approaching perihelion, the OSIRIS instrument observed the nucleus'
  very unique dumbbell-like shape recently. It arouses an interesting
  question as to what the coma will look like with the combination of the
  irregular shape and the rotation of the nucleus, as a result of solar
  radiation. A physics-based three dimensional coma model is highly
  desirable to study this topic. One candidate is Direct Simulation
  Monte Carlo (DSMC) method, and it has been successfully applied to
  such problems. However, since the comet may be considerably active
  closer to perihelion and the gas near the nucleus is dense, the time
  step in DSMC model has to be tiny to accommodate the small mean free
  path and the high collision frequency, which can make time-variable
  DSMC modeling computationally expensive. In this work, we develop
  a multi-neutral-fluid model based on BATS-R-US in the University of
  Michigan's SWMF (Space Weather Modeling Framework), which can serve as
  a useful alternative to DSMC methods to compute the inner coma. This
  model treats cometary heavy neutrals, hydrogen atoms and dusts of
  different particle sizes as separate fluids. In the model, we include
  different momentum and energy transfer coefficients for different
  fluids, heating from chemical reactions and frictions between gas and
  dust. With other necessary physics considered, it is able to give us
  a more physical picture than one fluid model. The preliminary results
  are presented and discussed. This work has been partially supported
  by NASA Planetary Atmospheres program grant NNX14AG84G and US Rosetta
  contracts JPL #1266313 and JPL #1266314.

Title: High Resolution Magnetotail Simulations of Bursty Bulk Flows
Authors: Buzulukova, N.; Dorelli, J.; Glocer, A.; Fok, M. C. H.;
   Toth, G.
Bibcode: 2014AGUFMSM23C4236B
Altcode:
  We present the results of high resolution resistive MHD simulations of
  bursty bulk flows using the BATSRUS magnetosphere model. We performed
  a number of runs with three levels of constant resistivity. For each
  resistivity level, we studied the dependence on tail resolution and
  looked for solutions where numerical resistivity was small compared
  to the set physical resistivity. For constant solar wind driving
  (southward Bz IMF), we found the formation of bursty bulk flows (BBFs)
  and dipolarization fronts when the resistivity was below a critical
  value. We extracted virtual s/c data through dipolarization fronts and
  BBFs and compared with observed properties of BBFs. We also studied
  the ionospheric response to BBF formation. By switching on/off the
  ring current module (CRCM) in the BATSRUS, we examined relationship
  between BBFs and ring current injections.

Title: Consequences of Kinetic Effects in Nonsymmetric Reconnection
    Configurations on Large-Scale Dynamical Processes in Magnetosphere
    and Solar Plasma
Authors: Kuznetsova, M. M.; Hesse, M.; Aunai, N.; Wendel, D. E.;
   Rastaetter, L.; Glocer, A.; Toth, G.
Bibcode: 2014AGUFMSM44B..04K
Altcode:
  One of the major conclusions of the GEM Reconnection Challenge at the
  dawn of the millennium was that reconnection rate is independent of the
  electron mass. This finding allowed to reduce the problem to hall-less
  pair plasma fluid description and reproduce kinetic reconnection
  rates in large-scale single-fluid simulations by incorporating
  kinetic non-gyrotropic corrections to the induction equation. It was
  demonstrated that nongyrotropic effects incorporated into symmetric
  magnetotail reconnection could significantly alter the global
  magnetosphere evolution. In this paper we will extend the approach to
  non-symmetric configurations relevant to planetary magnetospheres and
  solar corona. We will examine the applicability of the non-gyrotropic
  fluid approach to nonsymmetric magnetic reconnection and demonstrate
  consequences of local kinetic effects on global evolution.

Title: Magnetic reconnection in 3D magnetosphere models: magnetic
    separators and open flux production
Authors: Glocer, A.; Dorelli, J.; Toth, G.; Komar, C. M.; Cassak, P.
Bibcode: 2014AGUFMSM42A..03G
Altcode:
  There are multiple competing definitions of magnetic reconnection
  in 3D (e.g., Hesse and Schindler [1988], Lau and Finn [1990], and
  Boozer [2002]). In this work we focus on separator reconnection. A
  magnetic separator can be understood as the 3D analogue of a 2D x
  line with a guide field, and is defined by the line corresponding
  to the intersection of the separatrix surfaces associated with
  the magnetic nulls. A separator in the magnetosphere represents
  the intersection of four distinct magnetic topologies: solar wind,
  closed, open connected to the northern hemisphere, and open connected
  to the southern hemisphere. The integral of the parallel electric
  field along the separator defines the rate of open flux production,
  and is one measure of the reconnection rate. We present three methods
  for locating magnetic separators and apply them to 3D resistive MHD
  simulations of the Earth's magnetosphere using the BATS-R-US code. The
  techniques for finding separators and determining the reconnection rate
  are insensitive to IMF clock angle and can in principle be applied to
  any magnetospheric model. The present work examines cases of high and
  low resistivity, for two clock angles. We also examine the separator
  during Flux Transfer Events (FTEs) and Kelvin-Helmholtz instability.

Title: Multifluid MHD Simulations of the Plasma Environment of Comet
    Churyumov-Gerasimenko at Different Heliocentric Distances
Authors: Huang, Z.; Jia, X.; Rubin, M.; Fougere, N.; Gombosi, T. I.;
   Tenishev, V.; Combi, M. R.; Bieler, A. M.; Toth, G.; Hansen, K. C.;
   Shou, Y.
Bibcode: 2014AGUFM.P41C3928H
Altcode:
  We study the plasma environment of the comet Churyumov-Gerasimenko,
  which is the target of the Rosetta mission, by performing large scale
  numerical simulations. Our model is based on BATS-R-US within the
  Space Weather Modeling Framework that solves the governing multifluid
  MHD equations, which describe the behavior of the cometary heavy ions,
  the solar wind protons, and electrons. The model includes various mass
  loading processes, including ionization, charge exchange, dissociative
  ion-electron recombination, as well as collisional interactions between
  different fluids. The neutral background used in our MHD simulations
  is provided by a kinetic Direct Simulation Monte Carlo (DSMC) model. We
  will simulate how the cometary plasma environment changes at different
  heliocentric distances.

Title: Plasma environment of a weak comet - Predictions for Comet
    67P/Churyumov-Gerasimenko from multifluid-MHD and Hybrid models
Authors: Rubin, M.; Koenders, C.; Altwegg, K.; Combi, M. R.;
   Glassmeier, K. -H.; Gombosi, T. I.; Hansen, K. C.; Motschmann, U.;
   Richter, I.; Tenishev, V. M.; Tóth, G.
Bibcode: 2014Icar..242...38R
Altcode:
  The interaction of a comet with the solar wind undergoes various
  stages as the comet's activity varies along its orbit. For a comet like
  67P/Churyumov-Gerasimenko, the target comet of ESA's Rosetta mission,
  the various features include the formation of a Mach cone, the bow
  shock, and close to perihelion even a diamagnetic cavity. There are
  different approaches to simulate this complex interplay between the
  solar wind and the comet's extended neutral gas coma which include
  magnetohydrodynamics (MHD) and hybrid-type models. The first treats
  the plasma as fluids (one fluid in basic single fluid MHD) and the
  latter treats the ions as individual particles under the influence of
  the local electric and magnetic fields. The electrons are treated as a
  charge-neutralizing fluid in both cases. Given the different approaches
  both models yield different results, in particular for a low production
  rate comet. In this paper we will show that these differences can be
  reduced when using a multifluid instead of a single-fluid MHD model
  and increase the resolution of the Hybrid model. We will show that some
  major features obtained with a hybrid type approach like the gyration
  of the cometary heavy ions and the formation of the Mach cone can be
  partially reproduced with the multifluid-type model.

Title: Plasma Flows in the Heliosheath along the Voyager 1 and 2
    Trajectories due to Effects of the 11 yr Solar Cycle
Authors: Provornikova, E.; Opher, M.; Izmodenov, V. V.; Richardson,
   J. D.; Toth, G.
Bibcode: 2014ApJ...794...29P
Altcode:
  We investigate the role of the 11 yr solar cycle variations in the
  solar wind (SW) parameters on the flows in the heliosheath using a new
  three-dimensional time-dependent model of the interaction between the
  SW and the interstellar medium. For boundary conditions in the model we
  use realistic time and the latitudinal dependence of the SW parameters
  obtained from SOHO/SWAN and interplanetary scintillation data for the
  last two solar cycles (1990-2011). This data set generally agrees with
  the in situ Ulysses measurements from 1991 to 2009. For the first ~30
  AU of the heliosheath the time-dependent model predicts constant radial
  flow speeds at Voyager 2 (V2), which is consistent with observations
  and different from the steady models that show a radial speed decrease
  of 30%. The model shows that V2 was immersed in SW with speeds of
  500-550 km s<SUP>-1</SUP> upstream of the termination shock before
  2009 and in wind with upstream speeds of 450-500 km s<SUP>-1</SUP>
  after 2009. The model also predicts that the radial velocity along
  the Voyager 1 (V1) trajectory is constant across the heliosheath,
  contrary to observations. This difference in observations implies that
  additional effects may be responsible for the different flows at V1
  and V2. The model predicts meridional flows (VN) higher than those
  observed because of the strong bluntness of the heliosphere shape in
  the N direction in the model. The modeled tangential velocity component
  (VT) at V2 is smaller than observed. Both VN and VT essentially depend
  on the shape of the heliopause.

Title: Effects of crustal field rotation on the solar wind plasma
    interaction with Mars
Authors: Ma, Yingjuan; Fang, Xiaohua; Russell, Christopher T.;
   Nagy, Andrew F.; Toth, Gabor; Luhmann, Janet G.; Brain, Dave A.;
   Dong, Chuanfei
Bibcode: 2014GeoRL..41.6563M
Altcode:
  The crustal remnant field on Mars rotates with the planet at
  a period of 24 h 37 min, constantly varying the magnetic field
  configuration interacting with the solar wind. Until now, there has
  been no self-consistent modeling investigation on how this varying
  magnetic field affects the solar wind plasma interaction. Here we
  include the rotation of this localized crustal field in a multispecies
  single-fluid MHD model of Mars and simulate an entire day of solar
  wind interaction under normal solar wind conditions. The MHD model
  results are compared with Mars Global Surveyor (MGS) magnetic field
  observations and show very close agreement, especially for the field
  strength along almost all of the 12 orbits on the day simulated. Model
  results also show that the ion escape rates slowly vary with rotation,
  generally anticorrelating with the strength of subsolar magnetic crustal
  sources, with some time delay. In addition, it is found that in the
  intense crustal field regions, the densities of heavy ion components
  enhance significantly along the MGS orbit, implying strong influence
  of the crustal field on the ionospheric structures.

Title: High Order Schemes in BATS-R-US: Is it OK to Simplify Them?
Authors: Tóth, G.; Chen, Y.; van der Holst, B.; Daldorff, L. K. S.
Bibcode: 2014ASPC..488..273T
Altcode:
  We describe a number of high order schemes and their simplified variants
  that have been implemented into the University of Michigan global
  magnetohydrodynamics code BATS-R-US. We compare the various schemes
  with each other and the legacy 2nd order TVD scheme for various test
  problems and two space physics applications. We find that the simplified
  schemes are often quite competitive with the more complex and expensive
  full versions, despite the fact that the simplified versions are only
  high order accurate for linear systems of equations. We find that all
  the high order schemes require some fixes to ensure positivity in the
  space physics applications. On the other hand, they produce superior
  results as compared with the second order scheme and/or produce the
  same quality of solution at a much reduced computational cost.

Title: Global Magnetohydrodynamics Simulation of the Coronal Mass
Ejection on 2011 March 7: from Chromosphere to 1 AU
Authors: Jin, Meng; Manchester, W. B.; van der Holst, B.; Sokolov,
   I.; Toth, G.; Vourlidas, A.; de Koning, C.; Gombosi, T. I.
Bibcode: 2014shin.confE..10J
Altcode:
  Performing realistic simulations of solar eruptions and validating
  those simulations with observations are important goals in order to
  achieve accurate space weather forecasts. Here, we analyze results
  of a global magnetohydrodyanmic (MHD) simulation of the fast coronal
  mass ejection (CME) that occurred on 2011 March 7. The simulation is
  made using the newly developed Alfven Wave Solar Model (AWSoM), which
  describes the background solar wind starting from the upper chromosphere
  and expends to 24 Rs. Coupling of AWSoM to an inner heliosphere (IH)
  model with the Space Weather Modeling Framework extends the total domain
  beyond the orbit of Earth. Physical processes included in the model are
  multi-species thermodynamics, electron heat conduction (both collisional
  and collisionless formulation), optically thin radiative cooling and
  Alfven-wave pressure that accelerates the solar wind. The Alfven-wave
  description is physically self-consistent, including non-WKB reflection
  and physics-based apportioning of turbulent dissipative heating to both
  electrons and protons. Within this model, we initiate the CME by using
  the Gibson-Low (GL) analytical flux rope model and follow its evolution
  for days, in which time it propagates beyond 1 AU. A comprehensive
  validation study is performed using remote as well as the in situ
  observations from SDO, SOHO, STEREOA/B, and OMNI. Our results show
  that the new model can reproduce many of the observed features near
  the Sun (e.g., CME-driven EUV waves, deflection of the flux rope from
  the coronal hole, double-front in the white light images) and in the
  heliosphere (e.g., CME-CIR interaction, shock properties at 1 AU). By
  fitting the CME speeds near the Sun with observations, the CME-driven
  shock arrival time is within 1 hour of the observed arrival time and
  all the in situ parameters are correctly simulated, which suggests the
  global MHD model as a powerful tool for the space weather forecasting.

Title: The behavior of the flows within the heliosheath
Authors: Michael, Adam; Opher, Merav; Provornikova, Elena; Toth, Gabor
Bibcode: 2014shin.confE..61M
Altcode:
  The current Voyager measurements of the plasma flows reveal the complex
  nature of the heliosheath, the last boundary between the Solar System
  and the interstellar medium. These measurements are challenging
  the standard theories and models. We use a global 3D multi-fluid
  magnetohydrodynamic (MHD) model of the heliosphere to study the flows
  within the heliosheath. Our model has a grid resolution of 0.5 AU within
  the heliosphere, along both Voyager 1 and Voyager 2 trajectories,
  and describes the solar wind magnetic field as a monopole to avoid
  any numerical magnetic dissipation effects in the heliosheath. We find
  that the model predicts the heliosheath to be split into two regions,
  first a thermally dominated region downstream of the termination
  shock followed by a magnetically dominated region (? &lt; 1) just
  before the heliopause. We compare the solution to the same model
  with dipole description of the solar wind magnetic field. The dipole
  solar wind magnetic field includes a flat heliospheric current sheet
  where reconnection occurs due to numerical dissipation. The two models
  predict a considerably different heliosheath. We compare both models
  to observations along V1 and V2 and discuss whether we can use these
  models to predict when Voyager 2 is approaching the heliopause.

Title: Effects of Crustal Field Rotation on the Solar Wind Plasma
    Interaction with Mars
Authors: Ma, Yingjuan; Fang, Xiaohua; Russell, Christopher; Brain,
   Dave; Nagy, Andrew; Toth, Gabor; Luhmann, Janet; Dong, Chuanfei
Bibcode: 2014EGUGA..16.8381M
Altcode:
  The crustal field on Mars rotates constantly with the planet at a
  period of 24 h 37 min. In this study, we include the rotation of the
  crustal field in the multi-species single fluid MHD model of Mars
  and simulated one entire day of May 15, 2005 using normal solar
  wind condition to investigate how this rotation affects the solar
  wind plasma interaction. The MHD model results are compared with MGS
  magnetic field observations and show remarkably good agreement along
  almost all of the 12 orbits on that day. Model results also show that
  the ion escape fluxes vary slowly with rotation, anti-correlating with
  the strength of subsolar magnetic crustal sources. It is also found
  that near intense crustal field regions, the densities of the heavy
  ion components increase significantly, implying a strong influence of
  the crustal field on the low-altitude ionosphere.

Title: Solar wind interaction with Mars upper atmosphere: Results
    from the one-way coupling between the multifluid MHD model and the
    MTGCM model
Authors: Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth,
   Gabor; Nagy, Andrew F.; Najib, Dalal
Bibcode: 2014GeoRL..41.2708D
Altcode:
  The 3-D multifluid Block Adaptive Tree Solar-wind Roe Upwind
  Scheme (BATS-R-US) MHD code (MF-MHD) is coupled with the 3-D Mars
  Thermospheric general circulation model (MTGCM). The ion escape
  rate from the Martian upper atmosphere is investigated by using a
  one-way coupling approach, i.e., the MF-MHD model incorporates the
  effects of 3-D neutral atmosphere profiles from the MTGCM model. The
  calculations are carried out for two cases with different solar cycle
  conditions. The calculated total ion escape flux (the sum of three
  major ionospheric species, O<SUP>+</SUP>, O2+, and CO2+) for solar
  cycle maximum conditions (6.6×10<SUP>24</SUP> s<SUP>-1</SUP>) is
  about 2.6 times larger than that of solar cycle minimum conditions
  (2.5×10<SUP>24</SUP> s<SUP>-1</SUP>). Our simulation results show
  good agreement with recent observations of 2-3×10<SUP>24</SUP>
  s<SUP>-1</SUP> (O<SUP>+</SUP>, O2+, and CO2+) measured near solar
  cycle minimum conditions by Mars Express. An extremely high solar
  wind condition is also simulated which may mimic the condition of
  coronal mass ejections or corotating interaction regions passing
  Mars. Simulation results show that it can lead to a significant value
  of the escape flux as large as 4.3×10<SUP>25</SUP>s<SUP>-1</SUP>.

Title: Martian ionospheric responses to dynamic pressure enhancements
    in the solar wind
Authors: Ma, Y. J.; Fang, X.; Nagy, A. F.; Russell, C. T.; Toth, Gabor
Bibcode: 2014JGRA..119.1272M
Altcode:
  As a weakly magnetized planet, Mars ionosphere/atmosphere interacts
  directly with the shocked solar wind plasma flow. Even though many
  numerical studies have been successful in reproducing numerous features
  of the interaction process, these earlier studies focused mainly on
  interaction under steady solar wind conditions. Recent observations
  suggest that plasma escape fluxes are significantly enhanced in
  response to solar wind dynamic pressure pulses. In this study, we
  focus on the response of the ionosphere to pressure enhancements
  in the solar wind. Through modeling of two idealized events using a
  magnetohydrodynamics model, we find that the upper ionosphere of Mars
  responds almost instantaneously to solar wind pressure enhancements,
  while the collision dominated lower ionosphere (below ~150 km) does
  not have noticeable changes in density. We also find that ionospheric
  perturbations in density, magnetic field, and velocity can last more
  than an hour after the solar wind returns to the quiet conditions. The
  topside ionosphere forms complicated transient shapes in response, which
  may explain unexpected ionospheric behaviors in recent observations. We
  also find that ionospheric escape fluxes do not correlate directly with
  simultaneous solar wind dynamic pressure. Rather, their intensities
  also depend on the earlier solar wind conditions. It takes a few hours
  for the ionospheric/atmospheric system to reach a new quasi-equilibrium
  state.

Title: Comet 1P/Halley Multifluid MHD Model for the Giotto Fly-by
Authors: Rubin, M.; Combi, M. R.; Daldorff, L. K. S.; Gombosi, T. I.;
   Hansen, K. C.; Shou, Y.; Tenishev, V. M.; Tóth, G.; van der Holst,
   B.; Altwegg, K.
Bibcode: 2014ApJ...781...86R
Altcode:
  The interaction of comets with the solar wind has been the focus of
  many studies including numerical modeling. We compare the results
  of our multifluid MHD simulation of comet 1P/Halley to data obtained
  during the flyby of the European Space Agency's Giotto spacecraft in
  1986. The model solves the full set of MHD equations for the individual
  fluids representing the solar wind protons, the cometary light and
  heavy ions, and the electrons. The mass loading, charge-exchange,
  dissociative ion-electron recombination, and collisional interactions
  between the fluids are taken into account. The computational domain
  spans over several million kilometers, and the close vicinity of the
  comet is resolved to the details of the magnetic cavity. The model
  is validated by comparison to the corresponding Giotto observations
  obtained by the Ion Mass Spectrometer, the Neutral Mass Spectrometer,
  the Giotto magnetometer experiment, and the Johnstone Plasma Analyzer
  instrument. The model shows the formation of the bow shock, the
  ion pile-up, and the diamagnetic cavity and is able to reproduce the
  observed temperature differences between the pick-up ion populations and
  the solar wind protons. We give an overview of the global interaction
  of the comet with the solar wind and then show the effects of the
  Lorentz force interaction between the different plasma populations.

Title: Alfvén Wave Solar Model (AWSoM): Coronal Heating
Authors: van der Holst, B.; Sokolov, I. V.; Meng, X.; Jin, M.;
   Manchester, W. B., IV; Tóth, G.; Gombosi, T. I.
Bibcode: 2014ApJ...782...81V
Altcode: 2013arXiv1311.4093V
  We present a new version of the Alfvén wave solar model, a global model
  from the upper chromosphere to the corona and the heliosphere. The
  coronal heating and solar wind acceleration are addressed with
  low-frequency Alfvén wave turbulence. The injection of Alfvén
  wave energy at the inner boundary is such that the Poynting flux is
  proportional to the magnetic field strength. The three-dimensional
  magnetic field topology is simulated using data from photospheric
  magnetic field measurements. This model does not impose open-closed
  magnetic field boundaries; those develop self-consistently. The
  physics include the following. (1) The model employs three different
  temperatures, namely the isotropic electron temperature and the
  parallel and perpendicular ion temperatures. The firehose, mirror,
  and ion-cyclotron instabilities due to the developing ion temperature
  anisotropy are accounted for. (2) The Alfvén waves are partially
  reflected by the Alfvén speed gradient and the vorticity along the
  field lines. The resulting counter-propagating waves are responsible
  for the nonlinear turbulent cascade. The balanced turbulence due to
  uncorrelated waves near the apex of the closed field lines and the
  resulting elevated temperatures are addressed. (3) To apportion the
  wave dissipation to the three temperatures, we employ the results
  of the theories of linear wave damping and nonlinear stochastic
  heating. (4) We have incorporated the collisional and collisionless
  electron heat conduction. We compare the simulated multi-wavelength
  extreme ultraviolet images of CR2107 with the observations from
  STEREO/EUVI and the Solar Dynamics Observatory/AIA instruments. We
  demonstrate that the reflection due to strong magnetic fields in the
  proximity of active regions sufficiently intensifies the dissipation
  and observable emission.

Title: Effects of Solar wind Pressure Enhancement and the Diurnal
    Rotation of the Crustal Field on the Solar Wind Plasma Interaction
    with Mars
Authors: Ma, Yingjuan; Russell, C. T.; Bougher, Stephen; Nagy, Andrew;
   Toth, Gabor; Fang, Xiaohua
Bibcode: 2014cosp...40E1926M
Altcode:
  As Mars is a weakly magnetized planet, its ionosphere/atmosphere
  interacts directly with the shocked solar wind plasma flow. Recent
  observations suggest that plasma escape fluxes are significantly
  enhanced in response to solar wind dynamic pressure pulses. In this
  presentation, based on multi-species single-fluid MHD numerical
  simulations, we show the response of the ionosphere to pressure
  enhancements in the solar wind. We find that the upper ionosphere
  of Mars responds almost instantaneously to solar wind pressure
  enhancements, while the collision dominated lower ionosphere (below
  ~150 km) does not have noticeable changes in density. We also find
  that ionospheric perturbations in density, magnetic field, and
  velocity can last more than an hour after the solar wind returns
  to the quiet conditions. The topside ionosphere forms complicated
  transient shapes in response, which may explain unexpected ionospheric
  behavior in recent observations. We also find that ionospheric escape
  fluxes do not correlate directly with simultaneous solar wind dynamic
  pressure. Rather, their intensities depend in part on the earlier
  solar wind conditions. We also include the diurnal rotation of the
  crustal field in the MHD model to investigate how this rotation
  affects the solar wind plasma interaction. The MHD model results are
  compared with MGS magnetic field observations and show remarkably good
  agreement between the two. Model results also show that the ion escape
  fluxes vary slowly with rotation, anti-correlating with the strength
  of subsolar magnetic crustal sources. It is found that near intense
  crustal field regions, the densities of heavy ion components increase
  significantly, implying a strong influence on the upper ionosphere by
  the crustal field.

Title: Study of solar cycle effects in the heliosheath in the model
    based on SWAN/SOHO and IPS data at 1 AU
Authors: Provornikova, Elena; Richardson, John; Opher, Merav; Toth,
   Gabor; Izmodenov, Vladislav
Bibcode: 2014cosp...40E2636P
Altcode:
  Observations of plasma in the heliosheath by Voyager 1 and 2 showed
  highly variable and very different plasma flows. Voyager 2 has been
  observing nearly constant radial flow ~110 km/s indicating that
  the spacecraft is still far from the heliopause. Plasma velocity
  components determined from LECP on Voyager 1 rapidly decreased across
  the heliosheath to zero values in the stagnation region near the
  HP. Steady state models of the outer heliosphere do not explain such
  different flows. These puzzling observational data motivate us to
  explore different physical effects at the edges of the heliosphere in
  the models. In this work we focus on time-dependent effects related to
  11- year solar cycle. We use a 3D MHD multi-fluid model of interaction
  of the solar wind with the local interstellar medium (BATSRUS) with
  time-dependent boundary conditions for the supersonic solar wind. Used
  realistic boundary conditions (plasma density and velocity) at 1 AU were
  derived from the measurements of intensities of Lyman-alpha emission
  on SOHO/SWAN, OMNI data (in the ecliptic plane) and interplanetary
  scintillations data over two full solar cycles. We present results of
  the time-dependent model and discuss effects of realistic variations
  of the solar wind parameters on the flow in the heliosheath and in the
  vicinity of the heliopause. From comparison of model results with the
  Voyager 1 and 2 observations we found that the solar cycle effects can
  explain constant radial flow along the Voyager 2 but do not reproduce
  the decrease of radial flow to zero seen at Voyager 1.

Title: Predicting the time derivative of local magnetic perturbations
Authors: Tóth, Gábor; Meng, Xing; Gombosi, Tamas I.; Rastätter, Lutz
Bibcode: 2014JGRA..119..310T
Altcode:
  Some of the potentially most destructive effects of severe
  space weather storms are caused by the geomagnetically induced
  currents. Geomagnetically induced currents (GICs) can cause failures
  of electric transformers and result in widespread blackouts. GICs
  are induced by the time variability of the magnetic field and are
  closely related to the time derivative of the local magnetic field
  perturbation. Predicting dB/dt is rather challenging, since the local
  magnetic perturbations and their time derivatives are both highly
  fluctuating quantities, especially during geomagnetic storms. The
  currently available first principles-based and empirical models cannot
  predict the detailed minute-scale or even faster time variation of
  the local magnetic field. On the other hand, Pulkkinen et al. (2013)
  demonstrated recently that several models can predict with positive
  skill scores whether the horizontal component of dB/dt at a given
  magnetometer station will exceed some threshold value in a 20 min
  time interval. In this paper we investigate if one can improve the
  efficiency of the prediction further. We find that the Space Weather
  Modeling Framework, the best performing among the five models compared
  by Pulkkinen et al. (2013), shows significantly better skill scores
  in predicting the magnetic perturbation than predicting its time
  derivative, especially for large deviations. We also find that there is
  a strong correlation between the magnitude of dB/dt and the magnitude
  of the horizontal magnetic perturbation itself. Combining these two
  results one can devise an algorithm that gives better skill scores for
  predicting dB/dt exceeding various thresholds in 20 min time intervals
  than the direct approach.

Title: Geomagnetic Environment Modeling at the Community Coordinated
Modeling Center: Successes, Challenges and Perspectives.
Authors: Kuznetsova, Maria; Toth, Gabor; Hesse, Michael; Rastaetter,
   Lutz; Glocer, Alex
Bibcode: 2014cosp...40E1723K
Altcode:
  The Community Coordinated Modeling Center (CCMC,
  http://ccmc.gsfc.nasa.gov) hosts an expanding collection of modern
  space science and space weather models developed by the international
  space science community. The goals of the CCMC are to support the
  research and developmental work necessary to substantially increase
  the present-day space environment modeling capability and to maximize
  scientific return on investments into model development. CCMC is
  servicing models through interactive web-based systems, supporting
  community-wide research projects and designing displays and tools
  customized for specific applications. The presentation will review the
  current state of the geomagnetic environment modeling, highlight resent
  progress, and showcase the role of state-of-the-art magnetosphere
  models in advancing our understanding of fundamental phenomena in
  magnetosphere plasma physics.

Title: Multi-fluid MHD Study of the Solar Wind Induced Plasma Escape
    from the Martian Atmosphere
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Toth, G.; Dong, C.;
   Bougher, S. W.
Bibcode: 2013AGUFM.P13C..05M
Altcode:
  In this study, the multi-fluid MHD model (Najib et al., 2011)
  is further improved to include an electron pressure equation to
  self-consistently calculate the electron temperature. The electron
  pressure equation included in the improved model can accurately
  calculate the electron temperature and the electron pressure
  force. The electron temperature is also needed to calculate rates
  of some electron temperature dependent chemical reactions such as
  dissociative recombination and electron impact ionization. So the
  improvement of the model leads to a more accurate evaluation of the
  ion density in the ionosphere and a more accurate description of the
  interaction process. Model results of a typical case with electron
  pressure equation included are compared in detail to an identical case
  without the electron pressure equation to identify the effect of the
  improved physics. The two cases will be examined to identify changes
  in the global interaction patterns. Electron temperature will also
  be compared for the two cases to identify regions where temperatures
  differs the most. The ion density profiles at different locations
  will be compared to identify the changes of plasma density due to
  changes of recombination rates and impact ionization rates caused by
  different electron temperatures. The calculated electron temperature
  profile will also be compared to the only available pre-MAVEN electron
  observations from the Viking Retarding Potential Analyzer (RPA) (Hansen
  et al., 1977). Based on model results, two-dimensional maps of the ion
  densities and fluxes are to be generated in the tail region at various
  distances to locate the intense region for plasma bulk escape. We will
  also plan to fly through the 3D MHD model results using planned MAVEN
  orbits to predict when and where the spacecraft will pass different
  plasma boundaries (such as the bow shock, MPB, and ionopause), and
  the typical range of the plasma parameters in different regions.

Title: Global MHD simulations of Mercury's interaction with the
solar wind: Influence of the planetary conducting core on the
    magnetospheric interaction
Authors: Jia, X.; Slavin, J. A.; Gombosi, T. I.; Daldorff, L.; Toth, G.
Bibcode: 2013AGUFMSM21A2139J
Altcode:
  Mercury's comparatively weak intrinsic magnetic field and its close
  proximity to the Sun lead to a mini-magnetosphere that undergoes more
  direct space-weathering interactions than other planets. A unique
  aspect of the Mercury interaction system relates to the large ratio
  of the scale of the planet to the scale of the tiny magnetosphere and
  the presence of a large-size core (with radius ~ 80% of the planetary
  radius) composed of highly conducting material, implying that there
  is potentially strong feedback between the planet's interior and
  the magnetosphere, especially under conditions of strong solar wind
  driving. Understanding the solar wind-magnetosphere-exosphere-interior
  interaction at Mercury as a highly coupled system requires not only
  analysis of spacecraft data but also a modeling framework that is
  both comprehensive and inclusive. To this end, we have developed a new
  global MHD model of Mercury's interaction with the solar wind based on
  the BATSRUS code in which the interior of the planet (modeled as layers
  of different electric conductivities) is electrodynamically coupled to
  the surrounding space plasma environment. The new modeling capability
  allows for self-consistently characterizing the dynamical response of
  the Mercury system to time-varying external conditions. In particular,
  we have applied the coupled model to assess quantitatively the effect
  of induction arising from the planet's conducting core on the global
  magnetosphere. A set of idealized simulations have been carried out in
  which Mercury's magnetosphere is impacted by solar wind disturbances
  with different levels of pressure enhancement. Our results show that
  due to the induction effect, Mercury's core can impose strong global
  influences on the way Mercury responds to changes in the external
  environment, including modifying the global magnetospheric structure
  and affecting the extent to which the solar wind directly impacts the
  planetary surface. By applying the model to simulate extreme events,
  such as those observed by MESSENGER during impact of Coronal Mass
  Ejections (Slavin et al., 2013), we aim to obtain a deeper understanding
  of the tightly coupled Mercury system, and thereby to develop further
  constraints on the properties of the planet's interior.

Title: Two-way self-consistent coupling of HEIDI in SWMF
Authors: Ilie, R.; Liemohn, M. W.; Toth, G.
Bibcode: 2013AGUFMSM43A2281I
Altcode:
  In this study we present results from the two-way coupling between
  the kinetic Hot Electron and Ion Drift Integrator (HEIDI) model and
  the Space Weather Modeling Framework (SWMF). HEIDI solves the time
  dependent, gyration and bounced averaged kinetic equation for the phase
  space density of different ring current species and computes full pitch
  angle distributions for all local times and radial distances. This
  model was generalized to accommodate an arbitrary magnetic field
  and, through the coupling with SWMF, it obtains the magnetic field
  description along with the plasma distribution at the model boundaries
  from the Block Adaptive Tree Solar Wind Roe Upwind Scheme (BATS-R-US)
  magnetohydrodynamics (MHD) model within the SWMF. Electric field
  self-consistency is assured by the passing of convection potentials
  from the Ridley Ionosphere Model (RIM) within SWMF. Our study tests
  the various levels of coupling between the 3 models, highlighting the
  roles that the magnetic field, plasma sheet conditions and the cross
  polar cap potential play in the formation and evolution of the ring
  current. The results of the self-consistent coupling between HEIDI,
  BATSRUS and RIM during disturbed conditions emphasize the importance of
  a kinetic self-consistent approach to the description of the geospace.

Title: Evaluating the Importance of Outflow Velocity at the MHD
    Inner Boundary
Authors: Welling, D. T.; Liemohn, M. W.; Toth, G.; Glocer, A.
Bibcode: 2013AGUFMSA41A2105W
Altcode:
  Including an ionospheric source of magnetospheric plasma in global
  magnetohydrodynamic models (MHD) is an exercise in setting inner
  boundary mass density and radial velocity. Recently, in order to account
  for the complex processes that accelerate plasmas up from ionospheric
  altitudes to MHD inner boundary altitudes (typically 2.5 to 3 Earth
  Radii), empirical and first-principles-based models have been developed
  to set inner boundary conditions in a dynamic and activity-dependent
  manner. However, such measures are not necessary to achieve outflowing
  fluences of the order observed by various spacecraft. Spatially and
  temporally constant boundary conditions, even with zero radial velocity,
  have been shown to produce dynamic outflow patterns and supply the
  bulk of magnetospheric plasma. Noteworthy of this approach is the
  inherent assumption that no acceleration has occurred between the
  ionosphere and the inner boundary, that is, the ionosphere is simply
  a mass reservoir. This assumption is contrary to our understanding of
  the magnetosphere-ionosphere system, yet the net result - outflowing
  heavy and light ions that populate the rest of geospace - is similar
  to that when a more realistic outflow specification is applied. The
  implication is that radial velocity matters little when supplying
  outflow to global MHD models. This paper investigates the importance
  of radial velocity at the inner boundary of MHD codes in driving
  ionospheric outflows into the greater domain. Multi-fluid BATS-R-US
  is used to simulate an idealized storm, first using zero radial
  velocity at the inner boundary, then non-zero constant values, and
  finally with spatially and temporally dynamic values driven by the
  Polar Wind Outflow Model (PWOM), which sets radial velocity and number
  density based on physics-based modeling of gap region populations. The
  results, in terms of total fluence, spatial outflowing flux patterns,
  and overall magnetospheric response, are compared to investigate how
  the simulation depends on this value. Magnetospheric implications are
  evaluated via density, temperature, and composition within the lobes,
  plasmasheet, and ring current regions. MHD-derived global indices,
  such as DST and CPCP, will also be leveraged. The results of this
  study are a systematic test of the importance of sub-magnetosphere
  acceleration of ionospheric plasma in magnetospheric dynamics.

Title: The Challenge of Incorporating Charged Dust in the Physics
    of Flowing Plasma Interactions
Authors: Jia, Y.; Russell, C. T.; Ma, Y.; Lai, H.; Jian, L.; Toth, G.
Bibcode: 2013AGUFMSM53A2212J
Altcode:
  The presence of two oppositely charged species with very different mass
  ratios leads to interesting physical processes and difficult numerical
  simulations. The reconnection problem is a classic example of this
  principle with a proton-electron mass ratio of 1836, but it is not
  the only example. Increasingly we are discovering situations in which
  heavy, electrically charged dust particles are major players in a plasma
  interaction. The mass of a 1mm dust particle is about 2000 proton masses
  and of a 10 mm dust particle about 2 million proton masses. One example
  comes from planetary magnetospheres. Charged dust pervades Enceladus'
  southern plume. The saturnian magnetospheric plasma flows through
  this dusty plume interacting with the charged dust and ionized plume
  gas. Multiple wakes are seen downstream. The flow is diverted in one
  direction. The field aligned-current systems are elsewhere. How can
  these two wake features be understood? Next we have an example from
  the solar wind. When asteroids collide in a disruptive collision, the
  solar wind strips the nano-scale charged dust from the debris forming
  a dusty plasma cloud that may be over 10<SUP>6</SUP>km in extent and
  containing over 100 million kg of dust accelerated to the solar wind
  speed. How does this occur, especially as rapidly as it appears to
  happen? In this paper we illustrate a start on understanding these
  phenomena using multifluid MHD simulations but these simulations are
  only part of the answer to this complex problem that needs attention
  from a broader range of the community.

Title: Solar wind interaction with Mars' upper atmosphere: Results
    from 3-D studies using one-way coupling between the Multi-fluid MHD,
    the M-GITM and the AMPS models
Authors: Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy,
   A. F.; Tenishev, V.; Pawlowski, D. J.; Meng, X.; Combi, M. R.
Bibcode: 2013AGUFM.P12A..01D
Altcode:
  The study of the solar wind interaction with Mars upper
  atmosphere/ionosphere has triggered a great of interest in recent
  years. Among the large number of topics in this research area,
  the investigation of ion escape fluxes has become increasingly
  important due to its potential impact on the long-term evolution
  of Mars atmosphere (e.g., loss of water) over its history. In the
  present work, we adopt the 3-D Mars cold neutral atmosphere profiles
  (0~300 km) from the newly developed and validated Mars Global Ionosphere
  Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100km~5RM)
  from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator
  (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US
  Mars multi-fluid MHD model (100km~20RM) that can better simulate the
  interplay between Mars upper atmosphere and solar wind by considering
  the dynamics of individual ion species. The multi-fluid model solves
  separate continuity, momentum and energy equations for each ion species
  (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere
  model take into account the effects of solar cycle and seasonal
  variations on both cold and hot neutral atmospheres, allowing us to
  investigate the corresponding effects on the Mars upper atmosphere ion
  escape by using a one-way coupling approach, i.e., both the M-GITM
  and AMPS model outputs are used as the inputs for the multi-fluid
  model and M-GITM is used as input into the AMPS exosphere model. The
  calculations are carried out for selected cases with different nominal
  solar wind, solar cycle and crustal field orientation conditions. This
  work has the potential to provide predictions of ion escape rates for
  comparison to future data to be returned by the MAVEN primary mission
  (2014-2016) and thereby improve our understanding of present day escape
  processes. Acknowledgments: The work presented here was supported by
  NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.

Title: Modeling comet 1P/Halley's plasma environment using multifluid
    MHD
Authors: Rubin, M.; Combi, M. R.; Daldorff, L. K. S.; Gombosi, T. I.;
   Hansen, K. C.; Shou, Y.; Tenishev, V. M.; Tóth, G.; van der Holst,
   B.; Altwegg, K.
Bibcode: 2013EPSC....8...87R
Altcode:
  Observations by ESA's Giotto spacecraft at comet 1P/Halley on March
  14, 1986, allowed a detailed glance into the interaction between the
  neutral gas coma and the solar wind. For a highly productive comet
  such as 1P/Halley the plasma environment is remarkably diverse when
  probed at various cometocentric distances. We apply a global scale
  multifluid magnetohydrodynamics (MHD) approach in which the individual
  plasma components are treated as a set of coupled magnetized fluids
  ([1], [2]). This is a continuation of our previous work using a single
  species model ([3], [4]) and provides insight on some of the involved
  dynamical processes that might otherwise only be accessible by Monte
  Carlo Hybrid-type models.

Title: Pressure anisotropy in global magnetospheric simulations:
    Coupling with ring current models
Authors: Meng, X.; Tóth, G.; Glocer, A.; Fok, M. -C.; Gombosi, T. I.
Bibcode: 2013JGRA..118.5639M
Altcode:
  We have recently extended the global magnetohydrodynamic (MHD)
  model BATS-R-US to account for pressure anisotropy. Since the inner
  magnetosphere dynamics cannot be fully described even by anisotropic
  MHD, we coupled our anisotropic MHD model with two inner magnetospheric
  models: the Rice Convection Model (RCM) and the Comprehensive Ring
  Current Model (CRCM). The coupled models provide better representations
  of the near-Earth plasma, especially during geomagnetic storms. In this
  paper, we present the two-way coupling algorithms with both ring current
  models. The major difference between these two couplings is that the
  RCM assumes isotropic and constant pressures along closed field lines,
  while the CRCM resolves pitch angle anisotropy. For model validation,
  we report global magnetosphere simulations performed by the coupled
  models. The simulation results are compared to the results given by
  the coupled isotropic MHD and ring current models. We find that in
  the global MHD simulations coupled with ring current models, pressure
  anisotropy results in a thinner magnetosheath, a shorter tail, a much
  smaller Earthward plasma jet from the tail reconnection site, and is
  also important in controlling the magnetic field configuration. The
  comparisons with satellite data for the magnetospheric event simulations
  show improvements on reproducing the measured tail magnetic field and
  inner magnetospheric flow velocity when including pressure anisotropy
  in the ring current model coupled global MHD model.

Title: Ionospheric Responses to Discontinuities in the Solar Wind
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Toth, G.
Bibcode: 2013EPSC....8..845M
Altcode:
  The solar wind plasma flow and associated IMF are highly variable. Past
  studies about Mars mainly focus on its interactions with steady solar
  wind conditions. However recent study found that the total escape
  fluxes can be significantly enhanced during solar wind pressure pulses
  [1]. This study focuses on ionosphere response to solar wind 1) density
  variation and 2) magnetic field direction change. Through numerical
  modeling, we found that the upper ionosphere of Mars responses almost
  instantaneously to solar wind density enhancement, while the lower
  ionosphere (below ~150 km) do not have any noticeable changes in
  density. Current sheet crossing can cause only moderate changes in the
  upper ionosphere of Mars with several min time delays. We also found
  that perturbations in density and integrated escape fluxes caused by
  the solar wind variations could last more than an hour.

Title: Numerical Simulations of Coronal Mass Ejection on 2011 March 7:
    One-temperature and Two-temperature Model Comparison
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Oran, R.;
   Sokolov, I.; Toth, G.; Liu, Y.; Sun, X. D.; Gombosi, T. I.
Bibcode: 2013ApJ...773...50J
Altcode:
  During Carrington rotation (CR) 2107, a fast coronal mass ejection (CME;
  &gt;2000 km s<SUP>-1</SUP>) occurred in active region NOAA 11164. This
  event is also associated with a solar energetic particle event. In
  this study, we present simulations of this CME with one-temperature
  (1T) and two-temperature (2T: coupled thermodynamics of the electron
  and proton populations) models. Both the 1T and 2T models start from
  the chromosphere with heat conduction and radiative cooling. The
  background solar wind is driven by Alfvén-wave pressure and heated
  by Alfvén-wave dissipation in which we have incorporated the balanced
  turbulence at the top of the closed field lines. The magnetic field of
  the inner boundary is set up using a synoptic map from Solar Dynamics
  Observatory/Helioseismic and Magnetic Imager. The Titov-Démoulin
  flux-rope model is used to initiate the CME event. We compare the
  propagation of fast CMEs and the thermodynamics of CME-driven shocks in
  both the 1T and 2T CME simulations. Also, the synthesized white light
  images are compared with the Solar and Heliospheric Observatory/Large
  Angle and Spectrometric Coronagraph observations. Because there is no
  distinction between electron and proton temperatures, heat conduction
  in the 1T model creates an unphysical temperature precursor in front
  of the CME-driven shock and makes the shock parameters (e.g., shock
  Mach number, compression ratio) incorrect. Our results demonstrate
  the importance of the electron heat conduction in conjunction with
  proton shock heating in order to produce the physically correct CME
  structures and CME-driven shocks.

Title: Plasma flow in the outer heliosphere due to variations of
    the solar wind structure at 1 AU in 11-year solar cycle
Authors: Provornikova, Elena; Opher, Merav; Izmodenov, Vlad; Toth,
   Gabor
Bibcode: 2013shin.confE..67P
Altcode:
  Recent observations at Voyager 1 and 2 in the heliosheath - region
  of hot subsonic solar wind flow at the heliosphere boundary - show
  complex and very different plasma flows. Voyager 2 has been observing
  a constant radial flow 110 km/s indicating that the spacecraft is far
  from the heliopause. Meanwhile, in 2011 Voyager 1 entered a stagnation
  region at 120 AU with small/near-zero flow velocity components meaning
  that Voyager 1 may be very close to the HP. Steady state models of the
  outer heliosphere do not explain such different flows. These puzzling
  observational data motivate us to explore different physical effects
  at the edges of the heliosphere in the models. In this work we focus
  on time-dependent effects related to 11- year solar cycle. We use a
  global 3D MHD multi-fluid model of interaction of the solar wind with
  the local interstellar medium with time-dependent boundary conditions
  for the supersonic solar wind. Realistic boundary conditions (plasma
  density and velocity) at 1 AU were obtained from the measurements of
  intensities of Lyman-alpha emission on SOHO/SWAN, OMNI data (in the
  ecliptic plane) and interplanetary scintillations data over two full
  solar cycles. We present results of the time-dependent model and discuss
  effects of realistic variations of the solar wind parameters on the
  flow in the heliosheath and in the vicinity of the heliopause. From
  comparison of model results with the Voyager 1 and 2 observations we
  found that the solar cycle effects can explain constant radial flow
  along the Voyager 2 but do not reproduce the decrease of radial flow
  to zero seen at Voyager 1.

Title: A slow bow shock ahead of the heliosphere
Authors: Zieger, B.; Opher, M.; Schwadron, N. A.; McComas, D. J.;
   Tóth, G.
Bibcode: 2013GeoRL..40.2923Z
Altcode:
  Current estimates of plasma parameters in the local interstellar
  medium indicate that the speed of the interstellar wind, i.e.,
  the relative speed of the local interstellar cloud with respect to
  the Sun, is most likely less than both the fast magnetosonic speed
  (subfast) and the Alfvén speed (sub-Alfvénic) but greater than
  the slow magnetosonic speed (superslow). In this peculiar parameter
  regime, MHD theory postulates a slow magnetosonic shock ahead of the
  heliosphere, provided that the angle between the interstellar magnetic
  field and the interstellar plasma flow velocity is quite small (e.g.,
  15° to 30°). In this likely scenario, our multifluid MHD model of
  the heliospheric interface self-consistently produces a spatially
  confined quasi-parallel slow bow shock. Voyager 1 is heading toward
  the slow bow shock, while Voyager 2 is not, which means that the two
  spacecraft are expected to encounter different interstellar plasma
  populations beyond the heliopause. The slow bow shock also affects
  the density and spatial extent of the neutral hydrogen wall.

Title: Simulation of the Coronal Mass Ejection on 2011 March 7:
    from Chromosphere to 1 AU
Authors: Jin, Meng; Manchester, Ward; van der Holst, Bart; Oran, Rona;
   Sokolov, Igor; Toth, Gabor; Gombosi, Tamas I.; Vourlidas, Angelos;
   Liu, Yang; Sun, Xudong
Bibcode: 2013shin.confE...4J
Altcode:
  On 2011 March 7, a fast CME (&gt; 2000 km/s) occurred in NOAA
  11164. This event is also associated with a Solar Energetic Particle
  (SEP) event. In this study, we present the magnetohydrodynamics
  simulation results of this event by using the newly developed Alfven
  Wave SOlar Model (AWSOM) in Space Weather Modeling Framework (SWMF). The
  background solar wind starts from chromosphere with heat conduction
  and radiative cooling. The solar wind is driven by Alfven-wave pressure
  and heated by Alfven-wave dissipation. The magnetic field of the inner
  boundary is specified with a synoptic magnetogram from SDO/HMI. We
  initiate the CME by using the Gibson-Low flux rope model. In order to
  produce physically correct CME structures and CME-driven shocks, the
  electron and proton temperatures are separated so that the electron
  heat conduction is explicitly treated in conjunction with proton
  shock heating. We simulate the CME propagation to 1 AU. Comprehensive
  validation work is done by using the remote as well as the in-situ
  observation from SOHO, SDO, STEREOA/B, ACE, and WIND. Our results show
  that the new model can reproduce most of the observed features near the
  Sun and in the heliosphere. The CME-driven shock is well reproduced,
  which is important for modeling the SEP event with diffusive shock
  acceleration. We also try to compare the differences and similarities
  between this event and previous simulated extreme events (e.g., the
  2003 Halloween CMEs).

Title: Time-dependent solar wind flows in the heliosheath
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
Bibcode: 2013AGUSMSH21A..02P
Altcode:
  Recent observations on Voyager 1 and 2 spacecraft show complex and
  very different solar wind flows in the heliosheath region. Voyager
  2 has been observing constant radial flows (Richardson and Wang
  2013). At the beginning of 2011 Voyager 1 entered a region with zero
  and even negative radial velocity of the plasma flow (Krimigis et
  al. 2011). Since mid 2012 Voyager 1 continues observing a new region
  in the heliosheath with fast changing of intensities of anomalous and
  galactic cosmic rays. These puzzling observational data motivate us
  to explore different physical effects at the edges of the heliosphere
  in the models. In order to separate spatial from temporal effects the
  investigation of time-dependent effects are crucial. In this work we
  focus on time-dependent effects of the 11-year solar cycle. We use
  a global MHD multi-fluid model of interaction of the solar wind with
  the local interstellar medium with time-dependent boundary conditions
  for the supersonic solar wind. Realistic boundary conditions (plasma
  density and velocity) at 1 AU for the plasma were obtained from the
  measurements of Ly-alpha intensities on SOHO/SWAN, OMNI data and
  interplanetary scintillations data. We present effects of realistic
  variations of the solar wind dynamic pressure on the solar wind flow in
  the heliosheath and in the vicinity of the heliopause. Comparing the
  results of time-dependent model along the Voyager 1 and 2 trajectory
  with observational data we describe effects of solar cycle on the
  flows that Voyager measures.

Title: Structure of the Heliosheath and Heliopause
Authors: Opher, M.; Drake, J. F.; Swisdak, M. M.; Toth, G.
Bibcode: 2013AGUSMSH24A..06O
Altcode:
  We discuss the structure of the heliosheath (HS) and and heliopause (HP)
  when reconnection is taken place within the sector region. Observational
  constrains of reconnection within the sector are challenged by
  the resolution limitations of the magnetometer. However, indirect
  constraints such as the lack of conservation of magnetic flux in
  the heliosheath (Richardson et al. 2013) and the correlation of the
  variability of energetic particles with the sector region (Hill et
  al. 2013) indicate that reconnection might be taking place within
  the sector (Opher et al. 2011). The reconnected sector region in
  high beta plasma has a multitude of islands and is very similar to
  a crossing of a normal sector in terms of the overall configuration
  of the magnetic field and intensity. However, there is substantial
  reduction of magnetic tension. We show, that Rayleigh-Taylor (RT)
  instabilities can take place within the sector region where there is
  no magnetic tension to stabilize the interchange instability (Opher et
  al. 2013). The RT instability produces elongated flow structures that
  disturb the heliosheath flow pattern. This instability can explain the
  large differences between the flows at Voyager 1 and 2. V1 measurements
  indicate a constant decrease in the radial speed until a region with
  zero radial speeds while V2 radial speeds are constant. The structure of
  the HP has been explored with 2-D PIC simulations (Swisdak et al. 2013)
  to understand what underlies the complex particle and magnetic data
  seen by V1 in the latter half of 2012. We show using a global MHD
  model that because of draping the direction of the magnetic field
  in the interstellar medium (ISM) does not differ significantly from
  the azimuthal heliospheric field measured in the HS. Magnetic field
  profiles from cuts of the MHD simulation across the HP are used as
  input into the initial conditions of the PIC simulation. However, the
  HS in the PIC simulation is taken to have a sectored structure with a
  population of pickup ions.The sectored field reconnects first, forming
  magnetic islands with scales of the order of the sector spacing. These
  islands then begin reconnecting with the ISM across the HP, slowed
  by the higher density plasma in the ISM. The HP eventually develops a
  complex magnetic structure with nested magnetic islands where HS and
  ISM plasma has mixed. Multiple sharp jumps in the number density of
  the ISM plasma are seen in cuts across the HP which is revealed not
  as a single boundary but as a series of boundaries. The jumps occur at
  separatrices of magnetic islands that exhibit jumps in the population
  density but no jumps in the magnetic field direction. This important
  result is consistent with the striking absence of rotation of the
  magnetic field data seen during jumps in the ACR and GCR intensities
  seen by V1. Based on these simulation results and the Voyager magnetic
  and particle data we have constructed the possible magnetic structure
  of the HP boundary region, which includes a series of nested magnetic
  islands and separatrices, that produce a porous boundary. The jump
  in the magnetic field strength measured by Voyager on its approach to
  the HP very likely arises from the leakage of high pressure HS plasma
  across this porous boundary into the ISM where it is lost.

