Author name code: schwenn
ADS astronomy entries on 2022-09-14
author:"Schwenn, Rainer" 
------------------------------------------------------------------------  

Title: Multi-spacecraft observed magnetic clouds as seen by Helios
    mission
Authors: de Lucas, A.; Dal Lago, A.; Schwenn, R.; Clúa de Gonzalez,
   A. L.
Bibcode: 2011JASTP..73.1361D
Altcode:
  A large number of magnetic clouds (MCs) were observed during the
  operation period of the Helios mission. Some of the MCs were observed
  by multi-spacecraft, enabling a detailed study of their extension
  in the inner heliosphere when they pass by more than one observation
  location. In the present work, we analyzed 62 MCs, including 16 which
  were observed by multiple spacecraft and 46 observed by a single
  one. For those MCs observed by a single spacecraft, the cloud's axis,
  obtained using minimum variance analysis (MVA) on magnetic field data,
  could be an explanation for the fact that there were no observations
  at the other spacecraft. Highly inclined MCs, defined as MCs whose
  axes are inclined more than 45<SUP>∘</SUP> from the ecliptic plane,
  are less likely to be observed by two spacecraft that are close to
  the ecliptic plane.

Title: Interplanetary shock wave extent in the inner heliosphere as
    observed by multiple spacecraft
Authors: de Lucas, A.; Schwenn, R.; dal Lago, A.; Marsch, E.; Clúa
   de Gonzalez, A. L.
Bibcode: 2011JASTP..73.1281D
Altcode:
  For over an entire solar cycle, from the end of 1974 until the
  beginning of 1986, the twin Helios spacecraft explored the inner
  heliosphere. These in situ, high-resolution plasma and magnetic
  field measurements covered heliocentric distances between 0.3 and 1
  AU from the Sun and are of particular interest to studies of space
  weather phenomena. During this period the two spacecraft detected
  395 ICME-driven shocks and these waves were found to be driven
  by interplanetary coronal mass ejections (ICMEs). Based on these
  multi-spacecraft measurements, which include a third vantage point
  with the observations from ISEE-3/IMP-8, the longitudinal extent of the
  shock waves were measured in the inner heliosphere. It was found that
  shock waves have about a 50% chance to be observed by two different
  locations separated by 90°. In practice, one can expect with about a
  50% chance that the shock driven by a limb coronal mass ejections (CMEs)
  will hit the Earth, considering the expansion in longitude of shock
  waves driven by their associated ICMEs. For a larger separation the
  uncertainty increases, as only a few cases could be observed. With the
  absence of simultaneous solar disk observations one can then no longer
  unequivocally identify the shock waves observed at each spacecraft.

Title: Identification of prominence ejecta by the proton distribution
    function and magnetic fine structure in interplanetary coronal mass
    ejections in the inner heliosphere
Authors: Yao, Shuo; Marsch, Eckart; Tu, Chuan-Yi; Schwenn, Rainer
Bibcode: 2010JGRA..115.5103Y
Altcode: 2010JGRA..11505103Y
  This work presents in situ solar wind observations of three magnetic
  clouds (MCs) that contain cold high-density material when Helios 2
  was located at 0.3 AU on 9 May 1979, 0.5 AU on 30 March 1976, and 0.7
  AU on 24 December 1978. In the cold high-density regions embedded
  in the interplanetary coronal mass ejections we find (1) that the
  number density of protons is higher than in other regions inside the
  magnetic cloud, (2) the possible existence of He<SUP>+</SUP>, (3)
  that the thermal velocity distribution functions are more isotropic
  and appear to be colder than in the other regions of the MC, and the
  proton temperature is lower than that of the ambient plasma, and (4)
  that the associated magnetic field configuration can for all three MC
  events be identified as a flux rope. This cold high-density region is
  located at the polarity inversion line in the center of the bipolar
  structure of the MC magnetic field (consistent with previous solar
  observation work that found that a prominence lies over the neutral
  line of the related bipolar solar magnetic field). Specifically, for
  the first magnetic cloud event on 8 May 1979, a coronal mass ejection
  (CME) was related to an eruptive prominence previously reported as a
  result of the observation of Solwind (P78-1). Therefore, we identify
  the cold and dense region in the MC as the prominence material. It
  is the first time that prominence ejecta were identified by both the
  plasma and magnetic field features inside 1 AU, and it is also the first
  time that the thermal ion velocity distribution functions were used to
  investigate the microstate of the prominence material. Moreover, from
  our three cases, we also found that this material tended to fall behind
  the magnetic cloud and become smaller as it propagated farther away
  from the Sun, which confirms speculations in previous work. Overall,
  our in situ observations are consistent with three-part CME models.

