Author name code: gosic
ADS astronomy entries on 2022-09-14
author:"Gosic, Milan" 
------------------------------------------------------------------------  

Title: Unipolar versus Bipolar Internetwork Flux Appearance
Authors: Gosic, Milan; Katsukawa, Yukio; Bellot Rubio, L. R.; Del
   Toro Iniesta, Jose Carlos; Cheung, Mark; Orozco Suárez, David
Bibcode: 2022cosp...44.2513G
Altcode:
  Small-scale internetwork (IN) magnetic fields are considered to be
  the main building blocks of the quiet Sun magnetism. It is therefore
  of paramount importance to understand how these fields are generated
  on the solar surface. To shed new light on this open question,
  we studied the appearance modes and spatio-temporal evolution of
  individual IN magnetic elements inside one supergranular cell. For
  that purpose, we employed a high-resolution, high-sensitivity,
  long-duration Hinode/NFI magnetogram sequence. From identification
  of flux patches and magnetofrictional simulations, we show that there
  are two distinct populations of IN flux concentrations: unipolar and
  bipolar features. Bipolar features tend to be bigger, live longer
  and carry more flux than unipolar features. About $70$% of the total
  instantaneous IN flux detected inside the supergranule is in the form
  of bipoles. Both types of flux concentrations are uniformly distributed
  over the solar surface. However, bipolar features appear (randomly
  oriented) at a faster rate than unipolar features (68 as opposed to
  55~Mx~cm$^{-2}$~day$^{-1}$). Our results lend support to the idea that
  bipolar features may be the signature of local dynamo action, while
  unipolar features seem to be formed by coalescence of background flux.

Title: Emergence of internetwork magnetic fields into the chromosphere
    and transition region
Authors: Gosic, Milan; De Pontieu, Bart; Bellot Rubio, L. R.; Sainz
   Dalda, A.; Esteban Pozuelo, Sara
Bibcode: 2022cosp...44.2511G
Altcode:
  Internetwork (IN) magnetic fields are highly dynamic, short-lived
  magnetic structures that populate the interior of supergranular
  cells. Since they are spread all over the Sun, they may hold a
  significant fraction of the total magnetic energy stored in the
  photosphere. Therefore, it is crucial to understand their role in the
  quiet Sun magnetism and impact on the energetics and dynamics of the
  solar atmosphere. To provide new insights into this topic, we studied
  three flux emergence events and followed them as they emerge into the
  photosphere and reach the chromosphere and transition region. We used
  coordinated, high-resolution, multiwavelength observations obtained with
  the Swedish 1-m Solar Telescope (SST) and the Interface Region Imaging
  Spectrograph (IRIS). SST Fe I 6173 and Mg I b$_2$ 5173 magnetograms
  show the footpoints of the IN bipoles emerging at the solar surface
  and rising toward the upper solar atmosphere. For the first time, our
  spectropolarimetric measurements in the Ca II 8542 \AA\/ line provide
  direct observational evidence that IN fields are capable of reaching
  the chromosphere. IRIS observations reveal another important piece of
  information - small-scale IN loops can even reach transition region
  heights, and locally heat the upper solar atmosphere.

Title: The Solar Internetwork. III. Unipolar versus Bipolar Flux
    Appearance
Authors: Gošić, M.; Bellot Rubio, L. R.; Cheung, M. C. M.; Orozco
   Suárez, D.; Katsukawa, Y.; del Toro Iniesta, J. C.
Bibcode: 2022ApJ...925..188G
Altcode: 2021arXiv211103208G
  Small-scale internetwork (IN) magnetic fields are considered to be the
  main building blocks of quiet Sun magnetism. For this reason, it is
  crucial to understand how they appear on the solar surface. Here,
  we employ a high-resolution, high-sensitivity, long-duration
  Hinode/NFI magnetogram sequence to analyze the appearance modes and
  spatiotemporal evolution of individual IN magnetic elements inside a
  supergranular cell at the disk center. From identification of flux
  patches and magnetofrictional simulations, we show that there are
  two distinct populations of IN flux concentrations: unipolar and
  bipolar features. Bipolar features tend to be bigger and stronger
  than unipolar features. They also live longer and carry more flux
  per feature. Both types of flux concentrations appear uniformly over
  the solar surface. However, we argue that bipolar features truly
  represent the emergence of new flux on the solar surface, while
  unipolar features seem to be formed by the coalescence of background
  flux. Magnetic bipoles appear at a faster rate than unipolar features
  (68 as opposed to 55 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>), and provide
  about 70% of the total instantaneous IN flux detected in the interior
  of the supergranule.

Title: Emergence of Internetwork Magnetic Fields through the Solar
    Atmosphere
Authors: Gošić, M.; De Pontieu, B.; Bellot Rubio, L. R.; Sainz Dalda,
   A.; Pozuelo, S. Esteban
Bibcode: 2021ApJ...911...41G
Altcode: 2021arXiv210302213G
  Internetwork (IN) magnetic fields are highly dynamic, short-lived
  magnetic structures that populate the interior of supergranular
  cells. Since they emerge all over the Sun, these small-scale fields
  bring a substantial amount of flux, and therefore energy, to the solar
  surface. Because of this, IN fields are crucial for understanding
  the quiet Sun (QS) magnetism. However, they are weak and produce very
  small polarization signals, which is the reason why their properties
  and impact on the energetics and dynamics of the solar atmosphere are
  poorly known. Here we use coordinated, high-resolution, multiwavelength
  observations obtained with the Swedish 1 m Solar Telescope and the
  Interface Region Imaging Spectrograph (IRIS) to follow the evolution
  of IN magnetic loops as they emerge into the photosphere and reach
  the chromosphere and transition region. We studied in this paper three
  flux emergence events having total unsigned magnetic fluxes of 1.9 ×
  10<SUP>18</SUP>, 2.5 × 10<SUP>18</SUP>, and 5.3 × 10<SUP>18</SUP>
  Mx. The footpoints of the emerging IN bipoles are clearly seen
  to appear in the photosphere and to rise up through the solar
  atmosphere, as observed in Fe I 6173 Å and Mg I b<SUB>2</SUB> 5173
  Å magnetograms, respectively. For the first time, our polarimetric
  measurements taken in the chromospheric Ca II 8542 Å line provide
  direct observational evidence that IN fields are capable of reaching the
  chromosphere. Moreover, using IRIS data, we study the effects of these
  weak fields on the heating of the chromosphere and transition region.