Title: Propagation into the heliosheath of a large-scale solar wind
    disturbance bounded by a pair of shocks
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
Bibcode: 2013A&A...552A..99P
Altcode: 2013arXiv1303.5105P
  Context. After the termination shock (TS) crossing, the Voyager
  2 spacecraft has been observing strong variations of the magnetic
  field and solar wind parameters in the heliosheath. Anomalous cosmic
  rays, electrons, and galactic cosmic rays present strong intensity
  fluctuations. Several works suggested that the fluctuations might be
  attributed to spatial variations within the heliosheath. Additionally,
  the variability of the solar wind in this region is caused by different
  temporal events that occur near the Sun and propagate to the outer
  heliosphere. <BR /> Aims: To understand the spatial and temporal
  effects in the heliosheath, it is important to study these effects
  separately. In this work we explore the role of shocks as one type
  of temporal effects in the dynamics of the heliosheath. Although
  currently plasma in the heliosheath is dominated by solar minima
  conditions, with increasing solar cycle shocks associated with
  transients will play an important role. <BR /> Methods: We used a
  3D MHD multi-fluid model of the interaction between the solar wind
  and the local interstellar medium to study the propagation of a pair
  of forward-reverse shocks in the supersonic solar wind, interaction
  with the TS, and propagation to the heliosheath. <BR /> Results: We
  found that in the supersonic solar wind the interaction region between
  the shocks expands, the shocks weaken and decelerate. The fluctuation
  amplitudes of the plasma parameters vary with heliocentric distance. The
  interaction of the pair of shocks with the TS creates a variety of
  new waves and discontinuities in the heliosheath, which produce a
  highly variable solar wind flow. The collision of the forward shock
  with the heliopause causes a reflection of fast magnetosonic waves
  inside the heliosheath. <P />A movie is available in electronic form
  at <A href="http://www.aanda.org">http://www.aanda.org</A>

Title: Saturnian Local Time Effects in Titan's Interaction- A
    multi-fluid MHD study
Authors: Ma, Yingjuan; Russell, Chris; Nagy, Andrew; Toth, Gabor;
   Dougherty, Michele; Cravens, Tom
Bibcode: 2013EGUGA..15.3509M
Altcode:
  We use a multi-fluid MHD model to study the effects of Saturnian
  Local Time(SLT). The multi-fluid model improves the previously used
  7-species single-fluid MHD model by solving the density, velocity and
  pressure equations for each of the seven ion fluids. This model allows
  the motion of the different ion fluids to be decoupled. The model is
  first applied to an idealized case and the results are compared in
  detail with that of the 7-species single-fluid MHD model to illustrate
  the importance of the multi-fluid effects. Simulation results show
  that the multi-fluid model is able to reproduce asymmetric results
  along the convection electric field direction. The velocities patterns
  are different for different mass ion fluids. The heavier the ion is,
  the more significant is the flow along the convection electric field
  direction. Also the multi-fluid MHD model predicts that more heavy
  ions are escaping from the satellite as compared with the single-fluid
  model. We also apply the model to test the effects of SLT and find
  that the escaping fluxes of heavy ions vary significantly with SLT.

Title: CRCM + BATS-R-US two-way coupling
Authors: Glocer, A.; Fok, M.; Meng, X.; Toth, G.; Buzulukova, N.;
   Chen, S.; Lin, K.
Bibcode: 2013JGRA..118.1635G
Altcode:
  We present the coupling methodology and validation of a fully coupled
  inner and global magnetosphere code using the infrastructure provided
  by the Space Weather Modeling Framework (SWMF). In this model,
  the Comprehensive Ring Current Model (CRCM) represents the inner
  magnetosphere, while the Block-Adaptive-Tree Solar-Wind Roe-Type
  Upwind Scheme (BATS-R-US) represents the global magnetosphere. The
  combined model is a global magnetospheric code with a realistic ring
  current and consistent electric and magnetic fields. The computational
  performance of the model was improved to surpass real-time execution
  by the use of the Message Passing Interface (MPI) to parallelize the
  CRCM. Initial simulations under steady driving found that the coupled
  model resulted in a higher pressure in the inner magnetosphere and an
  inflated closed field-line region as compared to simulations without
  inner-magnetosphere coupling. Our validation effort was split into two
  studies. The first study examined the ability of the model to reproduce
  Dst for a range of events from the Geospace Environment Modeling (GEM)
  Dst Challenge. It also investigated the possibility of a baseline shift
  and compared two approaches to calculating Dst from the model. We
  found that the model did a reasonable job predicting Dst and Sym-H
  according to our two metrics of prediction efficiency and predicted
  yield. The second study focused on the specific case of the 22 July
  2009 moderate geomagnetic storm. In this study, we directly compare
  model predictions and observations for Dst, THEMIS energy spectragrams,
  TWINS ENA images, and GOES 11 and 12 magnetometer data. The model did
  an adequate job reproducing trends in the data. Moreover, we found
  that composition can have a large effect on the result.

Title: A global multispecies single-fluid MHD study of the plasma
    interaction around Venus
Authors: Ma, Y. J.; Nagy, A. F.; Russell, C. T.; Strangeway, R. J.;
   Wei, H. Y.; Toth, G.
Bibcode: 2013JGRA..118..321M
Altcode:
  This paper reports a new global multispecies single-fluid MHD model that
  was recently developed for Venus. This model is similar to the numerical
  model that has been successfully applied to Mars. Mass densities of
  proton and three important ionospheric ion species (O<SUP>+</SUP>,
  O<SUB>2</SUB><SUP>+</SUP>, and CO<SUB>2</SUB><SUP>+</SUP>) are
  self-consistently calculated in the model by including related
  chemical reactions and ion-neutral collision processes. The simulation
  domain covers the region from 100 km altitude above the surface
  up to 24 R<SUB>V</SUB> in the tail. An adaptive spherical grid
  structure is constructed with radial resolution of about 5 km in the
  lower ionosphere. Bow shock locations are well reproduced for both
  solar-maximum and solar-minimum conditions using appropriate solar wind
  parameters for each case. It is shown that the shock locations are
  farther from the planet during the solar maximum condition, because
  of both the enhanced solar radiation strength and the relatively
  small Mach number. The simulation results also agree well with Venus
  Express observations, as shown by comparisons between model results
  with magnetic fields observed by the spacecraft.

Title: Predicting the time derivative of local magnetic perturbations
    with physics based models
Authors: Toth, G.; Meng, X.; Liemohn, M. W.; Gombosi, T. I.
Bibcode: 2012AGUFMSM23C2330T
Altcode:
  The Space Weather Prediction Center (SWPC) expressed interest in
  predicting the time derivative of the local magnetic field perturbations
  (dB/dt). The dB/dt quantity is closely related to the geomagnetically
  induced currents (GIC) which is one of the most important quantities
  that the end-users of SWPC would like to receive. The Community
  Coordinated Modeling Center (CCMC) has run several models for several
  events to evaluate the predictive capabilities of the models. It
  was clear from the beginning that one cannot hope to predict the
  instantaneous value of dB/dt with the current models. For this
  reason it was decided that the models will attempt to predict if
  some component of dB/dt exceeds or not some threshold values in a
  time period. The models showed some success in doing so, and achieved
  positive (better than random) skill scores. Here we investigate if one
  can improve the efficiency of the prediction further. The idea is that
  the magnitude of dB/dt is quite strongly correlated to the magnitude
  of the magnetic perturbation dB. Our model, the Space Weather Modeling
  Framework, shows significantly better skill scores in predicting the
  magnetic perturbation than predicting dB/dt, especially for large
  deviations. This suggests that one can use the predicted value of dB
  to improve on the prediction accuracy of dB/dt. We find that this is
  indeed the case.

Title: Hall MHD Simulations of Comet 67P/Churyumov-Gerasimenko
Authors: Shou, Y.; Combi, M. R.; Rubin, M.; Hansen, K. C.; Toth, G.;
   Gombosi, T. I.
Bibcode: 2012AGUFM.P43C1932S
Altcode:
  Comets have highly eccentric orbits and a wide range of gas production
  rates and thus they are ideal subjects to study the interaction between
  the solar wind and nonmagnetized bodies. Hansen et al. (2007, Space
  Sci. Rev. 128, 133) used a fluid-based MHD model and a semi-kinetic
  hybrid particle model to study the plasma environment of comet
  67P/Churyumov-Gerasimenko (CG), the Rosetta mission target comet,
  at different heliocentric distances. They showed that for such a
  weak comet at a large heliocentric distance, the length scales of the
  cometosheath and the bow shock are comparable to or smaller than the ion
  gyroradius, which violates the underlying assumption for a valid fluid
  description of the plasma. As a result, the classical ideal MHD model
  is not able to always give physical results, while the hybrid model,
  which accounts for the kinetic effects of ions with both cometary
  and solar wind origin, is more reliable. However, hybrid models are
  computationally expensive and the results can be noisy. A compromise
  approach is Hall MHD [Toth et al., 2008], which includes the Hall
  term in the MHD equations and allows for the decoupling of the ion and
  electron fluids. We use a single ion species Hall MHD model to simulate
  the plasma environment of comet 67P/CG and compare the results with
  the two models mentioned above. We find that the Hall effect is capable
  of reproducing some features of the hybrid model and thus extends the
  applicability of MHD. In addition, this study helps to identify the
  conditions and regions in the cometary plasma where the Hall effect
  is not negligible. This work is supported by NSF Planetary Astronomy
  grant AST0707283 and JPL subcontract 1266313 under NASA grant NMO710889.

Title: Probing the Nature of the Heliosheath with the Heliospheric
    Neutral Atom Spectra Measured by IBEX in the Voyager 1 Direction
Authors: Opher, M.; Prested, C. L.; McComas, D. J.; Schwadron, N. A.;
   Toth, G.
Bibcode: 2012AGUFMSH13D..04O
Altcode:
  The Interstellar Boundary Explorer (IBEX) has been making detailed
  observations of neutrals from the boundaries of the heliosphere from
  0.2-6 keV. Recent studies using the accumulated measurements of three
  years of observations extended the IBEX spectra down to lower energies
  (Fusielier et al. ApJ 2012). We compare the modeled ENA spectra to
  the ones measured by IBEX in order to explore the sensitivity to the
  heliosheath flows and temperatures along the Voyager 1 trajectory. The
  models explored are: (a) single-ion, multi-fluid (SI-MF) (Opher
  et al. 2009) that includes the ionized thermal plasma (solar wind
  plus pick-up ions (PUIs) plus the neutral H atoms) in a multi-fluid
  approximation; and our recent model (b) multi-ion, multi-fluid (MI-MF)
  that treats the PUIs and the thermal ions as separate fluids with
  maxwellian distributions (Prested et al. 2012). The use of a maxwellian
  distribution for the transmitted PUIs is supported by works such as
  Wu et al. (2010). Additionally, in the modeled ENA spectra we account
  for effects, not present in the models, from: a) the zero flows in
  the stagnation region (Decker et al. Nature 2012), as from our model
  that included the sector region (Opher et al. ApJ 2012) 15-20AU before
  the heliopause; b) extra heating in the stagnation region equivalent
  to the missing ram pressure; c) extra heating due to reconnection
  in the stagnation region (Drake et al. 2010; Opher et al. 2011);
  d) kappa ion distribution with power spectra (~ 1.5 - 2.0) in the
  heliosheath as produced by models such as Gloeckler and Fisk (2010);
  e) kappa ion distribution in the outer heliosheath. We find that the
  models that invoked extra heating in the stagnation region (as in case
  (b)-(c)) best agree with the low energy IBEX data. We evaluate model
  results in terms of the number of free parameters versus the level of
  agreement and comment on the implications of the models.

Title: Space Weather Model Validations Using dBH/dt at High and
    Mid-Latitude Magnetometer Locations
Authors: Rastaetter, L.; Kuznetsova, M. M.; Pulkkinen, A.; Toth, G.;
   Raeder, J.; Wiltberger, M. J.
Bibcode: 2012AGUFMSM23B2305R
Altcode:
  As part to the model validation efforts performed at the Community
  Coordinated Modeling Center (CCMC), a Research-to-Operation (R2O)
  modeling challenge was started in 2010 to investigate the performance of
  first-principles and statistical models of the magnetosphere-ionosphere
  system to predict magnetic disturbances that can trigger geomagnetically
  induced currents. These models have to be able to run in real-time on
  a small-sized computer cluster in order to be able to support space
  weather operations. The outputs of the models are the horizontal
  magnetic perturbations ("delta-BH") at a given list of magnetometer
  stations that cover the high, middle and low latitudes. The "R2O
  challenge" is a continuation of the 2008 GEM challenge and involves
  the Space Weather Modeling Framework (SWMF), the OpenGGCM and the Lyon
  Fedder Mobarry (LFM) models of the global magnetosphere-ionosphere
  system and the Weimer and Weigel delta-BH specification models. These
  5 models have been run for 6 events of at least a day's length that
  include 2 strong storms, 3 intermediate sized storms and one weak
  event. We compared model outputs with 12 magnetometers that were
  selected for the original 2008 GEM challenge. In this paper we describe
  the calculation of the delta-BH values for the magnetosphere-ionosphere
  models that include currents in the ionosphere, field-aligned currents
  and the magnetosphere portions of the simulations. To validate the
  calculations performed at CCMC we compared our results to delta-BH
  computed during run-time by the Space Weather Modeling Framework (SWMF)
  model. We present the role and intensity of the contributions to the
  delta-BH signal coming from the three current systems. The evaluation
  of the model results is based on an event-based metric using counts of
  how often the observed or modeled time derivative of delta-BH ("dBH/dt")
  exceeds a threshold at least once in each of the time windows that cover
  the storm events. The resulting contingency table (number of hits, false
  alarms, misses and predicted non-events) for each threshold value and
  window length is converted to a single skill, such as the Heidke Skill
  Score that will be used to select models for space weather operations.

Title: The inner magnetosphere as simulated by the anisotropic
    BATS-R-US - CRCM model
Authors: Meng, X.; Toth, G.; Glocer, A.; Fok, M. H.; Gombosi, T. I.;
   Buzulukova, N.
Bibcode: 2012AGUFMSM41A2191M
Altcode:
  We have recently developed the two-way coupling between anisotropic
  BATS-R-US and the CRCM. The coupled model provides us an opportunity to
  examine the effects of pressure anisotropy on the inner magnetospheric
  dynamics self-consistently, especially during geomagnetic disturbed
  time. From the aspect of the CRCM, we investigate the differences
  between the isotropic-MHD-driven and anisotropic-MHD-driven
  simulations. We validate the coupled model through comparing the
  simulated pressure anisotropy, energy flux and other model outputs
  with TWINS and other satellite observations.

Title: New Adventures with the Space Weather Modeling Framework
Authors: Gombosi, T. I.; Toth, G.; van der Holst, B.; Sokolov, I.;
   Manchester, W. B.; Daldorff, L.; DeZeeuw, D.; Welling, D. T.; Ridley,
   A. J.; Liemohn, M. W.; Oran, R.; Meng, X.; Jin, M.
Bibcode: 2012AGUFMSM22D..03G
Altcode:
  This talk will present new capabilities implemented in the Space Weather
  Modeling Framework (SWMF) and new validation studies that were recently
  carried out at the University of Michigan. We will focus on four new
  developments: 1) the recently developed anisotropic plasma pressure
  simulation technique that made it possible to implement a sophisticated
  two-way coupling of the CRCM ring current model, 2) the newly developed
  solar wind model that starts at the chromosphere and extends beyond
  Earth orbit, 3) regional space weather impact modeling capability and 4)
  new validation studies using various magnetospheric storms.

Title: Solar wind flow in the heliosheath due to latitudinal and
    time variations over the solar cycle
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
Bibcode: 2012AGUFMSH11B2203P
Altcode:
  Recent observations by Voyager 2 in the heliosheath showed strong
  variations of the solar wind density, velocity and temperature. Magnetic
  field fluctuates considerably as observed on both Voyager 1 and
  2. Anomalous and galactic cosmic rays also present large fluctuations
  of intensity. Spatial variations and temporal effects in the solar
  wind due to solar cycle attribute to the observed fluctuations. In
  this work we aim to explore effects of realistic solar cycle on the 3D
  solar wind flow in the outer heliosphere. We use time and latitudinal
  variations of the solar wind density and velocity over two last solar
  cycles as the boundary conditions in a 3D MHD multi-fluid model of the
  interaction between the solar wind and interstellar medium based on
  BATSRUS code. These realistic boundary conditions at 1 AU for the plasma
  were obtained on the base of the measurements of Ly-alpha intensities
  on SOHO/SWAN and interplanetary scintillations data (IPS). In our
  simulation a numerical spatial grid is highly refined along the Voyager
  2 trajectory in order to capture disturbances propagating in the
  solar wind and compare the model with the observations. To validate
  the model and used boundary conditions we compare our results with
  Voyager 2 plasma data. In particular we focus on the time-dependent
  plasma flow in the heliosheath.

Title: Simulate the Coronal Mass Ejection on 2011 March 7 from
    Chromosphere to 1 AU
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Oran, R.;
   Sokolov, I.; Toth, G.; Gombosi, T. I.; Vourlidas, A.; Liu, Y.; Sun, X.
Bibcode: 2012AGUFMSH33E..04J
Altcode:
  On 2011 March 7, a fast CME (&gt; 2000 km/s) occurred in NOAA
  11164. This event is also associated with a Solar Energetic Particle
  (SEP) event. In this study, we present the magnetohydrodynamics
  simulation results of this event. We initiate the CME by using the
  Titov-Demoulin flux rope model. The background solar wind starts
  from chromosphere with heat conduction and radiative cooling. The
  solar wind is driven by Alfven-wave pressure and heated by Alfven-wave
  dissipation. The magnetic field of the inner boundary is specified with
  a synoptic magnetogram from SDO/HMI. In order to produce the physically
  correct CME structures and CME-driven shocks, the electron and proton
  temperatures are separated so that the electron heat conduction
  is explicitly treated in conjunction with proton shock heating. We
  simulate the CME propagation to 1 AU. A comprehensive validation work
  is done by using the remote as well as the in-situ observation from
  SOHO, STEREOA/B, ACE, and WIND. Our result shows that the new model
  can reproduce most of the observed features near the Sun and in the
  heliosphere. The CME-driven shock is well reproduced, which is important
  for modeling the SEP event with diffusive shock acceleration.

Title: Solar wind interaction with Mars Upper atmosphere: Results
    from the one-way coupling between the Multi-fluid MHD model and the
    M-TGCM model
Authors: Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Nagy, A. F.;
   Brain, D. A.; Najib, D.
Bibcode: 2012AGUFM.P21G..02D
Altcode:
  The study of the solar wind interaction with Mars upper
  atmosphere/ionosphere has triggered great interest in recent
  years. Among the large number of topics in this research area, the
  investigation of ion escape rates has become increasingly important due
  to its potential impact on the long-term evolution of Mars atmosphere
  (e.g., loss of water) over its history. In the present work, we adopt
  the 3D Mars neutral atmosphere profiles from the well-regarded Mars
  Thermospheric Global Circulation Model (M-TGCM) and one-way couple it
  with the 3D BATS-R-US Mars multi-fluid MHD model that solves separate
  momentum equations for each ion species. The M-TGCM model takes into
  account the effects of the solar cycle (solar minimum: F10.7=70 and
  solar maximum: F10.7=200 with equinox condition: Ls=0), allowing
  us to investigate the effects of the solar cycle on the Mars upper
  atmosphere ion escape by using a one-way coupling, i.e., the M-TGCM
  model outputs are used as inputs for the multi-fluid MHD model. A case
  for solar maximum with extremely high solar wind parameters is also
  investigated to estimate how high the escape flux can be for such an
  extreme case. Moreover, the ion escape flux along a satellite trajectory
  will be studied. This has the potential to provide predictions of ion
  escape rates for comparison to future data to be returned by the MAVEN
  mission (2012-2016). In order to make the code run more efficiently,
  we adopt a more appropriate grid structure compared to the one used
  previously. This new grid structure will benefit us to investigate
  the effects of some dynamic events (such as CME and dust storm) on
  the ion escape flux.

Title: Multi-fluid MHD study of Titan's plasma interaction
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Toth, G.; Dougherty,
   M. K.; Cravens, T. E.
Bibcode: 2012AGUFMSM32B..06M
Altcode:
  We study the plasma interaction around Titan using a three dimensional
  multi-fluid MHD model. The model calculates densities, velocities,
  and pressures of seven ion species which are important in either
  Titan's ionosphere or in the ambient plasma. The code uses a
  spherical grid structure with high radial resolution ~ 30 km in the
  lower ionosphere. The model is applied to an idealized case of Titan
  and the results are compared in detail with that of multi-species but
  single fluid model using the same set of plasma parameters. It is shown
  that the multi-fluid model is able to produce the flow separation of
  different ion fluids along the convection electric field direction. Also
  the multi-fluid model is in favor of the escape of the heavier ion
  species. The multi-fluid MHD model is also applied to a recent Titan
  flyby and compared with plasma observations of Cassini.

Title: Multi-Scale Simulations of Magnetospheric Dynamics for Steady
    Solar Wind Driving
Authors: Kuznetsova, M.; Rastaetter, L.; Glocer, A.; Hesse, M.; Toth,
   G.; Gombosi, T. I.
Bibcode: 2012AGUFMSM21E..03K
Altcode:
  The variety of magnetopsheric convection patterns for steady solar wind
  conditions is one of the major challenges in undertanding underlying
  mechanisms driving the magnetopshere. We utilize the multi-scale
  and multi-species global MHD code BATSRUS to analyse the relative
  contribution of solar wind conditions, ionosphere conductance pattern,
  plasma composition in inner magnetosphere and local conditions at
  the reconnection sites on the global magnetosphere dynamics. The
  primary mechanism controlling the dissipation in the vicinity of the
  reconnection site is incorporated into MHD description in terms of
  non-gyrotropic corrections to induction and energy equations. The
  non-gyrotropic terms reflecting ion kinetic effects depend on the
  local plasma and field parameters and ion Larmor radii. The varying
  plasma composition is incorporated into the multi-species description
  through the effective ion mass. Transitions between different modes
  of convection will be analysed.

Title: Viscosity in Global Magnetosphere Simulations
Authors: Daldorff, L.; Toth, G.; Meng, X.; Gombosi, T. I.
Bibcode: 2012AGUFMSM21B2280D
Altcode:
  The multiple scales involved in the magnetic reconnection process
  give rise to many instabilities. Unfortunately we are not able to
  capture these processes with today's global magnetosphere models. The
  mixing of the unstable regions can behave in a "viscous" fashion on
  larger scales. We therefore implemented viscosity into the BATS-R-US
  global magnetohydrodynamic code to look at how numerical and physical
  viscosity will influence the global magnetosphere simulations in
  addition to magnetic dissipation. Our long term goal is to obtain
  physically reasonable approximations of reconnection on large scales
  that do not depend on the grid resolution and numerical dissipation.

Title: Does a slow magnetosonic bow shock exist in the local
    interstellar medium?
Authors: Zieger, B.; Opher, M.; Schwadron, N. A.; McComas, D. J.;
   Toth, G.
Bibcode: 2012AGUFMSH11B2200Z
Altcode:
  The currently accepted best estimates of plasma parameters in the
  local interstellar medium suggest that the speed of the interstellar
  wind (i.e. the relative speed of the local interstellar cloud with
  respect to the Sun) is very slow (i.e., sub-Alfvenic; Opher et al.,
  Science, 2009; Schwadron et al., ApJ, 2011). This means that no fast
  magnetosonic bow shock can be formed in the local interstellar medium
  upstream of the heliosphere, [McComas et al., Science, 2012]. However,
  the existence of a slow magnetosonic bow shock may be possible. With
  current LISM parameters, the Mach number for upstream propagating slow
  magnetosonic waves in the pristine LISM is ~2.1, which suggests that a
  weak quasi-parallel slow bow shock (SBS) in front of our heliopshere
  may exist in some regions. Our new multi-ion, multi-fluid MHD model
  of the heliospheric interface [Prested et al., ApJ, 2012] produces
  such a slow magnetosonic bow shock only in the quasi-parallel region
  where theta_Bn (i.e. the angle between the interstellar magnetic field
  and the normal to the slow magnetosonic surface; SMS) is less than
  45 degrees. The SBS divides the LISM into two distinct regions with
  different plasma populations. One is the pristine LISM and the other
  is the hotter and slower compressed plasma population of the outer
  heliosheath that is spatially restricted to the downstream region of
  the quasi-parallel shock. Slow magnetosonic shocks are generally not
  observed in space plasmas due to their lack of stability. However,
  the plasma in the local interstellar medium exists in a regime not
  commonly observed in interplanetary space. We discuss the possible
  existence of the magnetosonic bow shock in front of the heliosphere,
  the arguments for and against its stability, and its implications for
  heliospheric measurements.

Title: Multi-ion, multi-fluid 3-D magnetohydrodynamic simulation of
    the outer heliosphere
Authors: Prested, Christina; Opher, Merav; Toth, Gabor
Bibcode: 2012arXiv1211.1908P
Altcode:
  Data from the Voyager probes and the Interstellar Boundary Explorer
  have revealed the importance of pick-up ions (PUIs) in understanding
  the character and behavior of the outer heliosphere, the region of
  interaction between the solar wind and the interstellar medium. In
  the outer heliosphere PUIs carry a large fraction of the thermal
  pressure, which effects the nature of the termination shock, and
  they are a dominate component of pressure in the heliosheath. This
  paper describes the development of a new multi-ion, multi-fluid 3-D
  magnetohydrodynamic model of the outer heliosphere. This model has the
  added capability of tracking the individual fluid properties of multiple
  ion populations. For this initial study two ion populations are modeled:
  the thermal solar wind ions and PUIs produced in the supersonic solar
  wind. The model also includes 4 neutral fluids that interact through
  charge-exchange with the ion fluids. The new multi-ion simulation
  reproduces the significant heating of PUIs at the termination shock,
  as inferred from Voyager observations, and provides properties of PUIs
  in the 3-D heliosheath. The thinning of the heliosheath due to the loss
  of thermal energy in the heliosheath from PUI and neutral interaction is
  also quantified. In future work the multi-ion, multi-fluid model will
  be used to simulate energetic neutral atom (ENA) maps for comparison
  with the Interstellar Boundary Explorer, particularly at PUI energies
  of less than 1 keV.

Title: TwoDSSM: Self-gravitating 2D shearing sheet
Authors: Gammie, Charles F.; McKinney, Jonathan C.; Noble, Scott C.;
   Tóth, Gábor; Del Zanna, Luca
Bibcode: 2012ascl.soft10025G
Altcode:
  TwoDSSM solves the equations of self-gravitating hydrodynamics in
  the shearing sheet, with cooling. TwoDSSM is configured to use a
  simple, exponential cooling model, although it contains code for a
  more complicated (and perhaps more realistic) cooling model based on a
  one-zone vertical model. The complicated cooling model can be switched
  on using a flag.

Title: A Numerical Study of Comet Mcnaught over a Wide Range of
    Heliocentric Distances
Authors: Shou, Yinsi; Combi, M. R.; Rubin, M.; Toth, G.
Bibcode: 2012DPS....4431412S
Altcode:
  A numerical study of Comet McNaught over a wide range of heliocentric
  distances Yinsi Shou, Michael R. Combi, Martin Rubin, Gabor Toth The
  Comet C/2006 P1 (McNaught) has a small perihelion distance (0.17 AU)
  and had a very high production rate during its passage close to the Sun
  in January and February of 2007. During that period, it was monitored by
  both ground- and space-based observatories, which provided substantial
  information about the comet. In early February, the Ulysses spacecraft
  encountered its ion tail and gave clues to the surrounding solar wind
  conditions and to the cometary environment. Therefore, Comet McNaught
  is an ideal object to study the cometary structures under extreme
  conditions and the solar wind-comet interaction over a wide range of
  heliocentric distances. A numerical study of Comet McNaught combining
  two models is conducted. First, a single species magnetohydrodynamics
  (MHD) [Gombosi et al. (1996, JGR 101, 15233)] simulation is performed
  using a set of ‘observed’ comet parameters as input. Then a
  chemistry model [Häberli et al. (1997, Icarus 130, 373)] extracts
  the streamlines from the MHD model and calculates the densities of
  different species accounting for photo-dissociation, photo-ionization,
  electron recombination, ion-molecule and charge-exchange reactions. The
  MHD results are able to give the diamagnetic cavity sizes and shock
  distances at various heliocentric distances while the chemistry model
  better resolves the distribution of the major chemical species in the
  cometary plasma environment. The combination of the two models allows
  us to obtain detailed information on the chemical composition of a
  much wider range of atoms and molecules compared to multi-species or
  multi-fluid MHD models and at much lower computational expense. Some
  preliminary results are presented and discussed. This work has been
  partially supported by grant AST-0707283 from the NSF Planetary
  Astronomy program and NASA Planetary Atmospheres program grant
  NNX09AB59G.

Title: HARM: A Numerical Scheme for General Relativistic
    Magnetohydrodynamics
Authors: Gammie, Charles F.; McKinney, Jonathan C.; Tóth, Gábor
Bibcode: 2012ascl.soft09005G
Altcode:
  HARM uses a conservative, shock-capturing scheme for evolving the
  equations of general relativistic magnetohydrodynamics. The fluxes are
  calculated using the Harten, Lax, &amp; van Leer scheme. A variant of
  constrained transport, proposed earlier by Tóth, is used to maintain a
  divergence-free magnetic field. Only the covariant form of the metric
  in a coordinate basis is required to specify the geometry. On smooth
  flows HARM converges at second order.

Title: Do Corotating Interaction Region Associated Shocks Survive
    When They Propagate into the Heliosheath?
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
Bibcode: 2012ApJ...756L..37P
Altcode:
  During the solar minimum at the distance of 42-52 AU from the Sun,
  Voyager 2 observed recurrent sharp, shock-like increases in the
  solar wind speed that look very much like forward shocks (Lazarus
  et al.). The shocks were produced by corotating interaction regions
  (CIRs) that originated near the Sun. After the termination shock
  (TS) crossing in 2007, Voyager 2 entered the heliosheath and
  has been observing the plasma emanated during the recent solar
  minima. Measurements show high variable flow, but there were no
  shocks detected in the heliosheath. When CIR-driven shocks propagate
  to the outer heliosphere, their structure changes due to collision
  and merging processes of CIRs. In this Letter, we explore an effect
  of the merging of CIRs on the structure of CIR-associated shocks. We
  use a three-dimensional MHD model to study the outward propagation of
  the shocks with characteristics similar to those observed by Voyager 2
  at ~45 AU (Lazarus et al. 1999). We show that due to merging of CIRs
  (1) reverse shocks disappear, (2) forward shocks become weaker due
  to interaction with rarefaction regions from preceding CIRs, and (3)
  forward shocks significantly weaken in the heliosheath. Merged CIRs
  produce compression regions in the heliosheath with small fluctuations
  of plasma parameters. Amplitudes of the fluctuations diminish as
  they propagate deeper in the sheath. We conclude that interaction
  of shocks and rarefaction regions could be one of the explanations,
  why shocks produced by CIRs are not observed in the heliosheath by
  Voyager 2 while they were frequently observed upstream the TS.

Title: The Coupled Evolution of Electrons and Ions in Coronal Mass
    Ejection-driven shocks
Authors: Manchester, W. B., IV; van der Holst, B.; Tóth, G.; Gombosi,
   T. I.
Bibcode: 2012ApJ...756...81M
Altcode:
  We present simulations of coronal mass ejections (CMEs) performed with
  a new two-temperature coronal model developed at the University of
  Michigan, which is able to address the coupled thermodynamics of the
  electron and proton populations in the context of a single fluid. This
  model employs heat conduction for electrons, constant adiabatic index
  (γ = 5/3), and includes Alfvén wave pressure to accelerate the solar
  wind. The Wang-Sheeley-Arge empirical model is used to determine the
  Alfvén wave pressure necessary to produce the observed bimodal solar
  wind speed. The Alfvén waves are dissipated as they propagate from
  the Sun and heat protons on open magnetic field lines to temperatures
  above 2 MK. The model is driven by empirical boundary conditions that
  includes GONG magnetogram data to calculate the coronal field, and
  STEREO/EUVI observations to specify the density and temperature at
  the coronal boundary by the Differential Emission Measure Tomography
  method. With this model, we simulate the propagation of fast CMEs and
  study the thermodynamics of CME-driven shocks. Since the thermal speed
  of the electrons greatly exceeds the speed of the CME, only protons
  are directly heated by the shock. Coulomb collisions low in the corona
  couple the protons and electrons allowing heat exchange between the
  two species. However, the coupling is so brief that the electrons never
  achieve more than 10% of the maximum temperature of the protons. We find
  that heat is able to conduct on open magnetic field lines and rapidly
  propagates ahead of the CME to form a shock precursor of hot electrons.

Title: Multi-fluid MHD study of the solar wind interaction with
    Venus at Solar max and Solar min conditions.
Authors: Ma, Y. J.; Nagy, A. F.; Russell, C. T.; Najib, D.; Toth, G.
Bibcode: 2012epsc.conf..137M
Altcode: 2012espc.conf..137M
  We study the solar wind interaction with Venus, using a new advanced
  multi-fluid MHD model that has been developed recently. The model is
  similar to the numerical model that was successfully applied to Mars
  (Najib et al., 2011). Mass densities, velocities and pressures of the
  protons and three important ionosphere ion species (O+, O2+ and CO2+)
  are self-consistently calculated by solving the individual coupled
  continuity, momentum and energy equations. The various chemical
  reactions and ion-neutral collision processes are considered in the
  model. The simulation domain covers the region from 100 km altitude
  above the surface up to 16 RV in the tail. An adaptive spherical
  grid structure is constructed with radial resolution of about 10 km
  in the lower ionosphere. The model is applied to both solar-maximum
  and solar-minimum conditions and model results are compared in detail
  with multi-species single fluid model results and VEX observations.

Title: Test of the weak cosmic censorship conjecture with a charged
    scalar field and dyonic Kerr-Newman black holes
Authors: Tóth, Gábor Zsolt
Bibcode: 2012GReGr..44.2019T
Altcode: 2012GReGr.tmp...85T; 2011arXiv1112.2382Z
  A thought experiment considered recently in the literature, in which
  it is investigated whether a dyonic Kerr-Newman black hole can be
  destroyed by overcharging or overspinning it past extremality by a
  massive complex scalar test field, is revisited. Another derivation of
  the result that this is not possible, i.e. the weak cosmic censorship
  is not violated in this thought experiment, is given. The derivation
  is based on conservation laws, on a null energy condition, and on
  specific properties of the metric and the electromagnetic field of
  dyonic Kerr-Newman black holes. The metric is kept fixed, whereas
  the dynamics of the electromagnetic field is taken into account. A
  detailed knowledge of the solutions of the equations of motion is
  not needed. The approximation in which the electromagnetic field
  is fixed is also considered, and a derivation for this case is also
  given. In addition, an older version of the thought experiment, in
  which a pointlike test particle is used, is revisited. The same result,
  namely the non-violation of the cosmic censorship, is rederived in a
  way which is simpler than in earlier works.

Title: Pressure anisotropy in global magnetospheric simulations:
    A magnetohydrodynamics model
Authors: Meng, X.; Tóth, G.; Liemohn, M. W.; Gombosi, T. I.; Runov, A.
Bibcode: 2012JGRA..117.8216M
Altcode: 2012JGRA..11708216M
  In order to better describe the space plasmas where pressure anisotropy
  has prominent effects, we extend the BATS-R-US magnetohydrodynamics
  (MHD) model to include anisotropic pressure. We implement the
  anisotropic MHD equations under the double adiabatic approximation with
  an additional pressure relaxation term into BATS-R-US and perform global
  magnetospheric simulations. The results from idealized magnetospheric
  simulations confirm previous studies: pressure anisotropy widens the
  magnetosheath, increases the density depletion in the vicinity of the
  magnetopause, enhances the nightside plasma pressure, and introduces an
  eastward ring current. In addition, we find that the flow speed in the
  magnetotail is significantly reduced by including pressure anisotropy
  in MHD simulations. Our model is validated through comparing the
  simulations to the THEMIS data on both the dayside and nightside of
  the magnetosphere during quiet times. The comparison to the results
  from isotropic MHD simulations implies that although anisotropic MHD
  is comparable to isotropic MHD in matching the measurement, it improves
  the simulated plasma velocity in some cases.

Title: What did we learn about the 3D Global Structure of the
    Heliosphere with Voyager and IBEX
Authors: Opher, Merav; Provornikova, Elena; Toth, Gabor; Drake, James;
   Swisdak, Marc; Izmodenov, Vladislav
Bibcode: 2012cosp...39.1407O
Altcode: 2012cosp.meet.1407O
  In this talk I will review what we have learned in the past couple
  of years about the global structure of the heliosphere. The recent
  measurements in-situ by the Voyager spacecrafts, combined with the
  all-sky images of the heliospheric boundaries by the Interstellar
  Boundary Explorer (IBEX) mission have transformed radically our
  knowledge of the boundaries of the heliosphere. Concepts that resisted
  decades are being revisited due to their puzzling measurements. In
  this talk, I will cover some of these puzzles and what are learning
  regarding the dynamic nature of the heliosphere and heliosheath. When
  uncovering the structure of the heliosheath it is crucial to separate
  spatial from temporal variations. We were fortunate that the extended
  solar minima conditions minimized temporal effects in the heliosphere
  and allowed us to uncover the spatial variations. With the increased
  solar activity becomes a challenge to incorporate temporal effects. I
  will review some of the puzzled observations of by Voyager spacecraft in
  the heliosheath indicating that the presence of the heliospheric current
  sheet might play a crucial role on organizing the heliosheath; affecting
  both the flows and transport of energetic particles. I will review
  as well our attempts to estimate the temporal effects that Corotating
  Interacting Regions have in the heliosheath. Finally, I will address how
  knowledge gained from missions such as Ulysses and future out of the
  ecliptic mission concepts as well as theoretical analysis of physical
  parameters that may be observed from the solar polar orbit will allow
  us a better understanding of the global structure of the heliosphere,
  in particular with its interaction with the interstellar medium.

Title: VAC: Versatile Advection Code
Authors: Tóth, Gábor; Keppens, Rony
Bibcode: 2012ascl.soft07003T
Altcode:
  The Versatile Advection Code (VAC) is a freely available general
  hydrodynamic and magnetohydrodynamic simulation software that works in
  1, 2 or 3 dimensions on Cartesian and logically Cartesian grids. VAC
  runs on any Unix/Linux system with a Fortran 90 (or 77) compiler and
  Perl interpreter. VAC can run on parallel machines using either the
  Message Passing Interface (MPI) library or a High Performance Fortran
  (HPF) compiler.

Title: 3D Global Structure of the Heliosheath with the Sector Region
Authors: Opher, Merav; Toth, Gabor; Drake, James; Swisdak, Marc
Bibcode: 2012cosp...39.1406O
Altcode: 2012cosp.meet.1406O
  No abstract at ADS

Title: Magnetohydrodynamics with Anisotropic Ion Pressure
Authors: Meng, X.; Tóth, G.; Gombosi, T. I.
Bibcode: 2012ASPC..459..340M
Altcode:
  To simulate the pressure anisotropy of space plasmas, we extended the
  global magnetohydrodynamics (MHD) model BATS-R-US based on the study
  of MHD with anisotropic ion pressure and isotropic electron pressure
  under both the classical and semirelativistic approximation. We
  derived the characteristic wave speeds for determining time steps and
  calculating numerical fluxes. Simulations of the Earth's magnetosphere
  validated the model's ability to reproduce the pressure anisotropy in
  the magnetosheath.

Title: MHD Modeling of Solar Wind Interaction with Mars
Authors: Ma, Yingjuan; Russell, C. T.; Najib, Dalal; Nagy, Andrew;
   Toth, Gabor
Bibcode: 2012cosp...39.1139M
Altcode: 2012cosp.meet.1139M
  No abstract at ADS

Title: Simulating radiative shocks in nozzle shock tubes
Authors: van der Holst, B.; Tóth, G.; Sokolov, I. V.; Daldorff,
   L. K. S.; Powell, K. G.; Drake, R. P.
Bibcode: 2012HEDP....8..161V
Altcode: 2011arXiv1109.4332V
  We use the recently developed Center for Radiative Shock Hydrodynamics
  (CRASH) code to numerically simulate laser-driven radiative shock
  experiments. These shocks are launched by an ablated beryllium disk
  and are driven down xenon-filled plastic tubes. The simulations
  are initialized by the two-dimensional version of the Lagrangian
  Hyades code which is used to evaluate the laser energy deposition
  during the first 1.1 ns. Later times are calculated with the CRASH
  code. CRASH solves for the multi-material hydrodynamics with separate
  electron and ion temperatures on an Eulerian block-adaptive-mesh
  and includes a multi-group flux-limited radiation diffusion and
  electron thermal heat conduction. The goal of the present paper is to
  demonstrate the capability to simulate radiative shocks of essentially
  three-dimensional experimental configurations, such as circular and
  elliptical nozzles. We show that the compound shock structure of
  the primary and wall shock is captured and verify that the shock
  properties are consistent with order-of-magnitude estimates. The
  synthetic radiographs produced can be used for comparison with future
  nozzle experiments at high-energy-density laser facilities.

Title: Modeling of heliosphere and magnetic reconnection in the
    heliosheath
Authors: Opher, Merav; Drake, Jim; Swisdak, Marc; Schoeffller, Kevin;
   Toth, Gabor
Bibcode: 2012shin.confE..53O
Altcode:
  The recent measurements in-situ by the Voyager spacecrafts,
  combined with the all-sky images of the heliospheric boundaries by
  the Interstellar Boundary Explorer (IBEX) mission have transformed
  radically our knowledge of the boundaries of the heliosphere. Concepts
  that resisted decades are being revisited due to their puzzling
  measurements. In particular after the crossing of the termination
  shock (TS) by V1 and then by V2, one of the first surprises was that
  both Voyager found no evidence for the acceleration of the anomalous
  cosmic rays at the TS as expected for approximately 25 years. Another
  challenge are the energetically particles intensities that are
  dramatically different at Voyager 1 and 2. In this talk I will review
  the state-of-the art of numerical modeling of the global heliosphere as
  well as our recent model that propose that reconnection is happening in
  the heliosheath within the sector region. All current global models of
  the heliosphere are based on the assumption that the magnetic field in
  the heliosheath is laminar. Recently, we proposed that the annihilation
  of the 'sectored' magnetic field within the heliosheath as it is
  compressed on its approach to the heliopause produces anomalous cosmic
  rays and also energetic electrons. As a product of the annihilation
  of the sectored magnetic field, densely packed magnetic islands (which
  further interact to form magnetic bubbles) are produced. These magnetic
  islands/bubbles will be convected with ambient flows as the sector
  region is carried to higher latitudes filling the heliosheath. As
  a result, the magnetic field in the heliosheath sector region will
  be disordered. I will review results from our three-dimensional MHD
  simulation for the first time included self-consistently the sector
  region and particle-in-cells simulations that followed the kinetic
  evolution of the reconnection of the multiple current sheets. We show
  that due to the high pressure of the interstellar magnetic field
  a north-south asymmetry develops such that the disordered sectored
  region fills a large portion of the northern part of the heliosphere
  with a smaller extension in the southern hemisphere. I will review
  observations that support this scenario indicating that the presence of
  the heliospheric current sheet, where the magnetic field reconnected
  might play a crucial role on organizing the heliosheath; affecting
  both the flows and transport of energetic particles.

Title: Simulating the long-term evolution of radiative shocks in
    shock tubes
Authors: van der Holst, B.; Toth, G.; Sokolov, I. V.; Torralva, B. R.;
   Powell, K. G.; Drake, R. P.
Bibcode: 2012arXiv1206.1370V
Altcode:
  We present the latest improvements in the Center for Radiative Shock
  Hydrodynamics (CRASH) code, a parallel block-adaptive-mesh Eulerian
  code for simulating high-energy-density plasmas. The implementation can
  solve for radiation models with either a gray or a multigroup method
  in the flux-limited-diffusion approximation. The electrons and ions are
  allowed to be out of temperature equilibrium and flux-limited electron
  thermal heat conduction is included. We have recently implemented
  a CRASH laser package with 3-D ray tracing, resulting in improved
  energy deposition evaluation. New, more accurate opacity models are
  available which significantly improve radiation transport in materials
  like xenon. In addition, the HYPRE preconditioner has been added to
  improve the radiation implicit solver. With this updated version of
  the CRASH code we study radiative shock tube problems. In our set-up,
  a 1 ns, 3.8 kJ laser pulse irradiates a 20 micron beryllium disk,
  driving a shock into a xenon-filled plastic tube. The electrons emit
  radiation behind the shock. This radiation from the shocked xenon
  preheats the unshocked xenon. Photons traveling ahead of the shock
  will also interact with the plastic tube, heat it, and in turn this
  can drive another shock off the wall into the xenon. We are now able
  to simulate the long term evolution of radiative shocks.

Title: Sensitivity of ENA emission to various plasma properties in
the outer heliosphere: insight from MHD models
Authors: Prested, Christina Lee; Opher, M.; Toth, G.; Schwadron, N.
Bibcode: 2012shin.confE..52P
Altcode:
  Using our new 3D multi-ion, multi-fluid MHD model of the outer
  heliosphere, we probe the nature of energetic neutral atom (ENA)
  emission in the heliosheath. How does ENA emission vary through the
  heliosheath and what properties of the plasma and neutrals is it
  most sensitive to? Where are the majority of ENA's produced and how
  does this insight affect our interpretation of the IBEX all-sky ENA
  maps? From this analysis we begin to answer these questions and engage
  in a dialogue on linking the MHD models of the outer heliosphere with
  the IBEX ENA maps.

Title: How does merging of CIRs affect shocks in the outer
    heliosphere?
Authors: Provornikova, Elena; Opher, Merav; Izmodenov, Vlad; Toth,
   Gabor
Bibcode: 2012shin.confE..56P
Altcode:
  Observations of the solar wind in the outer heliosphere by Voyager 2
  exhibit many examples of shocks. During the solar minimum in 1994-1997
  near the distance 45 AU from the Sun Voyager 2 observed recurrent
  shocks and shock-like structures that were produced by corotating merged
  interaction regions. Measurements of the heliosheath plasma, emanated
  during the recent solar minima, do not show existence of shocks in the
  heliosheath. We explore an effect of merging of corotating interaction
  regions (CIRs) in the solar wind on the structure of CIR associated
  shocks. Using a 3D MHD model of the solar wind interaction with the
  local interstellar medium, we show that due to interaction of shocks
  and rarefaction waves in a process of merging of CIRs, the shocks
  strongly weaken in the outer heliosphere. Presented study suggests
  that merging process could be one of the explanations why Voyager
  2 did not observe CIR associated shocks in the heliosheath while it
  showed several examples of shocks in the solar wind upstream the TS.

Title: Numerical Simulations of Coronal Mass Ejection on 2011 March 7:
    One-Temperature and Two-Temperature Model Comparison
Authors: Jin, Meng; Manchester, W. B.; van der Holst, B.; Oran, R.;
   Sokolov, I.; Toth, G.; Gombosi, T. I.
Bibcode: 2012shin.confE..42J
Altcode:
  During Carrington Rotation 2107, a fast CME (&gt; 2000 km/s) occurred
  in NOAA 11164. This event is also associated with a Solar Energetic
  Particle (SEP) event. In this study, we present simulations of this
  CME with one-temperature (1T) and two-temperature ( 2T: coupled
  thermodynamics of the electron and proton populations) models. Both
  the 1T and 2T models start from chromosphere with heat conduction
  and radiative cooling. The background solar wind is driven by
  Alfven-wave pressure and heated by Alfven-wave dissipation in which
  the counter-propagating waves are included. The magnetic field of the
  inner boundary is set up using the magnetogram from SDO/HMI. The Titov
  Demoulin flux-rope model is used to initiate the CME event. We compare
  the propagation of fast CMEs and the thermodynamics of CME-driven
  shocks in both the 1T and 2T CME simulations. Our results emphasize
  the importance of the explicit treatment of electron heat conduction
  in conjunction with proton shock heating in the CME simulation in order
  to produce the physically correct CME structures and CME-driven shocks.

Title: Near the Boundary of the Heliosphere: A Flow Transition Region
Authors: Opher, M.; Drake, J. F.; Velli, M.; Decker, R. B.; Toth, G.
Bibcode: 2012ApJ...751...80O
Altcode:
  Since April of 2010, Voyager 1 has been immersed in a region of near
  zero radial flows, where the solar wind seems to have stopped. The
  existence of this region contradicts current models that predict
  that the radial flows will go to zero only at the heliopause. These
  models, however, do not include the sector region (or include it in
  a kinematic fashion), where the solar magnetic field periodically
  reverses polarity. Here we show that the presence of the sector region
  in the heliosheath, where reconnection occurs, fundamentally alters
  the flows, giving rise to a Flow Transition Region (FTR), where the
  flow abruptly turns and the radial velocity becomes near zero or
  negative. We estimate, based on a simulation, that at the Voyager 1
  location, the thickness of the FTR is around 7-11 AU.

Title: Magnetospheric configuration and dynamics of Saturn's
magnetosphere: A global MHD simulation
Authors: Jia, Xianzhe; Hansen, Kenneth C.; Gombosi, Tamas I.; Kivelson,
   Margaret G.; Tóth, Gabor; DeZeeuw, Darren L.; Ridley, Aaron J.
Bibcode: 2012JGRA..117.5225J
Altcode: 2012JGRA..11705225J
  We investigate the solar wind interaction with Saturn's magnetosphere by
  using a global magnetohydrodynamic simulation driven by an idealized
  time-varying solar wind input that includes features of Corotating
  Interaction Regions typically seen at Saturn. Our model results indicate
  that the compressibility of Saturn's magnetosphere is intermediate
  between the Earth's and Jupiter's, and the magnetopause location
  appears insensitive to the orientation of the interplanetary magnetic
  field. The modeled dependences of both the magnetopause and bow shock
  locations on the solar wind dynamic pressure agree reasonably well
  with those of data-based empirical models. Our model shows that
  the centrifugal acceleration of mass-loaded flux tubes leads to
  reconnection on closed field lines forming plasmoids, an intrinsic
  process (“Vasyliūnas-cycle”) in Saturn's magnetosphere taking
  place independent of the external conditions. In addition, another type
  of reconnection process involving open flux tubes (“Dungey-cycle”)
  is also seen in our simulation when the external condition is favorable
  for dayside reconnection. Under such circumstances, plasmoid formation
  in the tail involves reconnection between open field lines in the lobes,
  producing stronger global impacts on the magnetosphere and ionosphere
  compared to that imposed by the Vasyliūnas-cycle directly. Our
  model also shows that large-scale tail reconnection may be induced
  by compressions driven by interplanetary shocks. In our simulation,
  large-scale tail reconnection and plasmoid formation take place in a
  quasi-periodic manner but the recurrence rate tends to be higher as the
  dynamic pressure becomes higher. While large-scale plasmoid release
  clearly is an important process in controlling the magnetospheric
  dynamics, it appears insufficient to account for all the losses of
  plasma added by the magnetospheric sources. We find that a large
  fraction of the planetary plasma is lost through the magnetotail
  near the flanks probably through relatively small-scale plasmoids,
  a situation that may also exist at Jupiter.

Title: Multi-fluid MHD study of the solar wind interaction with
    Venus at Solar max and Solar min conditions
Authors: Ma, Y.; Nagy, A. F.; Russell, C. T.; Najib, D.; Toth, G.
Bibcode: 2012EGUGA..1411974M
Altcode:
  We study solar wind interaction with Venus using a new advanced
  multi-fluid MHD model that has recently been developed. The model
  is similar to the numerical model that was successfully applied to
  Mars (Najib et al., 2011). Mass densities, velocities and pressures
  of the protons and major ionosphere ion species (O+, O2+ and CO2+)
  are self-consistently calculated by solvng the individual coupled
  continuity, momentum and energy equations. The various chemical
  reactions and ion-neutral collision processes are considered in the
  model. The simulation domain covers the region from 100 km altitude
  above the surface up to 16 RV in the tail. An adaptive spherical
  grid structure is constructed with radial resolution of about 10 km
  in the lower ionosphere. The model is applied to both solar-maximum
  and solar-minimum conditions and model results are compared in detail
  with multi-species single fluid model results and observations.

Title: Kinetic model of the inner magnetosphere with arbitrary
    magnetic field
Authors: Ilie, Raluca; Liemohn, Michael W.; Toth, Gabor; Skoug, Ruth M.
Bibcode: 2012JGRA..117.4208I
Altcode: 2012JGRA..11704208I
  Theoretical and numerical modifications to an inner magnetosphere
  model—Hot Electron Ion Drift Integrator (HEIDI)—were
  implemented, in order to accommodate for a nondipolar arbitrary
  magnetic field. While the dipolar solution for the geomagnetic
  field during quiet times represents a reasonable assumption in the
  near-Earth closed field region, during storm activity this assumption
  becomes invalid. HEIDI solves the time-dependent, gyration- and
  bounce-averaged kinetic equation for the phase space density of
  one or more ring current species. New equations are derived for the
  bounce-averaged coefficients for the distribution function, and their
  numerical implementation is discussed. Also, numerically solving
  all the bounce-averaged coefficients for the dipole case does not
  change the results significantly from the analytical approximation
  of Ejiri (1978). However, distorting the magnetic field changes all
  bounce-averaged coefficients that make up the kinetic equation. Initial
  simulations show that changing the magnetic field changes the whole
  topology of the ring current. This is because the drifts are altered due
  to dayside compression and nightside stretching of the field. Therefore,
  at certain locations, the nondipolar magnetic drifts can dominate the
  convective drifts, considerably altering the pressure distribution in
  the equatorial plane.

Title: Modeling solar zenith angle effects on the polar wind
Authors: Glocer, A.; Kitamura, N.; Toth, G.; Gombosi, T.
Bibcode: 2012JGRA..117.4318G
Altcode: 2012JGRA..11704318G
  We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically
  quiet conditions in the polar cap during solar maximum. The PWOM solves
  the gyrotropic transport equations for O<SUP>+</SUP>, H<SUP>+</SUP>,
  and He<SUP>+</SUP> along several magnetic field lines in the polar
  region in order to reconstruct the full 3D solution. We directly
  compare our simulation results to the data based empirical model
  of Kitamura et al. (2011) of electron density which is based on 63
  months of Akebono satellite observations. The modeled ion and electron
  temperatures are also compared with a statistical compilation of quiet
  time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos
  Satellites. The data and model agree reasonably well, albeit with some
  differences. This study shows that photoelectrons play an important
  role in explaining the differences between sunlit and dark results
  of electron density, ion composition, as well as ion and electron
  temperatures of the quiet time polar wind solution. Moreover, these
  results provide an initial validation of the PWOM's ability to model
  the quiet time “background” solution.

Title: Perpendicular flow deviation in a magnetized counter-streaming
    plasma
Authors: Jia, Y. -D.; Ma, Y. J.; Russell, C. T.; Lai, H. R.; Toth,
   G.; Gombosi, T. I.
Bibcode: 2012Icar..218..895J
Altcode:
  Charged dust exists in various regions in the Solar System. How
  this charged dust interacts with the surrounding plasma is not well
  understood. In this study we neglect the charging process and treat
  the charged dust as a fluid interacting with the ambient magnetized
  plasma fluid. The model reproduces the expected plasma deceleration
  with both positively charged and negatively charged dust, but a new
  effect arises. Negatively charged dust causes the magnetic field to
  bend in the direction of the convection electric field, while positively
  charged dust causes the opposite magnetic field bending. Consequently,
  the interaction does not only result in a perpendicular shift in the
  downstream current system, but also a rotation in these currents. We
  present quantitative results using the multi-fluid MHD code BATSRUS
  for both subsonic and supersonic interactions. We find that the same
  perpendicular bending exists for all counter-streaming interaction
  problems, independent of the shape of the dust cloud. The new model can
  be applied to plasma interaction studies including, but not limited to,
  charged dust particles in the solar wind, cometary plasma, the Enceladus
  plume, and active plasma releases, such as the Active Magnetospheric
  Particle Tracer Experiment (AMPTE) mission. The predicted behavior is
  consistent with observations at Enceladus.