Title: Identification of prominence ejecta by the proton distribution
    function and magnetic fine structure in ICMEs in the inner heliosphere
Authors: Marsch, Eckart; Yao, Shuo; Tu, Chuanyi; Schwenn, Rainer
Bibcode: 2010cosp...38.1876M
Altcode: 2010cosp.meet.1876M
  This work presents in-situ solar wind observations of three magnetic
  clouds that contain certain cold high-density material, when Helios
  2 was located at 0.3 AU, on 9 May 1979, 0.5 AU on 30 March 1976, and
  0.7 AU on 24 December 1978, respectively. In the cold high-density
  regions embedded in the ICMEs we find that (1) the number density of
  protons is higher than in other regions inside the magnetic cloud (MC),
  (2)the possible existence of He+, (3) the thermal velocity distribution
  functions (VDFs) are more isotropic and appear to be colder than in the
  other regions of the MC, and the proton temperature is lower than that
  of the ambient plasma, (4) the associated magnetic field configuration
  can for all three MC events be identified as a flux rope. This cold
  high-density region is located at the polarity inversion line in the
  center of the bipolar structure of the MC magnetic field (consistent
  with previous work of solar observation that a prominence lies over
  the neutral line of the related bipolar solar magnetic field ). It is
  the first time that prominence ejecta are identified by both the plasma
  and magnetic field features inside 1 AU, and that thermal ion velocity
  distribution functions are used to investigate the microstate of the
  prominence material. Overall, our in situ observations are consistent
  with the three-part CME models.

Title: Multi-spacecraft observation of a magnetic cloud
Authors: de Lucas, Aline; Dal Lago, Alisson; Schwenn, Rainer; Clúa de
   Gonzalez, Alicia L.; Marsch, Eckart; Lamy, Philippe; Damé, Luc; Curdt,
   W.; Davila, J.; Defise, J. M.; Fineschi, S.; Heinzel, P.; Howard, R.;
   Kuzin, S.; Schmutz, W.; Tsinganos, K.; Turck-Chièze, S.; Zhukov, A.
Bibcode: 2010cosp...38.1921D
Altcode: 2010cosp.meet.1921D
  Classical externally-occulted coronagraphs are presently limited in
  their performances by the distance between the external occulter and
  the front objective. The diffraction fringe from the occulter and
  the vignetted pupil which degrades the spatial resolution prevent
  useful observa-tions of the white light corona inside typically 2-2.5
  Rsun. Formation flying offers an elegant solution to these limitations
  and allows conceiving giant, externally-occulted coronagraphs
  us-ing a two-component space system with the external occulter on
  one spacecraft and the optical instrument on the other spacecraft
  at distances of hundred meters. Such an instrument has just been
  selected by ESA to fly (by the end of 2013) on its PROBA-3 mission,
  presently in phase B, to demonstrate formation flying. It will perform
  both high spatial resolution imaging of the solar corona as well as
  2-dimensional spectroscopy of several emission lines (in partic-ular
  the forbidden line of FeXIV at 530.285 nm) from the coronal base out
  to 3 Rsun using a Fabry-Perot interferometer. The classical design of
  an externally-occulted coronagraph is adapted to the formation flying
  configuration allowing the detection of the very inner corona as close
  as 0.05 Rsun from the solar limb. By tuning the position of the occulter
  spacecraft, it may even be possible to try reaching the chromosphere
  and the upper part of the spicules. ASPIICS/PROBA-3 mission, payload
  and scientific objectives are presented.

Title: Multi-spacecraft observation of a magnetic cloud
Authors: de Lucas, A.; Dal Lago, A.; Schwenn, R.; Clua de Gonzalez,
   A. L.; Marsch, E.; Gonzalez, W. D.
Bibcode: 2009AGUFMSH13B1515D
Altcode:
  During the time operation of the Helios mission, from 1974 to 1986,
  a large number of magnetic clouds was identified by the magnetic
  field and solar wind sensors onboard the probes. Among these magnetic
  clouds, some of them were identified by at least two probes, provided
  that IMP-8 and ISEE-3 were monitoring the dayside magnetosphere. The
  magnetic cloud observed on from DOY 029 to DOY 030/1977 by Helios 1,
  Helios 2, and IMP-8 represents a potential multi-spacecraft observed
  magnetic cloud. Despite the interaction with the high-speed stream
  that compressed the magnetic cloud, the minimum variance analysis
  technique showed the same direction of rotation of the magnetic field
  inside the magnetic cloud. This helped to associate the observation
  of the magnetic cloud at multi-spacecraft.