Title: Expected spectropolarimetric observables in the lower solar
    atmosphere from 3D radiative MHD models
Authors: Sainz Dalda, A.; Gosic, M.; Martinez-Sykora, J.
Bibcode: 2020AGUFMSH0010019S
Altcode:
  No abstract at ADS

Title: Lagrangian chaotic saddles and objective vortices in solar
    plasmas
Authors: Chian, Abraham C. -L.; Silva, Suzana S. A.; Rempel, Erico L.;
   Bellot Rubio, Luis R.; Gošić, Milan; Kusano, Kanya; Park, Sung-Hong
Bibcode: 2020PhRvE.102f0201C
Altcode:
  We report observational evidence of Lagrangian chaotic saddles
  in plasmas, given by the intersections of finite-time unstable and
  stable manifolds, using an ≈22 h sequence of spacecraft images of the
  horizontal velocity field of solar photosphere. A set of 29 persistent
  objective vortices with lifetimes varying from 28.5 to 298.3 min are
  detected by computing the Lagrangian averaged vorticity deviation. The
  unstable manifold of the Lagrangian chaotic saddles computed for ≈11
  h exhibits twisted folding motions indicative of recurring vortices in
  a magnetic mixed-polarity region. We show that the persistent objective
  vortices are formed in the gap regions of Lagrangian chaotic saddles
  at supergranular junctions.

Title: Chromospheric response to emergence of internetwork magnetic
    fields
Authors: Gosic, M.; De Pontieu, B.; Bellot Rubio, L.; Sainz Dalda, A.
Bibcode: 2020AGUFMSH0010006G
Altcode:
  Internetwork (IN) magnetic fields are weak, short-lived, but highly
  dynamic magnetic structures that emerge all over the Sun. They
  bring an enormous amount of magnetic flux and energy to the solar
  surface. Therefore, IN fields are of paramount importance for
  maintenance of the QS magnetism. Since these fields are ubiquitous,
  they may have a substantial impact on the energetics and dynamics of the
  solar atmosphere. In this work, we use coordinated, high-resolution,
  multiwavelength observations obtained with the Interface Region
  Imaging Spectrograph (IRIS) and the Swedish 1 m Solar Telescope (SST)
  to follow the evolution of IN magnetic loops as they emerge into the
  photosphere. The footpoints of the emerging IN bipoles are clearly
  visible as they appear in the photosphere and rise up through the
  solar atmosphere, as seen in SST magnetograms taken in the Fe I
  6173 Å and Mg I b2 5173 Å lines, respectively. Our polarimetric
  measurements, taken in the Ca II 8542 Å line, provide the first
  direct observational evidence that IN fields are capable of reaching
  the chromosphere. Moreover, using IRIS data, we describe in detail
  how individual IN bipoles affect the dynamics and energetics of the
  chromosphere and transition region.

Title: Chromospheric and TR diagnostics in a large scale numerical
simulation of flux emergence: Synthetic vs Real observables
Authors: Hansteen, V. H.; De Pontieu, B.; Testa, P.; Gosic, M.;
   Martinez-Sykora, J.
Bibcode: 2020AGUFMSH0010021H
Altcode:
  Field stored just below or rising to the photosphere will break through
  the surface and enter the upper atmosphere once the gradient of the
  subphotospheric field strength becomes sufficiently large. Opposite
  polarity flux bundles will reconnect in the photosphere and above,
  to form steadily longer loops that expand into the outer solar
  atmosphere, forming the corona. Some of the emerging flux is likely
  due to a local dynamo, but also the direct emergence of large scale
  magnetic structures from below is important, even in the quiet Sun. A
  significant proportion of this field likely reaches the chromosphere
  and may leave imprint on chromospheric dynamics and energetics. Using
  large scale numerical models (72x72x60) Mm and the high resolution
  spectra and slit jaw images from IRIS, as well as photospheric data
  from Hinode/SOT, and SDO/HMI we study the interactions between the
  magnetic flux caught in the granular flow field and the chromosphere
  and chromospheric field above. We will compare synthetic observables
  of the photospheric Fe I 617.3 nm line, the chromospheric Mg II h&amp;k
  lines, and the transition region Si IV lines, with their observational
  counterparts. We will also generate synthetic ALMA band 3 images. The
  comparison of synthetic observational data will let us draw conclusions
  as to the validity of the numerical modeling and the importance of flux
  emergence for the dynamics and energetics of the outer solar atmosphere.

Title: High-resolution observations of the solar photosphere,
    chromosphere, and transition region. A database of coordinated IRIS
    and SST observations
Authors: Rouppe van der Voort, L. H. M.; De Pontieu, B.; Carlsson,
   M.; de la Cruz Rodríguez, J.; Bose, S.; Chintzoglou, G.; Drews, A.;
   Froment, C.; Gošić, M.; Graham, D. R.; Hansteen, V. H.; Henriques,
   V. M. J.; Jafarzadeh, S.; Joshi, J.; Kleint, L.; Kohutova, P.;
   Leifsen, T.; Martínez-Sykora, J.; Nóbrega-Siverio, D.; Ortiz, A.;
   Pereira, T. M. D.; Popovas, A.; Quintero Noda, C.; Sainz Dalda, A.;
   Scharmer, G. B.; Schmit, D.; Scullion, E.; Skogsrud, H.; Szydlarski,
   M.; Timmons, R.; Vissers, G. J. M.; Woods, M. M.; Zacharias, P.
Bibcode: 2020A&A...641A.146R
Altcode: 2020arXiv200514175R
  NASA's Interface Region Imaging Spectrograph (IRIS) provides
  high-resolution observations of the solar atmosphere through ultraviolet
  spectroscopy and imaging. Since the launch of IRIS in June 2013, we
  have conducted systematic observation campaigns in coordination with
  the Swedish 1 m Solar Telescope (SST) on La Palma. The SST provides
  complementary high-resolution observations of the photosphere and
  chromosphere. The SST observations include spectropolarimetric imaging
  in photospheric Fe I lines and spectrally resolved imaging in the
  chromospheric Ca II 8542 Å, Hα, and Ca II K lines. We present
  a database of co-aligned IRIS and SST datasets that is open for
  analysis to the scientific community. The database covers a variety
  of targets including active regions, sunspots, plages, the quiet Sun,
  and coronal holes.