Title: A Global Two-temperature Corona and Inner Heliosphere Model:
    A Comprehensive Validation Study
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Gruesbeck,
   J. R.; Frazin, R. A.; Landi, E.; Vasquez, A. M.; Lamy, P. L.; Llebaria,
   A.; Fedorov, A.; Toth, G.; Gombosi, T. I.
Bibcode: 2012ApJ...745....6J
Altcode:
  The recent solar minimum with very low activity provides us a unique
  opportunity for validating solar wind models. During CR2077 (2008
  November 20 through December 17), the number of sunspots was near
  the absolute minimum of solar cycle 23. For this solar rotation,
  we perform a multi-spacecraft validation study for the recently
  developed three-dimensional, two-temperature, Alfvén-wave-driven
  global solar wind model (a component within the Space Weather Modeling
  Framework). By using in situ observations from the Solar Terrestrial
  Relations Observatory (STEREO) A and B, Advanced Composition Explorer
  (ACE), and Venus Express, we compare the observed proton state (density,
  temperature, and velocity) and magnetic field of the heliosphere with
  that predicted by the model. Near the Sun, we validate the numerical
  model with the electron density obtained from the solar rotational
  tomography of Solar and Heliospheric Observatory/Large Angle and
  Spectrometric Coronagraph C2 data in the range of 2.4 to 6 solar
  radii. Electron temperature and density are determined from differential
  emission measure tomography (DEMT) of STEREO A and B Extreme Ultraviolet
  Imager data in the range of 1.035 to 1.225 solar radii. The electron
  density and temperature derived from the Hinode/Extreme Ultraviolet
  Imaging Spectrometer data are also used to compare with the DEMT as
  well as the model output. Moreover, for the first time, we compare
  ionic charge states of carbon, oxygen, silicon, and iron observed in
  situ with the ACE/Solar Wind Ion Composition Spectrometer with those
  predicted by our model. The validation results suggest that most of the
  model outputs for CR2077 can fit the observations very well. Based on
  this encouraging result, we therefore expect great improvement for the
  future modeling of coronal mass ejections (CMEs) and CME-driven shocks.

Title: Multi-fluid MHD simulation of the solar wind interaction
    with Venus
Authors: Nagy, A. F.; Najib, D.; Ma, Y.; Russell, C. T.; Toth, G.
Bibcode: 2011AGUFMSA13A1865N
Altcode:
  This paper reports on a new advanced multi-fluid MHD model that
  has recently been developed for Venus. The model is similar to the
  numerical model that was successfully applied to Mars (Najib et al.,
  2011). Mass densities, velocities and pressures of the protons and
  major ionosphere ion species (O+, O2+ and CO2+) are self-consistently
  calculated by solving the individual coupled continuity, momentum
  and energy equations. The various chemical reactions and ion-neutral
  collision processes are considered in the model. The simulation domain
  covers the region from 100 km altitude above the surface up to 16 RV
  in the tail. An adaptive spherical grid structure is constructed with
  radial resolution of about 10 km in the lower ionosphere. The model
  is applied to both solar-maximum and solar-minimum conditions and
  model results are compared in detail with multi-species single fluid
  model results.

Title: 3D MHD modeling of non-stationary flow in the heliosheath
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.; Oran, R.
Bibcode: 2011AGUFMSH11A1910P
Altcode:
  Both Voyager 1 and 2 data show that the heliosheath region is highly
  dynamic. As we climb out of the extended solar minima, time variations
  will be more and more important. The variations in the solar wind
  parameters in the heliosheath can be affected by the propagation of
  different interplanetary disturbances to the outer heliosphere. Using
  a 3D MHD multi-fluid code based on BATS-R-US (Opher et al. 2009),
  with a highly resolved spatial grid in Voyager 2 direction (size of a
  cell 0.48 AU) we study the propagation of the solar wind large-scale
  structures in the heliosheath region. We present our first results on
  the propagation of a forward-reverse shock pair and an abrupt pulse of
  solar wind dynamic pressure in the heliosheath region. We discuss in
  details the structure of the flow in the heliosheath and the response
  of the heliopause to the disturbances. We analyze the intensity of
  variations of the plasma parameters (magnetic field and speed) as
  measured in Voyager 2. We conclude that reflected waves appear in
  the heliosheath and they may contribute to the variations in solar
  wind parameters measured at Voyager spacecrafts. We present as well
  the initial results from a realistic propagation of a global merged
  interaction regions (GMIR) from the Sun to the heliospheric boundaries
  using a new coupled inner heliosphere-to outer heliosphere module.

Title: Multi-fluid MHD study of Ion Loss from Titan's Atmosphere
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Toth, G.; Dougherty,
   M. K.; Cravens, T. E.
Bibcode: 2011AGUFMSM21B2014M
Altcode:
  We study the plasma interaction around Titan using our new three
  dimensional multi-fluid MHD model similar to the one that was used
  recently to study Mars [Najib et al., 2011]. The multi-fluid MHD model
  of Titan is solved using the Michigan BATSRUS code. The model calculates
  densities, velocities, and pressures of seven ion species which are
  important in either Titan's ionosphere or in the ambient plasma. The
  code uses a spherical grid structure with high radial resolution ~ 30
  km in the lower ionosphere. The model is applied to an idealized case
  of Titan and the results are compared in detail with that of a single
  fluid model using the same set of plasma parameters to illustrate the
  importance of multi-fluid effects near Titan. We present the calculated
  ion escape rates from both models and discuss the differences.

Title: Flow Transition Region in the Heliosheath
Authors: Opher, M.; Drake, J. F.; Velli, M.; Toth, G.
Bibcode: 2011AGUFMSH11A1908O
Altcode:
  The tilt between the solar rotation and magnetic axes creates a
  sector region. Recently, we argued that the magnetic field in the
  sector region in the heliosheath has reconnected (Opher et al. 2011)
  and is filled with magnetic structures disconnected from the sun,
  called "bubbles". Here we show, that the sector region affects the
  flows in the heliosheath such as to create a region where the flow
  abruptly turns and the radial flow is near zero or negative. We dub
  this the flow transition region (FTR). The FTR is formed due to several
  effects that we have explored. The sector region in the heliosheath
  defines two flows: the flow within the sector region (region 1)
  behaves like an un-magnetized flow while the flow outside the sector
  (region 2) is connected to the larger heliosphere through the laminar
  magnetic field. The region 1 flow is dominantly affected by the blunt
  heliopause ahead of it and is mostly radial. As the flow streamlines
  approach the heliopause they turn abruptly, creating the FTR.This
  region didn't exist in previous simulations with no sectors where the
  flows downstream of the termination shock turn almost immediately to
  the sides and to higher latitudes. The thickness of FTR varies and is
  thinner in the southern hemisphere. We estimate, based on a recent 3D
  MHD simulation (Opher et al. 2011) that at the Voyager 1 location the
  thickness of FTR is 10-12AU. The simulations accurately reproduce the
  Voyager 1 flows. Since 2010 Voyager 1 has been immersed in the FTR,
  based on the negligible flows detected (Krimigis et al. 2011). If no
  other temporal dependent effects change the overall structure of the
  heliosphere, Voyager 1 is expected to cross the heliopause in the
  next 3-5 years. The FTR is much narrower in the southern hemisphere
  and Voyager 2 is expected to enter that region in the next couple years.

Title: Modeling the quiet time outflow solution in the polar cap
Authors: Glocer, A.; Kitamura, N.; Gombosi, T. I.; Toth, G.
Bibcode: 2011AGUFMSM44A..05G
Altcode:
  We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically
  quiet conditions in the polar cap during solar maximum. The PWOM solves
  the gyrotropic transport equations for O<SUP>+</SUP>, H<SUP>+</SUP>, and
  He<SUP>+</SUP> along several magnetic field lines in the polar region
  in order to reconstruct the full 3D solution. We directly compare our
  simulation results to the data based empirical model of Kitamura et
  al. [2011] of electron density, which is based on 63 months of Akebono
  satellite observations. The modeled ion and electron temperatures
  are also compared with a statistical compilation of quiet time data
  obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites
  (Kitamura et al. [2011]). The data and model agree reasonably well. This
  study shows that photoelectrons play an important role in explaining
  the differences between sunlit and dark results, ion composition, as
  well as ion and electron temperatures of the quiet time polar wind
  solution. Moreover, these results provide validation of the PWOM's
  ability to model the quiet time "background" solution.

Title: The heliospheric structure during the recent solar minimum:
    shocks in the lower corona and the magnetic field structure in
    the heliosheath
Authors: Opher, M.; Drake, J. F.; Evans, R.; Provornikova, E.; Swisdak,
   M. M.; Schoeffler, K. M.; van der Holst, B.; Toth, G.
Bibcode: 2011AGUFMSH23D..06O
Altcode:
  In this talk we review the recent heliospheric structure as
  affected by the recent solar minimum. We will focus especially on
  two frontiers areas: a) evolution of shocks in the lower corona and
  b) the heliosheath. In particular, we will focus on how the recent
  extended minimum allowed us to separate spatial and temporal effects
  in the outer heliosphere. We will describe new phenomena that we were
  able to explore, the reconnection of the sectored magnetic field in the
  heliosheath. Very little is known on how shocks thought to be driven by
  CMEs, form and evolve in the lower corona. This is a crucial area since
  its has been shown by observations that they form low in the corona
  (1-4Rs) and coincide with the acceleration to GeV energies. We will
  describe our recent attempts (e.g., Evans et al. 2011; Das et al.;
  2011) to uncover the evolution of CMEs at these locations. All the
  current global models of the heliosphere are based on the assumption
  that the magnetic field in the heliosheath, in the region close to
  the heliopause is laminar and connect back to the Sun. We argue
  recently, based on Voyager observations that in that region the
  heliospheric magnetic field is not laminar but instead consists of
  magnetic bubbles, or magnetic structures disconnected from the Sun
  (Opher et al. 2011). The consequence is that the heliopause might
  be a porous membrane instead of a shield. As the sun increased its
  activity, it will be more complicated to disentangle temporal from
  spatial and global structure. We will comment on how the increased
  solar activity might affect the sector structure in the heliosheath as
  well as the implication for our understanding of how galactic cosmic
  rays enter the heliosphere. Due to the slow flows in the heliosheath,
  the heliosheath has a long time memory of solar activity. Moreover,
  Corotating Interaction Regions and Global Merged Interacting Regions
  are known to disturb the termination shock and heliopause as well
  as the heliosheath flows and fields. For example it is still poorly
  understood how temporal effects propagate in the heliosheath and affect
  the level of turbulence. We will present some of our recent work trying
  to understand how temporal effects, such as CIRs propagates from the
  sun into the outer heliosphere.

Title: Modeling Solar Wind and Coronal Mass Ejection During Carrington
    Rotation 2107
Authors: Jin, M.; Manchester, W. B.; van der Holst, B.; Gruesbeck,
   J. R.; Frazin, R. A.; Landi, E.; Vasquez, A. M.; Toth, G.; Gombosi,
   T. I.
Bibcode: 2011AGUFMSH53C..08J
Altcode:
  With the starting of solar cycle 24, the Sun begins to show more
  activity. New observations from Solar Dynamics Observatory (SDO) give
  us a great opportunity to test and validate our solar corona model
  for space weather forecasts. During Carrington Rotation 2107, an M3.7
  flare occurred in NOAA 11164 on 2011 March 7 with a fast CME (&gt; 2000
  km/s). There is also a Solar Energetic Particle (SEP) event associated
  with this CME. In this study, we will first model the steady state solar
  wind using a newly developed three-dimensional Alfven-wave-driven global
  solar wind model within the Space Weather Modeling Framework (SWMF),
  which includes counter propagating Alfven waves. The magnetic field of
  the inner boundary is set up using the magnetogram from SDO/HMI. The
  inner boundary condition for density and temperature are specified
  from the Differential Emission Measure Tomography (DEMT) of SDO/AIA
  data. A flux rope is then applied to the active region NOAA 11164 to
  initiate the CME event. The properties of CME-driven shocks in the
  model output are studied in detail, which will be used to simulate the
  related SEP event in the future. By using multispacecraft observations,
  we perform a validation study for the model results.

Title: Variation of Pick-up Ion Pressure throughout the Heliosheath:
    3-Dimensional Multi-ion, Multi-fluid Magnetohydrodynamic Simulation
    of the Outer Heliosphere
Authors: Prested, C. L.; Opher, M.; Toth, G.; Schwadron, N. A.
Bibcode: 2011AGUFMSH21C..07P
Altcode:
  The interaction between the solar system and interstellar medium (ISM)
  involves multiple populations of ions and neutrals of both heliosphere
  and local interstellar origin. Of special interest is the pick-up ion
  population generated in the inner heliosphere, as it carries upwards of
  80% the plasma pressure in the outer heliosphere [Richardson et al.,
  2008]. The Interstellar Boundary Explorer (IBEX) global energetic
  neutral atom (ENA) maps of the interstellar-heliosphere interaction
  show temporal variation in the interaction region upwards of 15% in ENA
  emission over a time scale of &lt; 6 months. The short time scale and
  magnitude of the variation implies that the origin of this variation
  comes from the solar system plasma, which has considerable solar
  cycle variation, and likely not from variability in the interstellar
  medium. The dynamic properties of the pressure dominant pick-up ions
  are a likely candidate for this temporal variation. We ask, how does
  the pick-up ion pressure vary through the heliosheath, spatially
  and temporally? In previous 3-dimensional magnetohydrodynamic (MHD)
  simulations of the outer heliosphere, a single plasma fluid was used
  to describe the behavior of the solar wind plasma and the pick-up
  ions. For simulating ENA maps, the single plasma fluid was assumed
  to have a kappa distribution, describing the thermal core of solar
  wind plasma and the suprathermal tail of pick-up ions [Prested et
  al., 2008]. These simulations captured the global structure of the
  heliosphere but lost information on how the pick-up ion population and
  the pressure it carries evolve through the ISM-heliosphere interaction
  region. This information is vital for understanding the energy-dependent
  temporal and spatial variations observed in the IBEX global maps. We
  have extended our previous 3-d MHD multifluid model [Opher et al., 2009]
  to include the solar wind and pick-up ions as 2 separate ion fluids
  [i.e. Glocer et al., 2009 ], in addition to treating 4 separate neutral
  populations. Additionally, we introduce temporal variation by simulating
  the global heliosphere with solar-minimum and solar-maximum solar wind
  conditions. We quantify how the pick-up ion pressure varies through the
  heliosheath under these conditions and validate our results through
  comparison with the Voyager 1 and 2 heliosheath measurements. From
  our analysis of the two extreme solar wind cases, we conclude whether
  or not variation in pick-up ion pressure could be responsible for the
  6-month, large scale variation seen in the IBEX global maps.

Title: Controlling Reconnection in Global Magnetospheric Simulations
Authors: Toth, G.; Meng, X.; Daldorff, L.; Ridley, A. J.; Gombosi,
   T. I.
Bibcode: 2011AGUFMSM31B2108T
Altcode:
  Magnetic reconnection plays a major role in determining the dynamics
  of the magnetosphere. Yet, the reconnection rate in most global
  magnetosphere models relies on numerical resistivity. This means,
  unfortunately, that the simulation results are sensitive to the
  numerical parameters, such as grid resolution and the choice of the
  numerical scheme. We are exploring how we can control the resistivity in
  a better way. As a preliminary study, we do grid convergence studies of
  reconnection with constant resistivity in 2 dimensions. We establish the
  relationship between the grid resolution and the achievable magnetic
  Reynolds number. Based on these results we can estimate the effective
  numerical resistivity in global magnetospheric simulations, and use
  an explicit resistivity to better control the reconnection rate.

Title: Anisotropic BATSRUS and CRCM two way coupling
Authors: Meng, X.; Toth, G.; Glocer, A.; Fok, M. H.; Gombosi, T. I.
Bibcode: 2011AGUFMSM51B2061M
Altcode:
  As a newly extended capability of the BATSRUS code, anisotropic
  MHD can solve for the anisotropic ion pressure and isotropic
  electron pressure. It does a good job on simulating the quiet time
  magnetosphere, and the coupling with the Rice Convection Model (RCM)
  produces reasonable solutions for geomagnetic storms. However, RCM
  assumes the isotropic distribution of particles, which ignores the
  anisotropy information from BATSRUS. In order to better represent
  the near-Earth magnetosphere especially during disturbed times, we
  couple the anisotropic BATSRUS to the Comprehensive Ring Current Model
  (CRCM), which resolves the pitch-angle distribution. We present the
  preliminary results here, including the coupling algorithm and some
  validation tests.

Title: Spatial and temporal signatures of flux transfer events in
    global simulations of magnetopause dynamics
Authors: Kuznetsova, M. M.; Sibeck, D. G.; Hesse, M.; Berrios, D.;
   Rastaetter, L.; Toth, G.; Gombosi, T. I.
Bibcode: 2011AGUFMSM53B..01K
Altcode:
  Flux transfer events (FTEs) were originally identified by transient
  bipolar variations of the magnetic field component normal to the nominal
  magnetopause centered on enhancements in the total magnetic field
  strength. Recent Cluster and THEMIS multi-point measurements provided
  a wide range of signatures that are interpreted as evidence for FTE
  passage (e.g., crater FTEs, traveling magnetic erosion regions). We use
  the global magnetohydrodynamic (MHD) code BATS-R-US developed at the
  University of Michigan to model the global three-dimensional structure
  and temporal evolution of FTEs during multi-spacecraft magnetopause
  crossing events. Comparison of observed and simulated signatures and
  sensitivity analysis of the results to the probe location will be
  presented. We will demonstrate a variety of observable signatures
  in magnetic field profile that depend on space probe location with
  respect to the FTE passage. The global structure of FTEs will be
  illustrated using advanced visualization tools developed at the
  Community Coordinated Modeling Center.

Title: Simulating the one-dimensional structure of Titan's upper
atmosphere: 3. Mechanisms determining methane escape
Authors: Bell, Jared M.; Bougher, Stephen W.; Waite, J. Hunter, Jr.;
   Ridley, Aaron J.; Magee, Brian A.; Mandt, Kathleen E.; Westlake,
   Joseph; DeJong, Anna D.; Bar-Nun, Akiva; Jacovi, Ronen; Toth, Gabor;
   De La Haye, Virginie; Gell, David; Fletcher, Gregory
Bibcode: 2011JGRE..11611002B
Altcode:
  This investigation extends the work presented by Bell et al. (2010a,
  2010b). Using the one-dimensional (1-D) configuration of the
  Titan Global Ionosphere-Thermosphere Model (T-GITM), we quantify
  the relative importance of the different dynamical and chemical
  mechanisms that determine the CH<SUB>4</SUB> escape rates calculated
  by T-GITM. Moreover, we consider the implications of updated Huygens
  Gas Chromatograph Mass Spectrometer (GCMS) determinations of both the
  <SUP>40</SUP>Ar mixing ratios and <SUP>15</SUP>N/<SUP>14</SUP>N isotopic
  ratios in work by Niemann et al. (2010). Combining the GCMS constraints
  in the lower atmosphere with the Ion Neutral Mass Spectrometer (INMS)
  measurements in work by Magee et al. (2009), our simulation results
  suggest that the optimal CH<SUB>4</SUB> homopause altitude is located
  at 1000 km. Using this homopause altitude, we conclude that topside
  escape rates of 1.0 × 10<SUP>10</SUP> CH<SUB>4</SUB> m<SUP>-2</SUP>
  s<SUP>-1</SUP> (referred to the surface) are sufficient to reproduce
  the INMS methane measurements in work by Magee et al. (2009). These
  escape rates of methane are consistent with the upper limits to
  methane escape (1.11 × 10<SUP>11</SUP> CH<SUB>4</SUB> m<SUP>-2</SUP>
  s<SUP>-1</SUP>) established by both the Cassini Plasma Spectrometer
  (CAPS) and Magnetosphere Imaging Instrument (MIMI) measurements of
  Carbon-group ions in the near Titan magnetosphere.

Title: Numerical investigation of the late-time Kerr tails
Authors: Rácz, István; Tóth, Gábor Zs
Bibcode: 2011CQGra..28s5003R
Altcode: 2011arXiv1104.4199R
  The late-time behavior of a scalar field on fixed Kerr background
  is examined in a numerical framework incorporating the techniques of
  conformal compactification and hyperbolic initial value formulation. The
  applied code is 1+(1+2) as it is based on the use of the spectral
  method in the angular directions while in the time-radial section
  fourth order finite differencing, along with the method of lines, is
  applied. The evolution of various types of stationary and non-stationary
  pure multipole initial states are investigated. The asymptotic decay
  rates are determined not only in the domain of outer communication but
  along the event horizon and at future null infinity as well. The decay
  rates are found to be different for stationary and non-stationary
  initial data, and they also depend on the fall off properties of
  the initial data toward future null infinity. The energy and angular
  momentum transfers are found to show significantly different behavior
  in the initial phase of the time evolution. The quasinormal ringing
  phase and the tail phase are also investigated. In the tail phase, the
  decay exponents for the energy and angular momentum losses at I^{\,+}
  are found to be smaller than at the horizon which is in accordance
  with the behavior of the field itself and it means that at late times
  the energy and angular momentum falling into the black hole become
  negligible in comparison with the energy and angular momentum radiated
  toward I^{\,+} . The energy and angular momentum balances are used as
  additional verifications of the reliability of our numerical method.

Title: The importance of thermal electron heating in Titan's
ionosphere: Comparison with Cassini T34 flyby
Authors: Ma, Y. J.; Russell, C. T.; Nagy, A. F.; Toth, G.; Dougherty,
   M. K.; Wellbrock, A.; Coates, A. J.; Garnier, P.; Wahlund, J. -E.;
   Cravens, T. E.; Richard, M. S.; Crary, F. J.
Bibcode: 2011JGRA..11610213M
Altcode:
  We use a new magnetohydrodynamic (MHD) model to study the effects of
  thermal-electron heating in Titan's ionosphere. This model improves the
  previously used multispecies MHD model by solving both the electron
  and ion pressure equations instead of a single plasma pressure
  equation. This improvement enables a more accurate evaluation of ion
  and electron temperatures inside Titan's ionosphere. The model is
  first applied to an idealized case, and the results are compared in
  detail with those of the single-pressure MHD model to illustrate the
  effects of the improvement. Simulation results show that the dayside
  ionosphere thermal pressure is larger than the upstream pressure
  during normal conditions, when Titan is located in the dusk region;
  thus Saturn's magnetic field is shielded by the highly conducting
  ionosphere, similar to the interaction of Venus during solar maximum
  conditions. This model is also applied to a special flyby of Titan,
  the T34 flyby, which occurred near the dusk region. It is shown that
  better agreement with the magnetometer data can be achieved using
  the two-fluid MHD model with the inclusion of the effects of thermal
  electron heating. The model results clearly demonstrate the importance
  of thermal-electron heating in Titan's ionosphere.

Title: A 3D Multi-fluid MHD Study of the Interaction of the Solar
    Wind with the Ionosphere/Atmosphere System of Venus.
Authors: Najib, D.; Nagy, A.; Toth, G.; Ma, Y. -J.
Bibcode: 2011epsc.conf..158N
Altcode: 2011DPS....43..158N
  We use the latest version of our four species multifluid model to
  study the interaction of the solar wind with Venus. The model solves
  simultaneously the continuity, momentum and energy equations of the
  different ions. The lower boundary of our model is at 100 km, below
  the main ionospheric peak, and the radial resolution is about 10 km in
  the ionosphere, thus the model does a very good job in reproducing the
  ionosphere and the associated processes. We carry out calculations for
  high and low solar activity conditions and establish the importance
  of mass loading by the extended exosphere of Venus. We demonstrate
  the importance of using the multi-fluid rather than a single fluid
  model. We also calculate the atmospheric escape of the ionospheric
  species and compare our model results with the observed parameters
  from Pioneer Venus and Venus Express.

Title: Perpendicular Flow Separation in a Magnetized Counterstreaming
Plasma: Application to the Dust Plume of Enceladus
Authors: Jia, Y. -D.; Ma, Y. J.; Russell, C. T.; Toth, G.; Gombosi,
   T. I.; Dougherty, M. K.
Bibcode: 2011epsc.conf...99J
Altcode: 2011DPS....43...99J
  The interaction of charged dust with a magnetized flowing plasma
  can be treated with a multi-fluid MHD simulation. We examine the
  interaction of the corotating Saturnian plasma with the charged-dust
  plume of Enceladus. The model produces plasma deceleration with both
  positively and negatively charged dust. In addition, the negatively
  charged dust causes plasma deflection in the direction of the motional
  electric field and a kink in the magnetic field extending in the
  same direction. Positively charged dust causes the opposite plasma
  deflection and the opposite magnetic field bending. These results agree
  with the magnetic signatures observed on Cassini plume flybys. The
  code has been tested on both subsonic and supersonic interactions and
  is applicable to solar wind dust pickup, ICME interactions with dust
  trails, cometary plasma pickup, active plasma releases such as the
  AMPTE barium release as well as the Enceladus plume.

Title: Rapid rebuilding of the outer radiation belt
Authors: Glocer, A.; Fok, M. -C.; Nagai, T.; Tóth, G.; Guild, T.;
   Blake, J.
Bibcode: 2011JGRA..116.9213G
Altcode:
  Recent observations by the radiation monitor (RDM) on the spacecraft
  Akebono have shown several cases of &gt;2.5 MeV radiation belt electron
  enhancements occurring on timescales of less than a few hours. Similar
  enhancements are also seen in detectors on board the NOAA/POES and
  TWINS 1 satellites. These intervals are shorter than typical radial
  diffusion or wave-particle interactions can account for. We choose two
  so-called “rapid rebuilding” events that occur during high speed
  streams (4 September 2008 and 22 July 2009) and simulated them with the
  Space Weather Modeling Framework configured with global magnetosphere,
  radiation belt, ring current, and ionosphere electrodynamics model. Our
  simulations produce a weaker and delayed dipolarization as compared
  to observations, but the associated inductive electric field in the
  simulations is still strong enough to rapidly transport and accelerate
  MeV electrons resulting in an energetic electron flux enhancement that
  is somewhat weaker than is observed. Nevertheless, the calculated
  flux enhancement and dipolarization is found to be qualitatively
  consistent with the observations. Taken together, the modeling results
  and observations support the conclusion that storm-time dipolarization
  events in the magnetospheric magnetic field result in strong radial
  transport and energization of radiation belt electrons.

Title: Reducing numerical diffusion in magnetospheric simulations
Authors: Tóth, Gábor; Meng, Xing; Gombosi, Tamas I.; Ridley, Aaron J.
Bibcode: 2011JGRA..116.7211T
Altcode:
  Physics-based global magnetosphere modeling requires large computational
  resources. It is still impractical to resolve the computational domain
  to the point where numerical errors become negligible. One possible
  way of reducing numerical diffusion is the “Boris correction”:
  the semirelativistic magnetohydrodynamics equations are solved with an
  artificially reduced speed of light. Here we introduce a new alternative
  approach, an Implicit Scheme with Limited Numerical Dissipation
  (ISLND). The fully implicit time stepping provides stability, and the
  wave speeds are limited in the dissipative numerical fluxes only. This
  limiting only affects the numerical scheme, and it does not modify the
  equations being solved. This approach can be employed for most total
  variation diminishing schemes. The differences between the Boris
  and ISLND schemes are demonstrated in simple numerical tests. We
  also perform several simulations for two magnetic storms using the
  global magnetosphere, the ionosphere electrodynamics, and the inner
  magnetosphere models of the Space Weather Modeling Framework, and we
  compare the Boris scheme with the limited numerical dissipation method
  and also with the unmodified base scheme at various grid resolutions. We
  find that for these particular simulations the Boris scheme and the
  ISLND scheme produce comparable results, both being significantly less
  diffusive than the unmodified scheme.

Title: A Global Two-Temperature Corona and Inner Heliosphere Model:
    A Validation Study
Authors: Jin, Meng; Manchester, W. B.; van der Holst, B.; Gruesbeck,
   J.; Frazin, R. A.; Vasquez, A. M.; Lamy, P. L.; Llebaria, A.; Fedorov,
   A.; Toth, G.; Gombosi, T. I.
Bibcode: 2011shin.confE..12J
Altcode:
  The recent solar minimum with very low activity provides us a unique
  opportunity for validating solar wind models. During CR2077 (2008,
  November 20 through December 17), the sunspots number reaches the
  absolute minimum of solar cycle 23. For this solar rotation, we
  perform a multi-spacecraft validation study for the recently developed
  three-dimensional, two-temperature, Alfven-wave-driven global solar wind
  model (a component within the Space Weather Modeling Framework). By
  using in situ observations from STEREO A and B, ACE/WIND and Venus
  Express, we compare the observed proton state (density, temperature and
  velocity) and magnetic field of the heliosphere with that predicted
  by the model. Near the Sun, we validate the numerical model with the
  electron density obtained from the solar rotational tomography of
  SOHO/LASCO-C2 data in the range of 2.4 to 6 solar radii. Electron
  temperature and density are determined from differential emission
  measure tomography of STEREO A and B EUVI data in the range of 1.035 to
  1.225 solar radii. Moreover, we compare ionic charge states of carbon,
  oxygen, silicon, and iron observed in situ with ACE/SWICS and that
  predicted by our model. The validation results suggest that most of
  the model outputs for CR2077 can fit the observations very well. Based
  on this encouraging result, we therefore expect great improvement for
  the modeling of CMEs and CME-driven shocks in the future.

Title: Is the Magnetic Field in the Heliosheath Laminar or a Turbulent
    Sea of Bubbles?
Authors: Opher, M.; Drake, J. F.; Swisdak, M.; Schoeffler, K. M.;
   Richardson, J. D.; Decker, R. B.; Toth, G.
Bibcode: 2011ApJ...734...71O
Altcode: 2011arXiv1103.2236O
  All current global models of the heliosphere are based on the assumption
  that the magnetic field in the heliosheath, in the region close to
  the heliopause (HP), is laminar. We argue that in that region the
  heliospheric magnetic field is not laminar but instead consists of
  magnetic bubbles. We refer to it as the bubble-dominated heliosheath
  region. Recently, we proposed that the annihilation of the "sectored"
  magnetic field within the heliosheath as it is compressed on its
  approach to the HP produces anomalous cosmic rays and also energetic
  electrons. As a product of the annihilation of the sectored magnetic
  field, densely packed magnetic islands (which further interact to form
  magnetic bubbles) are produced. These magnetic islands/bubbles will be
  convected with ambient flows as the sector region is carried to higher
  latitudes filling the heliosheath. We further argue that the magnetic
  islands/bubbles will develop upstream within the heliosheath. As a
  result, the magnetic field in the heliosheath sector region will be
  disordered well upstream of the HP. We present a three-dimensional
  MHD simulation with very high numerical resolution that captures the
  north-south boundaries of the sector region. We show that due to the
  high pressure of the interstellar magnetic field a north-south asymmetry
  develops such that the disordered sectored region fills a large portion
  of the northern part of the heliosphere with a smaller extension in the
  southern hemisphere. We suggest that this scenario is supported by the
  following changes that occurred around 2008 and from 2009.16 onward: (1)
  the sudden decrease in the intensity of low energy electrons (0.02-1.5
  MeV) detected by Voyager 2, (2) a sharp reduction in the intensity of
  fluctuations of the radial flow, and (3) the dramatic differences in
  intensity trends between galactic cosmic ray electrons (3.8-59 MeV) at
  Voyager 1 and 2. We argue that these observations are a consequence of
  Voyager 2 leaving the sector region of disordered field during these
  periods and crossing into a region of unipolar laminar field.

Title: Kinetic versus Multi-fluid Approach for Interstellar Neutrals
in the Heliosphere: Exploration of the Interstellar Magnetic Field
    Effects
Authors: Alouani-Bibi, Fathallah; Opher, Merav; Alexashov, Dimitry;
   Izmodenov, Vladislav; Toth, Gabor
Bibcode: 2011ApJ...734...45A
Altcode: 2011arXiv1103.3202A
  We present a new three-dimensional (3D) self-consistent two-component
  (plasma and neutral hydrogen) model of the solar wind interaction with
  the local interstellar medium (LISM). This model (K-MHD) combines
  the magnetohydrodynamic treatment of the solar wind and the ionized
  LISM component with a kinetic model of neutral interstellar hydrogen
  (LISH). The local interstellar magnetic field (B <SUB>LISM</SUB>)
  intensity and orientation are chosen based on an early analysis of the
  heliosheath flows. The properties of the plasma and neutrals obtained
  using the K-MHD model are compared to previous multi-fluid and kinetic
  models. The new treatment of LISH revealed important changes in the
  heliospheric properties not captured by the multi-fluid model. These
  include a decrease in the heliocentric distance to the termination
  shock (TS), a thinner heliosheath, and a reduced deflection angle (θ)
  of the heliosheath flows. The asymmetry of the TS, however, seems to
  be unchanged by the kinetic aspect of the LISH.

Title: CRASH: A Block-adaptive-mesh Code for Radiative Shock
    Hydrodynamics—Implementation and Verification
Authors: van der Holst, B.; Tóth, G.; Sokolov, I. V.; Powell, K. G.;
   Holloway, J. P.; Myra, E. S.; Stout, Q.; Adams, M. L.; Morel, J. E.;
   Karni, S.; Fryxell, B.; Drake, R. P.
Bibcode: 2011ApJS..194...23V
Altcode: 2011arXiv1101.3758V
  We describe the Center for Radiative Shock Hydrodynamics (CRASH)
  code, a block-adaptive-mesh code for multi-material radiation
  hydrodynamics. The implementation solves the radiation diffusion model
  with a gray or multi-group method and uses a flux-limited diffusion
  approximation to recover the free-streaming limit. Electrons and ions
  are allowed to have different temperatures and we include flux-limited
  electron heat conduction. The radiation hydrodynamic equations are
  solved in the Eulerian frame by means of a conservative finite-volume
  discretization in either one-, two-, or three-dimensional slab geometry
  or in two-dimensional cylindrical symmetry. An operator-split method
  is used to solve these equations in three substeps: (1) an explicit
  step of a shock-capturing hydrodynamic solver; (2) a linear advection
  of the radiation in frequency-logarithm space; and (3) an implicit
  solution of the stiff radiation diffusion, heat conduction, and
  energy exchange. We present a suite of verification test problems
  to demonstrate the accuracy and performance of the algorithms. The
  applications are for astrophysics and laboratory astrophysics. The
  CRASH code is an extension of the Block-Adaptive Tree Solarwind Roe
  Upwind Scheme (BATS-R-US) code with a new radiation transfer and
  heat conduction library and equation-of-state and multi-group opacity
  solvers. Both CRASH and BATS-R-US are part of the publicly available
  Space Weather Modeling Framework.

Title: Obtaining Potential Field Solutions with Spherical Harmonics
    and Finite Differences
Authors: Tóth, Gábor; van der Holst, Bart; Huang, Zhenguang
Bibcode: 2011ApJ...732..102T
Altcode: 2011arXiv1104.5672T
  Potential magnetic field solutions can be obtained based on the
  synoptic magnetograms of the Sun. Traditionally, a spherical harmonics
  decomposition of the magnetogram is used to construct the current-
  and divergence-free magnetic field solution. This method works
  reasonably well when the order of spherical harmonics is limited to
  be small relative to the resolution of the magnetogram, although some
  artifacts, such as ringing, can arise around sharp features. When the
  number of spherical harmonics is increased, however, using the raw
  magnetogram data given on a grid that is uniform in the sine of the
  latitude coordinate can result in inaccurate and unreliable results,
  especially in the polar regions close to the Sun. We discuss here
  two approaches that can mitigate or completely avoid these problems:
  (1) remeshing the magnetogram onto a grid with uniform resolution in
  latitude and limiting the highest order of the spherical harmonics to
  the anti-alias limit; (2) using an iterative finite difference algorithm
  to solve for the potential field. The naive and the improved numerical
  solutions are compared for actual magnetograms and the differences
  are found to be rather dramatic. We made our new Finite Difference
  Iterative Potential-field Solver (FDIPS) a publicly available code
  so that other researchers can also use it as an alternative to the
  spherical harmonics approach.

Title: Three-dimensional, multifluid, high spatial resolution MHD
    model studies of the solar wind interaction with Mars
Authors: Najib, Dalal; Nagy, Andrew F.; Tóth, Gábor; Ma, Yingjuan
Bibcode: 2011JGRA..116.5204N
Altcode:
  Our newly developed 3-D, multifluid MHD model is used to study the
  interaction of the solar wind with Mars. This model is based on the
  BATS-R-US code, using a spherical grid and a radial resolution equal
  to 10 km in the ionospheric regions. We solve separate continuity,
  momentum, and energy equations for each ion fluid and run our model
  for both solar minimum and maximum conditions. We obtain asymmetric
  densities, velocities, and magnetic pileup in the plane containing both
  the direction of the solar wind and the convective electric field. These
  asymmetries are the result of the decoupling of the individual ions;
  therefore, our model is able to account for the respective dynamics
  of the ions and to show new physical processes that could not be
  observed by the single-fluid model. Our results are consistent with
  the measured bow shock and magnetic pileup locations and with the
  Viking-observed ion densities. We also compute the escape fluxes for
  both solar minimum and solar maximum conditions and compare them to
  the single-fluid results and the observed values from Mars Express.

Title: The effects of dynamic ionospheric outflow on the ring current
Authors: Welling, D. T.; Jordanova, V. K.; Zaharia, S. G.; Glocer,
   A.; Toth, G.
Bibcode: 2011JGRA..116.0J19W
Altcode:
  The importance of ionospheric O<SUP>+</SUP> on the development of the
  storm time ring current is recognized but not well understood. The
  addition of this outflow in global MHD models has the potential
  to change the magnetic field configuration, particle densities and
  temperatures, and the convection electric field. This makes including
  heavy ion outflow in ring current simulations difficult, as this
  addition cannot be easily decoupled from a host of other changes. This
  study attempts to overcome this problem by using three coupled models,
  PWOM, RIM, and BATS-R-US, to drive a ring current model, RAM-SCB. The
  differences in drivers when outflow is included and is not included are
  compared to see how outflow changes ring current input. It is found
  that including this outflow reduces the convection electric field,
  lowers the plasma sheet number density and temperature, and increases
  the complexity of the plasma sheet ion composition both temporally and
  spatially. These changes cause an overall reduction in ring current
  energy density. Further simulations that attempt to isolate these
  effects find that the most important change in terms of ring current
  development is the drop in convection electric field. Local time
  dependencies of O<SUP>+</SUP> injections are found to be nontrivial
  as well. Capturing all of these effects requires a whole system,
  first-principles approach.

Title: CRASH: A Block-Adaptive-Mesh Code for Radiative Shock
    Hydrodynamics
Authors: van der Holst, B.; Toth, G.; Sokolov, I. V.; Powell, K. G.;
   Holloway, J. P.; Myra, E. S.; Stout, Q.; Adams, M. L.; Morel, J. E.;
   Drake, R. P.
Bibcode: 2011ascl.soft01008V
Altcode:
  CRASH (Center for Radiative Shock Hydrodynamics) is a block
  adaptive mesh code for multi-material radiation hydrodynamics. The
  implementation solves the radiation diffusion model with the gray or
  multigroup method and uses a flux limited diffusion approximation
  to recover the free-streaming limit. The electrons and ions are
  allowed to have different temperatures and we include a flux limited
  electron heat conduction. The radiation hydrodynamic equations are
  solved in the Eulerian frame by means of a conservative finite volume
  discretization in either one, two, or three-dimensional slab geometry
  or in two-dimensional cylindrical symmetry. An operator split method
  is used to solve these equations in three substeps: (1) solve the
  hydrodynamic equations with shock-capturing schemes, (2) a linear
  advection of the radiation in frequency-logarithm space, and (3)
  an implicit solve of the stiff radiation diffusion, heat conduction,
  and energy exchange. We present a suite of verification test problems
  to demonstrate the accuracy and performance of the algorithms. The
  CRASH code is an extension of the Block-Adaptive Tree Solarwind Roe
  Upwind Scheme (BATS-R-US) code with this new radiation transfer and
  heat conduction library and equation-of-state and multigroup opacity
  solvers. Both CRASH and BATS-R-US are part of the publicly available
  Space Weather Modeling Framework (SWMF).

Title: BATSRUS with Anisotropic Ion Pressure
Authors: Meng, X.; Toth, G.; Gombosi, T. I.
Bibcode: 2010AGUFMSM51B1816M
Altcode:
  We extend the capability of BATSRUS code to simulate anisotropic
  pressure. Several events are presented here, including quiet time as
  well as storms. The comparison with measurements, primarily Cluster
  and THEMIS data are shown. We also investigate the possibility of
  including a separate evolution equation for the (isotropic) electron
  pressure. The assumption of isotropy for electrons is reasonable
  for most space applications. We describe our progress with the
  implementation and testing.

Title: Simulating the one-dimensional structure of Titan's upper
atmosphere: 2. Alternative scenarios for methane escape
Authors: Bell, Jared M.; Bougher, Stephen W.; Waite, J. Hunter, Jr.;
   Ridley, Aaron J.; Magee, Brian A.; Mandt, Kathleen E.; Westlake,
   Joseph; Dejong, Anna D.; de La Haye, Virginie; Bar-Nun, Akiva; Jacovi,
   Ronen; Toth, Gabor; Gell, David; Fletcher, Gregory
Bibcode: 2010JGRE..11512018B
Altcode:
  In Bell et al. (2010) (paper 1), we provide a series of
  benchmark simulations that validate a newly developed Titan Global
  Ionosphere-Thermosphere Model (T-GITM) and calibrate its estimates of
  topside escape rates with recent work by Cui et al. (2008), Strobel
  (2009), and Yelle et al. (2008). Presently, large uncertainties exist
  in our knowledge of the density and thermal structure of Titan's
  upper atmosphere between the altitudes of 500 km and 1000 km. In this
  manuscript, we explore a spectrum of possible model configurations of
  Titan's upper atmosphere that are consistent with observations made by
  the Cassini Ion-Neutral Mass Spectrometer (INMS), Composite Infrared
  Spectrometer, Cassini Plasma Spectrometer, Magnetospheric Imaging
  Instrument, and by the Huygens Gas Chromatograph Mass Spectrometer
  and Atmospheric Science Instrument. In particular, we explore the
  ramifications of multiplying the INMS densities of Magee et al. (2009)
  by a factor of 3.0, which significantly alters the overall density,
  thermal, and dynamical structures simulated by T-GITM between 500 km
  and 1500 km. Our results indicate that an entire range of topside
  CH<SUB>4</SUB> escape fluxes can equivalently reproduce the INMS
  measurements, ranging from ∼10<SUP>8</SUP> - 1.86 × 10<SUP>13</SUP>
  molecules m<SUP>-2</SUP> s<SUP>-1</SUP> (referred to the surface). The
  lowest topside methane escape rates are achieved by scaling the INMS
  densities by a factor of 3.0 and either (1) increasing the methane
  homopause altitude to ∼1000 km or (2) including a physicochemical loss
  referred to as aerosol trapping. Additionally, when scaling the INMS
  densities by a factor of 3.0, we find that only Jeans escape velocities
  are required to reproduce the H<SUB>2</SUB> measurements of INMS.

Title: A Data-driven, Two-temperature Solar Wind Model with Alfvén
    Waves
Authors: van der Holst, B.; Manchester, W. B., IV; Frazin, R. A.;
   Vásquez, A. M.; Tóth, G.; Gombosi, T. I.
Bibcode: 2010ApJ...725.1373V
Altcode:
  We have developed a new three-dimensional magnetohydrodynamic
  (MHD) solar wind model coupled to the Space Weather Modeling
  Framework (SWMF) that solves for the different electron and proton
  temperatures. The collisions between the electrons and protons are
  taken into account as well as the anisotropic thermal heat conduction
  of the electrons. The solar wind is assumed to be accelerated by
  the Alfvén waves. In this paper, we do not consider the heating of
  closed magnetic loops and helmet streamers but do address the heating
  of the protons by the Kolmogorov dissipation of the Alfvén waves in
  open field-line regions. The inner boundary conditions for this solar
  wind model are obtained from observations and an empirical model. The
  Wang-Sheeley-Arge model is used to determine the Alfvén wave energy
  density at the inner boundary. The electron density and temperature
  at the inner boundary are obtained from the differential emission
  measure tomography applied to the extreme-ultraviolet images of the
  STEREO A and B spacecraft. This new solar wind model is validated
  for solar minimum Carrington rotation 2077 (2008 November 20 through
  December 17). Due to the very low activity during this rotation,
  this time period is suitable for comparing the simulated corotating
  interaction regions (CIRs) with in situ ACE/WIND data. Although we do
  not capture all MHD variables perfectly, we do find that the time of
  occurrence and the density of CIRs are better predicted than by our
  previous semi-empirical wind model in the SWMF that was based on a
  spatially reduced adiabatic index to account for the plasma heating.

Title: Is the Magnetic Field in the Heliosheath Sector Region and
    in the Outer Heliosheath Laminar?
Authors: Opher, M.; Drake, J. F.; Swisdak, M. M.; Toth, G.
Bibcode: 2010AGUFMSH23D..04O
Altcode:
  All the current global models of the heliosphere are based on the
  assumption that the magnetic field in the outer heliosheath close to
  the heliopause is laminar. We argue that in the outer heliosheath the
  heliospheric magnetic field is not laminar but instead consists of
  nested magnetic islands. Recently, we proposed (Drake et al. 2009)
  that the annihilation of the ``sectored'' magnetic field within the
  heliosheath as it is compressed on its approach to the heliopause
  produces the anomalous cosmic rays (ACRs) and also energetic
  electrons. As a product of the annihilation of the sectored magnetic
  field, densly-packed magnetic islands are produced. These magnetic
  islands will be convected with the ambient flows as the sector boundary
  is carried to higher latitudes filling the outer heliosheath. We
  further argue that the magnetic islands will develop upstream (but
  still within the heliosheath) where collisionless reconnection is
  unfavorable -- large perturbations of the sector structure near the
  heliopause will cause compressions of the current sheet upstream,
  triggering reconnection. As a result, the magnetic field in the
  heliosheath sector region will be disordered well upstream of the
  heliopause. We present a 3D MHD simulation with unprecedent numerical
  resolution that captures the sector boundary. We show that due to
  the high pressure of the interstellar magnetic field the disordered
  sectored region fills a large portion of the northern part of the
  heliosphere with a smaller extension in the southern hemisphere. We
  test these ideas with observations of energetic electrons, which
  because of their high velocity are most sensitive to the structure of
  the magnetic field. We suggest that within our scenario we can explain
  two significant anomalies in the observations of energetic electrons
  in the outer heliosphere: the sudden decrease in the intensity of low
  energy electrons (0.02-1.5MeV) from the LECP instrument on Voyager 2 in
  2008 (Decker 2010); and the dramatic differences in intensity trends
  between Galactic Cosmic Ray Electrons (3.8-59MeV) at Voyager 1 and 2
  (McDonald 2010). We argue that these observations are a consequence
  of Voyager 2 leaving the sector region of disordered field in mid 2008
  and crossing into a region of unipolar laminar field.

Title: Global MHD simulations of the interaction between Saturn's
    magnetosphere and the solar wind (Invited)
Authors: Jia, X.; Hansen, K. C.; Gombosi, T. I.; Kivelson, M. G.;
   Toth, G.; de Zeeuw, D.; Ridley, A. J.
Bibcode: 2010AGUFMSM31C..01J
Altcode:
  At Saturn, both the external (the solar wind) and the internal (the
  planet’s rotation and internal plasma source) conditions play an
  important role in affecting the global structure and dynamics of the
  magnetosphere. We have used 3D global MHD simulations to investigate
  the global configuration and dynamics of Saturn’s mass-loaded
  magnetosphere under different solar wind conditions. Our present
  model (BATSRUS) adopts a high-resolution, non-uniform spherical grid,
  which is crucial for capturing fine structures of the large-scale
  magnetospheric currents responsible for the coupling between the
  magnetosphere and the ionosphere. In order to examine the effects
  of the solar wind driving on dynamics of Saturn’s magnetosphere,
  we have used an idealized solar wind input with features typical of
  those of Corotating Interaction Regions (CIRs) seen at Saturn’s
  orbit. Our simulation results indicate that periodic large-scale
  plasmoid formation occurs in Saturn’s magnetotail, independent of
  the IMF conditions. However, the periodicity of plasmoid formation in
  the tail appears to be strongly affected by the upstream solar wind
  conditions. In this talk, we will compare the global magnetospheric
  configuration under different solar wind dynamic pressure and IMF
  conditions. In particular, we will discuss the interplay between the
  so-called “Vasyliunas-cycle” and “Dungey-cycle” in controlling
  the global plasma convection in Saturn’s magnetosphere. We will
  also show the ionospheric response to the solar wind driving, such
  as changes in the field-aligned currents and convection pattern,
  and discuss their relationship with dynamics in the magnetosphere.

Title: Modeling Ionospheric Outflows In Global Models (Invited)
Authors: Glocer, A.; Toth, G.; Fok, M. H.; Gombosi, T. I.; Welling,
   D. T.
Bibcode: 2010AGUFMSA33C..01G
Altcode:
  The magnetosphere contains a significant amount of ionospheric O+,
  particularly during geomagnetically active times. The presence
  of this ionospheric plasma has a notable impact on magnetospheric
  composition and processes. We present our methodology for including
  an ionospheric mass source into global models, and for tracking the
  consequences for the space environment system. An overview of our
  recent efforts is provided. In particular, we illustrate the effect
  that plasma of ionospheric origin can have on the magnetosphere by
  simulating extreme geospace events when the fraction of O+ is largest,
  and contrast those results with simulations of more moderate events. We
  also compare different techniques of modeling/tracking ionospheric
  outflow, and explore the implications for the storm-time ring current
  and magnetospheric magnetic field configuration.

Title: Numerical Simulation of Earth Directed CMEs with an Advanced
    Two-Temperature Coronal Model (Invited)
Authors: Manchester, W. B.; van der Holst, B.; Frazin, R. A.; Vasquez,
   A. M.; Toth, G.; Gombosi, T. I.
Bibcode: 2010AGUFMSH32A..02M
Altcode:
  We present progress on modeling Earth-directed CMEs including
  the December 12, 2008 CME and the May 13, 2005 campaign event from
  initiation to heliospheric propagation. Our earlier work on the 2005
  event followed the CME to the orbit of Saturn employing the coronal
  model of Cohen et al. (2007), which relies on a spatially varying
  adiabatic index (gamma) to produce the bimodal solar wind. This
  model was able to reproduce several features of the observed event,
  but suffered from artifacts of the artificially thermodynamics. We
  will examine results of a recent simulation performed with a new
  two-temperature solar corona model developed at the University of
  Michigan. This model employs heat conduction for both ion and electron
  species, constant adiabatic index (=5/3), and includes Alfven waves
  to drive the solar wind. The model includes SOHO/MDI magnetogram data
  to calculate the coronal field, and also uses SOHO/EIT observations
  to specify the density and temperature at the coronal boundary by
  the Differential Emission Measure Tomography (DEMT) method. The
  Wang-Sheeley-Arge empirical model is used to determine the Alfven
  wave pressure necessary to produce the observed solar wind speeds. We
  find that the new model is much better able to reproduce the solar
  wind densities, and also correctly captures the compression at the
  CME-driven shock due to the fixed adiabatic index.

Title: Component Reconnexion at the Heliopause
Authors: Moore, T. E.; Alouani-Bibi, F.; Opher, M.; Toth, G.; McComas,
   D. J.
Bibcode: 2010AGUFMSH21A1795M
Altcode:
  Extended X lines of component reconnection at the heliopause are derived
  from 3D MHD simulations of the steady state heliosphere (Alouani-Bibi
  et al 2010, Opher et al 2009). A similar study established this
  technique to describe the extended shape of reconnection X-lines at
  the magnetosphere, as result of its interaction with the interplanetary
  field of varying orientation (Moore et al., 2002). At the heliopause,
  reconnection X-line candidates are derived on the basis of geometrical
  criteria, allowing for shear angles between the interacting fields of
  less than 180 degree (Cowley 1976) and properties of the magnetic fields
  and flows outside (interstellar medium) and inside (interplanetary space
  beyond the termination shock) the heliopause. Kinetic effects addressed
  by Swisdak et al. (2009) and Opher et al. (2010) can inhibit large
  scale component reconnection, leading to more localized and nearly
  anti-parallel reconnection, possibly accounting for the persistent
  hot spot in IBEX heliopause ribbon.

Title: Multi-Scale Modeling of Global Magnetosphere Structure and
    Dynamics
Authors: Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.; Toth, G.;
   de Zeeuw, D.; Gombosi, T. I.
Bibcode: 2010AGUFMSM31B1868K
Altcode:
  To understand the role of magnetic reconnection in global evolution of
  magnetosphere and to place spacecraft observations into global context
  it is essential to perform global simulations with physically motivated
  model of dissipation that is capable to reproduce reconnection rates
  predicted by kinetic models. In our efforts to bridge the gap between
  small scale kinetic modeling and global simulations we introduced an
  approach that allows to quantify the interaction between large-scale
  global magnetospheric dynamics and microphysical processes in diffusion
  regions near reconnection sites. We utilized the high resolution global
  MHD code BATSRUS and incorporated primary mechanism controlling the
  dissipation in the vicinity of reconnection sites in terms of kinetic
  corrections to induction and energy equations. One of the key elements
  of the multiscale modeling of magnetic reconnection is identification
  of reconnection sites and boundaries of surrounding diffusion regions
  where non-MHD corrections are required. Reconnection site search in the
  equatorial plane implemented in our previous studies is extended to cusp
  and magnetpause reconnection, as well as for magnetotail reconnection
  in realistic asymmetric configurations. The role of feedback between
  the non-ideal effects in diffusion regions and global magnetosphere
  structure and dynamics will be discussed.

Title: Hydrogen deflection in the heliosphere and the effect of
    local interstellar magnetic field
Authors: Alouani-Bibi, F.; Opher, M.; Alexashov, D.; Toth, G.;
   Izmodenov, V.
Bibcode: 2010AGUFMSH21A1800A
Altcode:
  The interaction of solar wind plasma with the local interstellar
  medium is studied using a coupled 3D Kinetic-MHD model. We show that
  the deflection of hydrogen atoms that penetrates the heliosphere is
  affected by the orientation and magnitude of the local interstellar
  magnetic field (BLISM) as well as by the kinetic treatment of neutral H
  atoms. We show that the observed deflection by Lallement et al (2005,
  2010) of interstellar neutral hydrogen flow at the inner-heliosphere
  is attained for different orientations and magnitudes of BLISM. The
  hydrogen deflection plane (HDP, that is the plane containing the He and
  H vector directions) is not a unique indicator for defining both the
  BLISM orientation and magnitude. This study is done for a high intensity
  field, BLISM (4.4µG), based on the analysis of the heliospheric
  asymmetries (Opher et al. 2009) which used multi-fluid model of
  solar wind and local interstellar interaction. Comparisons between
  the kinetic and multi-fluid treatments of neutrals showed substantial
  reduction in the hydrogen deflection for the kinetic approach.