Title: Multi-spacecraft observations to study the shock extension
    in the inner heliosphere
Authors: de Lucas, Aline; Schwenn, Rainer; Marsch, Eckart; Lago,
   Alisson Dal; de Gonzalez, Alicia L. Clúa; Echer, Ezequiel; Gonzalez,
   Walter D.; da Silva, Marlos R.
Bibcode: 2009IAUS..257..481D
Altcode:
  The two Helios probes traveled at variable longitudinal and radial
  separations through the inner heliosphere. They collected most valuable
  high resolution plasma and magnetic field data for an entire solar
  cycle. The mission is still so successful that no other missions
  will collect the same kind of data in the next 20 years. One of the
  subjects studied after the success of the Helios mission was the
  identification of more than 390 shock waves driven by Interplanetary
  Coronal Mass Ejections (ICMEs). Combining the data from both probes,
  we make a statistical study for the extension of the shock waves in
  the interplanetary medium. For longitudinal separations of 90° we
  found a cutoff value at this angular separation. A shock has 50%
  of chance to be observed by both probes and the same probability
  for not being observed by two spacecrafts at the same time, when the
  angle between them is around 90°. We describe the dependence of the
  probability for shocks to be observed by both probes with decreasing
  spacecraft separation. Including plasma data from the ISEE-3 and IMP-8
  spacecrafts improves our statistical evaluation substantially.

Title: Exploring the global shock scenario at multiple points
between sun and earth: The solar transients launched on January 1
    and September 23, 1978
Authors: Berdichevsky, D. B.; Reames, D. V.; Wu, C. -C.; Schwenn, R.;
   Lepping, R. P.; MacDowall, R. J.; Farrugia, C. J.; Bougeret, J. -L.;
   Ng, C.; Lazarus, A. J.
Bibcode: 2009AdSpR..43..113B
Altcode:
  We revisit the transient interplanetary events of January 1 and
  September 23, 1978. Using in-situ and remote sensing observations at
  locations widely separated in longitudes and distances from the Sun,
  we infer that in both cases the overall shock surface had a very fast
  “nose” region with speeds &gt;900 and &gt;1500 km<SUP>-1</SUP>
  in the January and September events, respectively, and much slower
  flank speeds (∼600 km<SUP>-1</SUP> or less), suggesting a shock
  surface with a strong speed gradient with heliospheric longitude. The
  shock-nose regions are thus likely efficient acceleration sites of MeV
  ions, even at 1 AU from the Sun. Our 3D magnetohydrodynamics modeling
  suggests that a 24° × 24° localized disturbance at 18 solar radii
  injecting momentum 100 times the background solar wind input over 1
  h can produce a disturbance in semi-quantitative agreement with the
  observed shock arrival time, plasma density and velocity time series
  in the January 1978 event.

Title: Theoretical modeling for the stereo mission
Authors: Aschwanden, Markus J.; Burlaga, L. F.; Kaiser, M. L.; Ng,
   C. K.; Reames, D. V.; Reiner, M. J.; Gombosi, T. I.; Lugaz, N.;
   Manchester, W.; Roussev, I. I.; Zurbuchen, T. H.; Farrugia, C. J.;
   Galvin, A. B.; Lee, M. A.; Linker, J. A.; Mikić, Z.; Riley, P.;
   Alexander, D.; Sandman, A. W.; Cook, J. W.; Howard, R. A.; Odstrčil,
   D.; Pizzo, V. J.; Kóta, J.; Liewer, P. C.; Luhmann, J. G.; Inhester,
   B.; Schwenn, R. W.; Solanki, S. K.; Vasyliunas, V. M.; Wiegelmann, T.;
   Blush, L.; Bochsler, P.; Cairns, I. H.; Robinson, P. A.; Bothmer,
   V.; Kecskemety, K.; Llebaria, A.; Maksimovic, M.; Scholer, M.;
   Wimmer-Schweingruber, R. F.
Bibcode: 2008SSRv..136..565A
Altcode: 2006SSRv..tmp...75A
  We summarize the theory and modeling efforts for the STEREO mission,
  which will be used to interpret the data of both the remote-sensing
  (SECCHI, SWAVES) and in-situ instruments (IMPACT, PLASTIC). The
  modeling includes the coronal plasma, in both open and closed magnetic
  structures, and the solar wind and its expansion outwards from the Sun,
  which defines the heliosphere. Particular emphasis is given to modeling
  of dynamic phenomena associated with the initiation and propagation
  of coronal mass ejections (CMEs). The modeling of the CME initiation
  includes magnetic shearing, kink instability, filament eruption, and
  magnetic reconnection in the flaring lower corona. The modeling of CME
  propagation entails interplanetary shocks, interplanetary particle
  beams, solar energetic particles (SEPs), geoeffective connections,
  and space weather. This review describes mostly existing models of
  groups that have committed their work to the STEREO mission, but is by
  no means exhaustive or comprehensive regarding alternative theoretical
  approaches.