Title: Erratum: Supergranular turbulence in the quiet Sun: Lagrangian
    coherent structures
Authors: Chian, Abraham C. -L.; Silva, Suzana S. A.; Rempel, Erico
   L.; Gošić; , Milan; Bellot Rubio, Luis R.; Kusano, Kanya; Miranda,
   Rodrigo A.; Requerey, Iker S.
Bibcode: 2019MNRAS.489..707C
Altcode: 2019MNRAS.tmp.2225C
  No abstract at ADS

Title: Supergranular turbulence in the quiet Sun: Lagrangian coherent
    structures
Authors: Chian, Abraham C. -L.; Silva, Suzana S. A.; Rempel, Erico
   L.; Gošić; , Milan; Bellot Rubio, Luis R.; Kusano, Kanya; Miranda,
   Rodrigo A.; Requerey, Iker S.
Bibcode: 2019MNRAS.488.3076C
Altcode: 2019MNRAS.tmp.1841C; 2019arXiv190408472C
  The quiet Sun exhibits a wealth of magnetic activities that are
  fundamental for our understanding of solar magnetism. The magnetic
  fields in the quiet Sun are observed to evolve coherently, interacting
  with each other to form prominent structures as they are advected by
  photospheric flows. The aim of this paper is to study supergranular
  turbulence by detecting Lagrangian coherent structures (LCS) based on
  the horizontal velocity fields derived from Hinode intensity images at
  disc centre of the quiet Sun on 2010 November 2. LCS act as transport
  barriers and are responsible for attracting/repelling the fluid elements
  and swirling motions in a finite time. Repelling/attracting LCS are
  found by computing the forward/backward finite-time Lyapunov exponent
  (FTLE), and vortices are found by the Lagrangian-averaged vorticity
  deviation method. We show that the Lagrangian centres and boundaries
  of supergranular cells are given by the local maximum of the forward
  and backward FTLE, respectively. The attracting LCS expose the location
  of the sinks of photospheric flows at supergranular junctions, whereas
  the repelling LCS interconnect the Lagrangian centres of neighbouring
  supergranular cells. Lagrangian transport barriers are found within a
  supergranular cell and from one cell to other cells, which play a key
  role in the dynamics of internetwork and network magnetic elements. Such
  barriers favour the formation of vortices in supergranular junctions. In
  particular, we show that the magnetic field distribution in the quiet
  Sun is determined by the combined action of attracting/repelling LCS
  and vortices.

Title: Evolution of bipolar internetwork magnetic fields
Authors: Gosic, Milan; De Pontieu, Bart; Bellot Rubio, Luis Ramon
Bibcode: 2019AAS...23431102G
Altcode:
  Internetwork (IN) magnetic fields can be found inside supergranular
  cells all over the solar surface. Thanks to their abundance and
  appearance rate, IN fields are considered to be an essential contributor
  to the magnetic flux and energy budget of the solar photosphere, and
  may also play a major role in the energy budget of the chromosphere
  and transition region. Therefore, it is crucial to understand how
  IN magnetic fields appear, evolve, interact with the preexisting
  magnetic structures, and what impact they have on the upper solar
  atmosphere. Here, we analyze spatio-temporal evolution of IN magnetic
  bipolar structures, i.e, loops and clusters, employing multi-instrument
  (IRIS and SST), multi-wavelength observations of IN regions with the
  highest sensitivity and resolution possible. For the first time, our
  observations allow us to describe in detail how IN bipoles emerge in
  the photosphere and even reach the chromosphere. We estimate the field
  strengths of these IN magnetic structures both in the photosphere and
  the chromosphere, using full Stokes measurements in Fe I 6173 Å, Mg I
  b<SUB>2</SUB> 5173 Å, and Ca II 8542 Å. Employing the IRIS FUV and
  NUV spectra, we show that IN fields contribute to the chromospheric
  and transition region heating through interaction with the preexisting
  ambient fields.

Title: On the Origin of the Magnetic Energy in the Quiet Solar
    Chromosphere
Authors: Martínez-Sykora, Juan; Hansteen, Viggo H.; Gudiksen, Boris;
   Carlsson, Mats; De Pontieu, Bart; Gošić, Milan
Bibcode: 2019ApJ...878...40M
Altcode: 2019arXiv190404464M
  The presence of magnetic field is crucial in the transport of energy
  through the solar atmosphere. Recent ground-based and space-borne
  observations of the quiet Sun have revealed that magnetic field
  accumulates at photospheric heights, via a local dynamo or from
  small-scale flux emergence events. However, most of this small-scale
  magnetic field may not expand into the chromosphere due to the entropy
  drop with height at the photosphere. Here we present a study that uses
  a high-resolution 3D radiative MHD simulation of the solar atmosphere
  with non-gray and non-LTE radiative transfer and thermal conduction
  along the magnetic field to reveal that (1) the net magnetic flux
  from the simulated quiet photosphere is not sufficient to maintain a
  chromospheric magnetic field (on average), (2) processes in the lower
  chromosphere, in the region dominated by magnetoacoustic shocks,
  are able to convert kinetic energy into magnetic energy, (3) the
  magnetic energy in the chromosphere increases linearly in time until
  the rms of the magnetic field strength saturates at roughly 4-30 G
  (horizontal average) due to conversion from kinetic energy, (4) and
  that the magnetic features formed in the chromosphere are localized
  to this region.

Title: Recovering Thermodynamics from Spectral Profiles observed by
IRIS: A Machine and Deep Learning Approach
Authors: Sainz Dalda, Alberto; de la Cruz Rodríguez, Jaime; De
   Pontieu, Bart; Gošić, Milan
Bibcode: 2019ApJ...875L..18S
Altcode: 2019arXiv190408390S
  Inversion codes allow the reconstruction of a model atmosphere from
  observations. With the inclusion of optically thick lines that form in
  the solar chromosphere, such modeling is computationally very expensive
  because a non-LTE evaluation of the radiation field is required. In this
  study, we combine the results provided by these traditional methods
  with machine and deep learning techniques to obtain similar-quality
  results in an easy-to-use, much faster way. We have applied these
  new methods to Mg II h and k lines observed by the Interface Region
  Imaging Spectrograph (IRIS). As a result, we are able to reconstruct the
  thermodynamic state (temperature, line-of-sight velocity, nonthermal
  velocities, electron density, etc.) in the chromosphere and upper
  photosphere of an area equivalent to an active region in a few CPU
  minutes, speeding up the process by a factor of 10<SUP>5</SUP> -
  10<SUP>6</SUP>. The open-source code accompanying this Letter will
  allow the community to use IRIS observations to open a new window to
  a host of solar phenomena.