Title: 3D, multi-fluid, MHD calculations of Mars interaction with
    the solar wind
Authors: Najib, D.; Toth, G.; Nagy, A. F.; Curry, S.; Ma, Y.
Bibcode: 2010AGUFM.P53E1571N
Altcode:
  We use our 3D multi-fluid MHD model to simulate the interaction of the
  solar wind with non-magnetized planets, Mars in particular. We set
  the lower boundary to 100 km and consider photo and electron impact
  ionization as well as charge exchange in our chemistry. We also add
  more realistic physical processes to our model, and test it against
  different solar wind conditions. In addition, we are solving for
  the electron pressure and therefore for the electron fluid. We also
  calculate the escape fluxes and compare our results to observations.

Title: Numerical simulation of the solar wind disturbances propagating
    to the distant heliosphere
Authors: Provornikova, E. A.; Opher, M.; Izmodenov, V.; Toth, G.
Bibcode: 2010AGUFMSH51D1721P
Altcode:
  The propagation of waves in the solar wind plasma from 1 AU to the
  heliospheric boundaries is studied. First we consider the simple
  1D spherically symmetric model of the solar wind interaction with
  the local interstellar medium to describe the wave evolution in
  the supersonic solar wind flow in which parameters change with
  heliocentric distance. The hydrodynamics solution and the influence of
  the interstellar H atoms on the wave structure in the solar wind is
  discussed. The 2D kinetic-gasdynamic model (Izmodenov et al., 2005,
  2008) and 3D MHD model (Opher et al. 2009) are used to study the
  interaction of the different types of waves in the solar wind with
  the the termination shock and heliopause.

Title: Hall MHD Study of the Solar wind Interaction with Venus
Authors: Nagy, A. F.; Ma, Y.; Russell, C. T.; Zhang, T.; Wei, H.;
   Strangeway, R. J.; Toth, G.
Bibcode: 2010AGUFMSM33D..01N
Altcode:
  A multi-species, global, Hall MHD model is used to study the solar
  wind interaction with Venus ionosphere/atmosphere. This model is
  based on the numerical model that has been successfully applied to
  Mars (Ma et al., 2004), with Hall effect included. A self-consistent
  Venus ionosphere is calculated in the model with three ion species
  (O+, O2+ and CO2+). The related chemical reactions and collision
  processes are also considered. Our simulation domain covers the region
  from 100km altitude to 16 Rv in the tail. An adaptive spherical grid
  structure is used with radial resolution of about 15 km in the lower
  ionosphere. Mass-loading effect is examined for both solar maximum
  and solar minimum conditions. The importance of the Hall effect will
  be discussed. We also show comparisons between our model results
  with the magnetic fields observed by the magnetometer carried aboard
  Venus Express.

Title: Two Way Coupling RAM-SCB to the Space Weather Modeling
    Framework
Authors: Welling, D. T.; Jordanova, V. K.; Zaharia, S. G.; Toth, G.
Bibcode: 2010AGUFMSA41B1720W
Altcode:
  The Ring current Atmosphere interaction Model with Self-Consistently
  calculated 3D Magnetic field (RAM-SCB) has been used to successfully
  study inner magnetosphere dynamics during different solar wind and
  magnetosphere conditions. Recently, one way coupling of RAM-SCB
  with the Space Weather Modeling Framework (SWMF) has been achieved
  to replace all data or empirical inputs with those obtained through
  first-principles-based codes: magnetic field and plasma flux outer
  boundary conditions are provided by the Block Adaptive Tree Solar wind
  Roe-type Upwind Scheme (BATS-R-US) MHD code, convection electric field
  is provided by the Ridley Ionosphere Model (RIM), and ion composition
  is provided by the Polar Wind Outflow Model (PWOM) combined with a
  multi-species MHD approach. These advances, though creating a powerful
  inner magnetosphere virtual laboratory, neglect the important mechanisms
  through which the ring current feeds back into the whole system,
  primarily the stretching of the magnetic field lines and shielding of
  the convection electric field through strong region two Field Aligned
  Currents (FACs). In turn, changing the magnetosphere in this way changes
  the evolution of the ring current. To address this shortcoming, the
  coupling has been expanded to include feedback from RAM-SCB to the
  other coupled codes: region two FACs are returned to the RIM while
  total plasma pressure is used to nudge the MHD solution towards the
  RAM-SCB values. The impacts of the two way coupling are evaluated on
  three levels: the global magnetospheric level, focusing on the impact on
  the ionosphere and the shape of the magnetosphere, the regional level,
  examining the impact on the development of the ring current in terms
  of energy density, anisotropy, and plasma distribution, and the local
  level to compare the new results to in-situ measurements of magnetic
  and electric field and plasma. The results will also be compared to past
  simulations using the one way coupling and no coupling whatsoever. This
  work is the first to fully couple an anisotropic kinetic ring current
  code with a self-consistently calculated magnetic field to a set of
  global models.

Title: Modeling the Rapid Rebuilding of the Radiation Belts During
    High Speed Streams
Authors: Glocer, A.; Fok, M. H.; Nagai, T.; Toth, G.
Bibcode: 2010AGUFMSM24A..07G
Altcode:
  Recent observations by Akebono/RDM have shown several cases of
  &gt;2.5 MeV radiation belt electron enhancements occuring on time
  scales of less than a few hours. These intervals are shorter than
  typical radial diffusion or wave-particle interactions can account
  for. We choose two so-called "rapid rebuilding'' events that occur
  during high speed streams (July 22, 2009 and September 4, 2008) and
  simulated them with the coupled BATSRUS-RBE model. We demonstrate
  that strong dipolarization events in the magnetospheric magnetic field
  result in strong radial transport and energization of radiation belt
  electrons. The modeled enhancment, time scales, and commencment time
  are shown to be consistent with Akebono/RDM observations.

Title: Simulating the one-dimensional structure of Titan's upper
atmosphere: 1. Formulation of the Titan Global Ionosphere-Thermosphere
    Model and benchmark simulations
Authors: Bell, Jared M.; Bougher, Stephen W.; Waite, J. Hunter;
   Ridley, Aaron J.; Magee, Brian A.; Mandt, Kathleen E.; Westlake,
   Joseph; DeJong, Anna D.; Bar–Nun, Akiva; Jacovi, Ronen; Toth, Gabor;
   De La Haye, Virginie
Bibcode: 2010JGRE..11512002B
Altcode:
  We employ a newly developed Navier-Stokes model, the Titan Global
  Ionosphere-Thermosphere Model (T-GITM) to address the one dimensional
  (1-D) coupled composition, dynamics, and energetics of Titan's upper
  atmosphere. Our main goals are to delineate the details of this new
  theoretical tool and to present benchmark calibration simulations
  compared against the Ion-Neutral Mass Spectrometer (INMS) neutral
  density measurements. First, we outline the key physical routines
  contained in T-GITM and their computational formulation. Then, we
  compare a series of model simulations against recent 1-D work by Cui
  et al. (2008), Strobel (2008, 2009), and Yelle et al. (2008) in order
  to provide a fiducial for calibrating this new model. In paper 2 and a
  future paper, we explore the uncertainties in our knowledge of Titan's
  atmosphere between ∼500 km and 1000 km in order to determine how
  the present measurements constrain our theoretical understanding of
  atmospheric structures and processes.

Title: The effect of the magnetic field stretching on the development
    of the ring current
Authors: Ilie, R.; Toth, G.; Liemohn, M. W.; Skoug, R. M.
Bibcode: 2010AGUFMSM31B1871I
Altcode:
  While the dipolar solution for the geomagnetic field during quiet
  times represents a reasonable assumption, during storm activity this
  assumption becomes invalid. Theoretical and numerical modifications to
  an inner magnetosphere - Hot Electron Ion Drift Integrator (HEIDI)-
  model are implemented, in order to accommodate for a non-dipolar
  arbitrary magnetic field. HEIDI solves the time dependent, gyration and
  bounced averaged kinetic equation for the phase space density of one
  or more ring current species. In this study the effect of the magnetic
  field stretching on the build-up of the ring current is examined for
  both real and idealized input conditions.

Title: Self-consistent inner magnetosphere simulation driven by a
    global MHD model
Authors: Zaharia, Sorin; Jordanova, V. K.; Welling, D.; Tóth, G.
Bibcode: 2010JGRA..11512228Z
Altcode:
  We present results from a one-way coupling between the kinetic Ring
  Current Atmosphere Interactions Model with Self-Consistent B field
  (RAM-SCB) and the Space Weather Modeling Framework (SWMF). RAM-SCB
  obtains plasma distribution and magnetic field at model boundaries
  from the Block Adaptive Tree Solar Wind Roe Upwind Scheme (BATS-R-US)
  magnetohydrodynamics (MHD) model and convection potentials from the
  Ridley Ionosphere Model within SWMF. We simulate the large geomagnetic
  storm of 31 August 2005 (minimum SYM-H of -116 nT). Comparing SWMF
  output with Los Alamos National Laboratory geostationary satellite
  data, we find SWMF plasma to be too cold and dense if assumed to
  consist only of protons; this problem is alleviated if heavier ions are
  considered. With SWMF inputs, we find that RAM-SCB reproduces well storm
  time magnetosphere features: ring current morphology, dusk side peak,
  pitch angle anisotropy, and total energy. The RAM-SCB ring current and
  Dst are stronger than the SWMF ones and reproduce observations much
  better. The calculated field-aligned currents (FAC) compare reasonably
  well with 2 h averaged pictures from Iridium satellite data. As the
  ring current peak rotates duskward in the storm main phase, the region
  2 FACs rotate toward noon, a feature also seen in observations. Finally,
  the RAM-SCB magnetic field outperforms both the dipole and the BATS-R-US
  field at Cluster and Polar spacecraft locations. This study shows the
  importance of a kinetic self-consistent approach and the sensitive
  dependence of the storm time inner magnetosphere on plasma sheet
  conditions and the cross polar cap potential. The study showcases the
  RAM-SCB capability as an inner magnetosphere module coupled with a
  global MHD model.

Title: Improving the physics models in the Space Weather Modeling
    Framework
Authors: Toth, G.; Fang, F.; Frazin, R. A.; Gombosi, T. I.; Ilie,
   R.; Liemohn, M. W.; Manchester, W. B.; Meng, X.; Pawlowski, D. J.;
   Ridley, A. J.; Sokolov, I.; van der Holst, B.; Vichare, G.; Yigit,
   E.; Yu, Y.; Buzulukova, N.; Fok, M. H.; Glocer, A.; Jordanova, V. K.;
   Welling, D. T.; Zaharia, S. G.
Bibcode: 2010AGUFMSM51A1757T
Altcode:
  The success of physics based space weather forecasting depends on
  several factors: we need sufficient amount and quality of timely
  observational data, we have to understand the physics of the Sun-Earth
  system well enough, we need sophisticated computational models,
  and the models have to run faster than real time on the available
  computational resources. This presentation will focus on a single
  ingredient, the recent improvements of the mathematical and numerical
  models in the Space Weather Modeling Framework. We have developed a
  new physics based CME initiation code using flux emergence from the
  convection zone solving the equations of radiative magnetohydrodynamics
  (MHD). Our new lower corona and solar corona models use electron heat
  conduction, Alfven wave heating, and boundary conditions based on solar
  tomography. We can obtain a physically consistent solar wind model from
  the surface of the Sun all the way to the L1 point without artificially
  changing the polytropic index. The global magnetosphere model can now
  solve the multi-ion MHD equations and take into account the oxygen
  outflow from the polar wind model. We have also added the options
  of solving for Hall MHD and anisotropic pressure. Several new inner
  magnetosphere models have been added to the framework: CRCM, HEIDI
  and RAM-SCB. These new models resolve the pitch angle distribution
  of the trapped particles. The upper atmosphere model GITM has been
  improved by including a self-consistent equatorial electrodynamics
  and the effects of solar flares. This presentation will very briefly
  describe the developments and highlight some results obtained with
  the improved and new models.

Title: Two-fluid Mhd Study On Ion Loss From Titan'S Atmosphere
Authors: Ma, Yingjuan; Russell, C. T.; Nagy, A. F.; Toth, G.;
   Dougherty, M. K.; Cravens, T. E.; Wellbrock, A.; Coates, A. J.;
   Garnier, P.; Wahlund, J.; Crary, F. J.
Bibcode: 2010DPS....42.3617M
Altcode: 2010BAAS...42.1068M
  This presentation report progress on modeling of Titan's plasma
  interaction. The single fluid model is improved by including an
  electron energy equation in the Hall MHD model so that both electron
  temperature and ion temperature are self-consistently calculated. The
  plasma interaction with Titan is expected to vary as the moon moves
  around its orbit. Using the improved model, we compare the structure
  of the interaction under two extreme conditions, corresponding to
  upstream flow interacting with the nightside and dayside ionosphere
  respectively. Model results show that the dayside ionosphere is more
  extended and the flow is more disturbed in the 6 SLT case than in
  the 18 SLT case. We also calculate the ion escape rates under these
  conditions and compare with Cassini observations of the available low
  altitudes Cassini flybys in corresponding SLTs.

Title: Multi-Ion Magnetohydrodynamics
Authors: Toth, G.; Glocer, A.; Ma, Y.; Najib, D.; Gombosi, T.
Bibcode: 2010ASPC..429..213T
Altcode:
  We derive and numerically solve the full set of magnetohydrodynamic
  equations with multiple ion fluids. The numerical difficulties and the
  algorithmic solutions are discussed. We show some preliminary results
  for the interaction of Mars' ionosphere with the solar wind.

Title: Comparison of the open-closed separatrix in a global
magnetospheric simulation with observations: The role of the ring
    current
Authors: Rae, I. J.; Kabin, K.; Lu, J. Y.; Rankin, R.; Milan, S. E.;
   Fenrich, F. R.; Watt, C. E. J.; Zhang, J. -C.; Ridley, A. J.; Gombosi,
   T. I.; Clauer, C. R.; Tóth, G.; DeZeeuw, D. L.
Bibcode: 2010JGRA..115.8216R
Altcode: 2010JGRA..11508216R
  The development of global magnetospheric models, such as Space
  Weather Modeling Framework (SWMF), which can accurately reproduce
  and track space weather processes has high practical utility. We
  present an interval on 5 June 1998, where the location of the
  polar cap boundary, or open-closed field line boundary (OCB), can be
  determined in the ionosphere using a combination of instruments during
  a period encompassing a sharp northward to southward interplanetary
  field turning. We present both point- and time-varying comparisons
  of the observed and simulated boundaries in the ionosphere and
  find that when using solely the coupled ideal magnetohydrodynamic
  magnetosphere-ionosphere model, the rate of change of the OCB to a
  southward turning of the interplanetary field is significantly faster
  than that computed from the observational data. However, when the inner
  magnetospheric module is incorporated, the modeling framework both
  qualitatively, and often quantitatively, reproduces many elements of
  the studied interval prior to an observed substorm onset. This result
  demonstrates that the physics of the inner magnetosphere is critical
  in shaping the boundary between open and closed field lines during
  periods of southward interplanetary magnetic field (IMF) and provides
  significant insight into the 3-D time-dependent behavior of the Earth's
  magnetosphere in response to a northward-southward IMF turning. We
  assert that during periods that do not include the tens of minutes
  surrounding substorm expansion phase onset, the coupled SWMF model may
  provide a valuable and reliable tool for estimating both the OCB and
  magnetic field topology over a wide range of latitudes and local times.

Title: Including gap region field-aligned currents and magnetospheric
    currents in the MHD calculation of ground-based magnetic field
    perturbations
Authors: Yu, Yiqun; Ridley, Aaron J.; Welling, Dan T.; Tóth, Gabor
Bibcode: 2010JGRA..115.8207Y
Altcode: 2010JGRA..11508207Y
  Many high-latitude modeling studies utilize the horizontal ionospheric
  Hall current in calculating ground-based magnetic perturbations, but
  low-latitude and midlatitude studies should include current systems such
  as the magnetospheric, field-aligned, and Pedersen currents. Recently,
  by including all these current systems, a more precise ground-based
  perturbation calculator has been implemented in the Space Weather
  Modeling Framework. Using this new method, ground-based perturbations
  generated by different current systems are analyzed at low, middle,
  and high latitudes. As a result of the current systems, MLT-UT maps
  of ground-based perturbations are studied. Furthermore, nine storms
  events are simulated at more than 20 low-latitude and midlatitude
  magnetometer locations and compared with observational ground-based
  perturbations. These studies show that for specifying the northward
  component of the ground magnetic perturbations, the inclusion of
  magnetospheric, field-aligned, and Pedersen current is important
  and improves the prediction significantly over the prediction only
  considering the Hall current in the calculation. The improvement is
  the most during the storm main phase. However, for the vertical and
  eastward components of the perturbations, which were typically smaller
  than the northward component, the inclusion of these current systems
  actually made the specifications worse because the ring current in
  the model rotates more toward the dayside than in reality.

Title: Dynamics of ring current and electric fields in the inner
magnetosphere during disturbed periods: CRCM-BATS-R-US coupled model
Authors: Buzulukova, N.; Fok, M. -C.; Pulkkinen, A.; Kuznetsova, M.;
   Moore, T. E.; Glocer, A.; Brandt, P. C.; Tóth, G.; Rastätter, L.
Bibcode: 2010JGRA..115.5210B
Altcode: 2010JGRA..11505210B
  We present simulation results from a one-way coupled global MHD model
  (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and
  kinetic ring current models (Comprehensive Ring Current Model, CRCM,
  and Fok Ring Current, FokRC). The BATS-R-US provides the CRCM/FokRC
  with magnetic field information and plasma density/temperature at the
  polar CRCM/FokRC boundary. The CRCM uses an electric potential from
  the BATS-R-US ionospheric solver at the polar CRCM boundary in order
  to calculate the electric field pattern consistent with the CRCM
  pressure distribution. The FokRC electric field potential is taken
  from BATS-R-US ionospheric solver everywhere in the modeled region,
  and the effect of Region II currents is neglected. We show that for
  an idealized case with southward-northward-southward Bz IMF turning,
  CRCM-BATS-R-US reproduces well known features of inner magnetosphere
  electrodynamics: strong/weak convection under the southward/northward
  Bz; electric field shielding/overshielding/penetration effects; an
  injection during the substorm development; Subauroral Ion Drift or
  Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore,
  we find for the idealized case that SAID/PJ forms during the substorm
  growth phase, and that substorm injection has its own structure of
  field-aligned currents which resembles a substorm current wedge. For
  an actual event (12 August 2000 storm), we calculate ENA emissions and
  compare with Imager for Magnetopause-to-Aurora Global Exploration/High
  Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the
  global morphology of ring current and the fine structure of ring
  current injection. The FokRC-BATS-R-US shows the effect of a realistic
  description of Region II currents in ring current-MHD coupled models.

Title: Interaction of Saturn's magnetosphere and its moons:
    1. Interaction between corotating plasma and standard obstacles
Authors: Jia, Y. -D.; Russell, C. T.; Khurana, K. K.; Toth, G.;
   Leisner, J. S.; Gombosi, T. I.
Bibcode: 2010JGRA..115.4214J
Altcode: 2010JGRA..11504214J
  The interaction of Saturn's inner magnetosphere with its moons ranges
  from the addition of significant quantities of gas, dust, and plasma,
  causing significant consequences for the dynamics and energetics
  of the entire Saturnian magnetosphere, to the simple absorption of
  plasma and energetic particles by the icy moons with non-electrically
  conducting interiors. The interaction with these moons is complex with
  the contribution of many physical processes, depending on the geometry
  of any plume, the structure of the atmosphere, and its interaction with
  the surface and interior of the moon, the latter by induced fields. Our
  ultimate goal is to understand the complexities of this interaction
  and its temporal variations, especially at Enceladus. In this paper
  we use magnetohydrodynamics (MHD) code for addressing the flow around
  obstacles that are simpler than the Enceladus interaction. These
  simulations both help us understand the interaction with other icy moons
  and prepare us for the simulation of the flow around Enceladus. The
  processes involved include ordinary collisions, impact ionization,
  photoionization, and charge exchange. We examine a series of simple
  canonical interactions before we later apply our simulation where
  the multiple processes are occurring simultaneously with asymmetric
  geometries. We apply our 3-D MHD model to simulate the interaction
  between the Saturnian corotational plasma flow for the following cases:
  an absorbing body having an insulating surface; ion pickup via photo and
  impact ionization from a spherically symmetric neutral cloud; charge
  exchange with such a neutral cloud; and ion pickup at an insulating,
  absorbing body with an atmosphere acted upon by the sum of the three
  ionization processes. In addition to validating the model and obtaining
  a deeper understanding of the consequences of each interaction, we can
  immediately make some conclusions about the Enceladus interaction. We
  find that the magnetometer data are most consistent with the surface
  of Enceladus being absorbing and insulating, rather than the surface
  being reflecting and electrically conducting. For the conditions in
  the corotating flow at Enceladus, the perturbation to the plasma flow
  produced by photo/impact ionization is an order of magnitude smaller
  than that produced by charge exchange. Moreover, the perturbation to the
  magnetic field B<SUB>z</SUB> component by a spherically symmetric mass
  loading source alone is an order of magnitude smaller than that observed
  in the neighborhood of the plume. Thus, the perturbation observed
  in the magnetometer data is primarily due to the mass loading in the
  plume, which is primarily ion-neutral charge exchange. The geometry
  and source strength of the plume are investigated in a following paper.

Title: The Space Weather Modeling Framework (SWMF): Models and
    Validation
Authors: Gombosi, Tamas; Toth, Gabor; Sokolov, Igor; de Zeeuw, Darren;
   van der Holst, Bart; Ridley, Aaron; Manchester, Ward, IV
Bibcode: 2010cosp...38.4166G
Altcode: 2010cosp.meet.4166G
  In the last decade our group at the Center for Space Environment
  Modeling (CSEM) has developed the Space Weather Modeling Framework
  (SWMF) that efficiently couples together different models describing
  the interacting regions of the space environment. Many of these domain
  models (such as the global solar corona, the inner heliosphere or the
  global magneto-sphere) are based on MHD and are represented by our
  multiphysics code, BATS-R-US. SWMF is a powerful tool for coupling
  regional models describing the space environment from the solar
  photosphere to the bottom of the ionosphere. Presently, SWMF contains
  over a dozen components: the solar corona (SC), eruptive event generator
  (EE), inner heliosphere (IE), outer heliosphere (OH), solar energetic
  particles (SE), global magnetosphere (GM), inner magnetosphere (IM),
  radiation belts (RB), plasmasphere (PS), ionospheric electrodynamics
  (IE), polar wind (PW), upper atmosphere (UA) and lower atmosphere
  (LA). This talk will present an overview of SWMF, new results obtained
  with improved physics as well as some validation studies.

Title: A 3D Multi-fluid MHD Study of the Interaction of the Solar
    Wind with the Ionosphere/Atmosphere System of Mars.
Authors: Najib, Dalal; Nagy, Andrew; Toth, Gabor; Ma, Yingjuan
Bibcode: 2010cosp...38.1406N
Altcode: 2010cosp.meet.1406N
  We use our new four species multi-fluid model to study the interaction
  of the solar wind with Mars. The lower boundary of our model is at
  100 km, below the main ionospheric peak, and the radial resolution is
  about 10 km in the ionosphere, thus the model does a very good job in
  reproducing the ionosphere and the associated processes. We carry out
  calculations for high and low solar activity conditions and establish
  the importance of mass loading by the extended exosphere of Mars. We
  also calculate the atmospheric escape of the ionospheric species,
  including pick up ions. Finally, we compare our model results with
  the Viking, MGS and Mars Express observations.

Title: Exploring the Effects of Ionospheric Outflow on the Inner
    Magnetosphere using RAM-SCB
Authors: Welling, Daniel; Jordanova, Vania; Zaharia, Sorin; Toth, Gabor
Bibcode: 2010cosp...38.2212W
Altcode: 2010cosp.meet.2212W
  The Ring current Atmosphere interactions Model with Self-Consistently
  calculated 3D Mag-netic field (RAM-SCB) has been used to successfully
  study inner magnetosphere dynamics during different solar wind and
  magnetosphere conditions. Historically, this numerical model has relied
  on empirical formulations to provide magnetic field boundary conditions,
  ionospheric electric potential, and to specify heavy ion composition at
  the outer boundary. Either empirical models or observations typically
  specify plasma density and temperature at the boundary. Re-cently,
  RAM-SCB has been integrated into the Space Weather Modeling Framework,
  a flexible system that creates real time, two-way coupling between
  RAM-SCB, the multi-species version of BATS-R-US global MHD and the
  Polar Wind Outflow Model. Through these couplings, RAM-SCB receives
  first-principle derived magnetic and plasma boundary conditions as
  well as convective electric potentials from the SWMF and returns inner
  magnetosphere plasma pres-sure to correct the MHD solution. This
  work uses the newly coupled system to explore the relationship
  between ionospheric outflow and ring current plasma distribution and
  composition. Data-model comparisons of magnetic field and particle
  fluxes are used to investigate how well the coupled system represents
  real world conditions.

Title: Global Asymmetries in the Heliosphere: Signature of the
    Interstellar Magnetic Field
Authors: Opher, Merav; Alouani-Bibi, Fathallah; Izmodenov, Vladislav;
   Richardson, John; Toth, Gabor; Gombosi, Tamas
Bibcode: 2010cosp...38.1604O
Altcode: 2010cosp.meet.1604O
  In recent years it become clear that magnetic field effects, plays an
  important role in the Heliosphere, from shaping it and possible being
  responsible for the asymmetries observed in the Voyager data (e.g.,
  Opher et al. 2007, 2009). However, the strength and orientation of
  the field in the local interstellar medium near the heliosphere has
  been poorly constrained. Previous estimates of the field strength
  range from 1.8-2.5 G and the field was thought to be parallel to the
  Galactic plane or inclined by 38-60 (Lallement et al. 2005) or 60-90
  (Opher et al. 2007) to this plane. These estimates relied either on
  indirect observational inferences or modeling in which the interstellar
  neutral hydrogen was not taken into account. We will discuss recent
  work that indicate that based on asymmetries detected by Voyager 1
  and 2 and measurements of the deflection of the solar wind plasma
  flows in the heliosheath (Opher et al. 2009) indicate that the field
  strength in the local interstellar medium is strong, between 4-5 G
  (Other works such as Izmodenov 2009; Pogorelov et al. 2009; Ratkiewickz
  et al. 2009 found similar strength). The field is tilted 20-30 from
  the interstellar medium flow direction (resulting from the peculiar
  motion of the Sun in the Galaxy) and is at an angle of about 30 from
  the Galactic plane. We will discuss the effect of such magnetic field
  in the global asymmetries of the heliosphere. We further will comment
  on the effect on asymmetries of our recent model of Kinetic-MHD model
  treating the neutrals in kinetic fashion (Alouani-Bibi et al. 2010). We
  will relate our findings with the most recent results of IBEX that
  indicate that the interstellar magnetic field has a strong signature
  in the emission of energetic neutrals.

Title: Magnetosphere modeling using MHD with anisotropic pressure
Authors: Toth, Gabor; Meng, Xing; van der Holst, Bart; Gombosi, Tamas
Bibcode: 2010cosp...38.2066T
Altcode: 2010cosp.meet.2066T
  In several space physics systems, including the magnetosphere,
  the parallel and perpendicular (with respect to the magnetic
  field) components of the pressure tensor can become significantly
  different. The BATS-R-US code has recently been extended with the
  capability of solving the magnetohydrodynamic equations with an
  anisotropic ion pressure. The anisotropy is limited by instabilities
  and particle-particle and particle-wave interactions. These effects
  are taken into account as parameterized source terms. We use the total
  energy equation in combination with the two pressure equations so that
  we use a conservative scheme as much as possible. This is important to
  correctly capture the bow shock. We also have the option of allowing the
  electron temperature to be different from the ion temperature(s). In
  our current model the separate electron temperature is assumed to be
  isotropic. Our preliminary results indicate that using anisotropic ion
  pressure instead of isotropic pressure gives significantly different
  results. In this talk we will present a systematic comparison between
  the isotropic and anisotropic MHD models. We will use observational
  data from the WIND and Cluster satellites to validate our new model
  for the quiet magnetosphere as well as for magnetic storms.

Title: Hybrid simulation of interstellar wind interaction with solar
    wind plasma
Authors: Izmodenov, V.; Alouani Bibi, F.; Opher, M.; Aleksashov, D.;
   Toth, G.
Bibcode: 2009AGUFMSH21A1496I
Altcode:
  Iterative Hybrid (Kinetic / MHD) approach is used to study the
  interaction of the partly ionized interstellar wind with the fully
  ionized solar wind plasma. Charged and neutral components are coupled
  though charge exchange. The location and topology (e.g. asymmetries) of
  the Heliospheric boundaries (BS, HP and TS) are analyzed and compared
  to previous multi-fluid approach, where the kinetic description of
  neutrals was approximated by hydrodynamic multi neutral species (4
  species). Based on analysis of global heliospheric asymmetries, we use
  our best estimate for the interstellar magnetic field orientation and
  intensity. The iterative scheme is performed using the ionized fluid
  properties obtained with our 3D MHD code as a source term for the
  neutral H, which is treated by solving the Boltzmann Kinetic equation,
  the output of the later is fed back to the MHD code as plasma source
  terms. Each of these phases is allowed to reach a steady state before
  each iteration.

Title: Ion Loss from Titan's Atmosphere versus Local Time: A two-fluid
    MHD Study
Authors: Ma, Y.; Russell, C. T.; Nagy, A. F.; Toth, G.; Dougherty,
   M. K.; Cravens, T. E.; Wellbrock, A.; Coates, A. J.; Garnier, P.;
   Wahlund, J.; Crary, F. J.
Bibcode: 2009AGUFM.P13D..06M
Altcode:
  This presentation report recent progress on modeling of plasma
  interaction around Titan. The single fluid MHD model reproduces only
  the sum of the electron temperature and ion temperature. Our recent
  modeling includes an electron energy equation in the Hall MHD model so
  that both electron temperature and ion temperature ARE self-consistently
  calculated. The plasma interaction with Titan is expected to vary as the
  moon moves around its orbit. Using the improved model, we compare the
  structure of the interaction under two extreme conditions, corresponding
  to upstream flow interacting with the nightside and dayside ionosphere
  respectively. Model results show that the dayside ionosphere is more
  extended and the flow is more disturbed in the 6 SLT case than in the
  18 SLT case. We calculate the ion escape rates under these conditions
  and compare with Cassini observations of the only two available low
  altitudes Cassini flybys in Saturn's dawn (T5 flyby) and dusk (T34
  flyby) sectors.

Title: Global simulations of dynamic magnetosphere response to steady
    southward IMF driving
Authors: Patel, K.; Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.;
   Toth, G.; de Zeeuw, D.; Gombosi, T. I.
Bibcode: 2009AGUFMSM13B1608P
Altcode:
  We utilize the global MHD model BATS-R-US with incorporated
  nongyrotropic effects in diffusion regions to investigate the dynamic
  magnetosphere response to southward interplanetary magnetic field (IMF)
  driving. We analyze relative importance of the solar wind conditions,
  ionosphere conductance and dissipation mechanisms supporting the
  magnetotail reconnection in controlling the mode of magnetic energy
  release. The conditions for the quasi-periodic loading/unloading
  sawtooth response will be discussed.

Title: A new method for global magnetosphere simulations: an implicit
    scheme with limited numerical diffusion
Authors: Toth, G.; Meng, X.; Gombosi, T. I.
Bibcode: 2009AGUFMSM51A1321T
Altcode:
  We are introducing a new scheme to model the global magnetosphere
  with less numerical diffusion. The new scheme combines the stability
  of an implicit solver with a limited diffusive numerical flux. The
  new scheme is an alternative to the standard "Boris correction"
  that solves the semi-relativistic MHD equations with an artificially
  reduced speed of light. While the Boris correction is an efficient and
  well established method, it changes the time dependent behavior of the
  equations, since it artificially reduces the propagation speeds. The
  new scheme on the other hand does not modify the physics, only the
  numerical algorithm. We are comparing the limited numerical diffusion
  scheme with the Boris correction for idealized problems as well as
  for magnetic storm simulations.

Title: A 3D Multi-fluid MHD Study of the Interaction of the Solar
    Wind with the Ionosphere/Atmosphere System of Mars
Authors: Najib, D.; Nagy, A. F.; Ma, Y.; Toth, G.
Bibcode: 2009AGUFM.P11B1213N
Altcode:
  We use our new four species multi-fluid model to study the interaction
  of the solar wind with Mars. The lower boundary of our model is at
  100 km, below the main ionospheric peak, and the radial resolution
  is about 10 km in the ionosphere, thus the model does a very good
  job in reproducing the ionosphere and the associated processes. We
  carry out calculations for high and low solar activity conditions and
  establish the importance of the extended exosphere of Mars. We also
  calculate the atmospheric escape of the ionospheric species and the
  added contributions from charge exchange in the exosphere. Finally,
  we compare our model results with the Viking, MGS and Mars observations.

Title: Coupling HEIDI into the SWMF
Authors: Ilie, R.; Liemohn, M. W.; Toth, G.; Ridley, A. J.
Bibcode: 2009AGUFMSM11A1546I
Altcode:
  In this study we will present results from the Hot Electron and Ion
  Drift Integrator (HEIDI) model, which has been recently coupled into
  the Space Weather Modeling Framework (SWMF). HEIDI solves the time
  dependent, gyration and bounced averaged kinetic equation for the
  phase space density of different ring current species. An advantage
  of using HEIDI is that it computes full pitch angle distributions
  for all local times and radial distances. The largest modification
  and improvement to HEIDI is the inclusion of a non-dipolar, time
  dependent magnetic field. The bounce-averaged coefficients, which
  make up the bounce-averaged kinetic equation, have been rewritten to
  account for an arbitrary magnetic field. The gradient/curvature drift
  includes both azimuthal and radial components. Moreover, arbitrary grid
  sizes in radial, azimuthal, energy and pitch angle are allowed. HEIDI
  receives full and realistic magnetic field distributions from BATSRUS
  and the electric potential from the ionospheric electrodynamics model,
  through couplers within SWMF. Preliminary results of the self-consistent
  coupling between HEIDI and BATSRUS during idealized and realistically
  drive time-periods will be presented.

Title: Multifluid Block-Adaptive-Tree Solar wind Roe-type Upwind
Scheme: Magnetospheric composition and dynamics during geomagnetic
    storms—Initial results
Authors: Glocer, A.; Tóth, G.; Ma, Y.; Gombosi, T.; Zhang, J. -C.;
   Kistler, L. M.
Bibcode: 2009JGRA..11412203G
Altcode:
  The magnetosphere contains a significant amount of ionospheric
  O<SUP>+</SUP>, particularly during geomagnetically active times. The
  presence of ionospheric plasma in the magnetosphere has a notable
  impact on magnetospheric composition and processes. We present a
  new multifluid MHD version of the Block-Adaptive-Tree Solar wind
  Roe-type Upwind Scheme model of the magnetosphere to track the fate
  and consequences of ionospheric outflow. The multifluid MHD equations
  are presented as are the novel techniques for overcoming the formidable
  challenges associated with solving them. Our new model is then applied
  to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results
  are juxtaposed with traditional single-fluid MHD and multispecies MHD
  simulations from a previous study, thereby allowing us to assess the
  benefits of using a more complex model with additional physics. We
  find that our multifluid MHD model (with outflow) gives comparable
  results to the multispecies MHD model (with outflow), including a more
  strongly negative Dst, reduced CPCP, and a drastically improved magnetic
  field at geosynchronous orbit, as compared to single-fluid MHD with
  no outflow. Significant differences in composition and magnetic field
  are found between the multispecies and multifluid approach further away
  from the Earth. We further demonstrate the ability to explore pressure
  and bulk velocity differences between H<SUP>+</SUP> and O<SUP>+</SUP>,
  which is not possible when utilizing the other techniques considered.

Title: The link between pick-up ions and energetic neutral atoms
Authors: Alouani Bibi, F.; Opher, M.; Prested, C. L.; Schwadron,
   N. A.; Toth, G.
Bibcode: 2009AGUFMSH21B1508A
Altcode:
  We study the source (starting inside the termination shock) and
  transport of pick-up ions (PUI) linked to the generation of energetic
  neutral atoms (ENA). We use a three dimensional multi-fluid (seven
  populations: thermal protons, four neutral populations, PUI ions and
  ENA) magneto-hydrodynamic model. PUIs are injected into the simulation
  grid as an inner-boundary condition at 30 AU and appropriate PUI source
  terms are included inside the heliopause. At the inner-boundary, the
  PUI initial density and temperature are derived analytically assuming
  a Vasyliunas-Siscoe distribution function for these suprathermal
  particles. PUI production beyond the heliopause is neglected. The
  variations in the non-thermal solar wind pressure inside the heliopause
  as a result of PUI production and convection are analyzed. Implications
  of these pressure variations on the heliospheric boundaries and
  resulting ENA maps are discussed.

Title: Comparing Different Approaches of Modeling Magnetospheric
    Composition
Authors: Glocer, A.; Toth, G.; Fok, M. H.; Gombosi, T. I.; Yu, Y.;
   Moore, T.
Bibcode: 2009AGUFMSM22A..08G
Altcode:
  The magnetosphere contains a significant amount of ionospheric O+,
  particularly during geomagnetically active times. The presence of this
  ionospheric plasma has a notable impact on magnetospheric composition
  and processes. There currently exist only a handful of approaches to
  model magnetospheric composition: multi-fluid MHD, multi-species MHD,
  and individual particle tracing techniques. We present an overview
  of the advantages and disadvantages of these different approaches
  and provide a direct comparison of their results. Details of the new
  multi-fluid and multi-species MHD versions of the BATS-R-US model of
  the magnetosphere are given. The multi-fluid and multi-species MHD
  approaches are directly compared for May 4, 1998 and March 31, 2001
  geomagnetic storms. These approaches yield comparable results, namely
  a more strongly negative Dst, reduced CPCP, and a drastically improved
  magnetic field at geosynchronous orbit, as compared to single-fluid
  MHD with no ionospheric outflow. We also simulate the October 2002
  geomagnetic storm and directly compare our multi-fluid and multi-species
  simulations to the particle tracing approach used by Fok et al, [2008].

Title: Orientation and Magnitude of the Interstellar Magnetic Field
    from Heliosheath Flows
Authors: Opher, M.; Alouani Bibi, F.; Toth, G.; Richardson, J. D.;
   Izmodenov, V.; Gombosi, T. I.
Bibcode: 2009AGUFMSH32A..04O
Altcode:
  We show that the heliosheath flows can be used as a new and highly
  important data set to determine the interstellar magnetic field
  orientation and magnitude. We use a new three-dimensional model
  that includes both the plasma and the neutral H atoms as well as the
  interplanetary and interstellar magnetic fields. The field orientation
  and magnitude that we derive differ substantially from the those
  previously reported (Opher et al. 2006, 2007). We comment on the
  consequences of this result on the heliospheric global asymmetries (such
  as the field-aligned streaming of low energy particles, the distance of
  the termination shock, and the shape of the heliopause). We comments
  as well on the inference on the conditions on the local interstellar
  medium. We study the effect of numerical resolution and non-stationary
  on the model shock and find them to be negligible. We also comment
  on the possible effects of the tilt of current sheet, not included
  currently in the model (which at the time of the termination shock
  crossings of Voyager 1 and 2 was about 30 degrees). We present a
  simulation with a scaled down heliosphere which includes a dynamic
  time dependent current sheet.

Title: Coupling RAM-SCB to a Magnetospheric GCM and Polar Wind
    Outflow Model
Authors: Welling, D. T.; Jordanova, V.; Zaharia, S. G.; Toth, G.
Bibcode: 2009AGUFMSM13C1617W
Altcode:
  The Ring current Atmosphere interaction Model with Self-Consistently
  calculated 3D Magnetic field (RAM-SCB) has been used to successfully
  study inner magnetosphere dynamics during different solar wind and
  magnetosphere conditions. Historically, this numerical model has
  relied on empirical formulations to provide magnetic field boundary
  conditions, ionospheric electric potential, and to specify heavy ion
  content at the outer boundary. Either empirical models or observations
  typically specify plasma density at the boundary. Recently, RAM-SCB
  has been integrated into the Space Weather Modeling Framework,
  a flexible system that creates real time, two-way coupling between
  RAM-SCB, the multi-species version of BATS-R-US global MHD and the
  Polar Wind Outflow Model. Through these couplings, RAM-SCB receives
  first-principle derived magnetic and plasma boundary conditions from
  the SWMF and returns inner magnetosphere plasma pressure to correct the
  MHD solution. This paper summarizes the methodology used and presents
  simulation results of magnetospheric storms using the coupled codes. The
  impact of the coupling, especially the delivery of heavy ionospheric
  ions to RAM-SCB, on plasma pressure, energy density, and anisotropy
  in the inner magnetosphere are explored. Data-model comparisons are
  used to investigate how well the coupled system represents real world
  conditions.

Title: BATSRUS with Hall MHD and anisotropic pressure
Authors: Meng, X.; Toth, G.; Gombosi, T. I.
Bibcode: 2009AGUFMSM51A1344M
Altcode:
  We describe our progress in extending the capabilities of the BATS-R-US
  MHD code to model anisotropic pressure. In several space physics
  applications the assumption of isotropic pressure is not valid, and
  the parallel and perpendicular (with respect to the magnetic field)
  components of the pressure tensor can become significantly different. We
  will describe the equations and our progress with the implementation
  and testing of this new capability.

Title: A strong, highly-tilted interstellar magnetic field near the
    Solar System
Authors: Opher, M.; Bibi, F. Alouani; Toth, G.; Richardson, J. D.;
   Izmodenov, V. V.; Gombosi, T. I.
Bibcode: 2009Natur.462.1036O
Altcode:
  Magnetic fields play an important (sometimes dominant) role in the
  evolution of gas clouds in the Galaxy, but the strength and orientation
  of the field in the interstellar medium near the heliosphere has
  been poorly constrained. Previous estimates of the field strength
  range from 1.8-2.5μG and the field was thought to be parallel to the
  Galactic plane or inclined by 38-60° (ref. 2) or 60-90° (ref. 3)
  to this plane. These estimates relied either on indirect observational
  inferences or modelling in which the interstellar neutral hydrogen was
  not taken into account. Here we report measurements of the deflection of
  the solar wind plasma flows in the heliosheath to determine the magnetic
  field strength and orientation in the interstellar medium. We find that
  the field strength in the local interstellar medium is 3.7-5.5μG. The
  field is tilted ~20-30° from the interstellar medium flow direction
  (resulting from the peculiar motion of the Sun in the Galaxy) and is
  at an angle of about 30° from the Galactic plane. We conclude that
  the interstellar medium field is turbulent or has a distortion in the
  solar vicinity.

Title: Integration of the radiation belt environment model into the
    space weather modeling framework
Authors: Glocer, A.; Toth, G.; Fok, M.; Gombosi, T.; Liemohn, M.
Bibcode: 2009JASTP..71.1653G
Altcode:
  We have integrated the Fok radiation belt environment (RBE) model
  into the space weather modeling framework (SWMF). RBE is coupled
  to the global magnetohydrodynamics component (represented by the
  Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme, BATS-R-US,
  code) and the Ionosphere Electrodynamics component of the SWMF,
  following initial results using the Weimer empirical model for
  the ionospheric potential. The radiation belt (RB) model solves the
  convection-diffusion equation of the plasma in the energy range of 10
  keV to a few MeV. In stand-alone mode RBE uses Tsyganenko's empirical
  models for the magnetic field, and Weimer's empirical model for
  the ionospheric potential. In the SWMF the BATS-R-US model provides
  the time dependent magnetic field by efficiently tracing the closed
  magnetic field-lines and passing the geometrical and field strength
  information to RBE at a regular cadence. The ionosphere electrodynamics
  component uses a two-dimensional vertical potential solver to provide
  new potential maps to the RBE model at regular intervals. We discuss the
  coupling algorithm and show some preliminary results with the coupled
  code. We run our newly coupled model for periods of steady solar wind
  conditions and compare our results to the RB model using an empirical
  magnetic field and potential model. We also simulate the RB for an
  active time period and find that there are substantial differences in
  the RB model results when changing either the magnetic field or the
  electric field, including the creation of an outer belt enhancement
  via rapid inward transport on the time scale of tens of minutes.

Title: Multiscale Modeling of Reconnection: Effects on CME Dynamics
Authors: Evans, Rebekah Minnel; Kuznetsova, Maria M.; Opher, Merav;
   Toth, Gabor; Gombosi, Tamas I.
Bibcode: 2009shin.confE.189E
Altcode:
  Magnetic reconnection is believed to play a crucial role in
  the initiation and liftoff of a CME, and could continue during
  propagation. However, the best tool to study these events - advanced
  global MHD models - operates in the fluid regime and therefore is
  limited to unphysical numerical and/or ad hoc anomalous reconnection
  terms. Recently, efforts to include kinetic reconnection effects in a
  global MHD code were successfully implemented into the BATS-R-US model
  for the magnetotail. By applying the same techniques used in multiscale
  modeling of magnetospheric reconnection, we simulate for the first time
  the dissipation of magnetic energy of a CME as it propagates through
  the interplanetary medium and the feedback on the background solar
  wind. We initiate the CME using a modified Titov-Demoulin flux rope
  with the Space Weather Modeling Framework and determine the effects
  of the nongyrotropic corrections on the evolution out to 3Rsun.

Title: Modeling ionospheric outflows and their impact on the
    magnetosphere, initial results
Authors: Glocer, A.; Tóth, G.; Gombosi, T.; Welling, D.
Bibcode: 2009JGRA..114.5216G
Altcode: 2009JGRA..11405216G
  Ionospheric outflow has been shown to be a significant contributor to
  the plasma population of the magnetosphere during active geomagnetic
  conditions. We present the results of new efforts to model the source
  and effects of out-flowing plasma in the Space Weather Modeling
  Framework (SWMF). In particular, we develop and use the Polar Wind
  Outflow Model (PWOM), a field-aligned, multifluid, multifield line polar
  wind code to simulate the ionospheric outflow. The PWOM is coupled to
  the ionosphere electrodynamics and global magnetosphere components of
  the SWMF, so we can calculate the outflow and its resulting impact on
  magnetospheric composition and dynamics. By including the outflow as
  part of a coupled system, we study the consequences of outflow on the
  larger space environment system. We present our methodology for the
  magnetosphere-ionosphere coupling, as well as the effect of outflow on
  the magnetosphere during two geomagnetic storms. Moreover, we explore
  the use of multispecies MHD to track the resulting plasma composition
  in the magnetosphere. We find that, by including ionospheric outflow
  during geomagnetic storms, we can reduce the RMS error in the simulated
  magnetic field as compared with various GOES satellites by as much as
  50%. Additionally, we find that the outflow causes a strong decrease
  in Dst and in the cross-polar cap potential.

Title: Cavities of weak magnetic field strength in the wake of FTEs:
    Results from global magnetospheric MHD simulations
Authors: Kuznetsova, M. M.; Sibeck, D. G.; Hesse, M.; Wang, Y.;
   Rastaetter, L.; Toth, G.; Ridley, A.
Bibcode: 2009GeoRL..3610104K
Altcode:
  We use the global magnetohydrodynamic (MHD) code BATS-R-US
  to model multipoint observations of Flux Transfer Event (FTE)
  signatures. Simulations with high spatial and temporal resolution
  predict that cavities of weak magnetic field strength protruding
  into the magnetosphere trail FTEs. These predictions are consistent
  with recently reported multi-point Cluster observations of traveling
  magnetopause erosion regions (TMERs).

Title: Modeling the Radiation Belts During a Geomagnetic Storm
Authors: Glocer, A.; Fok, M.; Toth, G.
Bibcode: 2009AGUSMSM72A..07G
Altcode:
  We utilize the Radiation Belt Environment (RBE) model to simulate the
  radiation belt electrons during a geomagnetic storm. Particularly,
  we focus on the relative contribution of whistler mode wave-particle
  interactions and radial diffusion associated with rapid changes in the
  magnetospheric magnetic field. In our study, the RBE model obtains a
  realistic magnetic field from the BATS-R-US magnetosphere model at a
  regular, but adjustable, cadence. We simulate the storm with and without
  wave particle interactions, and with different frequencies for updating
  the magnetic field. The impacts of the wave-particle interactions,
  and the rapid variations in the magnetospheric magnetic field, can
  then be studied. Simulation results are also extracted along various
  satellite trajectories for direct comparison where appropriate.

Title: Simulations of Radiative Shocks in the Regime of SN Breakout
    Shocks.
Authors: Drake, R. Paul; Doss, F. W.; Fryxell, B.; Grosskopf, M. J.;
   Holloway, J. P.; van der Holst, B.; Huntington, C.; Kuranz, C. C.;
   Myra, E. S.; Powell, K. G.; Sokolov, I. V.; Stout, Q. F.; Toth, G.;
   Visco, A. J.
Bibcode: 2009AAS...21442706D
Altcode:
  We have entered an era when detection of shock breakout from SNe
  will become routine. Such shocks are radiative, as radiative energy
  transport is a dominant aspect of their dynamics. They are for a
  time in the regime where the system is optically thin outward from
  the density jump but optically thick inward. Accurate simulations of
  such shocks will be a challenge, as their radiation transport occurs
  on multiple scales and their hydrodynamics is unstable. In our Center
  for Radiative Shock Hydrodynamics we are developing a simulation code
  to simulate experimental radiative shocks that are in the regime of the
  SN breakout shocks. The code will feature block-adaptive hydrodynamics,
  realistic treatment of materials, and a variety of radiation transport
  options. We plan in due course to apply this code to SN breakout
  shocks. We will describe the code and show results of initial
  simulations of the experiments. The experiments produce such shock
  waves in Xe or Ar by using a laser to shock, ionize, and accelerate
  a Be plate into a gas-filled shock tube at above 100 km/s. We will
  discuss and show how structure develops in these systems due to both
  radiative energy transfer and hydrodynamic instability. <P />Supported
  by the DOE NNSA under the Predictive Sci. Academic Alliance Program
  by grant DE-FC52-08NA28616, the Stewardship Sci. Academic Alliances
  program by grant DE-FG52-04NA00064, and the Nat. Laser User Facility
  by grant DE-FG03-00SF22021.

Title: The Space Weather Modeling Framework
Authors: Toth, G.
Bibcode: 2009AGUSMSH22A..03T
Altcode:
  The Center for Space Environment Modeling (CSEM) at the University
  of Michigan has developed the Space Weather Modeling Framework
  (SWMF) that integrates independently developed models into a high
  performance simulation tool. The SWMF models a dozen physics domains
  spanning from the solar corona and heliosphere to the magnetosphere,
  ionosphere and thermosphere of the Earth. The SWMF can perform a
  realistic Sun-to-thermosphere simulation faster than real time on
  today's supercomputers. We also use subsets of the SWMF components
  to model various space physics systems. I will describe the current
  status of the SWMF and our plans for future development.

Title: 3D, Multi-fluid, MHD Calculations of the Solar Wind Interaction
    with Mars and the Associated Plasma Escape.
Authors: Najib, D.; Nagy, A.; Toth, G.; Ma, Y. -J.
Bibcode: 2009EGUGA..11.2219N
Altcode:
  We have used our new 3D, multi-fluid, MHD model to study the interaction
  of the solar wind with Mars. Our lower boundary is set at 100 km and
  we have a radial grid resolution of about 10 km in the ionosphere. We
  consider both photo and electron impact ionization, as well as charge
  exchange processes. We compare a number of calculated and measured
  parameters, such as bow shock and MPB locations. We also calculate the
  plasma escape fluxes, for a variety of solar and upstream conditions. We
  compare our calculated escape fluxes with the published, measured
  values obtained by the ASPERA instrument carried by Mars Express.

Title: Hall MHD on Block-Adaptive Grids
Authors: Tóth, G.; Ma, Y. -J.; Gombosi, T. I.
Bibcode: 2009ASPC..406..287T
Altcode:
  This proceedings paper is based on a much longer research paper that
  was published during the conference (Toth et al. 2008). We present
  a conservative second order accurate finite volume discretization
  of the magnetohydrodynamics equations including the Hall term on
  three dimensional block adaptive grids with Cartesian or generalized
  coordinates. Both explicit and implicit time integration schemes are
  developed. The parallel scaling and robustness are demonstrated by
  three dimensional simulations of planetary magnetospheres.

Title: Breakout Coronal Mass Ejection or Streamer Blowout: The
    Bugle Effect
Authors: van der Holst, B.; Manchester, W., IV; Sokolov, I. V.; Tóth,
   G.; Gombosi, T. I.; DeZeeuw, D.; Cohen, O.
Bibcode: 2009ApJ...693.1178V
Altcode:
  We present three-dimensional numerical magnetohydrodynamic (MHD)
  simulations of coronal mass ejections (CMEs) initiated by the breakout
  mechanism. The initial steady state consists of a bipolar active region
  embedded in the solar wind. The field orientation of the active region
  is opposite to that of the overarching helmet streamer, so that this
  pre-eruptive region consists of three arcades with a magnetic null
  line on the leading edge of the central arcade. By applying footpoint
  motion near the polarity inversion line of the central arcade, the
  breakout reconnection is turned on. During the eruption, the plasma in
  front of the breakout arcade gets swept up. The latter effect causes
  a pre-event swelling of the streamer. The width of the helmet streamer
  increases in time and follows a "bugle" pattern. In this paper, we will
  demonstrate that if this pre-event streamer swelling is insufficient,
  reconnection on the sides of the erupting breakout arcade/flux rope
  sets in. This will ultimately disconnect the helmet top, resulting in
  a streamer blowout CME. On the other hand, if this pre-event swelling
  is effective enough, the breakout reconnection will continue all the
  way to the top of the helmet streamer. The breakout mechanisms will
  then succeed in creating a breakout CME.

Title: Confronting Observations and Modeling: The Role of the
    Interstellar Magnetic Field in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Richardson, J. D.; Toth, G.; Gombosi, T. I.
Bibcode: 2009SSRv..143...43O
Altcode: 2008SSRv..tmp..178O
  Magnetic effects are ubiquitous and known to be crucial in space physics
  and astrophysical media. We have now the opportunity to probe these
  effects in the outer heliosphere with the two spacecraft Voyager 1
  and 2. Voyager 1 crossed, in December 2004, the termination shock and
  is now in the heliosheath. On August 30, 2007 Voyager 2 crossed the
  termination shock, providing us for the first time in-situ measurements
  of the subsonic solar wind in the heliosheath. With the recent in-situ
  data from Voyager 1 and 2 the numerical models are forced to confront
  their models with observational data. Our recent results indicate
  that magnetic effects, in particular the interstellar magnetic field,
  are very important in the interaction between the solar system and
  the interstellar medium. We summarize here our recent work that
  shows that the interstellar magnetic field affects the symmetry of
  the heliosphere that can be detected by different measurements. We
  combined radio emission and energetic particle streaming measurements
  from Voyager 1 and 2 with extensive state-of-the art 3D MHD modeling, to
  constrain the direction of the local interstellar magnetic field. The
  orientation derived is a plane ∼60°-90° from the galactic
  plane. This indicates that the field orientation differs from that
  of a larger scale interstellar magnetic field, thought to parallel
  the galactic plane. Although it may take 7-12 years for Voyager 2 to
  leave the heliosheath and enter the pristine interstellar medium,
  the subsonic flows are immediately sensitive to the shape of the
  heliopause. The flows measured by Voyager 2 in the heliosheath indicate
  that the heliopause is being distorted by local interstellar magnetic
  field with the same orientation as derived previously. As a result of
  the interstellar magnetic field the solar system is asymmetric being
  pushed in the southern direction. The presence of hydrogen atoms tend
  to symmetrize the solutions. We show that with a strong interstellar
  magnetic field with our most current model that includes hydrogen atoms,
  the asymmetries are recovered. It remains a challenge for future works
  with a more complete model, to explain all the observed asymmetries
  by V1 and V2. We comment on these results and implications of other
  factors not included in our present model.