Title: Analysis of the Fe X and Fe XIV line width in the solar corona
    using LASCO-C1 spectral data
Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.;
   Podlipnik, B.
Bibcode: 2008A&A...480..509M
Altcode: 2009arXiv0903.0496M
  Aims:The purpose of this paper is to analyze the variation in
  the line width with height in the inner corona (region above 1.1
  R<SUB>⊙</SUB>), by using the spectral data from LASCO-C1 aboard
  SOHO. We used data acquired at activity minimum (August-October 1996)
  and during the ascending phase of the solar cycle (March 1998). <BR
  />Methods: Series of images acquired at different wavelengths across
  the Fe X 637.6 nm (red) and Fe XIV 530.3 nm (green) coronal lines
  by LASCO-C1 allowed us to build radiance and width maps of the
  off-limb solar corona. <BR />Results: In 1996, the line width of Fe
  XIV was roughly constant or increased with height up to around 1.3
  R<SUB>⊙</SUB> and then it decreased. The Fe X line width increased
  with height up to the point where the spectra were too noisy to allow
  line width measurements (around 1.3 R<SUB>⊙</SUB>). Fe X showed
  higher effective temperatures as compared with Fe XIV. In 1998 the
  line width of Fe XIV was roughly constant with height above the limb
  (no Fe X data available).

Title: Space weather explorer   The KuaFu mission
Authors: Schwenn, R.; Donovan, E.; Marsch, E.; Wang, J. -S.; Xia,
   L. -D.; Zhang, Y. -W.; KuaFu Working Team
Bibcode: 2008AdSpR..41..190S
Altcode:
  The KuaFu mission is designed to explore the physical processes
  that are responsible for space weather, complementing planned
  in situ and ground-based programs, and also to make an essential
  contribution to the space weather application. KuaFu encompasses
  three spacecraft. KuaFu-A will be located at the L1 libration point
  and have instruments to observe solar extreme ultraviolet (EUV) and
  far ultraviolet (FUV) emissions and white-light coronal mass ejections
  (CMEs), and to measure radio waves, the local plasma and magnetic field,
  and high-energy particles. KuaFu-B1 and KuaFu-B2 will be in elliptical
  polar orbits chosen to facilitate continuous (24 h per day 7 days
  per week) observation of the northern polar aurora oval and the inner
  magnetosphere. The KuaFu mission is designed to observe globally the
  complete chain of disturbances from the solar atmosphere to geospace,
  including solar flares, CMEs, interplanetary clouds, shock waves, and
  their geo-effects, with a particular focus on dramatic space weather
  events such as magnetospheric substorms and magnetic storms. The mission
  start is targeted for the next solar maximum with launch hoped for
  in 2012. The initial mission lifetime will be 3 years. The overall
  mission design, instrument complement, and incorporation of recent
  technologies will advance our understanding of the physical processes
  underlying space weather, solve several key outstanding questions
  including solar CME initiation, Earth magnetic storm and substorm
  mechanisms, and advance our understanding of multi-scale interactions
  in and system-level behavior of our Sun Earth space plasma system.

Title: Mexican Coronagraph "Mextli" Project
Authors: Muñoz Martínez, Guadalupe; Jacinto, Juan Soto; Vargas
   Cardenas, Bernardo; Aguirre Marquez, Hector; Schwenn, Rainer
Bibcode: 2008cosp...37.2137M
Altcode: 2008cosp.meet.2137M
  Space weather forecasts require a variety of data and information in
  order to produce reliable results to predict important events affecting
  the Earth and the surrounding environment. One of the most important
  solar phenomena concerning the interplanetary conditions is coronal
  mass ejections. These events transport important amount of material and
  magnetic field to the interplanetary medium capable of interact with
  the magnetosphere in different ways. The only source of clear evidence
  of the early development of coronal mass ejections are, by now, white
  light images, provided by ground based and space coronagraphs. From
  these images the main kinematical parameters as speed and acceleration,
  as projected on the plane of the sky, are obtained. Basic information
  as the speed of the ejecta in the line of sight and the nature of
  the material carried require spectrographic observations of the
  phenomena. LASCO C1 on board of SOHO space mission provided valuable
  information in this field but propagation speeds greater than 10 km/s
  could not be detected from the images and it is not in operations
  since 1998. The Argentinean ground based coronagraph MICA has a design
  similar to C1 but using a narrow-band filters mechanism instead of the
  Fabry-Perot interferometer of C1. The purpose or Mextli project is to
  have a coronagraph with spectroscopic capabilities aimed to observe
  the inner solar corona between 2.5 and 15 solar radii in the emission
  of Fe XIV line at 530 +-N nm. Its main objective would be the early
  detection of dynamical events and its kinematical characterization. In
  order to achieve the objective pursued, the coronagraph will b e
  provided with a high speed CCD camera and an electronic Fabry Perot
  interferometer. The instrument will be constructed in Mexico in the
  frame of a collaboration project between the UNAM, INAOE and IPN and
  under the technical supervision of the MPS in Germany and the MICA
  team from Argentina.