Title: Convection-driven Generation of Ubiquitous Coronal Waves
Authors: Aschwanden, Markus J.; Gošic, Milan; Hurlburt, Neal E.;
   Scullion, Eamon
Bibcode: 2018ApJ...866...73A
Altcode:
  We develop a new method to measure the 3D kinematics of the
  subphotospheric motion of magnetic elements, which is used to study
  the coupling between the convection-driven vortex motion and the
  generation of ubiquitous coronal waves. We use the method of decomposing
  a line-of-sight magnetogram from MDI/SDO into unipolar magnetic charges,
  which yields the (projected) 2D motion [x(t), y(t)] and the (half) width
  evolution w(t) of an emerging magnetic element from an initial depth
  of d ≲ 1500 km below the photosphere. A simple model of rotational
  vortex motion with magnetic flux conservation during the emergence
  process of a magnetic element predicts the width evolution, i.e.,
  w(t)/w <SUB>0</SUB> = [B(t)/B <SUB>0</SUB>]<SUP>-1/2</SUP>, and an
  upper limit of the depth variation d(t) ≤ 1.3 w(t). While previous
  2D tracing of magnetic elements provided information on advection
  and superdiffusion, our 3D tracing during the emergence process of a
  magnetic element is consistent with a ballistic trajectory in the upward
  direction. From the estimated Poynting flux and lifetimes of convective
  cells, we conclude that the Coronal Multi-channel Polarimeter-detected
  low-amplitude transverse magnetohydrodynamic waves are generated by
  the convection-driven vortex motion. Our observational measurements
  of magnetic elements appear to contradict the theoretical random-walk
  braiding scenario of Parker.

Title: Emergence of internetwork magnetic fields through the solar
    atmosphere
Authors: Gosic, Milan; De Pontieu, Bart; Bellot Rubio, L. R.
Bibcode: 2018cosp...42E1261G
Altcode:
  Internetwork (IN) magnetic fields are highly dynamic, short-lived
  magnetic structures that populate the interior of supergranular
  cells. Since they emerge all over the Sun, these small-scale fields
  bring a substantial amount of flux, and therefore energy, to the solar
  surface. Because of this, IN fields are crucial for understanding the
  quiet Sun magnetism. However, they are weak and produce very small
  polarization signals, which is the reason why their properties and
  impact on the energetics and dynamics of the solar atmosphere are
  largely unknown. Here we use coordinated IRIS and SST observations
  of IN regions at high spatial and temporal resolution. They give us
  the opportunity to follow the evolution of IN magnetic loops as they
  emerge into the photosphere. For the first time, our polarimetric
  measurements provide a direct observational evidence of IN fields
  reaching the chromosphere. Moreover, we show that IN magnetic loops
  contribute to the chromospheric and transition region heating through
  interaction with preexisting ambient fields.

Title: Transport of Internetwork Magnetic Flux Elements in the Solar
Photosphere : Signatures of Large-Scale Flows and their Effect on
    Transport Statistics
Authors: Agrawal, Piyush; Rast, Mark; Gosic, Milan; Rempel, Matthias;
   Bellot Rubio, Luis
Bibcode: 2018tess.conf21704A
Altcode:
  The motions of small-scale magnetic &lt;span class="s1" flux elements
  in the solar photosphere can provide some measure of the Lagrangian
  properties of the convective &lt;span class="s1" flow. Measurements of
  these motions have been critical in estimating the turbulent diffusion
  coef&lt;span class="s1" ficient in &lt;span class="s1" flux-transport
  dynamo models and in determining the Alfvén wave excitation spectrum
  for coronal heating models. We examine the motions of internetwork
  &lt;span class="s1" flux elements in Hinode&lt;span class="s1"
  /Narrowband Filter Imager magnetograms and study the scaling of
  their mean squared displacement and the shape of their displacement
  probability distribution as a function of time. We &lt;span class="s1"
  find that the mean squared displacement scales super-diffusively with
  a slope of about 1.48. Super-diffusive scaling has been observed in
  other studies for temporal increments as small as 5 s, increments over
  which ballistic scaling would be expected. Using high-cadence MURaM
  simulations, we show that the observed super-diffusive scaling at short
  increments is a consequence of random changes in barycenter positions
  due to &lt;span class="s1" flux evolution. We also &lt;span class="s1"
  find that for long temporal increments, beyond granular lifetimes,
  the observed displacement distribution deviates from that expected
  for a diffusive process, evolving from Rayleigh to Gaussian. This
  change in distribution can be modeled analytically by accounting for
  supergranular advection along with granular motions. These results
  complicate the interpretation of magnetic element motions as strictly
  advective or diffusive on short and long timescales and suggest that
  measurements of magnetic element motions must be used with caution
  in turbulent diffusion or wave excitation models. We propose that
  passive tracer motions in measured photospheric &lt;span class="s1"
  flows may yield more robust transport statistics.

Title: Emergence of internetwork magnetic fields through the solar
    atmosphere
Authors: Gosic, Milan; De Pontieu, Bart; Bellot Rubio, Luis
Bibcode: 2018tess.conf21701G
Altcode:
  Internetwork (IN) magnetic fields are highly dynamic, short-lived
  magnetic structures that populate the interior of supergranular
  cells. Since they emerge all over the Sun, these small-scale fields
  bring a substantial amount of flux, and therefore energy, to the solar
  surface. Because of this, IN fields are crucial for understanding the
  quiet Sun magnetism. However, they are weak and produce very small
  polarization signals, which is the reason why their properties and
  impact on the energetics and dynamics of the solar atmosphere are
  largely unknown. Here we use coordinated IRIS and SST observations
  of IN regions at high spatial and temporal resolution. They give us
  the opportunity to follow the evolution of IN magnetic loops as they
  emerge into the photosphere. For the first time, our polarimetric
  measurements provide a direct observational evidence of IN fields
  reaching the chromosphere. Moreover, we show that IN magnetic loops
  contribute to the chromospheric and transition region heating through
  interaction with preexisting ambient fields.