Title: Time-dependent global MHD simulations of Cassini T32 flyby:
    From magnetosphere to magnetosheath
Authors: Ma, Y. J.; Russell, C. T.; Nagy, A. F.; Toth, G.; Bertucci,
   C.; Dougherty, M. K.; Neubauer, F. M.; Wellbrock, A.; Coates, A. J.;
   Garnier, P.; Wahlund, J. -E.; Cravens, T. E.; Crary, F. J.
Bibcode: 2009JGRA..114.3204M
Altcode: 2009JGRA..11403204M
  When the Cassini spacecraft flew by Titan on 13 June 2007,
  at 13.6 Saturn local time, Titan was directly observed to be
  outside Saturn's magnetopause. Cassini observations showed dramatic
  changes of magnetic field orientation as well as other plasma flow
  parameters during the inbound and outbound segments. In this paper,
  we study Titan's ionospheric responses to such a sudden change in
  the upstream plasma conditions using a sophisticated multispecies
  global MHD model. Simulation results of three different cases (steady
  state, simple current sheet crossing, and magnetopause crossing)
  are presented and compared against Cassini Magnetometer, Langmuir
  Probe, and Cassini Plasma Spectrometer observations. The simulation
  results provide clear evidence for the existence of a fossil field
  that was induced in the ionosphere. The main interaction features,
  as observed by the Cassini spacecraft, are well reproduced by the
  time-dependent simulation cases. Simulation also reveals how the fossil
  field was trapped during the interaction and shows the coexistence of
  two pileup regions with opposite magnetic orientation, as well as the
  formation of a pair of new Alfven wings and tail disconnection during
  the magnetopause crossing process.

Title: Confronting Observations and Modeling: The Role of the
    Interstellar Magnetic Field in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Richardson, J. D.; Toth, G.; Gombosi, T. I.
Bibcode: 2009fohl.book...43O
Altcode:
  Magnetic effects are ubiquitous and known to be crucial in space physics
  and astrophysical media. We have now the opportunity to probe these
  effects in the outer heliosphere with the two spacecraft Voyager 1
  and 2. Voyager 1 crossed, in December 2004, the termination shock and
  is now in the heliosheath. On August 30, 2007 Voyager 2 crossed the
  termination shock, providing us for the first time in-situ measurements
  of the subsonic solar wind in the heliosheath. With the recent in-situ
  data from Voyager 1 and 2 the numerical models are forced to confront
  their models with observational data. Our recent results indicate
  that magnetic effects, in particular the interstellar magnetic field,
  are very important in the interaction between the solar system and
  the interstellar medium. We summarize here our recent work that
  shows that the interstellar magnetic field affects the symmetry of
  the heliosphere that can be detected by different measurements. We
  combined radio emission and energetic particle streaming measurements
  from Voyager 1 and 2 with extensive state-of-the art 3D MHD modeling, to
  constrain the direction of the local interstellar magnetic field. The
  orientation derived is a plane ∼60°-90° from the galactic
  plane. This indicates that the field orientation differs from that
  of a larger scale interstellar magnetic field, thought to parallel
  the galactic plane. Although it may take 7-12 years for Voyager 2 to
  leave the heliosheath and enter the pristine interstellar medium,
  the subsonic flows are immediately sensitive to the shape of the
  heliopause. The flows measured by Voyager 2 in the heliosheath indicate
  that the heliopause is being distorted by local interstellar magnetic
  field with the same orientation as derived previously. As a result of
  the interstellar magnetic field the solar system is asymmetric being
  pushed in the southern direction. The presence of hydrogen atoms tend
  to symmetrize the solutions. We show that with a strong interstellar
  magnetic field with our most current model that includes hydrogen atoms,
  the asymmetries are recovered. It remains a challenge for future works
  with a more complete model, to explain all the observed asymmetries
  by V1 and V2. We comment on these results and implications of other
  factors not included in our present model.

Title: Investigating the Earth's magnetosphere response to IMF Bz
    magnitude using SWMF
Authors: Cai, X.; Clauer, R. C.; Ridley, A. J.; Toth, G.
Bibcode: 2008AGUFMSM23B1693C
Altcode:
  Observations indicate that the magnitude of southward interplanetary
  magnetic field (IMF) contributes to different magnetosphere response
  modes. Using the University of Michigan Space Weather Modeling
  Framework (SWMF), including a global magnetosphere model, coupled with
  an inner magnetosphere model and an ionosphere electrodynamics model,
  we attempt to quantify the role of the IMF Bz in determining the level
  of activity in the magnetosphere. In separate experiments, the IMF Bz
  component is set to -2.5 nT, - 5 nT, -10 nT, -15 nT and -20 nT while
  keeping the other input solar wind parameters constant. We have found
  that the magnetosphere becomes more and more active as IMF Bz becomes
  more negative. The average vertical magnetic field at geosynchronous
  orbit, at all local times, decrease systematically, i.e., the inner
  magnetosphere becomes more stretched as the IMF Bz becomes more
  negative. The standard deviation also becomes larger, implying that the
  magnetosphere shows more variability. When the IMF is weak (-2.5 nT),
  the magnetic field at local midnight is quasi-steady. The magnetosphere
  starts to show quasi- periodic (~ 2 hours) dipolarizations when IMF
  is -5 nT and stronger. However, as the IMF Bz becomes more negative,
  increased turbulence develops around the inner magnetosphere and appears
  to disrupt the periodic formation of the night side reconnection.

Title: Improvements in the Space Weather Modeling Framework
Authors: Ridley, A. J.; Liemohn, M.; Dezeeuw, D.; Ilie, R.; Sokolov,
   I.; Toth, G.; Yu, Y.
Bibcode: 2008AGUFMSA51A1530R
Altcode:
  The magnetosphere within the Space Weather Modeling Framework (SWMF)
  has been represented by a global magnetosphere model (BATSRUS), an
  inner magnetosphere model (the Rice Convection Model) and a model of
  the ionospheric electrodynamics. We present significant improvements
  in the SWMF: (1) We have implemented a spherical grid within BATSRUS
  and have utilized this for modeling the magnetosphere; (2) We have
  significantly improved the physics of the auroral oval within the
  ionospheric electrodynamics code, modeling a self-consistent diffuse and
  discrete auroral oval; (3) We utilize the multifluid MHD code within
  BATSRUS to allow for more accurate specification and differentiation
  of the density within the magnetosphere; and (4) we have incorporated
  the Hot Electron and Ion Drift Integrator (HEIDI) ring current code
  within the SWMF. We will present these improvements and show the
  quantitative differences within the model results when comparing to
  a suite of measurements for a number of different intervals.

Title: Magnetic Storm Simulation With Multiple Ion Fluids: Algorithm
Authors: Toth, G.; Glocer, A.; Gombosi, T.
Bibcode: 2008AGUFMSM11A1568T
Altcode:
  We describe our progress in extending the capabilities of the
  BATS-R-US MHD code to model multiple ion fluids. We solve the full
  multiion equations with no assumptions about the relative motion
  of the ion fluids. We discuss the numerical difficulties and the
  algorithmic solutions: the use of a total ion fluid in combination
  with the individual ion fluids, the use of point-implicit source
  terms with analytic Jacobian, using a simple criterion to separate
  the single-ion and multiion regions in our magnetosphere applications,
  and an artificial friction term to limit the relative velocities of the
  ion fluids to reasonable values. This latter term is used to mimic the
  effect of two-stream instabilities in a crude manner. The new code is
  fully integrated into the Space Weather Modeling Framework and it has
  been coupled with the ionosphere, inner magnetosphere and polar wind
  models to simulate the May 4 1998 magnetic storm.

Title: Non-steady Reconnection in Global Simulations of Magnetosphere
    Dynamics.
Authors: Kuznetsova, M.; Hesse, M.; Sibeck, D.; Rastaetter, L.; Toth,
   G.; Ridley, A.
Bibcode: 2008AGUFMSM23C..04K
Altcode:
  To analyze the non-steady magnetic reconnection during quasi-steady
  solar wind driving we employed high resolution global MHD model
  BATSRUS with non-MHD corrections in diffusion regions around the
  reconnection sites. To clarify the role of small-scale non-MHD effects
  on the global magnetospheric dynamic we performed simulations with
  different models of dissipation. We found that magnetopause surface is
  not in steady state even during extended periods of steady solar wind
  conditions. The so-called tilted reconnection lines become unstable
  due to formation of pressure bubbles, strong core field flux tubes,
  vortices, and traveling magnetic field cavities. Non-steady dayside
  reconnection results in formation of flux tubes with bended axis
  magnetically connecting magnetic field cavities generated at flanks
  and strong core segments formed near the subsolar region. We found
  that the rate of magnetic flux loading to the tail lobes is not very
  sensitive to the dissipation mechanism and details of the dayside
  reconnection. On the other hand the magnetotail reconnection rate,
  the speed of the reconnection site retreat and the global magnetotail
  dynamics strongly depend on the model of dissipation. THEMIS and Cluster
  observations are consistent with signatures predicted by simulations.

Title: Breakout coronal mass ejection or streamer blowout: the
    bugle effect
Authors: van der Holst, B.; Manchester, C.; Sokolov, I.; Toth, G.;
   Gombosi, T.; Dezeeuw, D.; Cohen, O.
Bibcode: 2008AGUFMSH23B1640V
Altcode:
  We present three-dimensional numerical magnetohydrodynamic
  simulations of coronal mass ejections (CMEs) initiated by the breakout
  mechanism. The initial steady state consists of a bipolar active region
  embedded in the solar wind. The field orientation of the active region
  is opposite to that of the overarching helmet streamer, so that this
  pre-eruptive region consists of three arcades with a magnetic null
  line on the leading edge of the central arcade. By applying footpoint
  motion near the polarity inversion line of the central arcade, the
  breakout reconnection is turned on. During the eruption, the plasma in
  front of the breakout arcade gets swept up. The latter effect causes
  a pre-event swelling of the streamer. The width of the helmet streamer
  increases in time and follows a "bugle" pattern. In this paper, we will
  demonstrate that if this pre- event streamer swelling is insufficient,
  reconnection on the sides of the erupting breakout arcade/flux rope
  sets in. This will ultimately disconnect the helmet top, resulting in
  a streamer blowout CME. On the other hand, if this pre-event swelling
  is effective enough, the breakout reconnection will continue all the
  way to the top of the helmet streamer. The breakout mechanisms will
  then succeed in creating a breakout CME.

Title: 3D, Multi-fluid, MHD Calculations Of Plasma Escape From Mars
Authors: Najib, D.; Toth, G.; Nagy, A.; Ma, Y.
Bibcode: 2008AGUFMSM13A1670N
Altcode:
  We use our new multi-fluid, MHD model to calculate plasma escape from
  Mars. Our lower boundary is set at 100 km and we have a radial grid
  resolution of about 10 km in the ionosphere. We consider both photo
  and electron impact ionization, as well as charge exchange processes
  in calculating the escape fluxes, using a variety of solar and upstream
  conditions.

Title: Storm-time Inner Magnetosphere: Self-consistent Kinetic
    Simulation Driven by the Space Weather Modeling Framework
Authors: Zaharia, S. G.; Jordanova, V. K.; Toth, G.
Bibcode: 2008AGUFMSM14A..03Z
Altcode:
  Accurately modeling inner magnetosphere dynamics requires proper
  treatment of both the kinetic drift physics as well as the interaction
  between particles and fields. Observations consistently show the inner
  magnetosphere magnetic field to be significantly depressed during
  geomagnetic storms. The field changes are caused by large amounts of
  injected ring current plasma, which in turn strongly influence the
  dynamic evolution of the plasma. We have developed a self-consistent
  inner magnetosphere code that treats this self- consistent interaction,
  through coupling a kinetic ring current model (RAM) with an Euler
  potential-based 3D plasma equilibrium code; in our approach, the
  magnetic field is computed in force balance with the kinetic model
  anisotropic pressures (anisotropy being critically important for the
  excitation of EMIC waves), and then fed back into the kinetic code. Here
  we report results from simulating a geomagnetic storm using this model,
  with plasma and magnetic field on the boundary supplied from the global
  BATSRUS MHD code from the Space Weather Modeling Framework (SWMF);
  we focus in particular on the following aspects: 1). the effect of
  the MHD model boundary vs. observation-based (from LANL satellites)
  boundary conditions; 2). the effect of magnetic self-consistency on
  ring current plasma pressure, anisotropy and EMIC wave instability;
  and 3). the relative magnitude of the induced vs. convective electric
  fields in the inner magnetosphere during the storm.

Title: Magnetic storm simulation with multiple ion fluids: results
    and analysis
Authors: Glocer, A.; Toth, G.; Gombosi, T.
Bibcode: 2008AGUFMSM11A1569G
Altcode:
  Ionosheric outflow can be a significant contributor to the plasma
  population of the magnetosphere during active geomagnetic conditions. We
  present preliminary results and analysis of new efforts to model the
  source and effects of out-flowing plasma in the Space Weather Modeling
  Framework (SWMF). In particular, we use the Polar Wind Outflow Model
  (PWOM), a field-aligned multi-fluid polar wind code to study the
  ionospheric outflow, and a newly developed multi-fluid version of
  the BATS-R-US model of the magnetosphere to track the fate of that
  outflow. We present our methodology and a description of the evolution
  of magnetospheric composition during the May 4th 1998 geomagnetic storm.

Title: Balancing Act: The Role of The Interstellar Magnetic Field
    and Neutral H in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Stone, E. C.; Toth, G.; Izmodenov, V.; Alexashov,
   V.; Gombosi, T. I.
Bibcode: 2008AGUFMSH14A..07O
Altcode:
  We present results from recently developed 5 fluid MHD model (4
  neutral fluids and 1 ionized fluid). We present a benchmark comparison
  between our model and the kinetic Moscow model for the case of strong
  interstellar magnetic field, and no interplanetary field. The presence
  of neutral H, as pointed out by previous works, has the effect of
  diminishing the global heliospheric asymmetries. With a stronger
  interstellar field, however, the asymmetries are increased. Results
  of the 5-fluid MHD model have been employed as an starting point for a
  new kinetic-MHD model that combines the BATS-R-US MHD code with the 3D
  Monte- Carlo Moscow code. We present first results of this new coupled
  model. We discuss these results and compare with our previous work
  (Opher et al. 2006, 2007). Our goal is to constrain the orientation
  and intensity of the interstellar magnetic field that can satisfy
  the different constraints from the observed asymmetries (energetic
  particles streaming (east- west); the 10AU differences between V1 and
  V2 crossing; radio emission; and neutral H deflection).

Title: Inner magnetosphere--global MHD coupled code: initial results
Authors: Buzulukova, N.; Fok, M.; Kuznetsova, M.; Pulkkinen, A.;
   Rastaetter, L.; Brandt, P.; Toth, G.
Bibcode: 2008AGUFMSM11A1571B
Altcode:
  We present results of a one-way coupling between a global MHD model
  (BATSRUS) and a ring current model with ionosphere feedback (CRCM). The
  MHD model provides magnetic field in all computational regions
  and electric field potential, temperature and density at the outer
  boundary. The ring current model calculates the plasma distribution (H+
  and e-) in the energy range 1-200keV, field-aligned currents of Region-2
  and electric fields. We consider inner magnetosphere dynamics during an
  idealized case with south-north-south Bz turning as well as a real event
  during the 12 August 2000 storm. For the idealized case, we reproduce
  basic features of the electric field in the inner magnetosphere:
  strong convection during southward IMF and shielding, weak convection
  during northward IMF and overshielding. Additionally, we estimate
  characteristic times for shielding/overshielding formation. For the 12
  August 2000 event we calculate ring current 3D fluxes and reconstruct
  energetic neutral atom (ENA) images. We compare the modeled ENA images
  with those observed by IMAGE HENA imager and investigate global ring
  current dynamics during 12 August 2000 event.

Title: Three-dimensional MHD Simulation of the 2003 October 28
Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
Authors: Manchester, Ward B., IV; Vourlidas, Angelos; Tóth, Gábor;
   Lugaz, Noé; Roussev, Ilia I.; Sokolov, Igor V.; Gombosi, Tamas I.;
   De Zeeuw, Darren L.; Opher, Merav
Bibcode: 2008ApJ...684.1448M
Altcode: 2008arXiv0805.3707M
  We numerically model the coronal mass ejection (CME) event of 2003
  October 28 that erupted from AR 10486 and propagated to Earth in less
  than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic
  (MHD) model is formulated by first arriving at a steady state corona
  and solar wind employing synoptic magnetograms. We initiate two
  CMEs from the same active region, one approximately a day earlier
  that preconditions the solar wind for the much faster CME on the
  28th. This second CME travels through the corona at a rate of
  over 2500 km s<SUP>-1</SUP>, driving a strong forward shock. We
  clearly identify this shock in an image produced by the Large Angle
  Spectrometric Coronagraph (LASCO) C3 and reproduce the shock and its
  appearance in synthetic white-light images from the simulation. We
  find excellent agreement with both the general morphology and the
  quantitative brightness of the model CME with LASCO observations. These
  results demonstrate that the CME shape is largely determined by its
  interaction with the ambient solar wind and may not be sensitive to the
  initiation process. We then show how the CME would appear as observed
  by wide-angle coronagraphs on board the Solar Terrestrial Relations
  Observatory (STEREO) spacecraft. We find complex time evolution of
  the white-light images as a result of the way in which the density
  structures pass through the Thomson sphere. The simulation is performed
  with the Space Weather Modeling Framework (SWMF).

Title: MHD Simulations of CME-Driven Shocks: Structures Relevant to
    Particle Acceleration
Authors: Manchester, W. B.; Toth, G.; Sokolov, I.; Zurbuchen, T. H.;
   Kota, J.
Bibcode: 2008AIPC.1039..273M
Altcode:
  Fast Coronal Mass Ejections (CMEs) drive strong shocks from the corona
  through interplanetary space where these large-scale disturbances
  accelerate particles typically associated with gradual events. The
  acceleration of solar energetic particles (SEPs) is strongly dependent
  on shock speed and geometry, which may exhibit significant temporal
  and spatial variations as the CME propagates. Here, we examine
  three-dimensional (3-D) magnetohydrodynamic simulations of CMEs,
  and find that the ambient solar wind structure strongly affects
  the evolution of CME-driven shocks. Variations in wind speed
  deform the shock front, resulting in strong meridional flows and
  compressions in the CME sheath. We also find that CMEs can cause stream
  interactions that result in high-latitude reverse shocks Sunward of the
  CME. Understanding and predicting such CME driven shocks is a necessary
  step in building a quantitative model of SEP acceleration and transport
  that can be used to forecast and mitigate radiation hazards.

Title: Hall magnetohydrodynamics on block-adaptive grids
Authors: Tóth, Gábor; Ma, Yingjuan; Gombosi, Tamas I.
Bibcode: 2008JCoPh.227.6967T
Altcode:
  We present a conservative second order accurate finite volume
  discretization of the magnetohydrodynamics equations including the Hall
  term. The scheme is generalized to three-dimensional block-adaptive
  grids with Cartesian or generalized coordinates. The second order
  accurate discretization of the Hall term at grid resolution changes
  is described in detail. Both explicit and implicit time integration
  schemes are developed. The stability of the explicit time integration is
  ensured by including the whistler wave speed for the shortest discrete
  wave length into the numerical dissipation, but then second order
  accuracy requires the use of symmetric limiters in the total variation
  diminishing scheme. The implicit scheme employs a Newton Krylov Schwarz
  type approach, and can achieve significantly better efficiency than
  the explicit scheme with an appropriate preconditioner. The second
  order accuracy of the scheme is verified by numerical tests. The
  parallel scaling and robustness are demonstrated by three-dimensional
  simulations of planetary magnetospheres.

Title: Modeling Ionospheric Outflows and Magnetosphere Composition
    During Quiet and Active Times
Authors: Glocer, A.; Toth, G.; Gombosi, T.
Bibcode: 2008AGUSMSM41A..03G
Altcode:
  Ionosheric outflow can be a significant contributor to the
  plasma population of the magnetosphere during active geomagnetic
  conditions. Most Magnetosphere- Ionosphere Coupling (MIC) models
  do not include this outflow in a physical manner; instead they rely
  on pressure gradient terms to draw plasma off the inner boundary of
  the magnetosphere. We present preliminary results of new ef- forts to
  model the source and effects of out-flowing plasma in the Space Weather
  Modeling Framework (SWMF). In particular, we use the Polar Wind Outflow
  Model (PWOM), a field-aligned multi-fluid polar wind code, coupled to
  the Iono- sphere Electrodynamics (IE), and Global Magnetosphere (GM)
  components of the SWMF. We present our methodology for the MIC, as well
  as the evolution of the outflow during a geomagnetic storm. Moreover,
  we explore the use of multi-species and multi-fluid MHD to track the
  resulting plasma composition in the magnetosphere.

Title: Multi-Fluid Simulations of a Coupled Ionosphere-Magnetosphere
    System
Authors: Gombosi, T. I.; Glocer, A.; Toth, G.; Ridley, A. J.; Sokolov,
   I. V.; de Zeeuw, D. L.
Bibcode: 2008AGUSMSM33A..02G
Altcode:
  In the last decade we have developed the Space Weather Modeling
  Framework (SWMF) that efficiently couples together different models
  describing the interacting regions of the space environment. Many
  of these domain models (such as the global solar corona, the inner
  heliosphere or the global magnetosphere) are based on MHD and are
  represented by our multiphysics code, BATS-R-US. BATS-R-US can solve the
  equations of "standard" ideal MHD, but it can also go beyond this first
  approximation. It can solve resistive MHD, Hall MHD, semi-relativistic
  MHD (that keeps the displacement current), multispecies (different
  ion species have different continuity equations) and multifluid (all
  ion species have separate continuity, momentum and energy equations)
  MHD. Recently we added two-fluid Hall MHD (solving the electron
  and ion energy equations separately) and are working on an extended
  magnetohydrodynamics model with anisotropic pressures. Ionosheric
  outflow can be a significant contributor to the plasma population of
  the magnetosphere during active geomagnetic conditions. This talk
  will present preliminary results of our simulations when we couple
  a new field- aligned multi-fluid polar wind code to the Ionosphere
  Electrodynamics (IE), and Global Magnetosphere (GM) components of the
  SWMF. We use multi-species and multi-fluid MHD to track the resulting
  plasma composition in the magnetosphere.

Title: Effects of Heavy Ions on Ring Current Dynamics from Dipolar,
    Empirical, or Self-Consistent Magnetic Field Simulations
Authors: Jordanova, V. K.; Zaharia, S.; Toth, G.
Bibcode: 2008AGUSMSM44A..04J
Altcode:
  The plasma composition in the near-Earth magnetosphere varies
  significantly with geomagnetic and solar activity, with H+ being the
  dominant ring current ion species during quiet time, and O+ contributing
  mostly during active time. We use our kinetic ring current-atmosphere
  interactions model (RAM) that has been recently extended for
  non-dipolar magnetic field geometry to investigate the effects of
  various O+/H+ composition ratios applied at the outer boundary on
  ring current dynamics. The RAM is coupled with a 3-D equilibrium
  model that calculates self-consistently the magnetic field in force
  balance with the anisotropic ring current ion distributions. Such
  anisotropy is critically important for the excitation of EMIC waves,
  whose characteristics depend strongly on the presence of both cold and
  energetic heavy ions (mainly He+ and O+) in the plasmas. We simulate
  the sunward transport, acceleration, and loss of ring current ions
  during a geomagnetic storm using this newly improved model with plasma
  and magnetic field boundary conditions supplied from the global BATSRUS
  model from the SWMF. Ring current development and EMIC wave instability
  during various storm phases are presented and their dependence on ion
  composition is discussed. The effect of non-dipolar magnetic field
  geometry and the feedback of a self-consistently computed magnetic
  field on ring current dynamics are investigated.

Title: Parallel Explicit/Implicit Time Stepping Scheme on
    Block-Adaptive Grids
Authors: Tóth, G.; de Zeeuw, D. L.; Ma, Y. -J.; Gombosi, T. I.;
   Powell, K. G.
Bibcode: 2008ASPC..385..237T
Altcode:
  This proceedings paper is mostly based on a much longer research
  paper tet{Toth2006}. We present a parallel explicit/implicit time
  integration scheme well suited for block-adaptive grids. Load balancing
  and the optimal choice of the time step for speed and robustness are
  discussed. The parallel efficiency of the scheme is demonstrated for
  a three-dimensional Hall magnetohydrodynamics problem.

Title: Role of periodic loading-unloading in the magnetotail versus
    interplanetary magnetic field B<SUB>z</SUB> flipping in the ring
    current buildup
Authors: Taktakishvili, A.; Kuznetsova, M. M.; Hesse, M.; Fok, M. -C.;
   RastäTter, L.; Maddox, M.; Chulaki, A.; Tóth, G.; Gombosi, T. I.;
   de Zeeuw, D. L.
Bibcode: 2008JGRA..113.3206T
Altcode:
  Introducing kinetic corrections into the to BATSRUS code in the
  magnetotail region leads to fast reconnection rates observed in
  kinetic simulations and quasi-periodic loading-unloading cycles in the
  magnetotail during a long period of steady southward interplanetary
  magnetic field (IMF) B<SUB>z</SUB> (Kuznetsova et al., 2006, 2007). We
  use the global MHD code BATSRUS output to drive the Fok Ring Current
  (FRC) model, which then exhibits quasi-periodic oscillations of
  geosynchronous energetic particle fluxes, similar to "sawtooth"
  injection profiles. We compare these results with the results of the FRC
  model driven by BATSRUS for periodically flipping IMF B<SUB>z</SUB>
  component, without kinetic corrections. The comparison shows the
  dominant role of quasi-periodic loading-unloading in the tail over
  the role of flipping IMF B<SUB>z</SUB> component in the formation
  of geosynchronous fluxes for various energies. This same result is
  confirmed by the analysis of particle number and energy content within
  geosynchronous orbit.

Title: Sun to Earth Simulation of 15-May-2005 Space Weather Event
Authors: Yuan, Xingqiu; Trichtchenko, Larisa; Rankin, Robert; Kabin,
   Konstantin; Toth, Gabor; Manchester, Ward, IV
Bibcode: 2008cosp...37.3570Y
Altcode: 2008cosp.meet.3570Y
  The numerical simulation of typical space weather events is a necessary
  step towards developing real-time space weather forecasting. It
  can help us to evaluate the physical model, to enhance the speed of
  calculations with reasonable reduced resolution, and provide a global
  picture of the transient disturbance interacting with the background
  solar wind. In this paper, the well-defined halo-CME space weather
  events of 15-May-2005 are chosen to investigate the propagation of
  the solar disturbance in the moderately fast background solar wind
  environment, and its successive geoeffectiveness. Detailed comparisons
  of the simulation results with the groundand satellitebased observations
  are presented. It is found that the simulation results are qualitatively
  in good agreement with the observations.

Title: Modeling Ionospheric Outflows and Magnetosphere Composition
    During Quiet and Active Times
Authors: Glocer, Alex; Toth, Gabor; Gombosi, Tamas
Bibcode: 2008cosp...37.1029G
Altcode: 2008cosp.meet.1029G
  Ionosheric outflow can be a significant contributor to the
  plasma population of the magnetosphere during active geomagnetic
  conditions. Most Magnetosphere-Ionosphere Coupling (MIC) models do
  not include this outflow in a physical manner; instead they rely on
  pressure gradient terms to draw plasma off the inner boundary of the
  magnetosphere. We present preliminary results of new efforts to model
  the source and effects of out-flowing plasma in the Space Weather
  Modeling Framework (SWMF). In particular, we use the Polar Wind Outflow
  Model (PWOM), a field-aligned multi-fluid polar wind code, coupled
  to the Ionosphere Electrodynamics (IE), and Global Magnetosphere (GM)
  components of the SWMF. We present our methodology for the MIC, as well
  as the evolution of the outflow during a geomagnetic storm. Moreover,
  we explore the use of multi-species and multi-fluid MHD to track the
  resulting plasma composition in the magnetosphere.

Title: Simulating the interaction of the 2007 April 19 CME with
    Comet Encke
Authors: Manchester, Ward, IV; Gombosi, Tamas; Frazin, Richard;
   Vourlidas, Angelos; Toth, Gabor; Cohen, Ofer; Hansen, Kenneth; Sokolov,
   Igor; van der Holst, Bart
Bibcode: 2008cosp...37.1896M
Altcode: 2008cosp.meet.1896M
  We model the propagation of a coronal mass ejection (CME) that was
  observed with LASCO on April 19, 2007. The resulting ICME was observed
  with SECCHI (STEREO A) to impact comet Encke on April 20. We compare the
  results of our three-dimensional global MHD simulation of this event
  with both sets of coronagraph observations. In particular, we make
  synthetic Thomson-scattered white light images from the simulation to
  quantitatively compare to the coronagraph images made with LASCO and
  SECCHI. We then propagate the CME into interplanetary space where it
  interacts with comet Encke. We simulate the complex response of the
  cometary plasma to the CME impact.

Title: When Magnetized Winds Collide: Role of the Interstellar
    Magnetic Field Shaping the Heliosphere
Authors: Opher, Merav; Stone, Edward; Richardson, John; Toth, Gabor;
   Alexashov, Dmitry; Izmodenov, Vladislav; Gombosi, Tamas
Bibcode: 2008cosp...37.2295O
Altcode: 2008cosp.meet.2295O
  Magnetic effects are ubiquitous and known to be crucial in space
  physics and astrophysical media; Space physics is an excellent
  plasma laboratory and provide observational data that add crucial
  constraints to theoretical models. Voyager 1 crossed in Dec 2004,
  the termination shock and is now in the heliosheath. On August 30,
  2007 Voyager 2 crossed the termination shock providing us for the
  first time with in-situ measurements of the subsonic solar wind in
  the heliosheath. In this talk I will review our recent results that
  indicate that magnetic effects, in particular the interstellar magnetic
  field, are very important in the interaction between the solar system
  and the interstellar medium. Recently, combining radio emission and
  energetic particle streaming measurements from Voyager 1 and 2 with
  extensive state-of-the art 3D MHD modeling, we were able to constrain
  the direction of the local interstellar magnetic field. Although might
  take 7-12 years for Voyager 2 to leave the heliosheath and enter the
  pristine interstellar medium, the subsonic flows are immediately
  sensitive to the shape of the heliopause. We show that the flows
  measured by Voyager 2 from days 258-350 indicate that the heliopause
  is being distorted by a local interstellar magnetic field 60° -90°
  from the galactic plane. This confirms our earlier prediction that
  the field orientation in the Local Interstellar Cloud differs that of
  a larger scale interstellar magnetic field, thought to parallel the
  galactic plane. As a result of the interstellar magnetic field the
  solar system is asymmetric being pushed in the southern direction. I
  will comment on these results and present preliminary results of the
  effect of H neutrals on our previous MHD results.

Title: Global MHD Simulations of Magnetospheric and Ionospheric
    Responses to the 5th June 1998 Event
Authors: Lu, Jianyong; Rae, Ian; Rankin, Robert; Zhang, Jichun; Kabin,
   Konstantin; Gombosi, T.; de Zeeuw, D. L.; Toth, G.
Bibcode: 2008cosp...37.1831L
Altcode: 2008cosp.meet.1831L
  Using WIND and ACE solar wind data, we have simulated the magnetospheric
  and ionospheric responses to the 5th June 1998 event with global
  MHD model SWMF. The chosen time period in our calculations includes
  a sharp northward turning and a southward turning in the IMF,
  followed by a period of relatively stead condition, respectively. We
  first investigate the calculation influence of running the code in
  different ways: (1) with or without RICE convection model, and (2)
  time-accurate run or local time stepping or some combinations of both
  to drive to a steady state before time-varying solar wind. We show that
  the simulated magnetospheric and ionospheric responses, such as the
  location of the polar cap boundary and ionospheric currents, can be
  significantly affected by the treatment of the steady conditions. We
  conclude that, with appropriate treatment of the true magnetospheric
  configuration, the modelling framework SWMF can accurately reflect the
  dynamic features of the solar wind-magnetosphere-ionosphere coupling
  and provide reliable results for estimating magnetic field topology
  and ionospheric responses.

Title: Multi-physics simulations of space weather
Authors: Gombosi, Tamas; Toth, Gabor; Sokolov, Igor; de Zeeuw, Darren;
   van der Holst, Bart; Cohen, Ofer; Glocer, Alex; Manchester, Ward,
   IV; Ridley, Aaron
Bibcode: 2008cosp...37.1047G
Altcode: 2008cosp.meet.1047G
  Presently magnetohydrodynamic (MHD) models represent the "workhorse"
  technology for simulating the space environment from the solar
  corona to the ionosphere. While these models are very successful in
  describing many important phenomena, they are based on a low-order
  moment approximation of the phase-space distribution function. In the
  last decade our group at the Center for Space Environment Modeling
  (CSEM) has developed the Space Weather Modeling Framework (SWMF) that
  efficiently couples together different models describing the interacting
  regions of the space environment. Many of these domain models (such
  as the global solar corona, the inner heliosphere or the global
  magnetosphere) are based on MHD and are represented by our multiphysics
  code, BATS-R-US. BATS-R-US can solve the equations of "standard"
  ideal MHD, but it can also go beyond this first approximation. It
  can solve resistive MHD, Hall MHD, semi-relativistic MHD (that keeps
  the displacement current), multispecies (different ion species have
  different continuity equations) and multifluid (all ion species have
  separate continuity, momentum and energy equations) MHD. Recently we
  added two-fluid Hall MHD (solving the electron and ion energy equations
  separately) and are working on extended magnetohydrodynamics with
  anisotropic pressures. This talk will show the effects of added physics
  and compare space weather simulation results to "standard" ideal MHD.

Title: D Breakout Coronal Mass Ejections in the Solar Wind
Authors: van der Holst, Bart; Toth, Gabor; Sokolov, Igor; Gombosi,
   Tamas; Manchester, Ward, IV; Cohen, Ofer; de Zeeuw, Darren
Bibcode: 2008cosp...37.3281V
Altcode: 2008cosp.meet.3281V
  The initiation and evolution of coronal mass ejections (CMEs) is
  studied by means of the breakout model embedded in a 3D solar wind in
  the framework of numerical magnetohydrodynamics. The initial steady
  equilibrium contains a pre-eruptive region consisting three arcades
  with alternating magnetic flux polarity and with correspondingly three
  neutral lines on the phtosphere. The magnetic tension of the overlying
  closed magnetic field of the helmet streamer keeps this structure
  in place. The most crucual element in the initial breakout topology
  is the existence of an X-point on the leading edge of the central
  arcade. By applying shear flow, the reconnection with the overlying
  helmet streamer field is turned on. The breakout reconnection opens
  the overlying field in an energetically efficient way. Initially,
  this process will speed up the CME. The simulations will exploit the
  new spherical grids in BATS-R-US to accurately capture the dynamics.

Title: Investigating the periodicity of sawtooth events using the
    Space Weather Modeling Framework (SWMF) - preliminary results
Authors: Cai, X.; Clauer, C. R.; Ridley, A. J.; Toth, G.; Liemohn,
   M. W.; Gombosi, T. I.; Kuznetsova, M. M.
Bibcode: 2007AGUFMSM32A..06C
Altcode:
  By introducing a non-gyrotropic correction to the induction equation
  in a BATS-R-US simulation, it has been reported that periodic
  dipolarizations similar to sawtooth oscillations are seen at
  geosynchronous orbit in the magnetosphere. However the simulated
  periodicity reported is around 60 minutes, while the observed
  periodicity, obtained from a analysis of around 400 individual teeth,
  is about 180 minutes. We report here preliminary results from an
  investigation that examines how solar wind parameters may affect the
  periodicity using a series of Space Weather Modeling Framework (SWMF)
  simulations which includes the non-gyrotropic BATS-R-US model. We
  examine the effects of the external driving conditions by systematically
  changing the magnitude of solar wind dynamic pressure and interplanetary
  magnetic field (IMF) southward component (Bz) in the simulations.

Title: Validating SWMF Particle Density and Energy: Initial Results
Authors: Welling, D. T.; Ridley, A. J.; Gombosi, T. I.; de Zeeuw,
   D.; Toth, G.
Bibcode: 2007AGUFMSM43E..01W
Altcode:
  First principle-based models can be a powerful tool for scientific
  and operational space weather forecasting and analysis. A key step
  for improving current models and preparing them for operational
  use is thorough data-model comparisons. Of particular interest
  is particle density and energy distribution in the magnetosphere,
  which are key values for spacecraft surface charging calculations. In
  this study, we compare particle density and energy spectrum values
  generated by the Space Weather Modeling Framework (SWMF) to in situ
  LANL geosynchronous measurements. The SWMF is configured to use a
  self-consistent ionospheric electrodynamics model, the BATSRUS global
  MHD model, and the Rice Convection Model (RCM). Coupling these models
  allows for tracing the magnetic field lines from the MHD solution to
  provide the RCM with an improved open/closed field line boundary. It
  also allows for the extraction of the RCM solution along any satellite
  trajectory by tracing the magnetic field line from the 3D location
  of the satellite to the 2D RCM ionospheric grid. The SWMF is further
  configured to run in near-real time on 32 Columbia SGI processors,
  creating a solution that better reflects the SWMF's capabilities in
  an operational environment. This study is an extension of previous
  work to validate the SWMF's modeled magnetic field.

Title: Modeling STEREO White-Light Observations of CMEs with 3D
    MHD Simulations
Authors: Manchester, M. B.; Vourlidas, A.; Toth, G.; Lugaz, N.;
   Sokolov, I.; Gombosi, T.; de Zeeuw, D.; Opher, M.
Bibcode: 2007AGUFMSH32A0785M
Altcode:
  We model the Thomson-scattered white-light appearance of a variety of
  3D MHD models of CMEs during solar minimum to reproduce large-scale
  features of SECCHI observations. We create a gallery of expected CME
  shapes at large elongations as seen by SECCHI. We examine evidence of
  shock propagation, magnetic clouds, CME pancaking, and complex time
  evolution as CMEs propagate at large elongation past the Thomson
  sphere. A key point is to determine how the structure of CMEs and
  CME-driven shocks are affected by interaction with the ambient solar
  wind. MHD models are performed with BATSRUS and SWMF, and formulated
  by first arriving at a steady state corona and solar wind employing
  synoptic magnetograms. We initiate CMEs from active regions low in
  the corona with magnetic flux ropes.

Title: The Orientation of the Local Interstellar Magnetic Field and
Induced Asymmetries of the Heliosphere: Neutrals-MHD model
Authors: Opher, M.; Stone, E. C.; Izmodenov, V.; Malama, Y.; Alexashov,
   D.; Toth, G.; Gombosi, T.
Bibcode: 2007AGUFMSH12B..03O
Altcode:
  We present the results of a 3D Neutral-MHD model of the heliosphere. The
  neutrals are treated in a multi-fluid approach coupled to the ionized
  component by charge exchange. Comparisons are made with previous studies
  that showed that the local interstellar magnetic field introduces
  asymmetries in the heliosphere that are consistent with Voyager 1 and
  2 observations of radio emissions and energetic particle streaming
  (Opher et al. Science 2007; Opher et al. ApJL 2006). We present,
  additionally, preliminary results of a 3D Kinetic-MHD model. The
  main advantage of this model is a rigorous kinetic description of
  interstellar H atoms, especially at the Bow Shock, Heliopause and
  Termination Shock interfaces. Differences of kinetic and multi-fluid
  approaches are discussed. The new model should provide refined estimates
  of the strength and direction of the local interstellar field and of
  the resulting distortions of the shape of the heliosphere.

Title: The Michigan Space Weather Modeling Framework (SWMF)
Authors: de Zeeuw, D.; Gombosi, T.; Ridley, A.; Toth, G.
Bibcode: 2007AGUFMSM41A0310D
Altcode:
  The Space Weather Modeling Framework (SWMF) developed at the
  University of MIchigan has been used to model a wide variety of space
  environments. It is especially well suited to space weather modeling
  and can follow the complete system from CME initiation to interaction
  with the upper atmosphere at Earth. A graphical user interface (GUI)
  has been developed to facilitate setup, execution, and visualization
  of model runs. This GUI has been enhanced to allow more complete
  visualization and model result analysis, including comparisons with
  data. Examples will be shown of the SWMF use through the GUI for a
  variety of space weather events.

Title: Numerical Simulations of the Interaction of Enceladus'
    Interaction With Saturn's Magnetosphere Using a 3D Multi-Species,
    Hall MHD Model
Authors: Najib, D.; Nagy, A. F.; Toth, G.; Combi, M. R.; Ma, Y. J.;
   Khurana, K.; Crary, F. F.; Coates, A. J.
Bibcode: 2007AGUFM.P43A1009N
Altcode:
  We have used our new multi-species, Hall MHD model to study the
  interaction of Saturn's magnetosphere with Enceladus. We used neutral
  densities, consistent with the values observed during the Cassini's
  July 14, 2005 flyby of Enceladus. We used a simple ion chemistry
  scheme and approximated the upstream conditions from CAPS and MAG
  observations. We compare our calculated plasma and magnetic field
  values with the observed ones.

Title: Modeling Ionospheric Outflow During a Geomagnetic Storm
Authors: Glocer, A.; Toth, G.; Gombosi, T.
Bibcode: 2007AGUFMSA51B0521G
Altcode:
  Ionosheric outflow can be a significant contributor to the
  plasma population of the magnetosphere during active geomagnetic
  conditions. Most Magnetosphere-Ionosphere Coupling (MIC) models do
  not include this outflow in a physical manner; instead they rely
  on pressure gradient terms to draw plasma off the inner boundary
  of the magnetosphere. We present preliminary results of new efforts
  to model the source and effects of out-flowing plasma in the Space
  Weather Modeling Framework (SWMF). In particular, we use the Polar
  Wind Outflow Model (PWOM), a field-aligned multi-fluid polar wind code,
  coupled to the Ionosphere Electrodynamics (IE), and Global Magnetosphere
  (GM) components of the SWMF. We present our methodology for the MIC,
  as well as the evolution of the outflow during a geomagnetic storm.

Title: Integration of the Radiation Belt Environment Model Into the
    Space Weather Modeling Framework
Authors: Toth, G.; Glocer, A.; Fok, M.; Gombosi, T.
Bibcode: 2007AGUFMSM12A..07T
Altcode:
  We have integrated the Fok Radiation Belt Environment model (RBE) into
  the Space Weather Modeling Framework (SWMF). RBE is coupled to the
  global magnetohydrodynamics component (represented by BATSRUS) of the
  SWMF. The radiation belt model solves the convection-diffusion equation
  of the plasma in the range of 10keV to a few MeV. In stand-alone mode
  RBE uses Tsyganenko's empirical models for the magnetic field. In the
  SWMF the BATSRUS model provides the time dependent magnetic field
  by efficiently tracing the closed magnetic field lines and passing
  the geometrical and field strength information to RBE at a regular
  cadence. We discuss the coupling algorithm and show some preliminary
  results with the coupled code. We run our new coupled model for periods
  of steady northward and southward IMF and compare our results to the
  radiation belt model using an empirical magnetic field model. We also
  simulate the radiation belts for an event of active time period.

Title: 3D global multi-species Hall-MHD simulation of the Cassini
    T9 flyby
Authors: Ma, Ying-Juan; Nagy, Andrew F.; Toth, Gabor; Cravens, Thomas
   E.; Russell, Christopher T.; Gombosi, Tamas I.; Wahlund, Jan-Erik;
   Crary, Frank J.; Coates, Andrew J.; Bertucci, César L.; Neubauer,
   Fritz M.
Bibcode: 2007GeoRL..3424S10M
Altcode:
  The wake region of Titan is an important component of Titan's
  interaction with its surrounding plasma and therefore a thorough
  understanding of its formation and structure is of primary interest. The
  Cassini spacecraft passed through the distant downstream region of
  Titan on 18:59:30 UT Dec. 26, 2005, which is referred to as the T9
  flyby and provided a great opportunity to test our understanding of the
  highly dynamic wake region. In this paper we compare the observational
  data (from the magnetometer, plasma analyzer and Langmuir probe) with
  numerical results using a 7-species Hall MHD Titan model. There is a
  good agreement between the observed and modeled parameters, given the
  uncertainties in plasma measurements and the approximations inherent
  in the Hall MHD model. Our simulation results also show that Hall MHD
  model results fit the observations better than the non-Hall MHD model
  for the flyby, consistent with the importance of kinetic effects in
  the Titan interaction. Based on the model results, we also identify
  various regions near Titan where Hall MHD models are applicable.

Title: Multiscale modeling of magnetospheric reconnection
Authors: Kuznetsova, M. M.; Hesse, M.; RastäTter, L.; Taktakishvili,
   A.; Toth, G.; de Zeeuw, D. L.; Ridley, A.; Gombosi, T. I.
Bibcode: 2007JGRA..11210210K
Altcode:
  In our efforts to bridge the gap between small-scale kinetic modeling
  and global simulations, we introduced an approach that allows to
  quantify the interaction between large-scale global magnetospheric
  dynamics and microphysical processes in diffusion regions near
  reconnection sites. We use the global MHD code BATS-R-US and replace
  an ad hoc anomalous resistivity often employed by global MHD models
  with a physically motivated dissipation model. The primary kinetic
  mechanism controlling the dissipation in the diffusion region in
  the vicinity of the reconnection site is incorporated into the MHD
  description in terms of nongyrotropic corrections to the induction
  equation. We developed an algorithm to search for reconnection
  sites in north-south symmetric magnetotail. Spatial scales of
  the diffusion region and magnitude of the reconnection electric
  field are calculated consistently using local MHD plasma and field
  parameters. The locations of the reconnection sites are constantly
  updated during the simulations. To clarify the role of nongyrotropic
  effects in the diffusion region on the global magnetospheric dynamics,
  we perform simulations with steady southward interplanetary magnetic
  field driving of the magnetosphere. Ideal MHD simulations with
  magnetic reconnection supported by numerical resistivity often produce
  quasi-steady configuration with almost stationary near-Earth neutral
  line (NENL). Simulations with nongyrotropic corrections demonstrate
  dynamic quasi-periodic response to the steady driving conditions. Fast
  magnetotail reconnection supported by nongyrotropic effects results
  in tailward retreat of the reconnection site with average speed of
  the order of 100 km/s followed by a formation of a new NENL in the
  near-Earth thin current sheet. This approach allowed to model for
  the first time loading/unloading cycle frequently observed during
  extended periods of steady low-mach-number solar wind with southward
  interplanetary magnetic field.

Title: Leakage of photospheric acoustic waves into non-magnetic
    solar atmosphere
Authors: Erdélyi, R.; Malins, C.; Tóth, G.; de Pontieu, B.
Bibcode: 2007A&A...467.1299E
Altcode:
  Aims:This paper aims to look at the propagation of synthetic
  photospheric oscillations from a point source into a two-dimensional
  non-magnetic solar atmosphere. It takes a particular interest in
  the leakage of 5-min global oscillations into the atmosphere, and
  aims to complement efforts on the driving of chromospheric dynamics
  (e.g. spicules and waves) by 5-min oscillations. <BR />Methods: A
  model solar atmosphere is constructed based on realistic temperature
  and gravitational stratification. The response of this atmosphere to
  a wide range of adiabatic periodic velocity drivers is numerically
  investigated in the hydrodynamic approximation. <BR />Results: The
  findings of this modelling are threefold. Firstly, high-frequency waves
  are shown to propagate from the lower atmosphere across the transition
  region experiencing relatively low reflection and transmitting energy
  into the corona. Secondly, it is demonstrated that driving the upper
  solar photosphere with a harmonic piston driver at around the 5 min
  period may generate three separate standing modes with similar periods
  in the chromosphere and transition region. In the cavity formed
  by the chromosphere and bounded by regions of low cut-off period
  at the photospheric temperature minimum and the transition region
  this is caused by reflection, while at either end of this region in
  the lower chromosphere and transition region the standing modes are
  caused by resonant excitation. Finally, the transition region becomes
  a guide for horizontally propagating surface waves for a wide range
  of driver periods, and in particular at those periods which support
  chromospheric standing waves. Crucially, these findings are the results
  of a combination of a chromospheric cavity and resonant excitation in
  the lower atmosphere and transition region.

Title: The Michigan Space Weather Modeling Framework (SWMF) Graphical
    User Interface
Authors: de Zeeuw, D.; Gombosi, T.; Toth, G.; Ridley, A.
Bibcode: 2007AGUSMSM23A..09D
Altcode:
  The Michigan Space Weather Modeling Framework (SWMF) is a powerful tool
  available for the community that has been used to model from the Sun
  to Earth and beyond. As a research tool, however, it still requires
  user experience with parallel compute clusters and visualization
  tools. Thus, we have developed a graphical user interface (GUI) that
  assists with configuring, compiling, and running the SWMF, as well as
  visualizing the model output. This is accomplished through a portable
  web interface. Live examples will be demonstrated and visualization
  of several archived events will be shown.

Title: Coupling a polar wind model to the Space Weather Modeling
    Framework (SWMF)
Authors: Glocer, A.; Gombosi, T.; Toth, G.; Hansen, K.; Ridley, A.
Bibcode: 2007AGUSMSA33A..05G
Altcode:
  Polar wind and other ionospheric outflows are a vital source of
  plasma to the magnetosphere. Ambipolar electric fields, Field Aligned
  Currents (FACs), Joule heating, centrifugal acceleration, wave-particle
  interactions, and other physical phenomenon accelerate plasma and
  can lead to mass flow from the ionosphere to the magnetosphere. Most
  Magnetosphere-Ionosphere Coupling (MIC) in models ignores these
  processes instead relying on pressure gradient terms to draw plasma
  off the inner boundary of the magnetosphere. We present preliminary
  results of new efforts to incorporate this important physics into the
  Space Weather Modeling Framework (SWMF). In particular, we use the
  Polar Wind Outflow Model (PWOM), a field-aligned multi-fluid polar
  wind code, and describe efforts to couple it to the Upper Atmosphere
  (UA), Ionosphere Electrodynamics (IE), and Global Magnetosphere (GM)
  components of the SWMF. We present our methodology for the MIC, as
  well as several controlled numerical experiments demonstrating the
  importance of different physical processes.

Title: Simulated CMEs and Predictions for STEREO
Authors: Manchester, M. B.; Vourlidas, A.; Gombosi, T.; Sokolov,
   I. V.; Cohen, O.; Toth, G.
Bibcode: 2007AGUSMSH41A..06M
Altcode:
  We compare results of our global MHD simulations of CMEs propagating
  from Sun-to-Earth to observations made with STEREO. We model a number
  of events of varying degree of complexity, and model the observations
  that are made by the SECCHI coronagraph suite and in situ observations
  by IMPACT and PLASTIC. We make synthetic Thomson-scattered white light
  images from the simulations as they would appear to the COR1, COR2,
  and wide-angle coronagraphs HI1 and HI2. We identify shock structures
  in the coronagraph images and follow their evolution to Earth orbit. At
  large elongation, we find complex time evolution of the white- light
  images as a result of three-dimensional structures encountering large
  variations in scattering efficiency as they pass through the Thomson
  sphere. We then compare the modeled ICME plasma structures with
  observations from PLASTIC. We also model solar energetic particles
  and compare them with IMPACT observations.

Title: Comparison of Hall MHD and the non-gyrotropic resistivity
    model in the global magnetohydrodynamic code BATSRUS
Authors: Toth, G.; Ma, Y.; Gombosi, T. I.; Kuznetsova, M. M.
Bibcode: 2007AGUSMSM51A..12T
Altcode:
  We have recently added Hall MHD to the global magnetohydrodynamic
  code BATSRUS. Compared to ideal or resistive MHD, Hall MHD provides
  a more realistic modeling of the interaction of the solar wind with
  unmagnetized bodies and the reconnection process in magnetospheres. On
  the other hand accurate modeling of reconnection is rather expensive
  due to the required resolution and the stiffness of the Hall MHD
  equations. The non-gyrotropic resistivity model of Kuznetsova et al. is
  a phenomenological approximation based on the results of particle
  simulations. It provides an inexpensive but surprisingly accurate
  model for the reconnection process. We will systematically compare
  the two approaches within the BATSRUS code.

Title: Numerical Investigation of the Homologous Coronal Mass Ejection
    Events from Active Region 9236
Authors: Lugaz, N.; Manchester, W. B., IV; Roussev, I. I.; Tóth,
   G.; Gombosi, T. I.
Bibcode: 2007ApJ...659..788L
Altcode:
  We present a three-dimensional compressible magneto-hydrodynamics
  (MHD) simulation of the three coronal mass ejections (CMEs) of 2000
  November 24, originating from NOAA active region 9236. These three
  ejections, with velocities around 1200 km s<SUP>-1</SUP> and associated
  with X-class flares, erupted from the Sun in a period of about 16.5
  hr. In our simulation, the coronal magnetic field is reconstructed
  from MDI magnetogram data, the steady-state solar wind is based on a
  varying polytropic index model, and the ejections are initiated using
  out-of-equilibrium semicylindrical flux ropes with a size smaller than
  the active region. The simulations are carried out with the Space
  Weather Modeling Framework. We are able to reproduce the shape and
  velocity of the CMEs as observed by the LASCO C3 coronograph. The
  complex ejecta resulting from the interaction of the three CMEs is
  preceded at Earth by a single shock wave, which, in our simulation,
  arrives at Earth 10 hr later than the shock observed by the Wind
  spacecraft. This article discusses the three-dimensional aspects
  of the propagation, interaction, and merging of the forward shock
  waves associated with the three ejections. Synthetic images from the
  Heliospheric Imagers onboard the STEREO spacecraft are produced, and we
  predict that the large density jump associated with the interaction of
  the shocks should be observed by those coronographs in the near future.