Title: A Statistical Analysis of Shock Wave Extension in the Inner
    Heliosphere as observed by the two Helios probes
Authors: de Lucas, Aline; Schwenn, Rainer; Marsch, Eckart; Dal Lago,
   Alisson; Clúa de Gonzalez, Alicia L.; Gonzalez Alarcon, Walter
   Demétrio
Bibcode: 2008cosp...37..661D
Altcode: 2008cosp.meet..661D
  The two Helios probes traveled at variable longitudinal and radial
  separations through the inner heliosphere. They collected most valuable
  high resolution plasma data for an entire solar cycle. The mission
  is still so successful that no other missions will collect the same
  kind of data in the next 20 years. One of the subjects studied after
  the success of the Helios mission was the identification of more
  than 390 shock waves driven by Interplanetary Coronal Mass Ejections
  (ICMEs). Combining the data from both probes, we make a statistical
  study for the extension of the shock waves in the interplanetary
  medium. For longitudinal separations of 90° we found a cutoff value
  at this angular separation. A shock has 50

Title: Consequences of the force-free model of magnetic clouds for
    their heliospheric evolution
Authors: Leitner, M.; Farrugia, C. J.; Möstl, C.; Ogilvie, K. W.;
   Galvin, A. B.; Schwenn, R.; Biernat, H. K.
Bibcode: 2007JGRA..112.6113L
Altcode: 2007JGRA..11206113L
  We examine the implications of the widely used, force-free, constant-α
  flux rope model of interplanetary magnetic clouds for the evolution
  of these mesoscale (fraction 1 AU) structures in the heliosphere,
  with special emphasis on the inner (≤1 AU) heliosphere. We employ
  primarily events observed by the Helios 1 and 2 probes between 0.3 and
  1 AU in the ascending and maximum phases of solar cycle 21 and by Wind
  at 1 AU in a similar phase of solar activity cycle. We supplement these
  data by observations from other spacecraft (e.g., Voyagers 1 and 2,
  Pioneers 10 and 11, and others). Our data set consists of 130 events. We
  explore three different approaches. In the first, we work with ensemble
  averages, binning the results into radial segments of width 0.1 AU in
  the range 0.3 ≤ r<SUB>h</SUB> ≤ 1 AU. Doing this, we find that in
  the inner heliosphere the modeled average central axial field strength,
  &lt;B<SUB>0</SUB>&gt;, varies with heliospheric distance r<SUB>h</SUB>
  as &lt;B<SUB>0</SUB>&gt; [nT] = 18.1 · r<SUB>h</SUB><SUP>-1.64</SUP>
  [AU], and the average diameter increases quasi-linearly as &lt;D&gt;
  [AU] = 0.23 r<SUB>h</SUB><SUP>1.14</SUP>. The orientation of the axis
  of the underlying magnetic flux tube in our data set is generally found
  to lie along the east-west direction and in the ecliptic plane at all
  values of r<SUB>h</SUB>, but there is considerable scatter about these
  average directions. In the second, we monitor the evolution of magnetic
  clouds in snapshot fashion, using seven spacecraft alignments. The
  results are in broad agreement with the statistics reported under
  step 1. In the final approach, we obtain the functional dependence
  of B<SUB>0</SUB> and D predicted by an analytic expression for a
  freely expanding Lundquist flux tube. We find D to vary linearly with
  r<SUB>h</SUB>, broadly similar to that obtained under approach 1. The
  maximum field strength scales as r<SUB>h</SUB><SUP>-2</SUP> compared to
  a r<SUB>h</SUB><SUP>-1.3</SUP> dependence obtained from statistics. We
  compare our findings with those of Bothmer and Schwenn (1998), who used
  a different methodology. The results obtained form a good background
  to the forthcoming Solar Terrestrial Relations Observatory (STEREO) and
  Sentinels missions and to multispacecraft studies of magnetic clouds.