Title: Chromospheric Heating due to Cancellation of Quiet Sun
    Internetwork Fields
Authors: Gošić, M.; de la Cruz Rodríguez, J.; De Pontieu, B.; Bellot
   Rubio, L. R.; Carlsson, M.; Esteban Pozuelo, S.; Ortiz, A.; Polito, V.
Bibcode: 2018ApJ...857...48G
Altcode: 2018arXiv180207392G
  The heating of the solar chromosphere remains one of the most
  important questions in solar physics. Our current understanding is that
  small-scale internetwork (IN) magnetic fields play an important role
  as a heating agent. Indeed, cancellations of IN magnetic elements in
  the photosphere can produce transient brightenings in the chromosphere
  and transition region. These bright structures might be the signature
  of energy release and plasma heating, probably driven by the magnetic
  reconnection of IN field lines. Although single events are not expected
  to release large amounts of energy, their global contribution to the
  chromosphere may be significant due to their ubiquitous presence
  in quiet Sun regions. In this paper, we study cancellations of IN
  elements and analyze their impact on the energetics and dynamics of
  the quiet Sun atmosphere. We use high-resolution, multiwavelength,
  coordinated observations obtained with the Interface Region Imaging
  Spectrograph and the Swedish 1 m Solar Telescope (SST) to identify
  cancellations of IN magnetic flux patches and follow their evolution. We
  find that, on average, these events live for ∼3 minutes in the
  photosphere and ∼12 minutes in the chromosphere and/or transition
  region. Employing multi-line inversions of the Mg II h and k lines,
  we show that cancellations produce clear signatures of heating in the
  upper atmospheric layers. However, at the resolution and sensitivity
  accessible to the SST, their number density still seems to be one
  order of magnitude too low to explain the global chromospheric heating.

Title: Investigating the Response of Loop Plasma to Nanoflare Heating
    Using RADYN Simulations
Authors: Polito, V.; Testa, P.; Allred, J.; De Pontieu, B.; Carlsson,
   M.; Pereira, T. M. D.; Gošić, Milan; Reale, Fabio
Bibcode: 2018ApJ...856..178P
Altcode: 2018arXiv180405970P
  We present the results of 1D hydrodynamic simulations of coronal
  loops that are subject to nanoflares, caused by either in situ
  thermal heating or nonthermal electron (NTE) beams. The synthesized
  intensity and Doppler shifts can be directly compared with Interface
  Region Imaging Spectrograph (IRIS) and Atmospheric Imaging Assembly
  (AIA) observations of rapid variability in the transition region (TR)
  of coronal loops, associated with transient coronal heating. We find
  that NTEs with high enough low-energy cutoff ({E}<SUB>{{C</SUB>}})
  deposit energy in the lower TR and chromosphere, causing blueshifts
  (up to ∼20 km s<SUP>-1</SUP>) in the IRIS Si IV lines, which
  thermal conduction cannot reproduce. The {E}<SUB>{{C</SUB>}} threshold
  value for the blueshifts depends on the total energy of the events
  (≈5 keV for 10<SUP>24</SUP> erg, up to 15 keV for 10<SUP>25</SUP>
  erg). The observed footpoint emission intensity and flows, combined
  with the simulations, can provide constraints on both the energy of the
  heating event and {E}<SUB>{{C</SUB>}}. The response of the loop plasma
  to nanoflares depends crucially on the electron density: significant
  Si IV intensity enhancements and flows are observed only for initially
  low-density loops (&lt;10<SUP>9</SUP> cm<SUP>-3</SUP>). This provides
  a possible explanation of the relative scarcity of observations of
  significant moss variability. While the TR response to single heating
  episodes can be clearly observed, the predicted coronal emission (AIA
  94 Å) for single strands is below current detectability and can only
  be observed when several strands are heated closely in time. Finally,
  we show that the analysis of the IRIS Mg II chromospheric lines can
  help further constrain the properties of the heating mechanisms.

Title: Persistent magnetic vortex flow at a supergranular vertex
Authors: Requerey, Iker S.; Cobo, Basilio Ruiz; Gošić, Milan;
   Bellot Rubio, Luis R.
Bibcode: 2018A&A...610A..84R
Altcode: 2017arXiv171201510R
  Context. Photospheric vortex flows are thought to play a key role
  in the evolution of magnetic fields. Recent studies show that these
  swirling motions are ubiquitous in the solar surface convection and
  occur in a wide range of temporal and spatial scales. Their interplay
  with magnetic fields is poorly characterized, however. <BR /> Aims:
  We study the relation between a persistent photospheric vortex flow
  and the evolution of a network magnetic element at a supergranular
  vertex. <BR /> Methods: We used long-duration sequences of continuum
  intensity images acquired with Hinode and the local correlation-tracking
  method to derive the horizontal photospheric flows. Supergranular
  cells are detected as large-scale divergence structures in the flow
  maps. At their vertices, and cospatial with network magnetic elements,
  the velocity flows converge on a central point. <BR /> Results: One
  of these converging flows is observed as a vortex during the whole
  24 h time series. It consists of three consecutive vortices that
  appear nearly at the same location. At their core, a network magnetic
  element is also detected. Its evolution is strongly correlated to
  that of the vortices. The magnetic feature is concentrated and
  evacuated when it is caught by the vortices and is weakened and
  fragmented after the whirls disappear. <BR /> Conclusions: This
  evolutionary behavior supports the picture presented previously,
  where a small flux tube becomes stable when it is surrounded by
  a vortex flow. <P />A movie attached to Fig. 2 is available at <A
  href="https://www.aanda.org/10.1051/0004-6361/201731842/olm">https://www.aanda.org</A>

Title: Occurrence and persistence of magnetic elements in the
    quiet Sun
Authors: Giannattasio, F.; Berrilli, F.; Consolini, G.; Del Moro,
   D.; Gošić, M.; Bellot Rubio, L.
Bibcode: 2018A&A...611A..56G
Altcode: 2018arXiv180103871G
  Context. Turbulent convection efficiently transports energy up to the
  solar photosphere, but its multi-scale nature and dynamic properties
  are still not fully understood. Several works in the literature have
  investigated the emergence of patterns of convective and magnetic
  nature in the quiet Sun at spatial and temporal scales from granular
  to global. <BR /> Aims: To shed light on the scales of organisation
  at which turbulent convection operates, and its relationship with
  the magnetic flux therein, we studied characteristic spatial and
  temporal scales of magnetic features in the quiet Sun. <BR /> Methods:
  Thanks to an unprecedented data set entirely enclosing a supergranule,
  occurrence and persistence analysis of magnetogram time series were
  used to detect spatial and long-lived temporal correlations in the
  quiet Sun and to investigate their nature. <BR /> Results: A relation
  between occurrence and persistence representative for the quiet Sun was
  found. In particular, highly recurrent and persistent patterns were
  detected especially in the boundary of the supergranular cell. These
  are due to moving magnetic elements undergoing motion that behaves
  like a random walk together with longer decorrelations ( 2 h) with
  respect to regions inside the supergranule. In the vertices of the
  supegranular cell the maximum observed occurrence is not associated
  with the maximum persistence, suggesting that there are different
  dynamic regimes affecting the magnetic elements.