Title: Understanding storm-time ring current development through
    data-model comparisons of a moderate storm
Authors: Zhang, Jichun; Liemohn, Michael W.; de Zeeuw, Darren L.;
   Borovsky, Joseph E.; Ridley, Aaron J.; Toth, Gabor; Sazykin, Stanislav;
   Thomsen, Michelle F.; Kozyra, Janet U.; Gombosi, Tamas I.; Wolf,
   Richard A.
Bibcode: 2007JGRA..112.4208Z
Altcode: 2007JGRA..11204208Z
  With three components, global magnetosphere (GM), inner magnetosphere
  (IM), and ionospheric electrodynamics (IE), in the Space Weather
  Modeling Framework (SWMF), the moderate storm on 19 May 2002 is
  globally simulated over a 24-hour period that includes the sudden
  storm commencement (SSC), initial phase, and main phase of the
  storm. Simulation results are validated by comparison with in situ
  observations from Geotail, GOES 8, GOES 10, Polar, LANL MPA, and
  the Sym-H and Dst indices. It is shown that the SWMF is reaching a
  sophistication level for allowing quantitative comparison with the
  observations. Major storm characteristics at the SSC, in the initial
  phase, and in the main phase are successfully reproduced. The simulated
  plasma parameters exhibit obvious dawn-dusk asymmetries or symmetries
  in the ring current region: higher density near the dawn and higher
  temperature in the afternoon and premidnight sectors; the pressure is
  highest on the nightside and exhibits a near dawn-dusk symmetry. In
  addition, it is found in this global modeling that the upstream solar
  wind/IMF conditions control the storm activity and an important
  plasma source of the ring current is in the solar wind. However,
  the ionospheric outflow can also affect the ring current development,
  especially in the main phase. Activity in the high-latitude ionosphere
  is also produced reasonably well. However, the modeled cross polar
  cap potential drop (CPCP) in the Southern Hemisphere is almost always
  significantly larger than that in the Northern Hemisphere during the
  May storm.

Title: Polar wind outflow model: Saturn results
Authors: Glocer, A.; Gombosi, T. I.; Toth, G.; Hansen, K. C.; Ridley,
   A. J.; Nagy, A.
Bibcode: 2007JGRA..112.1304G
Altcode: 2007JGRA..11201304G
  The Saturnian system's configuration and dynamics are to a large
  extent controlled by the planet's rapid rotation and the plasma in
  the magnetosphere. Therefore characterizing the relative importance
  of the various plasma sources is crucial to understanding Saturn's
  magnetosphere. Most research in this area focuses on the addition of
  mass from the icy satellites, the rings, and Titan, while comparatively
  little attention has been paid to the ionospheric source. We investigate
  the ionospheric source at high latitude using multifluid numerical
  simulations of Saturn's polar wind and find that the magnitude
  of the particle source rate out of the polar cap is between 2.1
  × 10<SUP>26</SUP> and 7.5 × 10<SUP>27</SUP> s<SUP>-1</SUP>. Our
  multifluid simulations are carried out using the Polar Wind Outflow
  Model (PWOM). This new model is capable of calculating the polar wind
  at Earth and Saturn by solving the gyrotropic transport equations. The
  polar wind at Saturn is modeled from below the peak ionospheric
  density to an altitude of one Saturn radius, yielding fluxes for
  H<SUB>3</SUB><SUP>+</SUP>, H<SUP>+</SUP>, and electrons. Because the
  neutral temperature is ill constrained, we calculate source rates
  for various Saturnian atmospheric profiles corresponding to neutral
  temperatures of 420, 600, 800, 1000, 1500 K. We compare the results with
  those calculated from other models and measurements where appropriate.

Title: Parallel Adaptive Solution of the MHD Equations and Its Role
    in the Space-Weather Modeling Framework
Authors: Powell, K. G.; Gombosi, T. I.; Stout, Q. F.; de Zeeuw, D. L.;
   Tóth, G.; Sokolov, I. V.; Ridley, A. J.; Hansen, K. C.; Manchester,
   W. B.; Roussev, I. I.
Bibcode: 2006ASPC..359...33P
Altcode:
  Over the last ten years, a collaboration of researchers in space
  physics, computer science and computational fluid dynamics has grown
  into the Center for Space Environment Modeling at the University of
  Michigan. The group has partnered with researchers at Rice, Stanford,
  NCAR, and NASA Goddard, among other institutions, to develop a
  first-principles-based software framework for modeling space-weather
  events. <P />In this paper, a solution-adaptive method for solving the
  MHD equations in a highly efficient manner on parallel computers is
  presented. In addition, an overview of the broader effort to develop
  the Space Weather Modeling Framework is given.

Title: The Polar Wind Outflow Model: Saturn Results
Authors: Nagy, A.; Glocer, A.; Gombosi, T.; Toth, G.; Hansen, K.;
   Ridley, A.
Bibcode: 2006AGUFMSM31C..03N
Altcode:
  The Saturnian system's configuration and dynamics are to a large
  extent controlled by the planet's rapid rotation and the plasma in
  the magnetosphere. Therefore, characterizing the relative importance
  of the various plasma sources is crucial to understanding Saturn's
  magnetosphere. Most research in this area focuses on the addition of
  mass from the icy satellites, the rings, and Titan, while comparatively
  little attention has been paid to the ionospheric source. We investigate
  the ionospheric source at high latitude using multi-fluid numerical
  simulations of Saturn's polar wind, and find that the magnitude of
  the particle source rate out of the polar cap is between 2.1×10^{26}
  and 7.5×10^{27} s-1. Our multi-fluid simulations are carried out
  using the Polar Wind Outflow Model (PWOM). This new model is capable of
  calculating the polar wind at Earth and Saturn by solving the gyrotropic
  transport equations. The polar wind at Saturn is modeled from below the
  peak ionospheric density to an altitude of one Saturn radius, yielding
  fluxes for H3+, H+, and electrons. Because the neutral temperature
  is ill constrained, we calculate source rates for various Saturnian
  atmospheric profiles corresponding to neutral temperatures of 420,
  600, 800, 1000, 1500 K. We compare the results with those calculated
  from other models and measurements where appropriate.

Title: 3D Global MHD Simulation of Titan's interaction with its
    surrounding plasma
Authors: Ma, Y.; Nagy, A. F.; Toth, G.; Najib, D.; Cravens, T. E.;
   Crary, F.; Coates, A. J.; Bertucci, C.; Neubauer, F. M.
Bibcode: 2006AGUFM.P21B..07M
Altcode:
  The interaction of Titan's ionosphere with its surrounding plasma
  flow is more complex than analogous solar wind-planet interactions,
  because of Titan's varying relative location in the Sun-Saturn
  system. We have studied the role of the angle between the direction
  of the solar radiation and the corotating plasma flow using our 3D
  multi-species MHD model. We also present results from a comparison
  between our model simulations and the observations corresponding to
  the T9 flyby of Cassini, using the measured upstream plasma parameters.

Title: Hall MHD Simulations on Block Adaptive Grids
Authors: Toth, G.; Ma, Y.; Gombosi, T. I.; Sokolov, I. V.
Bibcode: 2006AGUFMSM34B..02T
Altcode:
  We have recently extended the global magnetohydrodynamic (MHD) code
  BATSRUS to include the physics of Hall MHD. The numerical algorithm
  is developed on a block adaptive grid with explicit and implicit time
  integration. We discuss the algorithm, numerical tests, and initial
  simulation results applied to magnetospheric simulations. The effects
  of Hall MHD on the reconnection process is of particular initerest at
  the day-side magnetopause and in the magnetotail region.

Title: Collisionless Reconnection in Global Modeling of Magnetospheric
    Dynamics
Authors: Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.; Gombosi, T.;
   de Zeeuw, D.; Toth, G.
Bibcode: 2006AGUFMSM34B..03K
Altcode:
  Recent advances in small-scale kinetic modeling of magnetic reconnection
  significantly improved our understanding of physical mechanisms
  controlling the dissipation in the vicinity of the reconnection site in
  collisionless plasma. However the progress in studies of small-scale
  geometries was not very helpful for large scale simulations. Global
  magnetosphere simulations usually include non-ideal processes in
  terms of numerical dissipation and/or ad hoc anomalous resistivity. To
  understand the role of magnetic reconnection in global evolution of
  magnetosphere and to place spacecraft observations into global context
  it is desirable to perform global simulations with physically motivated
  model of dissipation that are capable to reproduce reconnection rates
  observed in kinetic models. In our efforts to bridge the gap between
  small scale kinetic modeling and global simulations we introduced an
  approach that allows to quantify the interaction between large-scale
  global magnetospheric dynamics and microphysical processes in diffusion
  regions near reconnection sites. We utilized the global MHD code BATSRUS
  and incorporate primary mechanism controlling the dissipation in the
  vicinity of the reconnection site in terms of non-gyrotropic corrections
  to the induction equation. We demonstrated that nongyrotropic effects
  can significantly alter the global magnetosphere evolution. Our approach
  allowed for the first time to model loading/unloading cycle in response
  to steady southward IMF driving. We will extend our approach to cases
  with nonzero IMF By and analyze the effects of solar wind parameters and
  ionospheric conductance on reconnection rate and global magnetosphere
  dynamics.

Title: Ring Current Decay of Moderate Storms at Solar Maximum:
    Global Modeling Using Superposed Epoch Upstream Conditions
Authors: Zhang, J.; Wolf, R. A.; Sazykin, S.; Toffoletto, F. R.;
   Liemohn, M. W.; de Zeeuw, D. L.; Ridley, A. J.; Toth, G.; Gombosi,
   T. I.
Bibcode: 2006AGUFMSM33D..06Z
Altcode:
  This study is an extension of our previous high-performance storm
  simulation with the coupled BATS-R-US (Block Adaptive Tree Solar-wind
  Roe-type Upwind Scheme) global magnetohydrodynamics (MHD) model, Rice
  Convection Model (RCM), and Ridley Ionosphere Model (RIM). In this
  work, the superposed epoch recovery phase of 34 moderate storms at
  solar maximum (July, 1999 -- June, 2002) is simulated for averaged
  upstream solar wind conditions with the standalone RCM and also
  with the coupled codes. Superposed epoch averages of Dst, Sym-H, and
  the Los Alamos Magnetospheric Plasma Analyzer (MPA) observations at
  geosynchronous orbit are used to validate the modeling results. In
  addition, parameters in the standalone RCM and the coupled codes are
  adjusted to systematically study the effects of interchange instability,
  charge exchange rate, particle drift intensity, and particle energy
  levels on the ring current decay. Computer experiments will also
  explore how magnetic field changes and time-dependent plasma-sheet
  density affect the recovery phase.

Title: Modeling the "gap" region between the ionosphere and
    magnetosphere
Authors: Glocer, A.; Gombosi, T.; Toth, G.; Hansen, K.; Ridley, A.
Bibcode: 2006AGUFMSA41B1419G
Altcode:
  The gap region refers to the 2-3 Re space between the outer boundary of
  most ionosphere models, and the inner boundary of most magnetosphere
  models. Ambipolar electric fields, Field Aligned Currents (FACs),
  Joule heating, centrifugal acceleration, wave-particle interactions,
  and other physical phenomenon in the gap region accelerate plasma and
  can lead to mass flow from the ionosphere to the magnetosphere. Most
  Magnetosphere-Ionosphere Coupling (MIC) models ignore these processes
  instead relying on pressure gradient terms to draw plasma off the
  inner boundary of the magnetosphere. We present preliminary results of
  new efforts to model the "gap" region in the Space Weather Modeling
  Framework (SWMF). In particular, we use the Polar Wind Outflow Model
  (PWOM), a field-aligned multi-fluid polar wind code, and describe
  efforts to couple it to the Upper Atmosphere (UA), Ionosphere
  Electrodynamics (IE), and Global Magnetosphere (GM) components of
  the SWMF. We present our methodology for the MIC, as well as several
  controlled numerical experiments demonstrating the importance of
  different physical processes in the gap region.

Title: 3D Global MHD Simulation of the Saturn Magnetospheric Plasma
    Interaction with Titan's Ionosphere
Authors: Ma, Yingjuan; Nagy, A. F.; Cravens, T. E.; Toth, G.; Crary,
   F. J.; Coates, A. J.; Dougherty, M. K.
Bibcode: 2006DPS....38.2703M
Altcode: 2006BAAS...38..527M
  The interaction between Titan's ionosphere and its surrounding plasma
  is simulated using our 3D multi-species MHD model.We compare the
  simulation results with the observations obtained during the T9 flyby,
  using the upstream plasma parameters measured during the flyby. The
  Hall term (JXB) is also included in the model to investigate the ion
  gyro-radii effect.

Title: Enhancement of Photospheric Meridional Flow by Reconnection
    Processes
Authors: Cohen, O.; Fisk, L. A.; Roussev, I. I.; Toth, G.; Gombosi,
   T. I.
Bibcode: 2006ApJ...645.1537C
Altcode:
  We simulate the two-dimensional transport of the open magnetic flux
  on the surface of the Sun. The temporal evolution of the flux density
  depends on the advective motions due to solar differential rotation
  and poleward meridional flow and on an effective spatial diffusive
  motion. The latter is a result of the uniform diffusion of field line
  footpoints in the network lanes and a nonuniform diffusion of field
  lines due to reconnection of open field lines with closed loops on the
  solar surface. The gradient of the diffusion coefficient represents an
  effective velocity in addition to the advective velocity. We investigate
  the behavior of the steady state solution for solar minimum and solar
  maximum conditions with spatially uniform and nonuniform diffusion
  coefficients. We find that for solar minimum conditions, the effect of
  spatial diffusion resulting from reconnection processes enhances the
  poleward meridional flow due to the large-scale preferred direction
  in the gradient of the diffusion coefficient. For solar maximum
  conditions, the net effect of spatial diffusion is minimal because of
  the isotropic and local gradients of the diffusion coefficient. Our
  simulation demonstrates that magnetic reconnection processes on the
  solar surface can be a mechanism to vary motions on the photosphere,
  in particular, poleward meridional flow.

Title: Understanding Ring Current Sources of Moderate and Intense
Storms at Solar Maximum: Global Modeling Using Superposed Epoch
    Upstream Conditions
Authors: Zhang, J.; Liemohn, M. W.; de Zeeuw, D. L.; Borovsky, J. E.;
   Ridley, A. J.; Toth, G.; Sazykin, S.; Thomsen, M. F.; Kozyra, J. U.;
   Gombosi, T. I.; Wolf, R. A.
Bibcode: 2006AGUSMSM53A..07Z
Altcode:
  With the Space Weather Modeling Framework (SWMF), we conduct storm
  simulations for superposed epoch upstream solar wind conditions of
  34 moderate storms and 64 intense storms at solar maximum (July,
  1999 - June, 2002). In comparison with superposed epoch averages of
  Dst, Sym-H, and the Los Alamos Magnetospheric Plasma Analyzer (MPA)
  observations at geosynchronous orbit, modeling results are validated. It
  is shown that the SWMF is sophisticated enough to make quantitative
  data-model comparisons. The major storm characteristics are successfully
  reproduced. With the two levels of storm intensity and different SWMF
  parameter settings, the influences on storms of upstream conditions,
  ionospheric outflow and ionospheric conductance are assessed. It
  is shown that the integrated energy input for a storm is much more
  important than the short-lived peaks in the upstream solar wind
  values. Consistent with the MPA averaged measurements, it is found that
  in the inner magnetosphere in the simulated main phase plasmas become
  denser near dawn than around duskside; plasma temperature is higher in
  the afternoon and pre-midnight sectors; but enhanced plasma pressure
  is always symmetric on the nightside with a peak at midnight. Possible
  reasons for these plasma parameter asymmetries and symmetries are
  investigated and discussed. <P />personal.umich.edu/~jichunz/

Title: The global ionosphere thermosphere model
Authors: Ridley, A. J.; Deng, Y.; Tóth, G.
Bibcode: 2006JASTP..68..839R
Altcode: 2006JATP...68..839R
  The recently created global ionosphere thermosphere model (GITM)
  is presented. GITM uses a three-dimensional spherical grid that
  can be stretched in both latitude and altitude, while having a fixed
  resolution in longitude. GITM is nontraditional in that it does not use
  a pressure-based coordinate system. Instead it uses an altitude-based
  grid and does not assume a hydrostatic solution. This allows the model
  to more realistically capture physics in the high-latitude region, where
  auroral heating is prevalent. The code can be run in a one-dimensional
  (1-D) or three-dimensional (3-D) mode. In 3-D mode, the modeling region
  is broken into blocks of equal size for parallelization. In 1-D mode,
  a single latitude and longitude is modeled by neglecting any horizontal
  transport or gradients, except in the ionospheric potential. GITM
  includes a modern advection solver and realistic source terms for the
  continuity, momentum, and energy equations. Each neutral species has
  a separate vertical velocity, with coupling of the velocities through
  a frictional term. The ion momentum equation is solved for assuming
  steady-state, taking into account the pressure, gravity, neutral
  winds, and external electric fields. GITM is an extremely flexible
  code—allowing different models of high-latitude electric fields,
  auroral particle precipitation, solar EUV inputs, and particle energy
  deposition to be used. The magnetic field can be represented by an
  ideal dipole magnetic field or a realistic APEX magnetic field. Many
  of the source terms can be controlled (switched on and off, or values
  set) by an easily readable input file. The initial state can be set
  in three different ways: (1) using an ideal atmosphere, where the user
  inputs the densities and temperature at the bottom of the atmosphere;
  (2) using MSIS and IRI; and (3) restarting from a previous run. A 3-D
  equinox run and a 3-D northern summer solstice run are presented. These
  simulations are compared with MSIS and IRI to show that the large-scale
  features are reproduced within the code. We conduct a second equinox
  simulation with different initial conditions to show that the runs
  converge after approximately 1.5 days. Additionally, a 1-D simulation
  is presented to show that GITM works in 1-D and that the dynamics are
  what is expected for such a model.

Title: Multi-Scale Modeling of Magnetospheric Reconnection.
Authors: Kuznetsova, M. M.; Hesse, M.; Rastatter, L.; Toth, G.;
   Dezeeuw, D. L.; Gombosi, T. I.
Bibcode: 2006AGUSMSM21A..04K
Altcode:
  One of the major challenges in modeling the magnetospheric magnetic
  reconnection is to quantify the interaction between large-scale global
  magnetospheric dynamics and microphysical processes in diffusion regions
  near reconnection sites. There is still considerable debate as to what
  degree microphysical processes on kinetic scales affect the global
  evolution and how important it is to substitute numerical dissipation
  and/or ad hoc anomalous resistivity by a physically motivated model
  of dissipation. Comparative studies of magnetic reconnection in small
  scale geometries demonstrated that MHD simulations that included
  non-ideal processes in terms of a resistive term η J did not produce
  the fast reconnection rates observed in kinetic simulations. For a broad
  range of physical parameters in collisionless magnetospheric plasma,
  the primary mechanism controlling the dissipation in the vicinity of
  the reconnection site is non-gyrotropic effects with spatial scales
  comparable with the particle Larmor radius. We utilize the global MHD
  code BATSRUS and incorporate nongyrotropic effects in diffusion regions
  in terms of corrections to the induction equation. We developed an
  algorithm to search for magnetotail reconnection sites, specifically
  where the magnetic field components perpendicular to the local current
  direction approaches zero and form an X-type configuration. Spatial
  scales of the diffusion region and magnitude of the reconnection
  electric field are calculated self-consistently using MHD plasma
  and field parameters in the vicinity of the reconnection site. The
  location of the reconnection sites is updated during the simulations. To
  clarify the role of nongyrotropic effects in diffusion region on the
  global magnetospheric dynamic we perform simulations with steady
  southward IMF driving of the magnetosphere. Ideal MHD simulations
  with magnetic reconnection supported by numerical resistivity
  produce steady configuration with almost stationary near-earth
  neutral line (NENL). Simulations with non-gyrotropic corrections
  demonstrate dynamic quasi-periodic response to the steady driving
  condition. The loading/unloading cycle in non-gyrotropic MHD results
  has a non-stationary reconnection site in the magnetotail, with the
  retreating during the stretching phase and then a new NENL forming in
  the resulting thin plasma sheet. We expect that this model will lead
  to improved representations of space weather event in the magnetosphere.

Title: Simulation of the Ejections From NOAA AR 9236 With the SWMF
Authors: Lugaz, N.; Manchester, W.; Toth, G.; Gombosi, T. I.
Bibcode: 2006AGUSMSA23A..01L
Altcode:
  NOAA active region 9236 produced a series of 5 X-class flares and
  5 full halo CMEs between November 24 and November 27, 2000. Some of
  these ejections interacted on their way to Earth and produced a complex
  ejecta observed by the ACE satellite. We performed a MHD simulation of
  the ejections of November 24 using the Space Weather Modeling Framework
  (SWMF). We are able to reproduce LASCO C2 and C3 coronograph images with
  good agreement and to get a better understanding of the interaction
  of multiple CMEs resulting in the formation of a long-lived magnetic
  storm at Earth.

Title: Understanding Ring Current Sources of Moderate and Intense
Storms at Solar Maximum: Global Modeling Using Superposed Epoch
    Upstream Conditions
Authors: Zhang, J. -C.; Liemohn, M. W.; de Zeeuw, D. L.; Borovsky,
   J. E.; Ridley, A. J.; Toth, G.; Sazykin, S.; Thomsen, M. F.; Kozyra,
   J. U.; Gombosi, T. I.; Swmf; Mpa Team
Bibcode: 2006cosp...36.3321Z
Altcode: 2006cosp.meet.3321Z
  With the Space Weather Modeling Framework SWMF we conduct storm
  simulations for superposed epoch upstream solar wind conditions of 34
  moderate storms and 64 intense storms at solar maximum July 1999 -
  June 2002 In comparison with superposed epoch averages of Dst Sym-H
  and the Los Alamos Magnetospheric Plasma Analyzer MPA observations
  at geosynchronous orbit modeling results are validated It is shown
  that the SWMF is sophisticated enough to make quantitative data-model
  comparisons The major storm characteristics are successfully reproduced
  With the two levels of storm intensity and different SWMF parameter
  settings the influences on storms of upstream conditions ionospheric
  outflow and ionospheric conductance are assessed It is shown that the
  integrated energy input for a storm is much more important than the
  short-lived peaks in the upstream solar wind values Consistent with the
  MPA averaged measurements it is found that in the inner magnetosphere
  in the simulated main phase plasmas become denser near dawn than
  around duskside plasma temperature is higher in the afternoon and
  pre-midnight sectors but enhanced plasma pressure is always symmetric on
  the nightside with a peak at midnight Possible reasons for these plasma
  parameter asymmetries and symmetries are investigated and discussed

Title: Space weather simulations with the Space Weather Modeling
    Framework
Authors: Gombosi, T.; Toth, G.; Sokolov, I.; Ridley, A.; de Zeeuw,
   D.; Manchester, W.; Clauer, R.
Bibcode: 2006cosp...36.1541G
Altcode: 2006cosp.meet.1541G
  The Space Weather Modeling Framework SWMF aims at providing a flexible
  framework for physics based space weather simulations The SWMF combines
  numerical models of the Solar Corona which includes the Eruptive
  Event Generator the Inner Heliosphere Solar Energetic Particles
  Global Magnetosphere Inner Magnetosphere Radiation Belt Ionosphere
  Electrodynamics and Upper Atmosphere into a parallel high performance
  model All the components can be replaced with alternatives and one has
  the option to use only a subset of the components The SWMF enables us
  to do simulations that were not possible with the individual components
  We highlight some numerical simulations obtained with the SWMF

Title: Kelvin-Helmholtz Instability and Turbulence Forming Behind
    a CME-driven Shock.
Authors: Manchester, W. B.; Opher, M.; Gombosi, T.; Dezeeuw, D.;
   Sokolov, I.; Toth, G.
Bibcode: 2005AGUFMSH53A1245M
Altcode:
  We have found that a fast CME propagating through a bimodal solar wind
  produces variety of unexpected results. By means of a three-dimensional
  (3-D) numerical ideal magnetohydrodynamics (MHD) model we explore the
  interaction of a fast CME with a solar wind that possesses fast and
  slow speed solar wind at high and low latitude respectively. Within
  this model system, a CME erupts from the coronal streamer belt with
  an initial speed in excess of 1000 km/s which naturally drives a
  forward shock. An indentation in the shock forms at low latitude
  where it propagates through the slow solar wind. This indentation
  causes the fast-mode shock to deflect the flow toward the impinging
  flux rope. The plasma flow then must reverses direction to move around
  the rope, resulting in strong velocity shears. The shear flow is shown
  to be susceptible to the Kelvin-Helmholtz instability, which results
  in significant turbulence producing an environment very conducive to
  particle acceleration.

Title: Understanding Storm-time Ring Current Sources through
    Data-Model Comparisons of a Moderate Storm, an Intense Storm and
    a Super-storm
Authors: Zhang, J.; Liemohn, M. W.; Dezeeuw, D. L.; Borovsky, J. E.;
   Ridley, A. J.; Toth, G.; Sazykin, S.; Thomsen, M. F.; Kozyra, J. U.;
   Gombosi, T. I.; Wolf, R. A.
Bibcode: 2005AGUFMSM22A..08Z
Altcode:
  With the Space Weather Modeling Framework (SWMF), the moderate
  storm on 19 May 2002, the intense storm on 11 May 2002, and the
  super-storm on 20 November 2003 are simulated. In comparison with
  in-situ observations from Wind, Geotail, Polar, Goes8, Goes10, Goes12,
  LANL MPA, and measured Sym-H, simulation results are validated. It is
  shown that the SWMF is sophisticated enough to make quantitative data-
  model comparisons. The major characteristics of the three storms are
  successfully reproduced. Observations and modeling results match better
  in the outer than inner magnetosphere; they match better during the
  quiet than disturbed times. With different SWMF parameter settings and
  storm sizes, the influences on storms of upstream solar wind conditions,
  ionospheric outflow and ionospheric conductance are assessed. Results
  from `virtual satellites', placed at geosynchronous orbit in the SWMF,
  show that plasma temperature and entropy are asymmetric on the nightside
  with a peak at 7:00 - 8:00 PM local time. After the solar wind shock
  hits the magnetosphere, the nightside plasma becomes denser closer
  to dawn and dusk. Possible reasons for the number density peaks are
  investigated and discussed.

Title: Statistical Study of the Probability of Titan Being in the
    Solar Wind or in Saturn's Magnetosheath
Authors: Lundberg, E. T.; Hansen, K. C.; Gombosi, T. I.; Toth, G.
Bibcode: 2005AGUFM.P43A0957L
Altcode:
  We present the results of a statistical study of the location of
  Titan relative to the bow shock and the magnetopause of Saturn's
  magnetosphere. Using statistical distributions of solar wind ram
  pressure at Saturn's orbit and the dependence of the magnetosphere's
  boundaries on this pressure we are able to calculate the probability of
  finding Titan in the solarwind, the magnetosheath or the magnetosphere
  for each point along its orbit. As a preliminary example consider Titan
  at the sub-solar point for 2004 solar wind conditions. We find that
  Titan would have spent 56.7% of its time in the magnetosphere, 42.1%
  in the magnetosheath and 1.3% in the solarwind for these conditions
  when at the sub-solar point. We will present statistics for Titan at
  a set of local times along its orbit as well as integrated over its
  entire orbit. We obtain solar wind conditions at the orbit of Saturn
  by propagating ACE and other spacecraft measurements of the solar wind
  conditions at the Earth radially outward using a 1D MHD model. The
  propagation is validated against Voyager, Pioneer and Cassini data. For
  our calculations, we use different models for the shape of the bow
  shock and magnetopause. These include the traditional Slavin model as
  well as a new boundary model generated by fitting geometric surfaces
  to a global 3D MHD model of Saturn's magnetosphere.

Title: Magnetic Reconnection in Global MHD Modeling of Magnetosphere
    Dynamics
Authors: Kuznetsova, M. M.; Hesse, M.; Rastatter, L.; Toth, G.;
   de Zeeuw, D.; Gombosi, T.
Bibcode: 2005AGUFMSM31B0418K
Altcode:
  One of the major challenges in global MHD modeling of magnetosphere
  dynamics is to find an accurate description of the reconnection rate. We
  will take advantage of recent progress in small-scale kinetic studies
  of magnetic reconnection, which demonstrated that the reconnection
  rate is controlled by ion nongyrotropic behavior near the reconnection
  site. It can then be expressed in terms of nongyrotropic corrections to
  the electric field. We will demonstrate that the reconnection electric
  field can be estimated as a convection electric field v x B at the edge
  of the non-MHD diffusion region. The BATSRUS adaptive grid structure
  allows to perform global simulations with spatial resolution near the
  reconnection site comparable with ion kinetic scales. To reproduce
  fast reconnection rates observed in kinetic simulations we modified
  the global MHD code BATSRUS by introducing nongyrotropic corrections
  to the magnetic induction equation. The role of the nongyrotropic
  effects near the reconnection site on the global magnetospheric
  dynamics will be analyzed. Testing the ability of global MHD models
  to describe magnetospheric dynamics is one of the elements of science
  based validation efforts at the Community Coordinated Modeling Center.

Title: Space Weather Modeling Framework: A new tool for the space
    science community
Authors: Tóth, GáBor; Sokolov, Igor V.; Gombosi, Tamas I.; Chesney,
   David R.; Clauer, C. Robert; de Zeeuw, Darren L.; Hansen, Kenneth
   C.; Kane, Kevin J.; Manchester, Ward B.; Oehmke, Robert C.; Powell,
   Kenneth G.; Ridley, Aaron J.; Roussev, Ilia I.; Stout, Quentin F.;
   Volberg, Ovsei; Wolf, Richard A.; Sazykin, Stanislav; Chan, Anthony;
   Yu, Bin; Kóta, József
Bibcode: 2005JGRA..11012226T
Altcode:
  The Space Weather Modeling Framework (SWMF) provides a high-performance
  flexible framework for physics-based space weather simulations, as well
  as for various space physics applications. The SWMF integrates numerical
  models of the Solar Corona, Eruptive Event Generator, Inner Heliosphere,
  Solar Energetic Particles, Global Magnetosphere, Inner Magnetosphere,
  Radiation Belt, Ionosphere Electrodynamics, and Upper Atmosphere into a
  high-performance coupled model. The components can be represented with
  alternative physics models, and any physically meaningful subset of the
  components can be used. The components are coupled to the control module
  via standardized interfaces, and an efficient parallel coupling toolkit
  is used for the pairwise coupling of the components. The execution
  and parallel layout of the components is controlled by the SWMF. Both
  sequential and concurrent execution models are supported. The SWMF
  enables simulations that were not possible with the individual physics
  models. Using reasonably high spatial and temporal resolutions in all
  of the coupled components, the SWMF runs significantly faster than
  real time on massively parallel supercomputers. This paper presents
  the design and implementation of the SWMF and some demonstrative
  tests. Future papers will describe validation (comparison of model
  results with measurements) and applications to challenging space
  weather events. The SWMF is publicly available to the scientific
  community for doing geophysical research. We also intend to expand
  the SWMF in collaboration with other model developers.

Title: Magnetic Reconnection Rate in Collisionless Plasma.
Authors: Patel, K.; Kuznetsova, M. M.; Hesse, M.; Rastatter, L.;
   Toth, G.; Gombosi, T.
Bibcode: 2005AGUFMSH51D..06P
Altcode:
  The physical processes controlling the magnetic reconnection rate are of
  principle importance for many phenomena in space plasma. Comparative
  study of magnetic reconnection in kinetic and fluid simulations
  demonstrated that the reconnection rate is controlled by ion
  nongyrotropic behavior near the reconnection site. We will demonstrate
  that reconnection electric field can be estimated as a convection
  electric field v x B at the edge of the non-MHD diffusion region and
  can be incorporated into the MHD description. We employ small scale
  and global MHD simulation codes and introduce non-ideal corrections
  to the induction equation in terms of nongyrotropic corrections to
  the electric field. The role of the nongyrotropic effects near the
  reconnection site on the global dynamics will be analyzed.

Title: Multiple Scales in the Solar Wind Interaction with the
    Magnetosphere
Authors: Gombosi, T. I.; Ridley, A. J.; de Zeeuw, D. L.; Sokolov,
   I. V.; Toth, G.
Bibcode: 2005AGUFMSM34A..01G
Altcode:
  The solar wind interaction with the magnetosphere takes place on many
  scales ranging from global scale current systems to mesoscale processes
  like ionospheric outflows, to microscale phenomena involving kinetic
  effects and reconnection. This talk will discuss a new computational
  tool, the Space Weather Modeling Framework (SWMF), that was specifically
  designed to self-consistently couple different physics domains described
  by different approximate models. SWMF can couple global MHD codes to
  kinetic drift physics models (such as RCM), as well as other mesoscale
  and/or microscale codes. We will show several simulations and data
  comparisons investigating the effects of various processes on the
  configuration and dynamics of the magnetosphere.

Title: Numerical Simulation of Transport of Open Magnetic Flux on
    the Solar Surface
Authors: Cohen, O.; Fisk, L. A.; Gombosi, T. I.; Roussev, I. I.;
   Toth, G.
Bibcode: 2005AGUFMSH41A1116C
Altcode:
  Following Fisk (2005), we simulate the transport and evolution
  of the open magnetic flux on the surface of the sun. The temporal
  evolution of the flux density depends on the convective motion due
  to solar differential rotation and poleward meridional flow, and an
  effective diffusive motion. The latter is a result of the diffusion
  of field-lines footpoints in the network lanes, and the diffusion of
  field-lines due to reconnection of open field lines with closed loops
  on the solar surface. The diffusion coefficient of the network lanes
  motion is constant everywhere, while the diffusion coefficient due
  to the reconnection process is non-uniform, and depends on the open
  flux density and the rate of emergence of the new magnetic loops. The
  gradient of the diffusion coefficient due to reconnection represents an
  effective velocity in addition to the convective motion. We investigate
  the behavior of the steady-state solution with constant and spatial
  diffusion coefficient; we also examine the behavior of the effective
  velocity due to the non-uniform diffusion coefficient. In the future,
  we plan to extend the current 2D model to a 3D geometry in order
  to investigate the role of the open flux in the evolution of the
  large-scale solar magnetic field and in solar wind acceleration,
  in the extent of a global model.

Title: Sun-to-Thermosphere Simulation of the October 28, 2003 Event
    With the Space Weather Modeling Framework
Authors: Toth, G.; de Zeeuw, D. L.; Gombosi, T. I.; Manchester, W. B.;
   Ridley, A. J.; Roussev, I. I.; Sokolov, I. V.
Bibcode: 2005AGUFMSM11A..05T
Altcode:
  Space weather forecasting requires faster than real-time simulations
  of the entire Sun-to-Earth model chain at high enough spatial and
  temporal resolution to resolve the important geoeffective features in
  the solar wind and the magnetosphere-ionosphere-thermosphere system. We
  present a complete end-to-end simulation of one of the most intensive
  solar storms, the October 28, 2003 CME. The physical domain models
  spanning from the Solar Corona model to the Upper Atmosphere model
  are self-consistently coupled together by the high-performance Space
  Weather Modeling Framework (SWMF). We discuss technological advances
  enabling the faster than real-time operation of the SWMF with high
  resolution. We also compare the simulation results with observations.

Title: Magnetotail Current Sheet Thinning in Global Simulations of
    Magnetosphere Dynamics.
Authors: Taktakishvili, A.; Kuznetsova, M.; Hesse, M.; Rastatter,
   L.; Toth, G.; de Zeeuw, D.; Gombosi, T.
Bibcode: 2005AGUFMSM23B0430T
Altcode:
  We perform simulations of magnetotail dynamics using the global MHD
  models at the Community Coordinated Modeling Center (CCMC). We select
  solar wind conditions which drive the accumulation of magnetic field in
  the tail lobes and subsequent magnetotail current sheet thinning. We
  will demonstrate the formation of bifurcated and triple-peak current
  sheets during this phase. In addition, we will analyze the dependence
  of the thin current sheet structure, location, rate of the thinning
  and timing of reconnection onset on solar wind conditions. Finally,
  we will discuss the role of dayside reconnection rate, of diffusion
  at the flanks, and of distant tail processes on the dynamics of the
  current sheet thinning.

Title: The Polar Wind as a Mass Source for Saturn's Magnetosphere
Authors: Glocer, A.; Gombosi, T.; Toth, G.; Hansen, K.; Ridley, A.
Bibcode: 2005AGUFM.P52A..06G
Altcode:
  Characterizing the relative importance of the various mass sources
  is crucial to understanding Saturn's magnetosphere. Most research in
  this area focuses on the addition of mass from the icy satellites and
  rings. Comparatively little attention has been paid to the ionospheric
  source. Our study addresses this issue by using multi-fluid numerical
  simulations of Saturn's polar wind to determine the magnitude of the
  contribution. We introduce a model capable of calculating the polar wind
  at Earth and Saturn, solving the gyrotropic transport equations. The
  polar wind at Saturn is calculated from below the peak ionospheric
  density to an altitude of one Saturn radius, giving fluxes for H3+,
  H+, and electrons. Similarly, at Earth the calculation ranges from
  200 km to approximately one Earth radius, providing fluxes for O+, H+,
  and He+. We calculate source rates for various atmospheric profiles,
  and compare the results with those calculated from other models and
  measurements where appropriate.

Title: Transport and Acceleration of Electrons from the Outer to
    the Inner Magnetosphere
Authors: Schriver, D.; Ashour-Abdalla, M.; Zelenyi, L.; Gombosi, T.;
   Ridley, A.; Toth, G.; Travnicek, P.
Bibcode: 2005AGUFMSM33C0469S
Altcode:
  To examine the transport and acceleration of electrons throughout the
  Earth's magnetosphere, a global model that follows electron motion
  in magnetic and electric fields representative of the magnetospheric
  configuration has been developed. The goal is to understand the
  formation of the seed electron population with energies &gt; keV located
  at about 10 R_E from the Earth in the equatorial plane. The results show
  that electrons launched in the outer magnetospere are adibatically
  compressed as they convect towards the magnetic midplane in the
  magnetotail forming a heated central plasma sheet towards the Earth. A
  group of electrons accelerated near a reconnection region located in the
  deep magnetotail also contributes to the plasma sheet population and the
  heated distribution function that forms in the seed region (at about 10
  R_E) is a combination of electrons that are accelerated adiabatically
  and non-adiabatically. The results also show that the seed electron
  distribution is highly anisotropic with the perpendicular temperature
  about 2 times the parallel temperature. Results that consider different
  magnetic activity levels will be discussed and comparisions with Cluster
  satellite data in the near-Earth plasma sheet region will be presented.

Title: Numerical simulations of vertical oscillations of a solar
    coronal loop
Authors: Selwa, M.; Murawski, K.; Solanki, S. K.; Wang, T. J.;
   Tóth, G.
Bibcode: 2005A&A...440..385S
Altcode:
  We consider the impulsive excitation of fast vertical kink standing
  waves in a solar coronal loop that is embedded in a potential
  arcade. The two-dimensional numerical model we implement includes the
  effects of field line curvature and nonlinearity on the excitation
  and damping of standing fast magnetosonic waves. The results of the
  numerical simulations reveal wave signatures which are characteristic
  of vertical loop oscillations seen in recent TRACE observational data.

Title: Global MHD simulations of Saturn's magnetosphere at the time
    of Cassini approach
Authors: Hansen, K. C.; Ridley, A. J.; Hospodarsky, G. B.; Achilleos,
   N.; Dougherty, M. K.; Gombosi, T. I.; Tóth, G.
Bibcode: 2005GeoRL..3220S06H
Altcode:
  We present the results of a 3D global magnetohydrodynamic simulation
  of the magnetosphere of Saturn for the period of Cassini's initial
  approach and entry into the magnetosphere. We compare calculated bow
  shock and magnetopause locations with the Cassini measurements. In order
  to match the measured locations we use a substantial mass source due
  to the icy satellites (~1 × 10<SUP>28</SUP> s<SUP>-1</SUP> of water
  product ions). We find that the location of bow shock and magnetopause
  crossings are consistent with previous spacecraft measurements,
  although Cassini encountered the surfaces further from Saturn than
  the previously determined average location. In addition, we find that
  the shape of the model bow shock and magnetopause have smaller flaring
  angles than previous models and are asymmetric dawn-to-dusk. Finally,
  we find that tilt of Saturn's dipole and rotation axes results in
  asymmetries in the bow shock and magnetopause and in the magnetotail
  being hinged near Titan's orbit (~20 R<SUB>S</SUB>).

Title: Cross-Disciplinary Modeling of Heliospheric Phenomena with
    the Space Weather Modeling Framework
Authors: Gombosi, T. I.; Toth, G.; Sokolov, I. V.; Stout, Q. F.;
   Clauer, C. R.; de Zeeuw, D. L.; Hansen, K. C.; Manchester, W. B.;
   Powell, K. G.; Ridley, A. J.; Roussev, I. I.
Bibcode: 2005AGUSMSH11B..01G
Altcode:
  The Space Weather Modeling Framework (SWMF) aims at providing a
  high-performance flexible plug-and-play type framework for physics
  based space weather simulations, as well as for various space physics
  applications. The SWMF combines numerical models of the Solar Corona,
  Eruptive Event Generator, Inner Heliosphere, Solar Energetic Particles,
  Global Magnetosphere, Inner Magnetosphere, Radiation Belt, Ionosphere
  Electrodynamics and Upper Atmosphere into a high performance coupled
  model. All the components can be replaced with alternatives, and one
  can use only a subset of the components. The components are coupled
  to the control module via standardized interfaces, and an efficient
  parallel coupling toolkit can be used for the pairwise coupling of
  the components. The SWMF enables us to do simulations that were not
  possible with the individual components. Using reasonably high spatial
  and temporal resolutions in all the coupled components, the SWMF can
  still run significantly faster than real time on massively parallel
  supercomputers. This talk presents the design and implementation of
  the SWMF with a demonstrative application to a space weather event.

Title: Fast Magnetotail Reconnection: Challenge to Global MHD Modeling
Authors: Kuznetsova, M. M.; Hesse, M.; Rastaetter, L.; Toth, G.;
   de Zeeuw, D.; Gombosi, T.
Bibcode: 2005AGUSMSM33A..02K
Altcode:
  Representation of fast magnetotail reconnection rates during substorm
  onset is one of the major challenges to global MHD modeling. Our
  previous comparative study of collisionless magnetic reconnection
  in GEM Challenge geometry demonstrated that the reconnection rate is
  controlled by ion nongyrotropic behavior near the reconnection site
  and that it can be described in terms of nongyrotropic corrections
  to the magnetic induction equation. To further test the approach we
  performed MHD simulations with nongyrotropic corrections of forced
  reconnection for the Newton Challenge setup. As a next step we employ
  the global MHD code BATSRUS and test different methods to model fast
  magnetotail reconnection rates by introducing non-ideal corrections
  to the induction equation in terms of nongyrotropic corrections,
  spatially localized resistivity, or current dependent resistivity. The
  BATSRUS adaptive grid structure allows to perform global simulations
  with spatial resolution near the reconnection site comparable with
  spatial resolution of local MHD simulations for the Newton Challenge. We
  select solar wind conditions which drive the accumulation of magnetic
  field in the tail lobes and subsequent magnetic reconnection and
  energy release. Testing the ability of global MHD models to describe
  magnetotail evolution during substroms is one of the elements of science
  based validation efforts at the Community Coordinated Modeling Center.

Title: Evolution of CME-driven Shocks in the Lower Corona for the
    October-November 2003 Events
Authors: Opher, M.; Manchester, W.; Gombosi, T.; Liewer, P.; Roussev,
   I.; Sokolov, I.; Dezeeuw, D.; Toth, G.
Bibcode: 2005AGUSMSH13B..03O
Altcode:
  While it is generally accepted that the largest energetic particle
  events are created by CME-driven shocks in interplanetary space, the
  relative importance of CME-driven shocks versus flare-related processes
  in creating energetic particles low in the corona is not understood
  and is an area of active research. We analyzed the formation of CME
  driven shocks in the lower corona for the Halloween Space Storms
  that occurred in late October and early November 2003. We used the
  Space Weather Modeling Framework (SWMF) developed at the University
  of Michigan to create a realistic corona. The CME was modeled as an
  out of equilibrium flux rope lying under a closed field region in the
  AR 10486. The MHD code was first used to create realistic background
  corona using observed photospheric fields for boundary conditions for
  the Carrington rotation 2008. The background corona was validated by
  comparing results from the model with in situ solar wind observations
  from ACE/WIND. We discuss the magnetosonic speed profile in the lower
  corona and the consequences for the CME shock formation. Consequences
  for the acceleration of particles to GeV/nucleon are discussed. The
  computational runs were performed at the supercomputer Columbia at
  NASA/AMES.

Title: Are high-latitude forward-reverse shock pairs driven by
    over-expansion?
Authors: Manchester, W. B.; Zurbuchen, T. H.; Gombosi, T. I.; de Zeeuw,
   D. L.; Sokolov, I. V.; Toth, G.
Bibcode: 2005AGUSMSH52A..04M
Altcode:
  During its passage through the high-latitude heliosphere, Ulysses
  observed Interplanetary CMEs (ICMEs) bounded by shocks. These
  forward-reverse shock pairs have only been observed at high latitude in
  the fast solar. It has been suggested (e.g. Gosling et al. 1995) that
  these shock pairs are the result of the expansion of the coronal mass
  ejection in the ambient solar wind, so called "over-expansion". Here
  we demonstrate and alternative explanation for forward-reverse
  shock pairs by means of a three-dimensional (3-D) numerical ideal
  magnetohydrodynamics (MHD) model of a CME interacting with the solar
  wind. Our global steady-state coronal model possesses fast and slow
  speed solar wind at high and low latitude respectively reminiscent of
  near solar minimum conditions. Within this model system, a CME erupts
  from the coronal streamer belt with an initial speed in excess of 1000
  km/s which naturally drives a forward shock. When the CME is greater
  than 40 Rs from the Sun, we find that a reverse shock forms poleward of
  the CME as a result of the interaction of the CME with the bimodal solar
  wind. In front of the CME, the slow wind is deflected to higher latitude
  while behind the CME, fast wind is deflected to low latitude. The
  deflected streams collide to form a reverse shock. The shock pair
  formed in this way naturally forms at high latitude in the fast wind
  stream. We will discuss these model results in the context of in situ
  solar wind data and make testable predictions based on this model.

Title: Effects of a Tilted Heliospheric Current Sheet in the
    Heliosheath
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; Dezeeuw, D.; Toth, G.
Bibcode: 2005AGUSMSH23A..07O
Altcode:
  Effects of a Tilted Heliospheric Current Sheet in the Heliosheath
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in a
  region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already
  crossed the Termination Shock, the first boundary of the Heliosphere
  (Krimigis et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An
  important aspect of this controversy is our poor understanding
  of this region. The region between the Termination Shock and the
  Heliopause, the Helisheath, is one of the most unknown regions
  theoretically. In the Heliosheath magnetic effects are crucial,
  as the solar magnetic field is compressed at the Termination Shock
  by the slowing flow. Therefore, to accurately model the heliosheath
  the inclusion of the solar magnetic field is crucial. Recently, our
  simulations showed that the Heliosheath presents remarkable dynamics,
  with turbulent flows and a presence of a jet flow at the current sheet
  that is unstable due to magnetohydrodynamic instabilities (Opher et
  al. 2003; 2004). We showed that to capture these phenomena, spatial
  numerical resolution is a crucial ingredient, therefore requiring the
  use of an adaptive mesh refinement (AMR). These previous works assumed
  that the solar rotation and the magnetic axis were aligned. Here we
  present including, for the first time, the tilt of the heliocurrent
  sheet using a 3D MHD AMR simulation with BATS-R-US code. We discuss
  the effects on the global structure of the Heliosheath, the flows,
  turbulence and magnetic field structure. We access the consequences for
  the observations measured by Voyager 1 since mid-2002. This intensive
  computational run was done at the supercomputer Columbia at NASA/AMES

Title: Validation of the Space Weather Modeling Framework for
    Northward IMF Conditions
Authors: Toth, G.; Ridley, A. J.; Oieroset, M.; de Zeeuw, D. L.;
   Gombosi, T. I.
Bibcode: 2005AGUSMSM42A..01T
Altcode:
  We have simulated the magnetosphere and the ionosphere for an extended
  period of northward interplanetary magnetic field (IMF) conditions
  that occurred between 17:00 UT October 22 2003 and 00:00 UT October
  24 2003. The Space Weather Modeling Framework (SWMF) is run with the
  coupled global magnetosphere (BATSRUS), inner magnetosphere (RCM)
  and ionosphere electro-dynamics (Ridley) components. The simulation
  results are compared with the magnetic field measurements of the GOES
  10, GOES 12, Polar, Wind and Geotail satellites, and with the density,
  temperature, magnetic field and velocity measured by the Cluster
  satellites. We examine the effects of the grid resolution, Joule
  heating, resistivity, and coupling with the Inner Magnetosphere. It
  is found that the coupling with the RCM significantly improves the
  agreement between the observed and simulated magnetic fields near
  the Earth. In order to better match the far-tail Wind observations,
  resistivity needs to be added to the simulation. This indicates that
  the numerical resistivity in the code is most likely too low in the
  reconnection sites. In addition, it is shown that the amount of Joule
  heating in the reconnection site has a strong influence on the density
  and temperature of the plasma sheet. This series of simulations also
  serve as a validation of the SWMF.

Title: Coronal Mass Ejection Shock and Sheath Structures Relevant
    to Particle Acceleration
Authors: Manchester, W. B., IV; Gombosi, T. I.; De Zeeuw, D. L.;
   Sokolov, I. V.; Roussev, I. I.; Powell, K. G.; Kóta, J.; Tóth, G.;
   Zurbuchen, T. H.
Bibcode: 2005ApJ...622.1225M
Altcode:
  Most high-energy solar energetic particles are believed to be
  accelerated at shock waves driven by coronal mass ejections (CMEs). The
  acceleration process strongly depends on the shock geometry and the
  structure of the sheath that forms behind the shock. In an effort
  to understand the structure and time evolution of such CME-driven
  shocks and their relevance to particle acceleration, we investigate
  the interaction of a fast CME with the ambient solar wind by means
  of a three-dimensional numerical ideal MHD model. Our global steady
  state coronal model possesses high-latitude coronal holes and a
  helmet streamer structure with a current sheet near the equator,
  reminiscent of near solar minimum conditions. Fast and slow solar
  winds flow at high and low latitude, respectively, and the Archimedean
  spiral geometry of the interplanetary magnetic field is reproduced by
  solar rotation. Within this model system, we drive a CME to erupt by
  introducing a Gibson-Low magnetic flux rope that is embedded in the
  helmet streamer in an initial state of force imbalance. The flux rope
  rapidly expands and is ejected from the corona with maximum speeds
  in excess of 1000 km s<SUP>-1</SUP>, driving a fast-mode shock from
  the inner corona to a distance of 1 AU. We find that the ambient solar
  wind structure strongly affects the evolution of the CME-driven shocks,
  causing deviations of the fast-mode shocks from their expected global
  configuration. These deflections lead to substantial compressions of
  the plasma and magnetic field in their associated sheath region. The
  sudden postshock increase in magnetic field strength on low-latitude
  field lines is found to be effective for accelerating particles to
  the GeV range.

Title: Modelling gravity gradient variation due to water mass
    fluctuations
Authors: Völgyesi, L.; Tóth, G.
Bibcode: 2005ggsm.conf..364V
Altcode:
  No abstract at ADS

Title: Determination of gravity anomalies from torsion balance
    measurements
Authors: Völgyesi, L.; Tóth, G.; Csapó, G.
Bibcode: 2005ggsm.conf..292V
Altcode:
  No abstract at ADS

Title: A Physics-Based Software Framework for Sun-Earth Connection
    Modeling
Authors: Toth, G.; Volberg, O.; Ridley, A. J.; Gombosi, T. I.;
   de Zeeuw, D.; Hansen, K. C.; Chesney, D. R.; Stout, Q. F.; Powell,
   K. G.; Kane, K. J.; Oehmke, R. C.
Bibcode: 2005mcsp.conf..383T
Altcode:
  No abstract at ADS

Title: Electron Transport in the Earth's Outer and Inner Magnetosphere
Authors: Schriver, D.; Ashour-Abdalla, M.; Zelenyi, L.; Gombosi, T.;
   Ridley, A. J.; Dezeeuw, D.; Toth, G.; Monostori, G.
Bibcode: 2004AGUFMSM33B..06S
Altcode:
  As electrons are transported from the solar wind and through the
  Earth's magnetosphere, they can be accelerated to energies &gt;
  10 keV when they reach the so-called seed region located at about 10
  R<SUB>E</SUB> radially from the Earth in the equatorial plane. As these
  seed electrons move closer to the Earth, wave-particle interactions
  can cause further acceleration of electrons to relativistic (MeV)
  energies. This process occurs during the recovery of magnetic storms,
  where relativistic electron fluxes are usually observed to be enhanced
  over pre-storm values in the inner magnetosphere near geosynchronous
  orbit. In this study, the transport of electrons from the solar wind and
  outer magnetosphere towards the seed region is examined. This is done
  by following electron trajectories from different starting points in a
  global model for the magnetospheric magnetic and electric fields. The
  electron particle trajectories are followed based on the guiding center
  approximation and both an empirical and an MHD model (BATS-R-US code)
  are used for the global magnetospheric fields. In regions where
  the local fields are very weak (e.g., near reconnection regions),
  non-adiabatic effects could be important and this is included when
  following electrons by switching from the guiding center approximation
  to a full trajectory calculation using the Lorentz force equation in
  these localized regions of space. Electron distribution functions
  formed at different locations in the magnetotail as well as in the
  seed region will be discussed.

Title: New Simulations of Saturn's Polar Wind
Authors: Glocer, A.; Gombosi, T.; Hansen, K.; Toth, G.
Bibcode: 2004AGUFM.P51A1417G
Altcode:
  We present preliminary results of a new simulation of Saturn's
  polar wind. The results include new vertical ion and electron density
  profiles, fluxes, and net source rates. Our model solves the 13 moment
  gyrotropic transport equations. The gyration dominated assumption
  allows us to assume that the flow is field aligned, and justifies the
  use of a one dimensional model. Furthermore, the effect of solar zenith
  angle and optical depth on the solar flux is taken into account. While
  capable of modeling transient behavior, only steady state results are
  presented. Similarly, the ability to include field aligned currents
  is built into the model, but their effect is not yet studied. By
  combining polar wind model output with a global MHD simulation of
  the magnetosphere-ionosphere system, we are able to calculate the net
  ionospheric source due to the polar wind. Like Earth, we expect that
  Saturn's ionosphere is an important source of magnetospheric plasma. The
  recent arrival of Cassini is giving unprecedented amounts of data. The
  time is therefore ripe for an attempt to characterize the ionospheric
  source at Saturn, and this simulation will help further this objective.