Title: Study of a Solar Streamer on March 1998 using LASCO-C1
    Spectral Data
Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.;
   Podlipnik, B.
Bibcode: 2007AIPC..895...75M
Altcode:
  The slow solar wind is supposed to originate from coronal regions
  associated with streamers. It is not clear yet how the closed magnetic
  field structures of streamers are opening up in order to release
  the plasma. An analysis of this subject, particularly of a streamer
  on March 1998, is done using LASCO-C1 spectral data. LASCO-C1 is
  an internally occulted coronagraph on the SOHO spacecraft. It has
  a tunable Fabry-Perot interferometer which allows taking spectral
  scans of selected coronal emission lines. From measured line profiles
  we deduced physical quantities like temperature and flow velocities
  along the line of sight. This way, we obtained information on the flow
  pattern in the low corona.

Title: Solar Dynamics and Its Effects on the Heliosphere and Earth
Authors: Baker, D. N.; Klecker, B.; Schwartz, S. J.; Schwenn, R.;
   von Steiger, R.
Bibcode: 2007sdeh.book.....B
Altcode:
  No abstract at ADS

Title: The dynamics of the minimum solar corona during the period
    August October 1996
Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.;
   Podlipnik, B.
Bibcode: 2007AdSpR..40.1049M
Altcode:
  The paper presents the dynamics of the solar corona at the minimum
  phase of the solar cycle (period August-October 1996), as inferred
  from LASCO-C1 spectral data. LASCO-C1 is an internally occulted
  coronagraph aboard the SOHO spacecraft. It has a tunable Fabry-Pérot
  interferometer which allows taking spectral scans of selected coronal
  emission lines. From measured line profiles we deduced physical
  quantities such as temperature and flow velocities along the line of
  sight. This way, we obtained information on the flow pattern in the
  low corona (1.1-1.6 solar radii).

Title: Solar Wind Sources and Their Variations over the Solar Cycle
Authors: Schwenn, R.
Bibcode: 2007sdeh.book...51S
Altcode:
  No abstract at ADS

Title: LASCO-C1 Spectral Analysis of Flows in the Inner Corona
Authors: Mierla, Marilena; Schwenn, Rainer; Teriaca, Luca; Stenborg,
   Guillermo; Podlipnik, Borut
Bibcode: 2007RoAJ...17..167M
Altcode:
  No abstract at ADS

Title: Coronal Mass Ejections
Authors: Kunow, H.; Crooker, N. U.; Linker, J. A.; Schwenn, R.;
   von Steiger, R.
Bibcode: 2007cme..conf.....K
Altcode:
  No abstract at ADS

Title: Petschek-type magnetic reconnection exhausts in the solar
wind well inside 1 AU: Helios
Authors: Eriksson, S.; Gosling, J. T.; Schwenn, R.
Bibcode: 2006AGUFMSM41A1437E
Altcode:
  Petschek-type reconnection exhausts can be recognized in solar
  wind plasma and magnetic field data as accelerated or decelerated
  plasma flows confined to magnetic field reversal regions. Using that
  characteristic signature, we have identified 28 reconnection exhausts
  in the Helios 1 and 2 data, thus extending observations of exhausts
  associated with local, quasi-stationary reconnection in the solar
  wind inward to heliocentric distances of 0.31 AU. Most of the exhaust
  jets identified in the Helios data had the same general physical
  character as solar wind exhausts observed at greater heliocentric
  distances and latitudes by ACE, Wind, and Ulysses. The magnitude of
  the velocity change from outside to inside an exhaust was generally
  comparable to, but somewhat less than (by a factor of 0.75 on average),
  the inflow Alfven speed. In a few of the Helios events plasma number
  densities within the exhausts were intermediate to densities observed
  immediately outside, indicating that transitions from outside to inside
  the exhausts were not always slow-mode-like on both sides. We have
  identified pairs of closely spaced, but independent, reconnection
  exhausts bounding regions where the heliospheric magnetic field
  folded back toward the Sun. We find that plasma and magnetic field
  conditions in the high-speed wind from coronal holes are not generally
  favorable for sustained magnetic reconnection and for the formation
  and propagation of Petschek-type exhausts. Finally, we have not yet
  identified reconnection events common to both spacecraft, partly
  because of a relative lack of times when high data rate observations
  were available from both spacecraft.