Title: Transport of Internetwork Magnetic Flux Elements in the
    Solar Photosphere
Authors: Agrawal, Piyush; Rast, Mark P.; Gošić, Milan; Bellot Rubio,
   Luis R.; Rempel, Matthias
Bibcode: 2018ApJ...854..118A
Altcode: 2017arXiv171101290A
  The motions of small-scale magnetic flux elements in the solar
  photosphere can provide some measure of the Lagrangian properties of
  the convective flow. Measurements of these motions have been critical
  in estimating the turbulent diffusion coefficient in flux-transport
  dynamo models and in determining the Alfvén wave excitation spectrum
  for coronal heating models. We examine the motions of internetwork
  flux elements in Hinode/Narrowband Filter Imager magnetograms and
  study the scaling of their mean squared displacement and the shape of
  their displacement probability distribution as a function of time. We
  find that the mean squared displacement scales super-diffusively with
  a slope of about 1.48. Super-diffusive scaling has been observed in
  other studies for temporal increments as small as 5 s, increments
  over which ballistic scaling would be expected. Using high-cadence
  MURaM simulations, we show that the observed super-diffusive scaling
  at short increments is a consequence of random changes in barycenter
  positions due to flux evolution. We also find that for long temporal
  increments, beyond granular lifetimes, the observed displacement
  distribution deviates from that expected for a diffusive process,
  evolving from Rayleigh to Gaussian. This change in distribution can be
  modeled analytically by accounting for supergranular advection along
  with granular motions. These results complicate the interpretation
  of magnetic element motions as strictly advective or diffusive on
  short and long timescales and suggest that measurements of magnetic
  element motions must be used with caution in turbulent diffusion or
  wave excitation models. We propose that passive tracer motions in
  measured photospheric flows may yield more robust transport statistics.

Title: Chromospheric Heating Driven by Cancellations of Internetwork
    Magnetic Flux
Authors: Gosic, M.; de la Cruz Rodriguez, J.; De Pontieu, B.; Bellot
   Rubio, L.; Esteban Pozuelo, S.; Ortiz-Carbonell, A. N.
Bibcode: 2017AGUFMSH41C..02G
Altcode:
  The heating of the solar chromosphere remains to be one of the
  most important questions in solar physics. It is believed that this
  phenomenon may significantly be supported by small-scale internetwork
  (IN) magnetic fields. Indeed, cancellations of IN magnetic flux can
  generate transient brightenings in the chromosphere and transition
  region. These bright structures might be the signature of energy release
  and plasma heating, probably driven by magnetic reconnection of IN field
  lines. Using high resolution, multiwavelength, coordinated observations
  recorded with the Interface Region Imaging Spectrograph (IRIS) and
  the Swedish 1-m Solar Telescope (SST), we analyzed cancellations of IN
  flux and their impact on the energetics and dynamics of the quiet Sun
  atmosphere. From their temporal and spatial evolution, we determine that
  these events can heat locally the upper atmospheric layers. However,
  employing multi-line inversions of the Mg II h &amp; k lines, we show
  that cancellations, although occurring ubiquitously over IN regions,
  are not capable of sustaining the total radiative losses of the quiet
  Sun chromosphere.

Title: Chromospheric heating due to internetwork magnetic flux
    cancellations
Authors: Gosic, Milan; de la Cruz Rodriguez, Jaime; De Pontieu, Bart;
   Bellot Rubio, Luis; Ortiz, Ada; Esteban Pozuelo, Sara
Bibcode: 2017SPD....4810404G
Altcode:
  The heating of the solar chromosphere is one of the most intriguing
  unanswered problems in solar physics. It is believed that this
  phenomenon may significantly be supported by small-scale internetwork
  (IN) magnetic fields. Indeed, cancellations of IN magnetic flux
  patches might be an efficient way to transport flux and energy from
  the photosphere to the chromosphere. Because of this, it is essential
  to determine where they occur, the rates at which they proceed, and
  understand their influence on the chromosphere. Here we study the
  spatial and temporal evolution of IN cancelling patches using high
  resolution, multiwavelength, coordinated observations obtained with
  the Interface Region Imaging Spectrograph (IRIS) and the Swedish
  1-m Solar Telescope (SST). Employing multi-line inversions of the
  Mg II h&amp;k lines we show that cancelling events, while occurring
  ubiquitously over IN regions, produce clear signatures of heating in
  the upper atmospheric layers. Using the RADYN code we determine the
  energy released due to cancellations of IN elements and discuss about
  their impact on the dynamics and energetics of the solar chromosphere.

Title: Flux appearance and disappearance rates in the solar
    internetwork
Authors: Gosic, Milan; Bellot Rubio, Luis; Del Toro Iniesta, Jose
   Carlos; Orozco Suarez, David; Katsukawa, Yukio
Bibcode: 2016SPD....4740105G
Altcode:
  The solar internetwork contains weak and highly dynamic magnetic
  fields that are essential to understanding the solar magnetism at small
  spatial and temporal scales. Therefore, it is important to determine
  how these fields are maintained on the solar surface. Using unique
  Hinode observations, we follow the evolution of individual magnetic
  elements in the interior of two supergranular cells at the disk
  center. From up to 38 hr of continuous measurements, we show that
  magnetic flux appears in internetwork regions at a rate of 120±3
  Mx cm<SUP>-2</SUP> day<SUP>-1</SUP> (3.7±0.4 × 10<SUP>24</SUP> Mx
  day<SUP>-1</SUP> over the entire solar surface). Flux disappears from
  the internetwork at a rate of 125±6 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>
  (3.9±0.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>) through fading of
  magnetic elements, cancellation between opposite-polarity features,
  and interactions with network patches, which converts internetwork
  elements into network features. The removal of flux from supergranules
  occurs mainly through fading and interactions with network, at nearly
  the same rate of about 50 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>. Our
  results demonstrate that the sources and sinks of internetwork magnetic
  flux are well balanced, reflecting the steady-state nature of the quiet
  Sun. Using the instantaneous flux appearance and disappearance rates,
  we successfully reproduce, for the first time, the temporal evolution
  of the total unsigned flux in the interior of supergranular cells.