Title: Coupling of a global MHD code and an inner magnetospheric
model: Initial results
Authors: de Zeeuw, Darren L.; Sazykin, Stanislav; Wolf, Richard A.;
   Gombosi, Tamas I.; Ridley, Aaron J.; Tóth, Gabor
Bibcode: 2004JGRA..10912219D
Altcode:
  This paper describes the coupling of BATS-R-US (Block Adaptive Tree
  Solar-wind Roe-type Upwind Scheme), a magnetohydrodynamics (MHD) code
  representing the Earth's global magnetosphere and its coupling to
  the ionosphere and solar wind, and the Rice Convection Model (RCM),
  which represents the inner magnetosphere and its coupling to the
  ionosphere. The MHD code provides a time-evolving magnetic field model
  for the RCM as well as continuously updated boundary conditions for
  the electric potential and plasma. The RCM computes the distribution
  functions of inner magnetospheric particles, including transport of
  inner plasmasheet and ring current particles by gradient/curvature
  drifts; it thus calculates more accurate inner magnetospheric pressures,
  which are frequently passed to the MHD model and used to nudge the
  MHD values. Results are presented for an initial run with the coupled
  code for the case of uniform ionospheric conductance with steady
  solar wind and southward interplanetary magnetic field (IMF). The
  results are compared with those for a run of the MHD code alone. The
  coupled-code run shows significantly higher inner magnetospheric
  particle pressures. It also exhibits several well-established
  characteristics of inner magnetospheric electrodynamics, including
  strong region-2 Birkeland currents and partial shielding of the inner
  magnetosphere from the main force of the convection electric field. A
  sudden northward turning of the IMF causes the ring current to become
  more nearly symmetric. The inner magnetosphere exhibits an overshielding
  (dusk-to-dawn) electric field that begins about 10 min after the
  northward turning reaches the magnetopause and lasts just over an hour.

Title: Space Weather Modeling Framework: Modeling the Sun-Earth
    System Faster Than Real Time
Authors: Toth, G.; Sokolov, I. V.; Kane, K. J.; Gombosi, T. I.; de
   Zeeuw, D. L.; Ridley, A. J.; Volberg, O.; Hansen, K. C.; Manchester,
   W. B.; Roussev, I. I.; Stout, Q. F.; Powell, K. G.
Bibcode: 2004AGUFMSH53B0325T
Altcode:
  The Space Weather Modeling Framework (SWMF) aims at providing a
  flexible plug-and-play type framework for physics based space weather
  simulations, as well as for various space physics applications. The SWMF
  combines numerical models of the Solar Corona (including an Eruptive
  Event Generator), the Inner Heliosphere, Solar Energetic Particles,
  Global Magnetosphere, Inner Magnetosphere, Radiation Belt, Ionosphere
  Electrodynamics and Upper Atmosphere into a high performance coupled
  model. All the components can be replaced with alternatives, and one can
  use only a subset of the components. The configuration, compilation and
  execution of the framework can be done with a user friendly Graphical
  User Interface. The components are coupled to the control module via
  standardized interfaces, and an efficient parallel coupling toolkit
  is used for the pairwise coupling of the components. The execution
  and parallel layout of the components is controlled by the SWMF. Both
  sequential and concurrent execution models are supported. The SWMF
  enables us to do simulations that were not possible with the individual
  components. Using reasonably high spatial and temporal resolutions in
  all the coupled components, the SWMF can still run significantly faster
  than real time on massively parallel super computers. We highlight
  some numerical simulations obtained with the SWMF.

Title: Effects of a Tilted Heliospheric Current Sheet in the
Heliosheath: 3D MHD Modeling
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; Dezeeuw, D.; Toth, G.
Bibcode: 2004AGUFMSH42A..02O
Altcode:
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in
  a region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already crossed
  the Termination Shock, the first boundary of the Heliosphere (Krimigis
  et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An important
  aspect of this controversy is our poor understanding of this region. The
  region between the Termination Shock and the Heliopause, the Helisheath,
  is one of the most unknown regions theoretically. In the Heliosheath
  magnetic effects are crucial, as the solar magnetic field is compressed
  at the Termination Shock by the slowing flow. Therefore, to accurately
  model the Heliosheath the inclusion of the solar magnetic field is
  crucial. Recently, our simulations showed that the Heliosheath presents
  remarkable dynamics, with turbulent flows and a presence of a jet
  flow at the current sheet that is unstable due to magnetohydrodynamic
  instabilities (Opher et al. 2003; 2004). We showed that to capture
  these phenomena, spatial numerical resolution is a crucial ingredient,
  therefore requiring the use of an adaptive mesh refinement (AMR). These
  previous works assumed that the solar rotation and the magnetic axis
  were aligned. Here we present for the first time results including
  the tilt of the heliocurrent sheet using a 3D MHD AMR simulation, with
  BATS-R-US code. We discuss the effects on the global structure of the
  Heliosheath, the flows, turbulence and magnetic field structure. We
  assess the consequences for the observations measured by Voyager 1
  since mid-2002.

Title: 3D Density Structure and LOS Observations of a Model CME
Authors: Manchester, W. B.; Lugaz, N.; Gombosi, T.; de Zeeuw, D.;
   Sokolov, I.; Toth, G.
Bibcode: 2004AGUFMSH21D..04M
Altcode:
  We present synthetic Thomson-scattered white-light images of a simulated
  coronal mass ejection (CME). The simulations are based on a 3-D MHD
  model of a CME propagating through a bimodal solar wind characteristic
  of solar minimum. The CME is driven by a 3-D Gibson-Low flux rope
  inserted in the helmet streamer of the steady-state corona. Synthetic
  coronograph images are produced that follow the evolution of the CME
  to 1 AU from several points of view. The white light images provide
  a basis for comparison with wide angle coronographs, like those of
  SMEI or STEREO. We find that a large amount of plasma is swept up
  from the solar wind by the CME-driven shock wave, which dominates the
  density structure far from the Sun. We also find that the shape of
  this compressed plasma is highly distorted by the variation in speed
  of the ambient solar wind. Comparisons of 2-D integrated images to the
  3-D density structure show that the viewing angle severely effects the
  line-of-sight appearance of the CME, as well as the estimated mass of
  the CME from such 2D images.

Title: CME Shock and Sheath Structures Relevant to Particle
    Acceleration
Authors: Manchester, W. B.; Kota, J.; Gombosi, T.; Igor, S. V.;
   Roussev, I.; de Zeeuw, D.; Powell, K.; Toth, G.; Zurbuchen, T.
Bibcode: 2004AGUFMSH33A1188M
Altcode:
  Most high-energy solar energetic particles (SEPs) are believed to be
  accelerated at shock waves driven by coronal mass ejections (CMEs). The
  acceleration process strongly depends on the shock geometry, and the
  structure of the sheath that forms behind the shock. In an effort
  to understand the structure and time evolution of such CME-driven
  shocks and their relevance to particle acceleration, we investigate
  the interaction of a fast CME with the ambient solar wind by means of
  a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD)
  model. Our global steady-state coronal model possesses high-latitude
  coronal holes and a helmet streamer structure with a current sheet
  near the equator, reminiscent of near solar minimum conditions. Fast
  and slow speed solar wind flow at high and low latitude respectively
  and the Archimedian spiral geometry of the interplanetary magnetic
  field is reproduced by solar rotation. Within this model system, we
  drive a CME to erupt by the introduction of a Gibson-Low magnetic flux
  rope that is embedded in the helmet streamer in an initial state of
  force imbalance. The flux rope rapidly expands and is ejected from the
  corona with maximum speeds in excess of 1000 km/s driving a fast-mode
  shock from the inner corona to a distance of 1 astronomical unit
  (AU). We find that the ambient solar wind structure strongly affects
  the evolution of the CME-driven shocks causing deviations of the of
  the fast-mode shocks from their expected global configuration. These
  deflections lead to substantial compressions of the plasma and magnetic
  field in their associated sheath region. The sudden post-shock increase
  in magnetic field strength on low latitude field lines is found to be
  effective for accelerating particles to the GeV range.

Title: Effects of a Tilted Heliospheric Current Sheet at the Edge
    of the Solar System
Authors: Opher, M.; Liewer, P.; Manchester, W.; Gombosi, T.; DeZeeuw,
   D.; Toth, G.
Bibcode: 2004AAS...205.4306O
Altcode: 2004BAAS...36.1412O
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in
  a region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already crossed
  the Termination Shock, the first boundary of the Heliosphere (Krimigis
  et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An important
  aspect of this controversy is our poor understanding of this region. The
  region between the Termination Shock and the Heliopause, the Helisheath,
  is one of the most unknown regions theoretically. In the Heliosheath
  magnetic effects are crucial, as the solar magnetic field is compressed
  at the Termination Shock by the slowing flow. Therefore, to accurately
  model the heliosheath the inclusion of the solar magnetic field is
  crucial.Recently, our simulations showed that the Heliosheath presents
  remarkable dynamics, with turbulent flows and a presence of a jet
  flow at the current sheet that is unstable due to magnetohydrodynamic
  instabilities (Opher et al. 2003; 2004). We showed that to capture
  these phenomena, spatial numerical resolution is a crucial ingredient,
  therefore requiring the use of an adaptive mesh refinement (AMR). These
  previous works assumed that the solar rotation and the magnetic axis
  were aligned. Here we present for the first time results including the
  tilt of the heliocurrent sheet using a 3D MHD AMR simulation , with
  BATS-R-US code. We discuss the effects on the global structure of the
  Heliosheath, the flows, turbulence and magnetic field structure. We
  access the consequences for the observations measured by Voyager 1
  since mid-2002.

Title: Space Weather Modeling Framework: An Overview and Application
    to the October 29, 2003 Storm
Authors: Ridley, A. J.; Gombosi, T.; Toth, G.; Sokolov, I. V.; de
   Zeeuw, D.; Chesney, D.; Volberg, O.; Powell, K.; Stout, Q.; Hansen,
   K.; Kane, K.
Bibcode: 2004AGUFMSA41B..04R
Altcode:
  The University of Michigan's Space Weather Modeling Framework
  (SMWF) aims at providing framework for physics based space weather
  simulations, as well as for various space physics applications. The
  SWMF combines numerical models of the Solar Corona, Inner Heliosphere,
  Solar Energetic Particles, Global Magnetosphere, Inner Magnetosphere,
  Radiation Belts, Ionosphere and Upper Atmosphere into a parallel, high
  performance model. We present SWMF results from the October 29, 2003
  storm, in which the global magnetosphere (BATSRUS), inner magnetosphere
  (RCM), ionospheric electrodynamics, and upper atmospheric models (GITM)
  are run together driven by data from the upstream ACE satellite. We
  will present comparisons between the simulation results and data from
  different magnetospheric satellites. We will further present model
  comparisons between the global magnetosphere run with and without the
  inner magnetosphere coupling.

Title: Space Environment Forecasting for the Exploration Initiative
    with the Space Weather Modeling Framework
Authors: Gombosi, T. I.; Toth, G.; Sokolov, I. V.; de Zeeuw, D. L.;
   Ridley, A. J.; Kane, K.; Volberg, O.; Hansen, K. C.; Manchester,
   W. B.; Roussev, I. I.; Clauer, C. R.; Powell, K. G.; Stout, Q. F.
Bibcode: 2004AGUFMSH53C..05G
Altcode:
  Robotic and human exploration of the solar system poses the challenge
  to model and eventually forecast the plasma and energetic particle
  environment throughout the inner heliosphere. This talk will describe
  the recently developed Space Weather Modeling Framework (SWMF) that
  combines numerical models of the solar corona (the global structure
  is determined by synoptic magnetograms), magnetically driven solar
  eruptions, the inner heliosphere out to Saturn's orbit, solar
  energetic particles, the global magnetosphere, the particle drift
  physics controlled inner magnetosphere, the radiation belts, the
  ionospheric electrodynamics and the upper atmosphere and ionosphere
  into a high performance coupled simulation. This powerful simulation
  tool is presently capable of running faster than real-time from the
  Sun to Earth and it will be further developed into a space weather
  forecasting tool for the Exploration initiative. Particular attention
  will be paid to predicting solar energetic particle spectra and fluxes
  throughout the inner heliosphere. The SWMF is capable of simulating
  the acceleration and transport of energetic particles together with a
  self-consistent description of interplanetary transients that generate
  and accelerate the SEP population.

Title: Three-dimensional MHD simulations of the magnetosphere
    of Uranus
Authors: Tóth, GáBor; KováCs, DáNiel; Hansen, Kenneth C.; Gombosi,
   Tamas I.
Bibcode: 2004JGRA..10911210T
Altcode:
  We have successfully simulated the magnetosphere of Uranus for the
  time period of the Voyager 2 flyby in January 1986. On the basis of the
  Voyager measurements, a self-consistent numerical solution is obtained
  with the parallel block adaptive three-dimensional (3-D) MHD code
  BATS-R-US. The time-dependent simulation has been carried out with a
  new explicit-implicit time integration scheme. By comparing corotating
  steady state solutions and a fully time-dependent 3-D simulation
  with the Voyager data, we show that the magnetosphere of Uranus at
  the time of the flyby can be regarded as stationary relative to the
  frame corotating with the planet. We obtained excellent agreement with
  the observed magnetic field vector along the whole path of the flyby,
  which includes the near-Uranus offset dipole field as well as several
  current sheet crossings in the tail. The location of the bow shock and
  the magnetopause also agree to high accuracy. We are confident that our
  numerical solution is a good representation of the three-dimensional
  magnetosphere of Uranus during the flyby. The numerical solution shows
  a twisted magnetotail with field lines that are also stretched due to
  the flow of plasma in the magnetotail.

Title: On the evolution of the solar wind between 1 and 5 AU at the
time of the Cassini Jupiter flyby: Multispacecraft observations of
    interplanetary coronal mass ejections including the formation of a
    merged interaction region
Authors: Hanlon, P. G.; Dougherty, M. K.; Forsyth, R. J.; Owens,
   M. J.; Hansen, K. C.; Tóth, G.; Crary, F. J.; Young, D. T.
Bibcode: 2004JGRA..109.9S03H
Altcode:
  The Cassini flyby of Jupiter occurred at a time near solar
  maximum. Consequently, the pre-Jupiter data set reveals clear and
  numerous transient perturbations to the Parker Spiral solar wind
  structure. Limited plasma data are available at Cassini for this period
  due to pointing restrictions imposed on the instrument. This renders
  the identification of the nature of such structures ambiguous,
  as determinations based on the magnetic field data alone are
  unreliable. However, a fortuitous alignment of the planets during this
  encounter allowed us to trace these structures back to those observed
  previously by the Wind spacecraft near the Earth. Of the phenomena that
  we are satisfactorily able to trace back to their manifestation at
  1 AU, two are identified as being due to interplanetary coronal mass
  ejections. One event at Cassini is shown to be a merged interaction
  region, which is formed from the compression of a magnetic cloud by two
  anomalously fast solar wind streams. The flux-rope structure associated
  with this magnetic cloud is not as apparent at Cassini and has most
  likely been compressed and deformed. Confirmation of the validity of the
  ballistic projections used here is provided by results obtained from a
  one-dimensional magnetohydrodynamic projection of solar wind parameters
  measured upstream near the Earth. It is found that when the Earth and
  Cassini are within a few tens of degrees in heliospheric longitude,
  the results of this one-dimensional model predict the actual conditions
  measured at 5 AU to an impressive degree. Finally, the validity of the
  use of such one-dimensional projections in obtaining quasi-solar wind
  parameters at the outer planets is discussed.

Title: Dual spacecraft observations of a compression event within
the Jovian magnetosphere: Signatures of externally triggered
    supercorotation?
Authors: Hanlon, P. G.; Dougherty, M. K.; Krupp, N.; Hansen, K. C.;
   Crary, F. J.; Young, D. T.; Tóth, G.
Bibcode: 2004JGRA..109.9S09H
Altcode:
  By using Cassini as an upstream solar wind monitor, we are able to
  infer increases in the interplanetary dynamic pressure upstream of
  Jupiter as the spacecraft approached the planet. Observations are made
  of the effect that these pressure increases had upon both the fields
  and particles within the Jovian magnetosphere as measured by the
  Galileo orbiter, which had subsequently reentered the magnetosphere
  on the duskside. As the external pressure increased, so too did
  the total field magnitude at Galileo (in particular the Bz and Bϕ
  components). In addition, strongly leading field angles were observed
  following the onset of the compression and strongly lagging fields
  during reexpansion. These observations are consistent with the concept
  of external control of the angular velocity of the magnetospheric plasma
  due to conservation of angular momentum within the system. Heating of
  the plasma can be seen as a pronounced increase in particle flux as
  measured by the Energetic Particles Detector (EPD) instrument aboard
  Galileo. Changes in plasma velocity inferred from energetic particle
  anisotropies at Galileo appear to be consistent with the behavior of the
  changing magnetic field angle. The overall behavior and response time of
  the system appears to be consistent with recently published theoretical
  modeling of the Jovian magnetosphere-ionosphere coupling system.

Title: Magnetic Effects Change Our View of the Heliosheath
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; Dezeeuw, D. L.; Toth, G.; Sokolov, I.
Bibcode: 2004AIPC..719..105O
Altcode: 2004astro.ph..6184O
  There is currently a controversy as to whether Voyager 1 has
  already crossed the termination Shock, the first boundary of the
  heliosphere. The region between the termination shock and the
  heliopause, the heliosheath, is one of the most unknown regions
  theoretically. In the heliosheath magnetic effects are crucial,
  as the solar magnetic field is compressed at the termination shock
  by the slowing flow. Recently, our simulations showed that the
  heliosheath presents remarkable dynamics, with turbulent flows and
  the presence of a jet flow at the current sheet that is unstable due
  to magnetohydrodynamic instabilities. In this paper we review these
  recent results, and present an additional simulation with constant
  neutral atom background. In this case the jet is still present but with
  reduced intensity. Further study, e.g., including neutrals and the tilt
  of the solar rotation from the magnetic axis, is required before we can
  definitively address how the heliosheath behaves. Already we can say
  that this region presents remarkable dynamics, with turbulent flows,
  indicating that the heliosheath might be very different from what we
  previously thought.

Title: Magnetic Effects at the Edge of the Solar System: MHD
    Instabilities, the de Laval Nozzle Effect, and an Extended Jet
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Bettarini, L.; Gombosi,
   T. I.; Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I.
Bibcode: 2004ApJ...611..575O
Altcode: 2004astro.ph..6182O
  To model the interaction between the solar wind and the interstellar
  wind, magnetic fields must be included. Recently, Opher et al. found
  that by including the solar magnetic field in a three-dimensional
  high-resolution simulation using the University of Michigan BATS-R-US
  code, a jet-sheet structure forms beyond the solar wind termination
  shock. Here we present an even higher resolution three-dimensional case
  in which the jet extends for 150 AU beyond the termination shock. We
  discuss the formation of the jet due to a de Laval nozzle effect and
  its subsequent large-period oscillation due to magnetohydrodynamic
  (MHD) instabilities. To verify the source of the instability, we
  also perform a simplified two-dimensional geometry MHD calculation
  of a plane fluid jet embedded in a neutral sheet with the profiles
  taken from our three-dimensional simulation. We find remarkable
  agreement with the full three-dimensional evolution. We compare both
  simulations and the temporal evolution of the jet, showing that the
  sinuous mode is the dominant mode that develops into a velocity-shear
  instability with a growth rate of 5×10<SUP>-9</SUP>s<SUP>-1</SUP>=0.027
  yr<SUP>-1</SUP>. As a result, the outer edge of the heliosphere presents
  remarkable dynamics, such as turbulent flows caused by the motion of
  the jet. Further study, including neutrals and the tilt of the solar
  rotation from the magnetic axis, is required before we can definitively
  address how this outer boundary behaves. Already, however, we can say
  that the magnetic field effects are a major player in this region,
  changing our previous notion of how the solar system ends.

Title: Magnetic Effects and our Changing View of the Heliosheath
Authors: Liewer, P. C.; Opher, M.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I.
Bibcode: 2004AAS...204.7208L
Altcode: 2004BAAS...36R.799L
  The Sun traveling through the interstellar medium carves out a
  bubble of solar wind called the Heliosphere. Recent observations
  indicate that Voyager 1, now beyond 90 AU, is in a region unlike
  any encountered in it's 26 years of exploration. There is currently
  a controversy as to whether or not Voyager 1 has already crossed the
  Termination Shock, the first boundary of the Heliosphere (Krimigis et
  al. 2003; McDonald et al. 2003, Burlaga et al. 2003). The controversy
  stems from different interpretations of observations from several
  instruments. Contributing to this controversy is our poor understanding
  of the outer heliosphere. The region between the Termination Shock and
  the Heliopause, the Heliosheath, is one of the most unknown regions
  theoretically. In the Heliosheath magnetic effects are crucial, as
  the solar magnetic field is compressed at the Termination Shock by the
  slowing flow. Recently, our simulations showed that the Heliosheath is
  remarkably dynamic, with turbulent flows resulting from an unstable
  jet flow at the current sheet (Opher et al. 2003; 2004). In this
  talk we review these recent results, and present additional results
  from simulations of the unstable jet with a constant neutral atom
  background. Further studies which include additional effects such
  as the tilt between the solar rotation axis and the magnetic axis,
  are required before we can definitively address the structure and
  dynamics of the outer heliosphere. Already we can say that this region
  presents remarkable dynamics, with turbulent flows, indicating that
  the Heliosheath might be very different from what we previously thought.

Title: Learning from our Sun: The Interaction of Stellar with
    Interstellar Winds
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I. V.
Bibcode: 2004AAS...204.0303O
Altcode: 2004BAAS...36..671O
  Stars have winds which interact with the interstellar medium. The
  intensity of the winds can be 10 million times greater than that of
  the solar wind. The magnetic fields of these stars can be orders of
  magnitude greater than that of the Sun. The rotation periods can be
  appreciably different from that of the Sun. A detailed description of
  the interaction of stellar winds with the interstellar winds has never
  been made. The interaction between the Sun and Interstellar Medium
  creates three major structures: Termination Shock, Heliopause and
  Bow Shock. Recently, we found (Opher et al. 2003, 2004) that beyond
  the region where the solar wind become subsonic, the Termination
  Shock, a jet-sheet structure forms in the equatorial plane of the
  Sun rotation axis. This structure forms due to the compression of the
  solar magnetic field by the interstellar wind. The structure of the
  jet-sheet resembles a the "brim of a baseball cap"- it extends beyond
  the Termination Shock for 150 AU (almost touching the Bow Shock) and
  has a width of 10AU. This result is due to a novel application of a
  state-of-art 3D Magnetohydrodynamic (MHD) code with a highly refined
  grid (0.75 AU 4 orders of magnitude smaller than the physical dimensions
  of the system). The jet-sheet is unstable and oscillates up and down
  due to a velocity shear instability. We showed that the sinuous mode
  is the dominant mode that develops into a velocity-shear-instability
  with a growth rate of 0.027 years<SUP>-1</SUP>. We are the first to
  predict the formation of this structure at the equatorial region in
  the interaction of magnetized rotating star and an external wind (for
  a stellar rotation and magnetic field axis aligned). In this work,
  we extend our previous solar studies and investigate the effect in
  other solar-like stars. We present the dependence of the jet-sheet
  structure and the velocity-shear instability on the star mass-loss rate
  and magnetic field. We discuss further applications to other stellar
  wind interactions and the observational limits for the detection of
  this structure.

Title: Modeling the Carrington Event: sun-to-earth propagation of
    a very fast CME
Authors: Manchester, W. B.; Ridley, A. J.; Gombosi, T.; de Zeeuw,
   D.; Sokolov, I. V.; Toth, G.
Bibcode: 2004AGUSMSH43A..06M
Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent propagation of a CME from the
  solar corona to Earth in just 18 hours. The simulations are performed
  using the BATS-R-US (Block Adaptive Tree Solarwind Roe Upwind Scheme)
  code. We begin by developing a global steady-state model of the corona
  that possesses high-latitude coronal holes and a helmet streamer
  structure with a current sheet at the equator. The Archimedian spiral
  topology of the interplanetary magnetic field is reproduced along with
  fast and slow speed solar wind. Within this model system, we drive a
  CME to erupt by the introduction of a Gibson-Low magnetic flux rope
  that is embedded in the helmet streamer in an initial state of force
  imbalance. The flux rope rapidly expands driving a very fast CME with
  an initial speed of in excess of 4000 km/s and slowing to a speed of
  nearly 2000 km/s at Earth. We find our model predicts a thin sheath
  around the flux rope, passing the earth in only two hours. Shocked solar
  wind temperatures at 1 AU are in excess of 10 million degrees. Physics
  based AMR allows us to capture the structure of the CME focused on a
  particular Sun-Earth line with high spatial resolution given to the
  bow shock ahead of the flux rope.

Title: Parallel field line and stream line tracing algorithms for
    space physics applications
Authors: Toth, G.; de Zeeuw, D.; Monostori, G.
Bibcode: 2004AGUSMSM54A..04T
Altcode:
  Field line and stream line tracing is required in various space physics
  applications, such as the coupling of the global magnetosphere and inner
  magnetosphere models, the coupling of the solar energetic particle and
  heliosphere models, or the modeling of comets, where the multispecies
  chemical equations are solved along stream lines of a steady state
  solution obtained with single fluid MHD model. Tracing a vector field is
  an inherently serial process, which is difficult to parallelize. This
  is especially true when the data corresponding to the vector field is
  distributed over a large number of processors. We designed algorithms
  for the various applications, which scale well to a large number of
  processors. In the first algorithm the computational domain is divided
  into blocks. Each block is on a single processor. The algorithm folows
  the vector field inside the blocks, and calculates a mapping of the
  block surfaces. The blocks communicate the values at the coinciding
  surfaces, and the results are interpolated. Finally all block surfaces
  are defined and values inside the blocks are obtained. In the second
  algorithm all processors start integrating along the vector field inside
  the accessible volume. When the field line leaves the local subdomain,
  the position and other information is stored in a buffer. Periodically
  the processors exchange the buffers, and continue integration of the
  field lines until they reach a boundary. At that point the results
  are sent back to the originating processor. Efficiency is achieved
  by a careful phasing of computation and communication. In the third
  algorithm the results of a steady state simulation are stored on a hard
  drive. The vector field is contained in blocks. All processors read in
  all the grid and vector field data and the stream lines are integrated
  in parallel. If a stream line enters a block, which has already been
  integrated, the results can be interpolated. By a clever ordering
  of the blocks the execution speed can be increased dramatically. The
  communication occurs via file in an asynchronous manner. Disk access
  efficiency is improved by caching the data in memory.

Title: Modeling a space weather event from the Sun to the Earth:
    CME generation and interplanetary propagation
Authors: Manchester, Ward B.; Gombosi, Tamas I.; Roussev, Ilia;
   Ridley, Aaron; de Zeeuw, Darren L.; Sokolov, I. V.; Powell, Kenneth
   G.; Tóth, GáBor
Bibcode: 2004JGRA..109.2107M
Altcode:
  We present a three-dimensional (3-D) numerical ideal
  magnetohydrodynamics (MHD) model describing the time-dependent expulsion
  of a coronal mass ejection (CME) from the solar corona propagating
  to 1 astronomical unit (AU). The simulations are performed using the
  Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. We
  begin by developing a global steady-state model of the corona that
  possesses high-latitude coronal holes and a helmet streamer structure
  with a current sheet at the equator. The Archimedean spiral topology
  of the interplanetary magnetic field is reproduced along with fast
  and slow speed solar wind. Within this model system, we drive a CME
  to erupt by the introduction of a Gibson-Low magnetic flux rope that
  is anchored at both ends in the photosphere and embedded in the helmet
  streamer in an initial state of force imbalance. The flux rope rapidly
  expands and is ejected from the corona with maximum speeds in excess
  of 1000 km/s. Physics-based adaptive mesh refinement (AMR) allows us to
  capture the structure of the CME focused on a particular Sun-Earth line
  with high spatial resolution given to the bow shock ahead of the flux
  rope as well as to the current sheet behind. The CME produces a large
  magnetic cloud at 1 AU (&gt;100 R<SUB>⊙</SUB>) in which Bz undergoes
  a full rotation from north to south with an amplitude of 20 nT. In a
  companion paper, we find that the CME is very effective in generating
  strong geomagnetic activity at the Earth in two ways. First, through
  the strong sustained southward Bz (lasting more than 10 hours) and,
  second, by a pressure increase associated with the CME-driven shock
  that compresses the magnetosphere.

Title: Three-dimensional MHD simulation of a flux rope driven CME
Authors: Manchester, Ward B.; Gombosi, Tamas I.; Roussev, Ilia; de
   Zeeuw, Darren L.; Sokolov, I. V.; Powell, Kenneth G.; Tóth, GáBor;
   Opher, Merav
Bibcode: 2004JGRA..109.1102M
Altcode:
  We present a three-dimensional (3-D) numerical ideal
  magnetohydrodynamics (MHD) model, describing the time-dependent
  expulsion of plasma and magnetic flux from the solar corona that
  resembles a coronal mass ejection (CME). We begin by developing a
  global steady-state model of the corona and solar wind that gives
  a reasonable description of the solar wind conditions near solar
  minimum. The model magnetic field possesses high-latitude coronal
  holes and closed field lines at low latitudes in the form of a
  helmet streamer belt with a current sheet at the solar equator. We
  further reproduce the fast and slow speed solar wind at high and low
  latitudes, respectively. Within this steady-state heliospheric model,
  conditions for a CME are created by superimposing the magnetic field
  and plasma density of the 3-D Gibson-Low flux rope inside the coronal
  streamer belt. The CME is launched by initial force imbalance within
  the flux rope resulting in its rapid acceleration to a speed of over
  1000 km/s and then decelerates, asymptotically approaching a final
  speed near 600 km/s. The CME is characterized by the bulk expulsion of
  ∼10<SUP>16</SUP> g of plasma from the corona with a maximum of ∼5 ×
  10<SUP>31</SUP> ergs of kinetic energy. This energy is derived from the
  free magnetic energy associated with the cross-field currents, which is
  released as the flux rope expands. The dynamics of the CME are followed
  as it interacts with the bimodal solar wind. We also present synthetic
  white-light coronagraph images of the model CME, which show a two-part
  structure that can be compared with coronagraph observations of CMEs.

Title: First 3D MHD simulations of the inner magnetosphere with an
embedded drift physics model: The October 22-23, 1996 magnetic storm
Authors: de Zeeuw, D. L.; Gombosi, T. I.; Liemohn, M. W.; Ridley,
   A. J.; Tóth, G.; Sazykin, S.; Wolf, R. A.
Bibcode: 2004cosp...35...75D
Altcode: 2004cosp.meet...75D
  This paper describes the coupling of BATS-R-US, a magnetohydrodynamics
  (MHD) code representing the Earth's global magnetosphere and its
  coupling to the ionosphere and solar wind, and the Rice Convection Model
  (RCM), which represents the inner magnetosphere and its coupling to the
  ionosphere. The MHD code provides a time-evolving magnetic field model
  for the RCM as well as continuously updated boundary conditions for
  the electric potential and plasma. The RCM computes the distribution
  functions of inner magnetospheric particles, including transport of
  inner plasmasheet and ring-current particles by gradient/curvature
  drifts; it thus calculates more accurate inner magnetospheric pressures,
  which are frequently passed to the MHD model and used to nudge the
  MHD values. Results are presented with the coupled code first for
  the case of uniform ionospheric conductance with steady solar wind
  and southward IMF. The results are compared with those from a run
  of the MHD code alone. The coupled-code run shows significantly
  higher inner magnetospheric particle pressures. It also exhibits
  several well-established characteristics of inner magnetospheric
  electrodynamics, including strong region-2 Birkeland currents and
  partial shielding of the inner magnetosphere from the main force of
  the convection electric field. A sudden northward turning of the IMF
  causes the ring current to become more nearly symmetric. The inner
  magnetosphere exhibits an overshielding (dusk-to-dawn) electric field
  that begins about 10 minutes after the northward turning reaches
  the magnetopause and lasts just over an hour. A second coupled-code
  run was made for a moderate storm (Oct 22-23 1996). This event
  is characterized by a long period of mildly (5-10nT) Southward IMF
  followed by a Northward turning and roughly 600km/s velocities. While
  the maximum field aligned current in the coupled code was often larger
  than for MHD alone, the ionospheric cross polar cap potentials were
  smaller due to current closure through the enhanced region 2 current
  region. Many of the features described in the simpler first case above
  are also evident here, including significant stretching of the tail.

Title: A virtual upstream solar wind monitor for the Cassini mission
    at Saturn
Authors: Hansen, K. C.; Glocer, A.; Toth, G.; Gombosi, T. I.
Bibcode: 2004cosp...35.3063H
Altcode: 2004cosp.meet.3063H
  In order to provide solar wind conditions upstream of Saturn, we
  have developed a method to propagate the solar wind radially outward
  from the Earth to Saturn using a 1D MHD code. We will present the
  initial results and validation studies of our method. Having upstream
  solar wind conditions will add significant value to the Cassini
  measurements by allowing correlation studies between solar wind
  and magnetospheric phenomena. In order to understand the response of
  Saturn's magnetosphere to solar wind driving, we must have knowledge of
  the solar wind conditions while at the same time making magnetospheric
  measurements. These could be either remote measurements of the aurora or
  in situ measurements in the magnetosphere. During Cassini's nominal four
  year mission, a favorable alignment where Cassini can measure the solar
  wind while at the same time imaging the aurora will occur only for a
  few month period during the first orbit. In addition, it is obvious that
  Cassini cannot make solar wind measurements and in situ magnetospheric
  measurements simultaneously. In order to overcome these limitations and
  to provide solar wind conditions more often during the Cassini mission,
  we have developed a method to propagate solar wind conditions measured
  at the Earth out to Saturn using a 1D MHD code. Because the method does
  not take into account solar longitudinal variations, this method is
  expected to work reasonably well only during the period where the Sun,
  the Earth and Saturn are aligned (opposition). We have validated the
  model and the time range around opposition of its applicability using
  Cassini data from the Jupiter flyby (Dec. 2000) and from more recent
  Cassini measurements (Jan. 2004). In addition, using ISEE3 (1979-1982)
  data as input at 1AU, we have been able to model 10 opposition periods
  and compare model results with Pioneer 11, Voyager 1 and Voyager
  2 data. During this time, the three spacecraft were at a range of
  radial distances between Jupiter and Saturn. We have shown the model to
  work reasonably well during a period of roughly a month, centered at
  opposition. We will discuss the strength and weaknesses of the model
  during solar maximum and solar minimum conditions as well as ways to
  extend the model after the launch of Stereo near the end of 2005.

Title: Eruption of a Buoyantly Emerging Magnetic Flux Rope
Authors: Manchester, W. B.; Fan, Y.; Gombosi, T.; de Zeeuw, D.;
   Sokolov, I.; Toth, G.
Bibcode: 2003AGUFMSH22A0178M
Altcode:
  We present a three-dimensional numerical ideal magnetohydrodynamic
  simulation designed to model the emergence of magnetic flux passing
  from below the photosphere into the corona. For the initial state, we
  prescribe a plane parallel atmosphere that comprises the convection
  zone, isothermal photosphere and chromosphere, and isothermal
  corona. Embedded in this system is a isolated horizontal magnetic
  flux rope located 10 photospheric pressure scale heights below the
  photosphere. The flux rope is uniformly twisted with plasma temperature
  inside the tube reduced to compensate for the magnetic pressure. Density
  is reduced in the middle of the rope so that this section buoyantly
  rises. The early evolution of precedes with the middle of the rope
  rising to the photosphere and expanding into the corona. Just as it
  seems the system might approach equilibrium, the upper part of the
  flux rope begins to separate from the lower, mass ladened part. The
  separation occurs by stretching of the field to form a current sheet
  where reconnection severs the field lines to form a new system of closed
  flux. This flux then erupts into the corona. Essential to the eruption
  process are shearing motions driven by the Lorentz force which naturally
  occurs as the rope expands in the pressure stratified atmosphere. The
  shearing motions transport axial flux and energy to the expanding
  portion of the magnetic field which contributes to the eruption. Once
  the axial flux is largely transported from the submerged field, the
  expansion of the magnetic field in the corona begins to decelerate.

Title: Dual Spacecraft Observations of a Compression Event Within
    the Jovian Magnetosphere
Authors: Hanlon, P. G.; Dougherty, M. K.; Krupp, N.; Hansen, K. C.;
   Crary, F. J.; Young, D. T.; Toth, G.
Bibcode: 2003AGUFMSM31C1125H
Altcode:
  By using Cassini as an upstream solar wind monitor we were able to
  infer increases in the interplanetary dynamic pressure upstream of
  Jupiter as the spacecraft approached the planet. Observations are made
  of the effect that these pressure increases had upon both the fields
  and particles within the Jovian magnetosphere as measured by the
  Galileo orbiter, which had subsequently re-entered the magnetosphere
  on the dusk side. As the external pressure increased, so too did the
  total field magnitude at Galileo (in particular the B-z and B-phi
  components). In addition strongly leading field angles were observed
  subsequent to the onset of the compression and strongly lagging fields
  during re-expansion, this being consistent with the concept of external
  control of the angular velocity of the magnetospheric plasma due to
  conservation of angular momentum within the system. Heating of the
  plasma can be seen clearly as a pronounced increase in particle flux
  as measured by the EPD instrument aboard Galileo. Changes in plasma
  velocity as inferred from energetic particle anisotropies at Galileo
  appear to be well correlated with the behavior of the changing magnetic
  field angle. The overall behavior and response time of the system
  appears to be comparable to that predicted by recent theoretical
  modeling of the Jovian magnetosphere-ionosphere coupling system.

Title: MHD Simulations of the Magnetosphere of Uranus: Successful
    Comparison With Voyager 2
Authors: Tóth, G.; Tóth, G.; Kovacs, D.; Hansen, K. C.; Gombosi,
   T. I.
Bibcode: 2003AGUFMSM31C1130T
Altcode:
  We have successfully simulated the magnetosphere of Uranus for the time
  period of the Voyager 2 flyby in January 1986. Based on the Voyager
  measurements, a self-consistent numerical solution is obtained with the
  parallel block adaptive 3D MHD code BATSRUS. By comparing corotating
  steady state solutions and fully time dependent 3D simulations with the
  Voyager data we show that the magnetosphere of Uranus at the time of the
  flyby can be regarded as stationary relative to the frame corotating
  with the planet. We obtained excellent agreement with the observed
  magnetic field along the whole path of the flyby, which includes the
  close by offset dipole field as well as several current sheet crossings
  in the tail. The location of the bow shock and the magnetopause also
  agree to high accuracy. We are confident that our numerical solution
  is a good representation of the 3 dimensional magnetosphere of Uranus
  during the flyby. The numerical solution shows a twisted magnetotail
  and field lines are also stretched due to the flow of plasma in the
  magnetotail. The time dependent simulations were carried out with an
  explicit-implicit time integration scheme, while stationary solutions
  were obtained with the local time stepping scheme. Even with these
  advanced numerical schemes the time dependent simulation required a
  full day on 30 CPU-s.

Title: Modeling the May 1, 1998 CME propagation from the Sun to
    the Earth
Authors: Manchester, W. B.; Roussev, I.; Sokolov, I.; Ridley, A.;
   Gombosi, T.; de Zeeuw, D.; Hansen, K.; Toth, G.
Bibcode: 2003AGUFMSM11D..01M
Altcode:
  We present a three-dimensional numerical ideal magnetohydrodynamics
  model describing the halo coronal mass ejection (CME) of May 1, 1998
  propagating from the solar corona to 1 A.U. We begin by developing a
  realistic global steady-state model of the corona and solar wind in
  which the magnetic field is derived from synoptic magnetograms. The
  Archimedian spiral topology of the interplanetary magnetic field is
  reproduced along with fast and slow speed solar wind. Within this model
  system, we drive the CME eruption by placing a Gibson-Low magnetic
  flux rope in the helmet streamer of the pre-event active region. The
  flux rope is in an initial state of force imbalance and expands at
  such a rate as to approximate the observed speed of the May 1, 1998
  CME. Physics based AMR of the BATS-R-US (Block Adaptive Tree Solarwind
  Roe Upwind Scheme) code allows us to capture the structure of the
  CME on a particular Sun-Earth line with high spatial resolution. In
  particular, we highly resolve the the bow shock ahead of the flux
  rope as well as to the current sheet behind. We compare our model
  CME plasma parameters at 1 AU to observed values. In a companion
  paper, we use the model CME-perturbed solar wind as input for an
  Earth-Magnetospheric/Ionosphere/Thermosphere simulation and compare
  the geoffectiveness of the Earth-system model to observations.

Title: Doing It In The SWMF Way: From Separate Space Physics
    Simulation Programs To The Framework For Space Weather Simulation.
Authors: Volberg, O.; Toth, G.; Sokolov, I.; Ridley, A. J.; Gombosi,
   T. I.; de Zeeuw, D. C.; Hansen, K. C.; Chesney, D. R.; Stout, Q. F.;
   Powell, K. G.; Kane, K. J.; Oehmke, R. C.
Bibcode: 2003AGUFMSM22A0223V
Altcode:
  The NASA-funded Space Weather Modeling Framework (SWMF) is developed
  to provide "plug and play" type Sun-to-Earth simulation capabilities
  serving the space physics modeling community. In its fully developed
  form, the SWMF will comprise a series of interoperating models of
  physics domains, ranging from the surface of the Sun to the upper
  atmosphere of the Earth. In its current form the SWMF links together
  five models: Global Magnetosphere, Inner Heliosphere, Ionosphere
  Electrodynamics, Upper Atmosphere, and Inner Magnetosphere. The
  framework permits to switch models of any type. The SWMF is a structured
  collection of software building blocks that can be used or customized
  to develop Sun-Earth system modeling components, and to assemble them
  into application. The SWMF consist of utilities and data structures
  for creating model components and coupling them. The SWMF contains
  Control Model, which controls initialization and execution of the
  components. It is responsible for component registration, processor
  layout for each component and coupling schedules. A component is
  created from the user-supplied physics code by adding a wrapper,
  which provides the control functions and coupling interface to
  perform the data exchange with other components. Both the wrapper and
  coupling interface are constructed from the building blocks provided
  by the framework itself. The current SWMF implementation is based on
  the latest component technology and uses many important concepts of
  Object-Oriented Programming emulated in Fortran 90. Currently it works
  on Linux Beowulf clusters, SGI Origin 2000 and Compaq ES45 machines.

Title: Entry and Acceleration of Solar Wind Electrons in the Earth's
    Outer Magnetosphere
Authors: Schriver, D.; Ashour-Abdalla, M.; Zelenyi, L.; Gombosi, T.;
   Ridley, A.; de Zeeuw, D.; Toth, G.; Monostori, G.
Bibcode: 2003AGUFMSH42A0484S
Altcode:
  It is well known that during the recovery of magnetic storms,
  relativistic electron fluxes are usually enhanced over pre-storm values
  in the inner magnetosphere near geosynchronous orbit. Although the
  final acceleration of electrons to MeV energies most likely occurs
  in the inner magnetosphere, observations indicate that an enhanced
  flux of energized electrons (&gt; 10 keV) forms in the so-called
  seed region located at about 10 RE radially from the Earth in the
  equatorial plane. To examine the acceleration of electrons from the
  solar wind to the seed region, a study is being undertaken whereby
  electron trajectories are followed starting upstream of the bow shock,
  through the magnetopause and throughout the outer magnetosphere. The
  entry locations of electrons will be examined along with acceleration
  mechanisms that occur between the solar wind and seed region. The
  electron particle trajectories are followed based on the guiding center
  approximation in a global MHD model of the solar wind interaction with
  the Earth's magnetosphere for various interplanetary magnetic field
  (IMF) conditions.

Title: Magnetic Effects at the Edge of the Solar System: MHD
    Instabilities, the de Laval nozzle effect and an Extended Jet
Authors: Opher, M.; Liewer, P.; Velli, M.; Bettarini, L.; Gombosi,
   T. I.; Manchester, W.; Dezeeuw, D. L.; Toth, G.; Sokolov, I.
Bibcode: 2003AGUFMSH11C1114O
Altcode:
  To model the interaction between the solar system and the interstellar
  wind magnetic fields, ionized and neutral components besides cosmic
  rays must be included. Recently (Opher et al. ApJL 2003) found, that
  by including the solar magnetic field in an high resolution run with
  the University of Michigan BATS-R-US code, a jet-sheet structure forms
  beyond the Termination Shock. Here we discuss the formation of the jet
  and its subsequent large period oscillation due to magnetohydrodynamic
  instabilities. We perform in a simplified two dimensional geometry
  resistive magnetohydrodynamic calculation of a plane fluid jet embedded
  in a neutral sheet with the profiles taken from our simulation. We
  find remarkable agreement with the full three dimensional evolution. We
  present an even higher resolution three dimensional case where the jet
  extends for 150AU beyond the Termination Shock. We compare the temporal
  evolution of the jet showing that the sinuous mode is the dominant mode
  that develops into a velocity-shear-instability with a growth rate of
  5 x 10<SUP>-9</SUP> sec<SUP>-1</SUP>=0.027 years<SUP>-1</SUP>. As a
  result the outer edge of the heliosphere presents remarkable dynamics,
  such as turbulence and flows caused by the motion of the jet. Further
  study, e.g., including neutrals and the tilt of the solar rotation
  from the magnetic axis, is required before we can definitively address
  how this outer boundary behaves. Already, however, we can say that the
  magnetic field effects are a major player in this region changing our
  previous notion of how the solar system ends.

Title: A Three-dimensional Model of the Solar Wind Incorporating
    Solar Magnetogram Observations
Authors: Roussev, I. I.; Gombosi, T. I.; Sokolov, I. V.; Velli, M.;
   Manchester, W., IV; DeZeeuw, D. L.; Liewer, P.; Tóth, G.; Luhmann, J.
Bibcode: 2003ApJ...595L..57R
Altcode:
  We present a new compressible MHD model for simulating the
  three-dimensional structure of the solar wind under steady state
  conditions. The initial potential magnetic field is reconstructed
  throughout the computational volume using the source surface method, in
  which the necessary boundary conditions for the field are provided by
  solar magnetogram data. The solar wind in our simulations is powered
  by the energy interchange between the plasma and large-scale MHD
  turbulence, assuming that the additional energy is stored in the
  ``turbulent'' internal degrees of freedom. In order to reproduce
  the observed bimodal structure of the solar wind, the thermodynamic
  quantities for the initial state are varied with the heliographic
  latitude and longitude depending on the strength of the radial
  magnetic field.

Title: Parallel, Adaptive-Mesh-Refinement MHD for Global Space-Weather
    Simulations
Authors: Powell, Kenneth G.; Gombosi, Tamas I.; de Zeeuw, Darren L.;
   Ridley, Aaron J.; Sokolov, Igor V.; Stout, Quentin F.; Tóth, Gábor
Bibcode: 2003AIPC..679..807P
Altcode:
  The first part of this paper reviews some issues representing
  major computational challenges for global MHD models of the space
  environment. These issues include mathematical formulation and
  discretization of the governing equations that ensure the proper jump
  conditions and propagation speeds, regions of relativistic Alfvén
  speed, and controlling the divergence of the magnetic field. The
  second part of the paper concentrates on modern solution methods that
  have been developed by the aerodynamics, applied mathematics and DoE
  communities. Such methods have recently begun to be implemented
  in space-physics codes, which solve the governing equations
  for a compressible magnetized plasma. These techniques include
  high-resolution upwind schemes, block-based solution-adaptive grids
  and domain decomposition for parallelization. We describe the space
  physics MHD code developed at the University of Michigan, based on
  the developments listed above.

Title: Probing the Edge of the Solar System: Formation of an Unstable
    Jet-Sheet
Authors: Opher, Merav; Liewer, Paulett C.; Gombosi, Tamas I.;
   Manchester, Ward; DeZeeuw, Darren L.; Sokolov, Igor; Toth, Gabor
Bibcode: 2003ApJ...591L..61O
Altcode: 2003astro.ph..5420O
  The Voyager spacecraft is now approaching the edge of the solar
  system. Near the boundary between the solar system and the interstellar
  medium we find that an unstable ``jet-sheet'' forms. The jet-sheet
  oscillates up and down because of a velocity shear instability. This
  result is due to a novel application of a state-of-the-art
  three-dimensional MHD code with a highly refined grid. We assume
  as a first approximation that the solar magnetic and rotation axes
  are aligned. The effect of a tilt of the magnetic axis with respect
  to the rotation axis remains to be seen. We include in the model
  self-consistently magnetic field effects in the interaction between
  the solar and interstellar winds. Previous studies of this interaction
  had poorer spatial resolution and did not include the solar magnetic
  field. This instability can affect the entry of energetic particles
  into the solar system and the intermixing of solar and interstellar
  material. The same effect found here is predicted for the interaction
  of rotating magnetized stars possessing supersonic winds and moving
  with respect to the interstellar medium, such as O stars.

Title: Adaptive Mesh Refinement for conservative systems:
    multi-dimensional efficiency evaluation
Authors: Keppens, R.; Nool, M.; Tóth, G.; Goedbloed, J. P.
Bibcode: 2003CoPhC.153..317K
Altcode: 2004astro.ph..3124K
  Obtainable computational efficiency is evaluated when using an Adaptive
  Mesh Refinement (AMR) strategy in time accurate simulations governed
  by sets of conservation laws. For a variety of 1D, 2D, and 3D hydro-
  and magnetohydrodynamic simulations, AMR is used in combination with
  several shock-capturing, conservative discretization schemes. Solution
  accuracy and execution times are compared with static grid simulations
  at the corresponding high resolution and time spent on AMR overhead
  is reported. Our examples reach corresponding efficiencies of 5
  to 20 in multi-dimensional calculations and only 1.5-8% overhead is
  observed. For AMR calculations of multi-dimensional magnetohydrodynamic
  problems, several strategies for controlling the ∇.B=0 constraint
  are examined. Three source term approaches suitable for cell-centered B
  representations are shown to be effective. For 2D and 3D calculations
  where a transition to a more globally turbulent state takes place, it
  is advocated to use an approximate Riemann solver based discretization
  at the highest allowed level(s), in combination with the robust
  Total Variation Diminishing Lax-Friedrichs method on the coarser
  levels. This level-dependent use of the spatial discretization acts
  as a computationally efficient, hybrid scheme.

Title: Interpreting Coronagraph Data used Simulated White Light
    Images and 3D MHD Models of CMEs
Authors: Liewer, P. C.; Opher, M.; Velli, M.; Manchester, W.; DeZeeuw,
   D.; Gombose, T.; Roussev, I.; Sokolov, I.; Toth, G.; Powell, K.
Bibcode: 2003SPD....34.0511L
Altcode: 2003BAAS...35Q.816L
  We use a 3D time-dependent MHD model of a CME to try to understand the
  relationship between the CME structure and the bright features seen
  in coronagraph images. Questions addressed include whether the bright
  leading edge seen in LASCO coronagraph images of CMEs corresponds to
  compressed coronal material or shocked solar wind. We will analyze
  the evolution of the density and magnetic field as the CME propagates
  for CMEs of various field strengths and initial speeds. Coronagraph
  line-of-sight (LOS) images show 2D projections of the 3D density
  structure of the CME. Synthetic coronagraph images will be computed
  for the various CME cases to relate the structure to the LOS images. We
  use the University of Michigan BATS-R-US time-dependent adaptive grid
  MHD code to compute the CME evolution. The CME is created by inserting
  a flux-rope CME into a steady-state solution for the corona. The flux
  rope is anchored at both ends in the photosphere and embedded in a
  helmet streamer; it is not initially in equilibrium. The subsequent
  evolution of the flux rope - its expansion and propagation through the
  corona to 1 AU - is computed self-consistently with the evolution of
  the background corona and solar wind.

Title: The Formation of an Unstable Jet-Sheet at the Edge of the
    Solar System
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; DeZeeuw, D.; Sokolov, I.; Toth, G.
Bibcode: 2003SPD....34.0604O
Altcode: 2003BAAS...35Q.818O
  We find that the boundary between the solar system and the interstellar
  medium an unstable jet-sheet forms. The jet is unstable and oscillates
  up and down due to Kelvin-Helmholtz type instability. We use a
  state-of-art 3D MHD code art with an adaptive grid mesh especially
  designed to refine the region at the current sheet and in the region
  between the termination shock and the heliopause. In the present study
  we assume as a first approximation that the solar magnetic field and
  rotation axis are aligned. We include in the model self-consistently
  magnetic field effects in the interaction between the solar and
  interstellar winds. Previous studies of this interaction had poorer
  spatial resolution and did not include the solar magnetic field. We
  present results from three different resolutions (ranging from 0.5AU to
  6AU at the current sheet) and discuss the effect of resolution on the
  characteristics of the jet such as strength and width. We show that in
  order to resolve the jet, there is a need of a resolution higher than
  3-4AU, the resolution used in previous studies. The neutrals interacting
  with the plasma component by charge-exchange interactions can affect
  the formation of the jet and we present results discussing their effect.

Title: HARM: A Numerical Scheme for General Relativistic
    Magnetohydrodynamics
Authors: Gammie, Charles F.; McKinney, Jonathan C.; Tóth, Gábor
Bibcode: 2003ApJ...589..444G
Altcode: 2003astro.ph..1509G
  We describe a conservative, shock-capturing scheme for evolving the
  equations of general relativistic magnetohydrodynamics. The fluxes are
  calculated using the Harten, Lax, &amp; van Leer scheme. A variant of
  constrained transport, proposed earlier by Tóth, is used to maintain
  a divergence-free magnetic field. Only the covariant form of the metric
  in a coordinate basis is required to specify the geometry. We describe
  code performance on a full suite of test problems in both special
  and general relativity. On smooth flows we show that it converges at
  second order. We conclude by showing some results from the evolution
  of a magnetized torus near a rotating black hole.

Title: Modeling a space weather event from the Sun to the Earth:
    Magnetospheric Storm Results
Authors: Ridley, A.; de Zeeuw, D.; Gombosi, T.; Hansen, K.; Manchester,
   W.; Sokolov, I.; Toth, G.
Bibcode: 2003EAEJA.....7651R
Altcode:
  This papers shows magnetospheric results from one of the first ever
  Sun to Earth MHD simulations. The University of Michigan's BATSRUS
  MHD code was used to launch a Coronal Mass Ejection (CME) near
  the solar surface and simulate the propagation of the CME through
  interplanetary space. Because the CME was tracked using adaptive mesh
  refinement, the resolution within the shock was 1/8 of a solar radius
  (14 Earth radii, or R_e) at 1 AU. The CME had large field strengths
  (27 nT), densities (35 cm<SUP>-3</SUP>), and velocities (540 km/s)
  at 1 AU. Two dimensional results from the CME simulation at 1 AU were
  used to drive the magnetospheric simulation. This allowed gradients and
  correct propagation planes to be resolved at the upstream boundary. The
  magnetospheric simulation was run using a maximum resolution of 1/8
  R_e at the inner boundary, which was set to 2.5 R_e, and a minimum
  resolution of 8 R_e near the side and outflow boundaries. The location
  of the dayside magnetopause was tracked over time as well latitude of
  the last closed field line. The strength of the auroral precipitation
  and cross polar cap were also investigated. The magnetospheric and
  ionospheric results from this simulation will be presented.