Title: Petschek-type magnetic reconnection exhausts in the solar
wind well inside 1 AU: Helios
Authors: Gosling, J. T.; Eriksson, S.; Schwenn, R.
Bibcode: 2006JGRA..11110102G
Altcode:
  Petschek-type reconnection exhausts can be recognized in solar
  wind plasma and magnetic field data as accelerated or decelerated
  plasma flows confined to magnetic field reversal regions. Using that
  characteristic signature, we have identified 28 reconnection exhausts
  in the Helios 1 and 2 data, thus extending observations of exhausts
  associated with local, quasi-stationary reconnection in the solar wind
  inward to heliocentric distances of 0.31 AU. Most of the exhaust jets
  identified in the Helios data had the same general physical character
  as solar wind exhausts observed at greater heliocentric distances and
  latitudes by ACE, Wind, and Ulysses. The magnitude of the velocity
  changes from outside to inside the exhausts was generally comparable
  to, but somewhat less than (by a factor of 0.75 on average), the
  inflow Alfvén speeds. In a few of the Helios events, plasma number
  densities within the exhausts were intermediate to densities observed
  immediately outside, indicating that transitions from outside to inside
  the exhausts were not always slow-mode-like on both sides. We have
  identified pairs of closely spaced, but independent, reconnection
  exhausts bounding regions where the heliospheric magnetic field
  folded back toward the Sun. We find that plasma and magnetic field
  conditions in the high-speed wind from coronal holes are not generally
  favorable for sustained magnetic reconnection and for the formation
  and propagation of Petschek-type exhausts. Finally, we have not yet
  identified reconnection events common to both spacecraft, partially
  because of a relative lack of times when high data rate observations
  were available from both spacecraft.

Title: Space Weather: The Solar Perspective
Authors: Schwenn, Rainer
Bibcode: 2006LRSP....3....2S
Altcode:
  The term space weather refers to conditions on the Sun and in
  the solar wind, magnetosphere, ionosphere, and thermosphere that
  can influence the performance and reliability of space-borne and
  ground-based technological systems and that can affect human life and
  health. Our modern hi-tech society has become increasingly vulnerable
  to disturbances from outside the Earth system, in particular to
  those initiated by explosive events on the Sun: Flares release
  flashes of radiation that can heat up the terrestrial atmosphere
  such that satellites are slowed down and drop into lower orbits,
  solar energetic particles accelerated to near-relativistic energies
  may endanger astronauts traveling through interplanetary space, and
  coronal mass ejections are gigantic clouds of ionized gas ejected
  into interplanetary space that after a few hours or days may hit the
  Earth and cause geomagnetic storms. In this review, I describe the
  several chains of actions originating in our parent star, the Sun,
  that affect Earth, with particular attention to the solar phenomena
  and the subsequent effects in interplanetary space.

Title: Solar Wind Sources and Their Variations Over the Solar Cycle
Authors: Schwenn, R.
Bibcode: 2006SSRv..124...51S
Altcode: 2007SSRv..tmp...50S
  In this paper I will briefly summarize the present status of our
  knowledge on the four different sorts of solar wind, their sources
  and their short- and long-term variations. First: the fast solar wind
  in high-speed streams that emerges from coronal hole regions. Second:
  the slow solar wind emerging from the non-active Sun near the global
  heliospheric current sheet above helmet streamers and underlying active
  regions. Third: the slow solar wind filling most of the heliosphere
  during high solar activity, emerging above active regions in a highly
  turbulent state, and fourth: the plasma expelled from the Sun during
  coronal mass ejections. The coronal sources of these different flows
  vary dramatically with the solar activity cycle.

Title: Foreword
Authors: Baker, D. N.; Klecker, B.; Schwartz, S. J.; Schwenn, R.;
   von Steiger, R.
Bibcode: 2006SSRv..124D...7B
Altcode:
  The topic of Solar Dynamics and its Effects on the Heliosphere and
  Earth was addressed with a workshop at the International Space Science
  Institute, under the auspices of the International Living with a Star
  program, held in April 2005. It started out with an assessment and
  description of the reasons for solar dynamics and how it couples into
  the heliosphere. The three subsequent sections were each devoted to
  following one chain of events from the Sun all the way to the Earth's
  magnetosphere and ionosphere: The normal solar wind chain, the chain
  associated with coronal mass ejections, and the solar energetic
  particles chain. The final section was devoted to common physical
  processes occuring both at the Sun and in the magnetosphere such as
  reconnection, shock acceleration, dipolarisation of magnetic field,
  and others.

Title: Observation of a bright coronal downflow by SOHO/EIT
Authors: Tripathi, D.; Solanki, S. K.; Schwenn, R.; Bothmer, V.;
   Mierla, M.; Stenborg, G.
Bibcode: 2006A&A...449..369T
Altcode:
  A distinct coronal downflow has been discovered in the course of a
  prominence eruption associated coronal mass ejection (CME) imaged by
  EIT (Extreme ultraviolet Imaging Telescope) and LASCO (Large Angle
  Spectrometric Coronagraph) on board SOHO (Solar and Heliospheric
  Observatory) on 5-Mar.-2000. Evolution of the prominences seen by EIT
  was tracked into the LASCO/C2 and C3 field-of-view where they developed
  as the core of a typical three-part CME. In contrast to the inflow
  structures reported earlier in the literatures, which were dark and
  were interpreted as plasma voids moving down, the downflow reported
  here was bright. The downflow, which was only seen in EIT FOV had an
  onset time that coincided with the deceleration phase of the core
  of the CME. The downflow showed a rapid acceleration followed by a
  strong deceleration. The downflow followed a curved path which may be
  explained by material following the apex of a contracting magnetic loop
  sliding down along other field lines, although other explanations are
  also possible. Irrespective of the detailed geometry, this observation
  provides support for the pinching off of the field lines drawn-out by
  the erupting prominences and the contraction of the arcade formed by
  the reconnection.