Title: The Solar Internetwork. II. Flux Appearance and Disappearance
    Rates
Authors: Gošić, M.; Bellot Rubio, L. R.; del Toro Iniesta, J. C.;
   Orozco Suárez, D.; Katsukawa, Y.
Bibcode: 2016ApJ...820...35G
Altcode: 2016arXiv160205892G
  Small-scale internetwork magnetic fields are important ingredients of
  the quiet Sun. In this paper we analyze how they appear and disappear
  on the solar surface. Using high resolution Hinode magnetograms,
  we follow the evolution of individual magnetic elements in the
  interior of two supergranular cells at the disk center. From up to
  38 hr of continuous measurements, we show that magnetic flux appears
  in internetwork regions at a rate of 120 ± 3 Mx cm<SUP>-2</SUP>
  day<SUP>-1</SUP> (3.7 ± 0.4 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>
  over the entire solar surface). Flux disappears from the internetwork
  at a rate of 125 ± 6 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP> (3.9
  ± 0.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>) through fading of
  magnetic elements, cancelation between opposite-polarity features,
  and interactions with network patches, which converts internetwork
  elements into network features. Most of the flux is lost through
  fading and interactions with the network, at nearly the same rate of
  about 50 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>. Our results demonstrate
  that the sources and sinks of internetwork magnetic flux are well
  balanced. Using the instantaneous flux appearance and disappearance
  rates, we successfully reproduce the time evolution of the total
  unsigned flux in the two supergranular cells.

Title: Super-diffusion versus competitive advection: a simulation
Authors: Del Moro, D.; Giannattasio, F.; Berrilli, F.; Consolini,
   G.; Lepreti, F.; Gošić, M.
Bibcode: 2015A&A...576A..47D
Altcode: 2015arXiv150105444D
  Context. Magnetic element tracking is often used to study the transport
  and diffusion of the magnetic field on the solar photosphere. From the
  analysis of the displacement spectrum of these tracers, it has recently
  been agreed that a regime of super-diffusivity dominates the solar
  surface. Quite habitually this result is discussed in the framework of
  fully developed turbulence. <BR /> Aims: However, the debate whether
  the super-diffusivity is generated by a turbulent dispersion process,
  by the advection due to the convective pattern, or even by another
  process is still open, as is the question of the amount of diffusivity
  at the scales relevant to the local dynamo process. <BR /> Methods:
  To understand how such peculiar diffusion in the solar atmosphere
  takes place, we compared the results from two different data sets
  (ground-based and space-borne) and developed a simulation of passive
  tracers advection by the deformation of a Voronoi network. <BR />
  Results: The displacement spectra of the magnetic elements obtained by
  the data sets are consistent in retrieving a super-diffusive regime for
  the solar photosphere, but the simulation also shows a super-diffusive
  displacement spectrum: its competitive advection process can reproduce
  the signature of super-diffusion. <BR /> Conclusions: Therefore, it
  is not necessary to hypothesize a totally developed turbulence regime
  to explain the motion of the magnetic elements on the solar surface.

Title: The solar internetwork
Authors: Gosic, Milan
Bibcode: 2015PhDT.......305G
Altcode:
  No abstract at ADS

Title: The Solar Internetwork. I. Contribution to the Network
    Magnetic Flux
Authors: Gošić, M.; Bellot Rubio, L. R.; Orozco Suárez, D.;
   Katsukawa, Y.; del Toro Iniesta, J. C.
Bibcode: 2014ApJ...797...49G
Altcode: 2014arXiv1408.2369G
  The magnetic network (NE) observed on the solar surface harbors a
  sizable fraction of the total quiet Sun flux. However, its origin and
  maintenance are not well known. Here we investigate the contribution
  of internetwork (IN) magnetic fields to the NE flux. IN fields permeate
  the interior of supergranular cells and show large emergence rates. We
  use long-duration sequences of magnetograms acquired by Hinode and
  an automatic feature tracking algorithm to follow the evolution of NE
  and IN flux elements. We find that 14% of the quiet Sun (QS) flux is
  in the form of IN fields with little temporal variations. IN elements
  interact with NE patches and modify the flux budget of the NE either
  by adding flux (through merging processes) or by removing it (through
  cancellation events). Mergings appear to be dominant, so the net flux
  contribution of the IN is positive. The observed rate of flux transfer
  to the NE is 1.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP> over the entire
  solar surface. Thus, the IN supplies as much flux as is present in the
  NE in only 9-13 hr. Taking into account that not all the transferred
  flux is incorporated into the NE, we find that the IN would be able
  to replace the entire NE flux in approximately 18-24 hr. This renders
  the IN the most important contributor to the NE, challenging the view
  that ephemeral regions are the main source of flux in the QS. About 40%
  of the total IN flux eventually ends up in the NE.

Title: Pair separation of magnetic elements in the quiet Sun
Authors: Giannattasio, F.; Berrilli, F.; Biferale, L.; Del Moro, D.;
   Sbragaglia, M.; Bellot Rubio, L.; Gošić, M.; Orozco Suárez, D.
Bibcode: 2014A&A...569A.121G
Altcode: 2014arXiv1409.1010G
  The dynamic properties of the quiet Sun photosphere can be investigated
  by analyzing the pair dispersion of small-scale magnetic fields
  (i.e., magnetic elements). By using 25 h-long Hinode magnetograms
  at high spatial resolution (0.3 arcsec), we tracked 68 490 magnetic
  element pairs within a supergranular cell near the disk center. The
  computed pair separation spectrum, calculated on the whole set of
  particle pairs independently of their initial separation, points
  out what is known as a super-diffusive regime with spectral index
  γ = 1.55 ± 0.05, in agreement with the most recent literature, but
  extended to unprecedented spatial and temporal scales (from granular
  to supergranular). Furthermore, for the first time, we investigated
  here the spectrum of the mean square displacement of pairs of magnetic
  elements, depending on their initial separation r<SUB>0</SUB>. We found
  that there is a typical initial distance above (below) which the pair
  separation is faster (slower) than the average. A possible physical
  interpretation of such a typical spatial scale is also provided.