Title: On the evolution of the Solar Wind between 1 and 5 AU at
    solar maximum and its effect upon Jovian auroral emission
Authors: Hanlon, P. G.; Dougherty, M. K.; Forsyth, R. J.; Hansen,
   K. C.; Pryor, W.; Crary, F.; Tóth, G.
Bibcode: 2003EAEJA....12234H
Altcode:
  The Cassini fly-by of Jupiter occurred at a time of solar maximum,
  and as a consequence, the in-situ measurements taken in the Solar Wind
  upstream of the planet, reveal numerous Interplanetary Coronal Mass
  Ejections (ICMEs). A fortuitous alignment of the planets allowed us
  to trace these events back to observations taken at the Earth. In
  particular one event observed by Cassini is shown to be a Merged
  Interaction Region (MIR), created from the coalescence of multiple
  ICMEs between 1 and 5 AU. We examine results from a one dimensional
  Magneto-hydrodynamic (MHD) simulation of the Solar Wind at Earth
  propagated out to Cassini and compare with the in-situ data taken. It
  is found that by integrating along the nominal Parker Spiral field we
  can to some extent, correct for the changing angular offset between the
  two points of observation by obtaining a fractional increase or decrease
  in the propagation time of the events observed. The results of this MHD
  simulation are then allowed to propagate further to the planet allowing
  comparisons to be made between the state of the Solar Wind and remote
  observations of the planetary aurorae that were taken simultaneously.

Title: Modeling a space weather event from the sun to earth: CME
    generation and interplanetary propagation
Authors: Manchester, W.; de Zeeuw, D.; Gombosi, T.; Hansen, K.;
   Ridley, A.; Roussev, I.; Sokolov, I.; Toth, G.
Bibcode: 2003EAEJA.....6645M
Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from the
  solar corona propagating all the way to 1 A.U.. The simulations are
  performed using the BATS-R-US (Block Adaptive Tree Solarwind Roe Upwind
  Scheme) code. We begin by developing a global steady-state model of the
  corona that possesses high-latitude coronal holes and a helmet streamer
  structure with a current sheet at the equator. The Archimedian spiral
  topology of the interplanetary magnetic field is reproduced along with
  fast and slow speed solar wind. Within this model system, we drive a
  CME to erupt by the introduction of a Gibson-Low magnetic flux rope that
  is anchored at both ends in the photosphere and embedded in the helmet
  streamer in an initial state of force imbalance. The flux rope rapidly
  expands and is ejected from the corona with maximum speeds in excess
  of 1500 km/sec. Physics based AMR allows us to capture the structure
  of the CME focused on a particular Sun-Earth line with high spatial
  resolution given to the bow shock ahead of the flux rope as well as
  to the current sheet behind. We find our model CME plasma parameters
  at 1 AU to be geoeffective and use this as solar wind input for an
  Earth-Magnetospheric simulation in a companion paper.

Title: Global flow patterns and ionospheric convection in Jupiter's
    magnetosphere
Authors: Hansen, K. C.; de Zeeuw, D. L.; Gombosi, T. I.; Ridley,
   A. J.; Toth, G.; Sokolov, I.
Bibcode: 2003EAEJA.....6812H
Altcode:
  The size and configuration of Jupiter's magnetosphere is controlled
  by the ambient solar wind conditions, Jupiter's strong rotation
  and intrinsic magnetic field and the plasma sources internal to the
  magnetosphere. We will examine the relative importance of each of these
  factors using our 3D global magnetohydrodynamic (MHD) model of the
  Jovian magnetosphere. This model uses adaptive mesh refinement (AMR)
  to model the global Jovian system, including the mass loading region
  near Io's orbit. The inner boundary of the MHD model, at 3 R_J, is
  coupled to a height integrated ionospheric electric potential model. We
  will present results of the coupled model and show similarities
  and differences to other planetary magnetospheres. We will show
  that Jupiter's magnetosphere without mass loading and rotation is
  Earth-like in all but size. Adding rotation determines, to a large
  extent, the flow pattern in the magnetosphere. The addition of mass
  loading, although extremely important, does not change the character
  or topology of the magnetospheric convection but instead modifies
  the locations of magnetospheric features such as the bow shock, the
  magnetopause and the location of reconnection sites. In addition, we
  will show how features like the magnetospheric "wings" [Song, ASR, 2001]
  at the Earth are manifest and modified in the magnetosphere of Jupiter.

Title: 3D MHD description of the region beyond the termination shock:
    The behaviour of the Current Sheet
Authors: Opher, M.; Liewer, P.; Gombosi, T.; Manchester, W.; Dezeeuw,
   D. L.; Powell, K.; Sokolov, I.; Toth, G.; Velli, M.
Bibcode: 2002AGUFMSH21A0485O
Altcode:
  A fully self consistent MHD study of the heliosheath region is carried
  out, using BATSRUS, a three dimensional time dependent adaptive grid
  magnetohydrodynamic (MHD) model. The heliosheath, located between
  the termination shock and the heliopause, has not been studied in
  detail. At the termination shock the solar wind passes from a supersonic
  to a subsonic regime decelerating until it reaches the heliopause
  where it is diverted to the heliotail. This region is intersected
  in the equatorial plane (assuming a no-tilt for the dipole field)
  by a current sheet as the solar magnetic field changes polarity. One
  of the major questions is whether the current sheet remains at the
  equatorial plane. The magnetic field of the solar wind is included. In
  order to isolate the effects at this region we assumed no magnetic
  field in the interstellar medium. We observe a much faster flow of the
  current sheet, where the compressed azimuthal magnetic field is absent,
  leading to large velocity shear. With BATSRUS, we were able to obtain
  high resolution needed to analyze the behavior of this complicated
  regime, in particular the stability of the current sheet. We report
  the results and comment on the major processes responsible.

Title: 3D MHD Simulation of CME Propagation from Solar Corona to 1 AU
Authors: Manchester, W. B.; Roussev, I.; Opher, M.; Gombosi, T.;
   Dezeeuw, D.; Toth, G.; Sokolov, I.; Powell, K.
Bibcode: 2002AGUFMSH21A0501M
Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from
  the solar corona propagating all the way to 1 A.U.. The simulations
  are performed using the BATS-R-US (Block Adaptive Tree Solarwind Roe
  Upwind Scheme) code. We begin by developing a global steady-state
  model of the corona that possesses high-latitude coronal holes and
  a helmet streamer structure with a current sheet at the equator. The
  Archimedian spiral topology of the interplanetary magnetic field is
  reproduced along with fast and slow speed solar wind at high and
  low latitudes respectively. Within this model system, we drive a
  CME to erupt by the introduction of a Gibson-Low magnetic flux rope
  that is anchored at both ends in the photosphere and embedded in the
  helmet streamer in an initial state of force imbalance. The flux rope
  then rapidly accelerates to speeds in excess of 1500 km/sec driving
  a strong MHD shock as part of the CME. We find that both the shock
  front and the flux rope are strongly effected by bi-modal solar wind
  as the CME travels to 1 AU. Physics based AMR allows us to capture
  the complexity of the CME development and propagation focused on a
  particular Sun-Earth line. The applied numerical algorithm is designed
  to use optimal computational resources for the sake of tracing CMEs
  with very high spatial resolution all the way from Sun to Earth. We
  compare the model CME plasma parameters at 1 AU to observations and
  find the event to be geoeffective.

Title: University of Michigan MHD results of the Geospace Global
    Circulation Model metrics challenge
Authors: Ridley, A. J.; Hansen, K. C.; Tóth, G.; de Zeeuw, D. L.;
   Gombosi, T. I.; Powell, K. G.
Bibcode: 2002JGRA..107.1290R
Altcode:
  We present University of Michigan MHD code results of the "metrics
  challenge." We have simulated the magnetospheric and ionospheric
  configuration during the 16-17 April 1999 CME, the 10-11 December 1998
  time period, and the 5-6 November 1998 time period. The simulation
  results were compared to the DMSP cross-track velocities, and the RMS
  differences were examined. We have found that the code reproduces the
  DMSP data quite accurately except for the sharpness of the gradients
  and the transients which were observed. The cross polar cap potential
  was well matched, as was the location of the convection reversal
  boundary. In addition, the code reproduced features of statistical
  models of the ionospheric electric potential.

Title: BAIKAL experiment: status report
Authors: Osipova, E.; Pavlov, A.; Pańkov, L.; Panfilov, A.;
   Pliskovsky, E.; Klimov, A.; Pokhil, P.; Polecshuk, V.; Popova, E.;
   Prosin, V.; Rosanov, M.; Rubtzov, V.; Semeney, Y.; Spiering, C.;
   Streicher, O.; Tarashanky, B.; Thon, T.; Toth, G.; Vasiliev, R.;
   Wischnewski, R.; Yashin, I.; Zhukov, V.
Bibcode: 2002NuPhS.110..504O
Altcode: 2001astro.ph.12446D
  We review the present status of the Baikal Neutrino Project and present
  the results obtained with the deep underwater neutrino telescope NT-200.

Title: Towards an Operational Sun-to-Earth Model for Space Weather
    Forecasting
Authors: Gombosi, T. I.; Clauer, C. R.; De Zeeuw, D. L.; Hansen,
   K. C.; Manchester, W. B.; Powell, K. G.; Ridley, A. J.; Roussev, I.;
   Sokolov, I. V.; Toth, G.; Wolf, R. A.; Sazykin, S.; Holzer, T. E.;
   Low, B. C.; Richmond, A. D.; Roble, R. G.
Bibcode: 2002AGUSMSH51B..06G
Altcode:
  We are presently developing a physics based, modular, large-scale
  model of the solar-terrestrial environment simulating space weather
  phenomena and providing a framework to test theories and explore the
  possibility of operational use in space weather forecasting. This talk
  will describe the main components of the model (a global MHD code,
  an upper atmosphere and ionosphere model, and the inner magnetosphere
  drift physics model). We will also discuss the testing and transitioning
  the model through CCMC to operational use by NOAA SEC and the Air
  Force. Particular attention will be paid to the need of validation
  and metrics studies.

Title: Studying the Complexity in Dynamics and Magnetic Topology of
    CME with 3D MHD Simulations Involving Dynamic AMR
Authors: Roussev, I. I.; Manchester, W. B.; Gombosi, T. I.; De Zeeuw,
   D. L.; Sokolov, I. V.; Toth, G.
Bibcode: 2002AGUSMSH21A..01R
Altcode:
  It is of fundamental importance in solar, heliospheric,
  and magnetospheric physics to explore the high degree of
  variability and complex internal magnetic and plasma structure of
  CMEs. Three-dimensional (3D) magnetohydrodynamic (MHD) simulations
  provide excellent grounds for studying the complexity in dynamics of
  this and other solar phenomena. We present some results on state-of-art
  numerical experiments of CME propagation, including dynamic Adaptive
  Mesh Refinement (AMR). All computations presented here are carried out
  using the BATS-R-US (Block Adaptive Tree Solarwind Roe Upwind Scheme)
  code and involve 3D MHD. The CME is initiated through an eruption of
  twisted flux rope in the solar corona. The MHD shock created ahead of
  the CME is essential in determining geoeffective events. The physics
  based AMR allows to reveal the complexity of the CME development and
  propagation on the particular ray Sun-Earth. The applied numerical
  algorithm is designed to use optimal computational resources for the
  sake of tracing CMEs with very high spatial resolution all the way
  from Sun to Earth, and beyond. We further discuss the differences in
  using various criteria for mesh refinement on the overall physical
  picture of the CME dynamics.

Title: 3D MHD Simulations of Flux Rope Driven CMEs
Authors: Manchester, W. B.; Roussev, I.; Opher, M.; Gombosi, T.;
   DeZeeuw, D.; Toth, G.; Sokolov, I.; Powell, K.
Bibcode: 2002AGUSMSH22D..03M
Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from
  the solar corona propagating all the way to 1 A.U.. The simulations
  are performed using the BATS-R-US (Block Adaptive Tree Solarwind Roe
  Upwind Scheme) code. We begin by developing a global steady-state
  model of the corona that possesses high-latitude coronal holes and
  a helmet streamer structure with a current sheet at the equator. The
  Archimedian spiral topology of the interplanetary magnetic field is
  reproduced along with fast and slow speed solar wind at high and low
  latitudes respectively. Within this model system,we drive a CME to erupt
  by the introduction of a twisted magnetic flux rope that is anchored at
  both ends in the photosphere and embedded in the helmet streamer. The
  flux rope configuration that we employ was first developed by Gibson
  and Low as part of a 3D self-similar model of a CME. In this case,
  the flux rope has the form of a spherical ball of twisted magnetic
  field distorted to a tear shape by a stretching transformation. The
  stretch transformation produces an outward radially directed Lorentz
  force within the flux rope that rapidly accelerates the leading edge of
  the rope to speeds of 1800 km/sec, driving a strong shock as part of
  the CME. We follow the evolution of the CME from the low corona as it
  makes its way through the heliosphere. We explore the dynamics of the
  expanding flux rope as it interacts with the rotating, bi-modal solar
  wind to determine significant MHD effects. Finally we present synthetic
  white-light coronagraph images of the model CME which show a three-part
  structure that can be compared with observations of CME structure.

Title: 3D adaptive grid MHD simulations of the global heliosphere
    with self- consistent fluid neutral hydrogen
Authors: Opher, M.; Liewer, P.; Gombosi, T.; Manchester, W.; Dezeeuw,
   D.; Powell, K.; Sokolov, I.; Toth, G.
Bibcode: 2002cosp...34E.835O
Altcode: 2002cosp.meetE.835O
  A three dimensional adaptive grid magnetohydrodynamic (MHD) model of
  the interaction of the solar wind with the local interstellar medium
  is presented. The code used is the BATS-R-US time-dependent adaptive
  grid three-dimensional magnetohydrodynamic, which is similar to the
  code used by Linde et al. JGR, 103, 1889 (1998). The magnetic field
  of both the solar wind and the interstellar medium are included. The
  latitute dependence of the solar wind is also taken into account. The
  neutral atoms are included self-consistently as a fluid, without
  assuming constant the density, velocity or temperature as previous
  3D MHD studies. The location of the termination shock and heliopause
  in the steady state solution for different values and directions of
  interstellar magnetic field are presented and compared with previous
  results. We also present results where we isolated the effects of
  neutrals and magnetic field showing their relative importance, in
  particular the heliopause.

Title: Simulations of erupting flux rope driven CMEs
Authors: Manchester, W.; Gombosi, T.; de Zeeuw, D.; Powell, K.;
   Roussev, I.; Sokolov, I.; Toth, G.
Bibcode: 2002cosp...34E2635M
Altcode: 2002cosp.meetE2635M
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from
  the solar corona. We begin by developing a global steady-state model
  of the corona that possesses highlatitude coronal holes and a helmet
  streamer structure with a current sheet at the equator. The Archimedian
  spiral topology of the interplanetary magnetic field is reproduced
  along with fast and slow speed solar wind at high and low latitudes
  respectively. Within this model system, we drive a CME to erupt by
  the introduction of a twisted magnetic flux rope that is anchored at
  both ends in the photosphere and embedded in the helmet streamer. The
  flux rope configuration that we employ was first developed by Gibson
  and Low as part of a 3D self-similar model of a CME. In this case,
  the flux rope has the form of a spherical ball of twisted magnetic
  field distorted to a tear shape by a stretching transformation. The
  stretch transformation produces an outward radially directed Lorentz
  force within the flux rope that rapidly accelerates the leading edge
  of the rope to speeds of 1200 km/sec, driving strong shock as part
  of the CME. We follow the evolution of the CME from the low corona as
  it makes its way through the heliosphere. We explore the dynamics of
  the expanding flux rope as it interacts with the rotating, bi-modal
  solar wind to determine significant MHD effects. Finally we present
  synthetic white-light coronagraphs images of the model CME to determine
  the degree to which they match observations of CME structure.

Title: Development of an Integrated Predictive MHD Space Weather
    Model from the Solar Surface to the Earth's Upper Atmosphere
Authors: Clauer, C. R.; Gombosi, T. I.; Powell, K. G.; Stout, Q. F.;
   Toth, G.; Dezeeuw, D.; Ridley, A. J.; Wolf, R. A.; Roble, R. G.;
   Holzer, T. E.
Bibcode: 2002swsm.conf..149C
Altcode:
  No abstract at ADS

Title: Using dynamic AMR to simulate geoeffective interplanetary
    transients
Authors: Roussev, I.; Manchester, W.; Gombosi, T.; de Zeeuw, D.;
   Sokolov, I.; Toth, G.
Bibcode: 2002cosp...34E.555R
Altcode: 2002cosp.meetE.555R
  It is of fundamental importance for solar, heliospheric, and
  magnetospheric physics to explore the complex dynamic evolution and
  geoeffectiveness of coronal transients, commonly known as CMEs, all the
  way from their origin at the Sun, through the interplanetary space, to
  Earth. In this light, three-dimensional (3D) magnetohydrodynamic (MHD)
  simulations provide excellent grounds for studying the complexity in
  dynamics of this and other solar phenomena. We present some results
  on state-of-art numerical experiments of CME propagation, including
  dynamic Adaptive Mesh Refinement (AMR). All computations presented here
  are carried out using the BATS-R-US (Block Adaptive Tree Solarwind
  Roe Upwind Scheme) code and involve 3D time-dependent MHD. The
  CME is initiated through an eruption of double-twisted magnetic
  flux rope originating from the solar corona. The MHD shock formed
  ahead of the solar transient is essential in determining geoeffective
  events. The physics based AMR allows us to examine in great detail the
  complexity of the CME development and propagation on the particular
  ray Sun-Earth. The applied numerical algorithm is designed to use
  optimal computational resources for the sake of tracing CMEs with very
  high spatial resolution all the way from Sun to Earth, and beyond. We
  further discuss the differences in using various criteria for mesh
  refinement on the overall physical picture of the CME dynamics.

Title: Pulsar wind nebulae in supernova remnants. Spherically
    symmetric hydrodynamical simulations
Authors: van der Swaluw, E.; Achterberg, A.; Gallant, Y. A.; Tóth, G.
Bibcode: 2001A&A...380..309V
Altcode:
  A spherically symmetric model is presented for the interaction of
  a pulsar wind with the associated supernova remnant. This results
  in a pulsar wind nebula whose evolution is coupled to the evolution
  of the surrounding supernova remnant. This evolution can be divided
  in three stages. The first stage is characterised by a supersonic
  expansion of the pulsar wind nebula into the freely expanding ejecta
  of the progenitor star. In the next stage the pulsar wind nebula is
  not steady; the pulsar wind nebula oscillates between contraction and
  expansion due to interaction with the reverse shock of the supernova
  remnant: reverberations which propagate forward and backward in
  the remnant. After the reverberations of the reverse shock have
  almost completely vanished and the supernova remnant has relaxed to
  a Sedov solution, the expansion of the pulsar wind nebula proceeds
  subsonically. In this paper we present results from hydrodynamical
  simulations of a pulsar wind nebula through all these stages in
  its evolution. The simulations were carried out with the Versatile
  Advection Code.

Title: 3D Global MHD Simulations of Flux-Rope-Driven CMEs
Authors: Gombosi, T. I.; Manchester, W. B.; De Zeeuw, D. L.; Toth,
   G.; Powell, K. G.; Sokolov, I.
Bibcode: 2001AGUFMSH12B0759G
Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME form the
  solar corona. We begin by developing a 3D MHD model of a steady-state
  helmet streamer enveloped by a solar wind. We then drive the helmet
  streamer to erupt in a CME by introduction of a twisted magnetic flux
  rope that is anchored at both ends in the photosphere and embedded
  in the helmet streamer. We follow the evolution of the CME from the
  low corona as it makes its way through heliosphere. We explore the
  dynamics of the expanding flux rope as it interacts with the rotating,
  bi-modal solar wind to determine significant MHD effects such as
  shock formation. Finally we present synthetic white-light coronagraphs
  images of the model CME to determine the degree to which they match
  observations of CME structure.

Title: Inner Magnetosphere Simulations - Coupling the Michigan MHD
    Model with the Rice Convection Model.
Authors: De Zeeuw, D.; Sazykin, S.; Ridley, A.; Toth, G.; Gombosi,
   T.; Powell, K.; Wolf, D.
Bibcode: 2001AGUFMSM42A0830D
Altcode:
  The adaptive-grid Michigan MHD model (BATSRUS) has been coupled to a
  new high performance Rice Convection Model (RCM). This fully coupled
  code allows us to self-consistently simulate the physics in the
  inner magnetosphere, including Region 1 and Region 2 currents. We will
  describe the two models and how they are coupled, report on the results
  of a synthetic event with the coupled code and show a comparison with
  and without coupling.

Title: 3D MHD Simulation of a Coronal Arcade Eruption by Self-Induced
    Shearing
Authors: Manchester, W. B.; Toth, G.; De Zeeuw, D. L.; Gombosi, T. I.;
   Powell, K. G.
Bibcode: 2001AGUFMSH12B0758M
Altcode:
  We present the results of a three-dimensional time-dependent
  magnetohydrodynamic(MHD) simulation of the nonlinear development of
  instabilities of a magnetically-sheared arcade and show how it relates
  to coronal mass ejections (CMEs). To model the arcade eruption, we
  capitalize on a family of analytical solutions for initial states, which
  describe magnetic arcades in uniform gravity that are characterized
  by magnetic shear. In our simulations we find that such an arcade is
  unstable when subjected to small velocity perturbations and responds
  by slowly rising and expanding. Most significantly, we find shearing
  motions naturally arise in conjunction with the instability. This
  field line shearing is in response to the Lorentz, force which drives
  large amplitude Alfvén waves, which transport magnetic shear from the
  lower to the upper extremities of the arcade. The self-induced shear
  Alfvén waves, coupled with magnetic buoyancy, provide a powerful
  feedback mechanism that drives the arcades to a loss of equilibrium
  and eruption following a long period of expansion. The simulation
  of the arcade eruption is significant with regard to CME initiation
  for two major reasons. First, the arcade eruption is the result of
  undriven MHD instabilities and second, magnetic field line shearing
  is an intrinsic aspect of the instability that occurs spontaneously.

Title: Combined Explicit-Implicit Techniques for Faster than Real-Time
    Space Weather Simulations
Authors: Toth, G.; Powell, K. G.; De Zeeuw, D. L.; Gombosi, T. I.
Bibcode: 2001AGUSM..SM52A03T
Altcode:
  The Alfvén speed can approach the speed of light near the Earth. This
  poses a severe problem for numerical modeling of the magnetosphere,
  since the time steps of an explicit time integration scheme are
  limited by the CFL numerical stability condition: the waves must not
  propagate more than one cell size in one time step. In a well resolved
  simulation, the cell size may be as small as several 100 km-s, which
  limits the time step to be less than 0.01 or even 0.001 seconds. On
  the other hand, typical time scales of the magnetosphere are on the
  order of minutes. This discrepancy calls for the use of implicit
  time stepping techniques, which are not limited by the CFL stability
  condition. We are reporting our preliminary results with a newly
  implemented Newton-Krylov-Schwarz type implicit time stepping scheme
  in our block-adaptive parallel 3D MHD code. The linear problems arising
  from the Newton scheme are solved with a parallel Krylov subspace type
  iterative scheme using a Schwarz type preconditioner. We also explore
  the possibility of combining the implicit and explicit time stepping
  schemes: the expensive but stable implicit scheme is used near the
  Earth where the wave speeds are high, while the inexpensive explicit
  scheme is employed where the stability condition on the time step is
  not restrictive.

Title: Results of the Michigan MHD Metrics Challenge
Authors: Ridley, A. J.; Gombosi, T.; De Zeeuw, D.; Toth, G.; Powell, K.
Bibcode: 2001AGUSM..SM32A06R
Altcode:
  We present University of Michigan MHD code results of the so-called
  "Metrics Challenge". We have simulated the magnetospheric and
  ionospheric configuration during the CME of April 16 - 17, 1999. The
  simulation results were compared with DMSP cross track velocities
  and the RMS differences were examined. We have found that the code
  reproduces the DMSP data accurately except for the sharpness of the
  gadients and the transients which were observed. The cross polar cap
  potential was well matched, as was the location of the convection
  reversal boundary.

Title: Coupled MHD-Inner Magnetosphere Simulations of Geomagnetic
    Storms
Authors: De Zeeuw, D.; Sazykin, S.; Ridley, A.; Toth, G.; Gombosi,
   T.; Clauer, B.; Powell, K.; Wolf, D.; Spiro, B.
Bibcode: 2001AGUSM..SM32A02D
Altcode:
  The adaptive-grid Michigan MHD model (BATSRUS) has been coupled to a
  new high Rice Convection Model (RCM). This fully coupled code gives
  the possibility to realistically undertake global MHD simulations of
  a magnetic storm and the computation of both Region 1 and Region 2
  currents. We will review details of the two models and their coupling,
  and report on the results of our first storm time simulation with the
  coupled code and show a comparison with observations. We will discuss
  the global observations provided by arrays of magnetometers which
  measure the temporal and spatial development of the ring current as
  well as high latitude global electrodynamic parameters derived from
  the AMIE and LiMIE data inversion techniques.

Title: Adaptive mesh refinement MHD for global simulations
Authors: Gombosi, T. I.; Tóth, G.; de Zeeuw, D. L.; Powell, K. G.;
   Stout, Q. F.
Bibcode: 2001sps..proc...88G
Altcode:
  Techniques that have become common in aerodynamics codes have
  recently begun to be implemented in space-physic codes, which solve
  the governing equations for a compressible plasma. These techniques
  include high-resolution upwind schemes, block-based solution-adaptive
  grids and domain decomposition for parallelization. While some
  of these techniques carry over relatively straightforwardly from
  aerodynamics to space physics, space physics simulations pose some new
  challenges. This paper gives a brief review of the state-of-the-art in
  modern space-physics codes, including a validation study of several of
  the techniques in common use. A remaining challenge is that of flows
  that include regions in which relativistic effects are important;
  some background and preliminary results for these problems are
  given. 1 Governing equations The governing equations for an ideal,
  non-relativistic, compressible plasma may be written in a number of
  different forms. In primitive variables, the governing equations,
  which represent a combination of the Euler equations of gasdynamics
  and the Maxwell equations of electromagnetics, may be written as:
  ∂ρ ∂t + u · ρ + ρ · u = 0 ρ ∂u ∂t + ρu · u + p -
  j × B = 0 ∂B ∂t + × E = 0 ∂p ∂t + u · p + γp · u = 0
  (1) where the current density j and the electric field vector E are
  related to the magnetic field B by Amp`ere's law and Ohm's

Title: Storage of a Strong Magnetic Field Below the Solar Convection
Zone (CD-ROM Directory: contribs/rempel)
Authors: Rempel, M.; Schüssler, M.; Moreno-Insertis, F.; Tóth, G.
Bibcode: 2001ASPC..223..738R
Altcode: 2001csss...11..738R
  No abstract at ADS

Title: Pulsar wind nebulae in supernova remnants
Authors: van der Swaluw, E.; Achterberg, A.; Gallant, Y. A.; Tóth, G.
Bibcode: 2000astro.ph.12440V
Altcode:
  A spherically symmetric model is presented for the interaction of
  a pulsar wind with the associated supernova remnant. This results
  in a pulsar wind nebula whose evolution is coupled to the evolution
  of the surrounding supernova remnant. This evolution can be divided
  in three stages. The first stage is characterised by a supersonic
  expansion of the pulsar wind nebula into the freely expanding ejecta
  of the progenitor star. In the next stage the pulsar wind nebula is
  not steady; the pulsar wind nebula oscillates between contraction and
  expansion due to interaction with the reverse shock of the supernova
  remnant: reverberations which propagate forward and backward in
  the remnant. After the reverberations of the reverse shock have
  almost completely vanished and the supernova remnant has relaxed to
  a Sedov solution, the expansion of the pulsar wind nebula proceeds
  subsonically. In this paper we present results from hydrodynamical
  simulations of a pulsar wind nebula through all these stages in
  its evolution. The simulations were carried out with the Versatile
  Advection Code.

Title: Storage of magnetic flux at the bottom of the solar convection
    zone
Authors: Rempel, M.; Schüssler, M.; Tóth, G.
Bibcode: 2000A&A...363..789R
Altcode:
  We consider the mechanical equilibrium of a layer of axisymmetric
  toroidal magnetic field located in a subadiabatically stratified
  region near the bottom of the solar convection zone, with particular
  emphasis on the effects of spherical geometry. We determine equilibrium
  configurations and simulate numerically how these are reached from a
  non-equilibrium initial situation. While a subadiabatic stratification
  is essential for suppressing the buoyancy force, the latitudinal
  component of the magnetic curvature force is balanced by a latitudinal
  pressure gradient (in the case of a large subadiabaticity, as in the
  radiative interior) or by the Coriolis force due to a toroidal flow
  along the field lines (in the case of small subadiabaticity, as in
  a layer of convective overshoot). The latter case is found relevant
  for storing the magnetic flux generated by the solar dynamo. The
  corresponding equilibrium properties are similar to those of isolated
  magnetic flux tubes. Significant variations of the differential rotation
  at the bottom of the convection zone in the course of the solar cycle
  are expected for such a kind of equilibrium.

Title: Solar Physics Simulations with the Versatile Advection Code
Authors: Tóth, G.
Bibcode: 1999ESASP.448..389T
Altcode: 1999mfsp.conf..389T; 1999ESPM....9..389T
  No abstract at ADS

Title: Wave Heating and Nonlinear Dynamics of Coronal Loops
Authors: Beliën, A. J. C.; Martens, P. C. H.; Keppens, R.; Tóth, G.
Bibcode: 1999ASPC..184..248B
Altcode:
  We present the first results of 2.5D nonlinear magnetohydrodynamic
  wave heating simulations of solar coronal loops with inclusion
  of the modeling of the coupling to the transition region and
  chromosphere. Magnetic flux tubes with fixed lengths are considered
  but the coronal extent of the loops as situated in between the two
  transition regions can vary dynamically. The numerical simulations
  were carried out with the Versatile Advection Code. The loops are
  excited with linearly polarized Alfvén waves at the chromospheric
  base. The main finding is that resonant absorption is not efficient
  since most of the Poynting flux that enters the loop will be used to
  support all the nonlinearly generated magnetoacoustic motions and the
  corresponding compression of coronal plasma.

Title: On the Azimuthal Stability of Shock Waves around Black Holes
Authors: Molteni, Diego; Tóth, Gábor; Kuznetsov, Oleg A.
Bibcode: 1999ApJ...516..411M
Altcode: 1998astro.ph.12453M
  Analytical studies and numerical simulations of time-dependent axially
  symmetric flows onto black holes have shown that it is possible
  to produce stationary shock waves with a stable position for both
  ideal inviscid and moderately viscous accretion disks. We perform
  several two-dimensional numerical simulations of accretion flows in
  the equatorial plane to study shock stability against nonaxisymmetric
  azimuthal perturbations. We find a peculiar new result. A very small
  perturbation seems to produce an instability as it crosses the shock,
  but after some small oscillations, the shock wave suddenly transforms
  into an asymmetric closed pattern and stabilizes with a finite radial
  extent, despite the fact that the inflow and outflow boundary conditions
  are perfectly symmetric. The main characteristics of the final flow are:
  (1) The deformed shock rotates steadily without any damping. It is
  a permanent feature, and the thermal energy content and the emitted
  energy vary periodically with time. (2) This behavior is also stable
  against further perturbations. (3) The average shock is still very
  strong and well defined, and its average radial distance is somewhat
  larger than that of the original axially symmetric circular shock. (4)
  Shocks obtained with larger angular momentum exhibit more frequencies
  and beating phenomena. (5) The oscillations occur in a wide range
  of parameters, so this new effect may have relevant observational
  consequences, such as (quasi-) periodic oscillations, for the accretion
  of matter onto black holes. Typical timescales for the periods are 0.01
  and 1000 s for black holes with 10 and 10<SUP>6</SUP> M<SUB>solar</SUB>,
  respectively.

Title: Nonlinear dynamics of Kelvin-Helmholtz unstable magnetized
jets: Three-dimensional effects
Authors: Keppens, R.; Tóth, G.
Bibcode: 1999PhPl....6.1461K
Altcode: 1999astro.ph..1383K
  A numerical study of the Kelvin-Helmholtz instability in compressible
  magnetohydrodynamics is presented. The three-dimensional simulations
  consider shear flow in a cylindrical jet configuration, embedded in
  a uniform magnetic field directed along the jet axis. The growth of
  linear perturbations at specified poloidal and axial mode numbers
  demonstrate intricate nonlinear coupling effects. The physical
  mechanisms leading to induced secondary Kelvin-Helmholtz instabilities
  at higher mode numbers are identified. The initially weak magnetic
  field becomes locally dominant in the nonlinear dynamics before
  and during saturation. Thereby, it controls the jet deformation
  and eventual breakup. The results are obtained using the Versatile
  Advection Code [G. Tóth, Astrophys. Lett. Commun. 34, 245 (1996)],
  a software package designed to solve general systems of conservation
  laws. An independent calculation of the same Kelvin-Helmholtz unstable
  jet configuration using a three-dimensional pseudospectral code gives
  important insights into the coupling and excitation events of the
  various linear mode numbers.

Title: Numerical simulation of prominence oscillations
Authors: Schutgens, N. A. J.; Tóth, G.
Bibcode: 1999A&A...345.1038S
Altcode: 1999astro.ph..3128S
  We present numerical simulations, obtained with the Versatile Advection
  Code, of the oscillations of an inverse polarity prominence. The
  internal prominence equilibrium, the surrounding corona and the inert
  photosphere are well represented. Gravity and thermodynamics are not
  taken into account, but it is argued that these are not crucial. The
  oscillations can be understood in terms of a solid body moving through
  a plasma. The mass of this solid body is determined by the magnetic
  field topology, not by the prominence mass proper. The model also
  allows us to study the effect of the ambient coronal plasma on the
  motion of the prominence body. Horizontal oscillations are damped
  through the emission of slow waves while vertical oscillations are
  damped through the emission of fast waves.

Title: Simulations of small-scale explosive events on the Sun
Authors: Innes, D. E.; Tóth, G.
Bibcode: 1999SoPh..185..127I
Altcode: 1999astro.ph..1342I
  Small-scale explosive events or microflares occur throughout the
  chromospheric network of the Sun. They are seen as sudden bursts of
  highly Doppler-shifted spectral lines of ions formed at temperatures
  in the range 2×104−5×105 K. They tend to occur near regions of
  cancelling photospheric magnetic fields and are thought to be directly
  associated with magnetic field reconnection. Recent observations have
  revealed that they have a bi-directional jet structure reminiscent
  of Petschek reconnection. In this paper compressible MHD simulations
  of the evolution of a current sheet to a steady Petschek, jet-like
  configuration are computed using the Versatile Advection Code. We
  obtain velocity profiles that can be compared with recent ultraviolet
  line-profile observations. By choosing initial conditions representative
  of magnetic loops in the solar corona and chromosphere, it is possible
  to explain the fact that jets flowing outward into the corona are more
  extended and appear before jets flowing towards the chromosphere. This
  model can reproduce the high Doppler-shifted components of the line
  profiles, but the brightening at low velocities, near the center of
  the bi-directional jet, cannot be explained by this simple MHD model.

Title: Growth and saturation of the Kelvin-Helmholtz instability
    with parallel and antiparallel magnetic fields
Authors: Keppens, Rony; Tóth, G.; Westermann, R. H. J.; Goedbloed,
   J. P.
Bibcode: 1999JPlPh..61....1K
Altcode: 1999astro.ph..1166K
  Available from <A
  href="http://journals.cambridge.org/bin/bladerunner?REQUNIQ=1105385252&amp;REQSESS=958582&amp;118000REQEVENT=&amp;REQINT1=18471&amp;REQAUTH=0">http://journals.cambridge.org/bin/bladerunner?REQUNIQ=1105385252&amp;REQSESS=958582&amp;118000REQEVENT=&amp;REQINT1=18471&amp;REQAUTH=0</A>

Title: A high Reynolds number algorithm for polytropic accretion
    disk studies
Authors: Nauta, Michiel D.; Toth, Gabor
Bibcode: 1998A&A...336..791N
Altcode:
  An algorithm is proposed to study two-dimensional vortices in thin,
  polytropic accretion disks. It is based on a method which has been
  used to study vortices in planetary atmospheres. It is special in
  that it conserves both energy and potential enstrophy in the absence
  of dissipation. This leads to desirable stability properties which
  permit calculations at relatively high Reynolds numbers. The algorithm
  is tested and compared to existing methods, in particular with a Total
  Variation Diminishing method.

Title: Implicit and semi-implicit schemes in the Versatile Advection
Code: numerical tests
Authors: Toth, G.; Keppens, R.; Botchev, M. A.
Bibcode: 1998A&A...332.1159T
Altcode:
  We describe and evaluate various implicit and semi-implicit
  time integration schemes applied to the numerical simulation of
  hydrodynamical and magnetohydrodynamical problems. The schemes were
  implemented recently in the software package Versatile Advection
  Code, which uses modern shock capturing methods to solve systems of
  conservation laws with optional source terms. The main advantage
  of implicit solution strategies over explicit time integration is
  that the restrictive constraint on the allowed time step can be
  (partially) eliminated, thus the computational cost is reduced. The
  test problems cover one and two dimensional, steady state and time
  accurate computations, and the solutions contain discontinuities. For
  each test, we confront explicit with implicit solution strategies.

Title: Nonlinear MHD Simulations of Wave Dissipation in Flux Tubes
Authors: Poedts, S.; Tóth, G.; Beliën, A. J. C.; Goedbloed, J. P.
Bibcode: 1997SoPh..172...45P
Altcode: 1997ESPM....8...45P
  The phase mixing and resonant dissipation of Alfvén waves is studied in
  both the 'closed' magnetic loops and the 'open' coronal holes observed
  in the hot solar corona. The resulting energy transfer from large
  to small length scales contributes to the heating of these magnetic
  structures. The nonlinear simulations show that the periodically varying
  shear flows that occur in the resonant layers are unstable. In coronal
  holes, the phase mixing of running Alfvén waves is speeded up by the
  'flaring out' of the magnetic field lines in the lower chromosphere.

Title: Numerical Simulation of Magnetohydrodynamic Flows
Authors: Toth, G.
Bibcode: 1997CoKon.100..259T
Altcode: 1997CoKon..12..259T
  This review deals with the numerical simulation of magnetohydrodynamic
  flows. A general overview of the different numerical techniques
  compares their advantages, disadvantages and points to the appropriate
  application areas. Some specific schemes, and their implementation in
  the Versatile Advection Code are discussed in more detail.

Title: A General Code for Modeling MHD Flows on Parallel Computers:
    Versatile Advection Code
Authors: Tóth, G.
Bibcode: 1996ApL&C..34..245T
Altcode:
  No abstract at ADS

Title: A General Code for Modeling MilD Flows on Parallel Computers:
    VersatileAdvection Code
Authors: Toth, G.
Bibcode: 1996mpsa.conf..471T
Altcode: 1996IAUCo.153..471T
  No abstract at ADS

Title: Simulations of the Wardle Instability of C-Type Shock Waves
Authors: Tóth, G.
Bibcode: 1995Ap&SS.233..301T
Altcode:
  C-type shocks in the partially ionized ISM are modelled by numerical
  simulations. Under certain conditions the shocks are subject to the
  Wardle instability, which initially makes the shock front rippled, then
  in the non-linear stage can produce density variations in both the ion
  and neutral fluids. A systematic search in the numerically accessible
  parameter space is done to determine the wave vector k<SUB>max</SUB>
  and the growth rates <SUB>max</SUB> of the fastest growing modes. The
  neutral Alfvén number, and the angleθ <SUB>s</SUB>between the shock
  normal and the upstream magnetic field determine the strength and
  obliqueness of the shock, as well as the dimensionless parameters of
  the fastest growing mode. The results confirm and extend Wardle's linear
  analysis. The non-linear evolution shows saturation of the instability
  and the formation of high density regions that detach from the shock
  front with the downstream flow. Numerical difficulties are partially
  solved by an implicit treatment of the ion-neutral friction terms,
  but strong shocks still can not be modelled efficiently. A fully
  implicit method for the ions and the magnetic field is used to model
  C-type shocks with low fractional ionization and high ion Alfvén speed.

Title: Simulations of the Wardle instability of C-type shock waves
Authors: Toth, Gabor
Bibcode: 1995MNRAS.274.1002T
Altcode:
  C-type shocks in the partially ionized interstellar medium (ISM) are
  modelled by numerical simulations. Under certain conditions the shocks
  are subject to the Wardle instability, which initially makes the shock
  front rippled, and then, in the non-linear stage, can produce density
  enhancements in both the ion and neutral fluids. A systematic search in
  the numerically accessible parameter space is carried out to determine
  the wave vector k_max and the growth rate s_max of the fastest growing
  modes. The neutral Alfven number, A^(n)=v_s/v^(n)A, where v_s is the
  shock speed and v^(n)A is the Alfven speed in the limit of strong
  coupling between the two fluids, and the angle theta_s between the
  shock normal and the upstream magnetic field determine the strength and
  obliqueness of the shock, as well as the dimensionless parameters of
  the fastest growing mode. The results confirm and extend Wardle's linear
  analysis. The non-linear evolution shows saturation of the instability
  and the formation of regions with enhanced density that detach from
  the shock front with the downstream flow. Numerical difficulties are
  partially solved by an implicit treatment of the ion-neutral friction
  terms, but strong shocks still cannot be modelled efficiently. A fully
  implicit method for the ions and the magnetic field is used to model
  C-type shocks with low fractional ionization and high ion Alfven speed.

Title: Numerical Study of Two-Fluid C-Type Shock Waves
Authors: Toth, Gabor
Bibcode: 1994ApJ...425..171T
Altcode:
  C-type magnetohydrodynamic shocks in the partially ionized interstellar
  medium are studied in the two-fluid approximation. The ionized fluid
  can move along the magnetic field lines, while it interacts with the
  neutral fluid via ion-neutral elastic scattering. I use an explicitly
  flux-conserving two-dimensional Eulerian flux-corrected transport code
  to study the dynamics of two-fluid shocks. A numerical instability
  intrinsic to two-fluid problems was discovered, and a solution to
  the problem is proposed. The code can successfully simulate C-type
  shocks. The results of the linear stability analysis by Wardle are
  confirmed, and the nonlinear behavior of the instability is explored.

Title: Instability of C-shocks in the ISM.
Authors: Tóth, G.
Bibcode: 1994nsa..book..224T
Altcode:
  C-type MHD shocks in the partially ionized ISM are studied in the
  two-fluid approximation. The ionized fluid can move along the magnetic
  field lines, while it interacts with the neutral fluid via ion-neutron
  elastic scattering. The author uses an explicitly flux conserving
  2-dimensional Eulerian FCT (Flux Corrected Transport) code to study
  the dynamics of two-fluid shocks. A numerical instability intrinsic
  to two-fluid problems was discovered, and a fix to the problem is
  proposed. The code can successfully simulate C-type shocks. The
  results of the linear stability analysis by Wardle are confirmed,
  and the non-linear behavior of the instability is explored.

Title: Oscillatory Instability of Radiative Shocks with Transverse
Magnetic Field: Linear Analysis and Nonlinear Simulations
Authors: Toth, G.; Draine, B. T.
Bibcode: 1993ApJ...413..176T
Altcode:
  We examine the stability of plane-parallel radiative shocks with
  a transverse magnetic field, for radiative cooling laws in which
  Lambda varies as rho-squared T exp alpha; the instability is a global
  thermal one driving a periodic oscillation of the shock front, and
  corresponding oscillation in the instantaneous shock speed. The two
  dimensionless parameters determining the stability of the system are
  alpha, the exponent of the power law, and the Alfven Mach number MA. We
  determine the stable and unstable regions of this 2D parameter space
  for the fundamental mode and the first seven overtone modes through
  linear analysis of the hydrodynamical equations. As expected, the
  magnetic field has a stabilizing influence. For alpha greater than
  0, even a relatively weak magnetic field can stabilize against all
  modes. For alpha greater than 0.5, even weaker fields are sufficient
  to suppress thermal instability. We also determine the linear growth
  rates and frequencies of the fundamental mode and the first and second
  overtones for 12 pairs of the parameters alpha and MA.

Title: Instability of Radiative and C-Type MHD Shock Waves
Authors: Toth, Gabor
Bibcode: 1993PhDT........30T
Altcode:
  Radiative shocks with a cooling law Lambda ~ rho^2T^alpha can be subject
  to a global thermal instability which drives a periodic oscillation of
  the shock front. The stabilizing effect of a transverse magnetic field
  is examined. The two dimensionless parameters determining the stability
  of the system are alpha and the Alfven Mach number M<SUB>A</SUB>. The
  stable and unstable regions of this two-dimensional parameter space are
  determined through linear analysis. For alpha &gt; 0 even a relatively
  weak magnetic field (M<SUB>A</SUB> &lt; 8) can stabilize against all
  modes. The results are confirmed by means of numerical simulations. The
  simulations show saturation or secondary shock formation in the
  non-linear regime. Radiative shocks with v_{s } _sp{~}&lt; 160km s^{-1}
  radiative shocks in the "warm ISM" may be magnetically stabilized. In
  higher density gas, however, the magnetic field is not strong enough
  to appreciably affect the shock stability. Next the dynamics of C-type
  MHD shocks in the partially ionized ISM are studied in the two-fluid
  approximation by an explicitly flux conserving two-dimensional
  Eulerian FCT code. A numerical instability intrinsic to two-fluid
  problems is discovered, and a fix to the problem is proposed. The code
  can successfully simulate a rippling instability of the shock front
  discovered by Wardle through linear analysis. Numerical simulations are
  presented to find the wave vector vec k<SUB>max</SUB> and the growth
  rate s<SUB>max</SUB> of the fastest growing modes. For perpendicular
  shocks the analytic calculations are confirmed, while for oblique
  shocks k_ {|} equiv k cos phi<SUB>k</SUB>, the component of the wave
  vector lying in the plane of the magnetic field and the shock normal,
  is found to be the critical parameter determining s<SUB>max</SUB>. The
  phi<SUB>max</SUB> angle is only weakly constrained. These results
  confirm and generalize the predictions of the linear analysis. The
  simulation of a weak perpendicular shock shows that saturation of the
  Wardle-instability occurs only when the density perturbations reach
  an amplitude comparable to the total density jump through the shock
  front. The simulations show a strong transient amplification of the
  initial perturbations, thus to some extent the amplitude and spectrum
  of the seed perturbations in the ambient ISM will contribute to the
  selection of the dominant growing mode.

Title: Instability of radiative and C-type MHD shock waves
Authors: Tóth, Gábor
Bibcode: 1993PhDT.......130T
Altcode:
  No abstract at ADS

Title: Oscillatory instability of radiative shocks with transverse
magnetic field: linear analysis and nonlinear simulations.
Authors: Tóth, G.; Draine, B. T.
Bibcode: 1992BAAS...24.1261T
Altcode:
  No abstract at ADS

Title: Oscillatory Instability of Radiative Shocks with Transverse
Magnetic Field: Linear Analysis and Nonlinear Simulations
Authors: Toth, G.; Draine, B. T.
Bibcode: 1992AAS...181.8605T
Altcode:
  We examine the stability of plane-parallel radiative shocks with
  a transverse magnetic field, for radiative cooling laws Lambda ~
  rho (2) T(alpha ). The instability of interest is a global thermal
  instability which drives a periodic oscillation of the shock front,
  and corresponding oscillation in the instantaneous shock speed. The two
  dimensionless parameters determining the stability of the system are
  alpha , the exponent of the power law, and the Alfven Mach number
  M_Aequiv v_s/v_A, where v_s is the average shock speed and v_A is
  the Alfven velocity in the preshock medium. We determine the stable
  and unstable regions of this two dimensional parameter space for
  the fundamental mode and the first seven overtone modes through
  linear analysis of the hydrodynamical equations. As expected, the
  magnetic field has a stabilizing influence. For alpha &gt;0 even a
  relatively weak magnetic field (M_A &lt; 8) can stabilize against
  all modes. For alpha &gt; 0.5 even weaker fields (M_A &lt; 33) are
  sufficient to suppress thermal instability. We also determine the
  linear growth rates and frequencies of the fundamental mode and the
  first and second overtones for twelve pairs of the parameters alpha
  and M_A. A fully dynamical numerical simulation of these twelve cases
  confirms the results of the linear analysis, and also explores the
  nonlinear behavior of the oscillations. In most of the unstable cases
  the amplitude of the shock front oscillation saturates at a level of 5%
  to 10% of the length of the cooling region. In the least stable cases,
  however, the flow develops multiple shocks. Using a simple approximation
  to the cooling function for shocked interstellar gas, we show that v_s
  &lt; ~= 160kms(-1) radiative shocks in interstellar gas with n_H &lt;
  ~eq0.4cm(-3) (the "warm ionized medium" or "warm neutral medium") may
  be magnetically stabilized. In higher density gas, however, the magnetic
  field is not strong enough to appreciably affect the shock stability.

Title: Oscillatory Instability of Radiative Shocks with Transverse
Magnetic Field: Linear Analysis and Nonlinear Simulations
Authors: Tóth, G.; Draine, B. T.
Bibcode: 1992AAS...181.8505T
Altcode: 1992BAAS...24.1259T
  No abstract at ADS

Title: Galactic Disks, Infall, and the Global Value of Omega
Authors: Toth, G.; Ostriker, J. P.
Bibcode: 1992ApJ...389....5T
Altcode:
  The thinness and coldness of galactic disks can be used to set
  stringent limits on the current rate of infall of satellite systems
  onto spiral galaxies. After reviewing the literature concerning
  numerical results, we develop analytical arguments which confirm
  and considerably extend prior work. For infalling satellites on
  isotropically oriented circular orbits, we show that, due to scattering,
  the thermal energy gain of the disk exceeds the satellite energy loss
  from dynamical friction by a factor of 1.6, with 25% deposited in
  z motion and 75% in planar motions. This factor almost compensates
  for the frictional loss to the halo, with halo-to-disk loss rates
  being approximately 2.87rρ_h_(r)/{SIGMA}_d_(r). For our chosen
  Galactic model this corresponds to 62% of the energy deposited in
  the spherical component at the solar radius. While satellite infall
  will thicken disks by perturbing the stellar orbits, it will cause
  adiabatic contraction too. If there is gas infall, this makes the disk
  thinner by settling down in the galactic plane. However, the first
  effect dominates, the ratio between stellar heating and gas cooling
  being 0.11(v_rot/σ_normal_)^2^~7 for equal masses added in stars
  and gas. Applying these arguments to current models for our Galaxy,
  we find that no more than 4% of its mass inside the solar radius
  can have accreted within the last 5 billion years, or else its scale
  height and its Toomre Q-parameter would exceed observed values. We
  find that tidal stripping of infalling dwarfs is not a large effect
  unless core radii significantly exceed 1 kpc. In standard cold dark
  matter-dominated models for the growth of structure with {OMEGA}_tot_
  = 1, the mass accreted in dark matter lumps rises faster than t^2/3^
  and would exceed 28% in the last 5 Gyr. If our Galaxy is typical (and
  the prevalence of spiral structure indicates that this is so), then
  such models for the growth of structure may be ruled out. There is
  no such difficulty in open universes, since accretion declines after
  a time t_1/2_= H^-1^_0<SUB>pi</SUB>{OMEGA}_0_/(1 - {OMEGA}^3/2^, nor
  is there a problem if {OMEGA} = 1 in the form of radiation, {LAMBDA},
  or a hot component which would not accrete. Heating from satellite
  infall may account for a substantial fraction of the increase of
  velocity dispersion and scale height with age that is observed in our
  Galaxy. In addition, since the satellite infall events are discrete, the
  age-velocity dispersion relation should reflect this, and the velocity
  distribution will have a non-Gaussian tail, which will contribute to
  a thick disk.

Title: Three-Point Correlations of Galaxy Clusters
Authors: Toth, Gabor; Hollosi, Joseph; Szalay, Alexander S.
Bibcode: 1989ApJ...344...75T
Altcode:
  We estimate the irreducible angular three-point correlation function
  of Abell clusters in distance classes 5 and 6 with Galactic latitude
  |b^II^| &gt;= 40^deg^ from the Abell and Abell, Corwin, and Olowin
  catalog and of clusters identified in the Shane-Wirtanen catalog
  (Shectman). We find that the distribution of these clusters satisfies
  a relation between the two- and three-point correlation functions:

Title: Angular Cross-Correlation of Abell Clusters in Different
    Distance Classes
Authors: Szalay, A. S.; Hollosi, J.; Toth, G.
Bibcode: 1989ApJ...339L...5S
Altcode:
  We estimate the angular autocorrelation and cross-correlation functions
  of the D = 1... 4, D = 5, and D = 6 distance class Abell clusters. While
  the autocorrelation functions can be described by a power-law form w(θ)
  is proportional to θ^-1^, the cross-correlations are found to be much
  flatter. Moreover, there is a strong anticorrelation between the most
  distant D = 6 and the closest D = 1... 4 subsamples. We believe this to
  be an artifact of the cluster identification process presumably due to
  the finite angular size of the cluster. This anticorrelation seems to
  contradict some recent estimations of projection contaminations in the
  Abell catalog. We suggest that the angular proximity of a foreground
  cluster may have caused a background cluster not to be counted as it
  was thought to be a subcluster or it was erroneously assigned to a
  nearer distance class.

Title: Three-Point Correlations of Abell Clusters
Authors: Toth, Gabor; Hollosi, Joseph; Szalay, Alex S.
Bibcode: 1988LNP...310..195T
Altcode: 1988lssu.work..195T
  The irreducible three-point correlations of Abell clusters are estimated
  using all distance class 5 + 6 clusters with a latitude greater than
  or equal to 40 deg. It is found that the clusters satisfy a relation
  between the two- and three-point correlation functions similar to that
  for galaxies. There is a strong discrepancy between the northern and
  southern galactic caps.

Title: Three-point correlations of Abell clusters.
Authors: Tóth, G.; Hollósi, J.; Szalay, A. S.
Bibcode: 1988lssu.conf..195T
Altcode:
  The authors estimate the irreducible three-point correlations of
  Abell clusters using all distance class 5+6 clusters with latitude
  |b<SUP>II</SUP>| ≥ 40°. They find that these clusters satisfy a
  relation between the two- and three-point correlation functions:
  ζ(r,s,u) ≈ Q(ξ(r)ξ(s) + ξ(s)ξ(u) + ξ(u)ξ(r)) similar to
  that for galaxies. The value of Q has large uncertainties: Q =
  0.9±0.5. Higher order terms seem to be absent in ζ. Several error
  estimation methods are applied.

Title: Book Reviews
Authors: Hodgson, R. G.; Smith, R. J.; Brasch, K. R.; Tóth, G.;
   McIntosh, P. S.; Trusell, F. C.
Bibcode: 1963StAst..17...74H
Altcode: 1963JALPO..17...74H
  Six books are reviewed: The System of Minor Planets by Günter
  D. Roth; Star Gazing with Telescope and Camera by George T. Keene;
  Der Sternhimmel 1963, Edited by Robert A. Naef; The Physics of the
  Moon by P. Hedervari; Solar Research, by Giorgio Abetti; and Soviet
  Science of Interstellar Space, by S. Pikelner.