Title: Flux emergence in the solar internetwork and its contribution
    to the network
Authors: Gosic, Milan; Katsukawa, Yukio; Orozco Suarez, David; Bellot
   Rubio, L. R.
Bibcode: 2014cosp...40E1055G
Altcode:
  Network and internetwork magnetic fields are believed to play a
  crucial role in the energy budget of the solar atmosphere. Therefore,
  it is essential to understand how they are maintained on the
  solar surface. Using high resolution Hinode/NFI magnetograms at
  disk center, we automatically follow quiet Sun magnetic elements
  from their appearance to disappearance. From up to 40 hours of
  continuous measurements, we derive the flux emergence rate in the
  solar internetwork to be around 40 Mx cm(-2) day(-1) . We show
  that internetwork fields appearing in the interior of individual
  supergranular cells contribute flux to the surrounding network at
  a rate of 2×10(19) Mx h(-1) . In only 10-20 hours, internetwork
  elements can transfer as much flux as resides in network features,
  establishing them as the most important source of flux for the network
  and the quiet Sun flux budget.

Title: Diffusion of Solar Magnetic Elements up to Supergranular
    Spatial and Temporal Scales
Authors: Giannattasio, F.; Del Moro, D.; Berrilli, F.; Bellot Rubio,
   L.; Gošić, M.; Orozco Suárez, D.
Bibcode: 2013ApJ...770L..36G
Altcode: 2013arXiv1305.4006G
  The study of spatial and temporal scales on which small magnetic
  structures (magnetic elements) are organized in the quiet Sun
  may be approached by determining how they are transported on the
  solar photosphere by convective motions. The process involved
  is diffusion. Taking advantage of Hinode high spatial resolution
  magnetograms of a quiet-Sun region at the disk center, we tracked
  20,145 magnetic elements. The large field of view (~50 Mm) and the
  long duration of the observations (over 25 hr without interruption at
  a cadence of 90 s) allowed us to investigate the turbulent flows at
  unprecedented large spatial and temporal scales. In the field of view
  an entire supergranule is clearly recognizable. The magnetic element
  displacement spectrum shows a double-regime behavior: superdiffusive
  (γ = 1.34 ± 0.02) up to granular spatial scales (~1500 km) and
  slightly superdiffusive (γ = 1.20 ± 0.05) up to supergranular scales.

Title: Turbulent diffusion on the solar photosphere through 24-hour
    continuous observations of magnetic elements
Authors: Giannattasio, F.; Berrilli, F.; Del Moro, D.; Bellot Rubio,
   L.; Orozco Suarez, D.; Gosic, M.
Bibcode: 2012AGUFMSH13A2242G
Altcode:
  Solar atmosphere is a unique laboratory for the study of turbulent
  flows under extreme conditions (e.g. very high Reynolds numbers). The
  turbulent nature of the flow may be approached by determining how
  magnetic flux elements are transported on the solar surface, and
  measuring the spatio-temporal scales on which these small magnetic
  structures are organized. The process involved is diffusion. Several
  works explored this topic, both by simulations and observations,
  and the results are often contradictory, ranging from fully-developed
  turbulent scenarios to normal-diffusive motions. We analyze 24-hour
  continuous Hinode SOT observations of a supergranular region (for the
  first time these long scales are explored), studying the evolution of
  the mutual distance between magnetic element pairs and its scaling laws,
  in order to investigate the diffusion process. We find a super-diffusive
  behavior, with a gamma index depending on the spatial scale selected.

Title: Evolution of internetwork magnetic fields inside supergranular
    cells
Authors: Gosic, Milan; Katsukawa, Yukio; Bellot Rubio, Luis; Orozco
   Suarez, David
Bibcode: 2012cosp...39..657G
Altcode: 2012cosp.meet..657G
  To understand the formation of small-scale magnetic fields in the quiet
  Sun and their contribution to the solar activity, it is essential to
  investigate the properties of internetwork magnetic fields. Using
  Hinode/NFI magnetograms of very high sensitivity (7 Mx/cm^{2}),
  spatial resolution (0.16 arcsec/pixel), and cadence (90 s), we
  follow the evolution of magnetic fields inside of a supergranular
  cell located at disk center. In 5 hours of continuous measurements
  covering an area of 20.8 × 23.2 arcsec^{2}, we manually track 2415
  magnetic elements from appearance to disappearance and derive their
  physical properties. The average values of the magnetic flux, effective
  diameter, lifetime, and horizontal velocity are 3 × 10^{17} Mx, 0.5 Mm,
  17 min, and 2 km/s, respectively. We also investigate how the physical
  parameters of the individual elements vary as a function of time,
  flux, and spatial position. Using this unique data set, we determine
  with unprecedented accuracy the flux emergence and disappearance rate
  in the solar internetwork.

Title: On the solar abundance of indium
Authors: Vitas, N.; Vince, I.; Lugaro, M.; Andriyenko, O.; Gošić,
   M.; Rutten, R. J.
Bibcode: 2008MNRAS.384..370V
Altcode: 2008MNRAS.tmp...25V; 2007arXiv0711.2166V
  The generally adopted value for the solar abundance of indium is over
  six times higher than the meteoritic value. We address this discrepancy
  through numerical synthesis of the 451.13-nm line on which all indium
  abundance studies are based, both for the quiet Sun and the sunspot
  umbra spectrum, employing standard atmosphere models and accounting
  for hyperfine structure and Zeeman splitting in detail. The results,
  as well as a re-appraisal of indium nucleosynthesis, suggest that
  the solar indium abundance is close to the meteoritic value, and
  that some unidentified ion line causes the 451.13-nm feature in the
  quiet-Sun spectrum.

Title: Program of Telluric Lines Monitoring
Authors: Vince, I.; Kos, P.; Latkovic, O.; Martinovic, N.; Gosic,
   M.; Stojadinovic, J.
Bibcode: 2006SerAJ.173..101V
Altcode:
  A new observational program of telluric lines monitoring was introduced
  at Belgrade Astronomical Observatory. The ultimate goal of this program
  is to investigate the properties of Earth's atmosphere through modeling
  the observed profiles of telluric lines. The program is intend to
  observe infrared molecular oxygen lines that were selected according to
  spectral sensitivity of the available CCD camera. In this paper we give
  the initial and the final selection criteria for spectral lines included
  in the program, the description of equipment and procedures used for
  observations and reduction, a review of preliminary observational
  results with the estimated precision, and a short discussion on the
  comparison of the theoretical predictions and the measurements.