Title: CME Disturbance Forecasting
Authors: Siscoe, G.; Schwenn, R.
Bibcode: 2006SSRv..123..453S
Altcode: 2006SSRv..tmp...71S
  CME disturbances at Earth arise from the sheath that arrives in front
  of the ICME and from the ICME itself. The geoeffective environment is
  qualitatively different in the sheath than within the ICME. Consequently
  two types of forecast procedures using solar observations of phenomena
  associated with the release of the CME as input parameters have been
  developed to treat the two types of environment. This chapter surveys
  efforts that have resulted in implementable (at least in principle)
  forecast algorithms for sheath and ICME disturbances and discusses
  uncertainties associated with both.

Title: Foreword
Authors: Kunow, H.; Crooker, N. U.; Linker, J. A.; Schwenn, R.;
   von Steiger, R.
Bibcode: 2006SSRv..123....1K
Altcode: 2006SSRv..tmp...62K
  No abstract at ADS

Title: Coronal Observations of CMEs.  Report of Working Group A
Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.;
   Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.;
   Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.;
   Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J.
Bibcode: 2006SSRv..123..127S
Altcode: 2006SSRv..tmp...58S
  CMEs have been observed for over 30 years with a wide variety of
  instruments. It is now possible to derive detailed and quantitative
  information on CME morphology, velocity, acceleration and mass. Flares
  associated with CMEs are observed in X-rays, and several different
  radio signatures are also seen. Optical and UV spectra of CMEs both on
  the disk and at the limb provide velocities along the line of sight
  and diagnostics for temperature, density and composition. From the
  vast quantity of data we attempt to synthesize the current state of
  knowledge of the properties of CMEs, along with some specific observed
  characteristics that illuminate the physical processes occurring during
  CME eruption. These include the common three-part structures of CMEs,
  which is generally attributed to compressed material at the leading
  edge, a low-density magnetic bubble and dense prominence gas. Signatures
  of shock waves are seen, but the location of these shocks relative
  to the other structures and the occurrence rate at the heights where
  Solar Energetic Particles are produced remains controversial. The
  relationships among CMEs, Moreton waves, EIT waves, and EUV dimming
  are also cloudy. The close connection between CMEs and flares suggests
  that magnetic reconnection plays an important role in CME eruption
  and evolution. We discuss the evidence for reconnection in current
  sheets from white-light, X-ray, radio and UV observations. Finally, we
  summarize the requirements for future instrumentation that might answer
  the outstanding questions and the opportunities that new space-based
  and ground-based observatories will provide in the future.

Title: Coronal Mass Ejections
Authors: Kunow, H.; Crooker, N. U.; Linker, J. A.; Schwenn, R.;
   von Steiger, R.
Bibcode: 2006cme..book.....K
Altcode:
  No abstract at ADS

Title: CME Disturbance Forecasting
Authors: Siscoe, G.; Schwenn, R.
Bibcode: 2006cme..book..453S
Altcode:
  CME disturbances at Earth arise from the sheath that arrives in front
  of the ICME and from the ICME itself. The geoeffective environment is
  qualitatively different in the sheath than within the ICME. Consequently
  two types of forecast procedures using solar observations of phenomena
  associated with the release of the CME as input parameters have been
  developed to treat the two types of environment. This chapter surveys
  efforts that have resulted in implementable (at least in principle)
  forecast algorithms for sheath and ICME disturbances and discusses
  uncertainties associated with both.

Title: Coronal Observations of CMEs
Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.;
   Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.;
   Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.;
   Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J.
Bibcode: 2006cme..book..127S
Altcode:
  CMEs have been observed for over 30 years with a wide variety of
  instruments. It is now possible to derive detailed and quantitative
  information on CME morphology, velocity, acceleration and mass. Flares
  associated with CMEs are observed in X-rays, and several different
  radio signatures are also seen. Optical and UV spectra of CMEs both on
  the disk and at the limb provide velocities along the line of sight
  and diagnostics for temperature, density and composition. From the
  vast quantity of data we attempt to synthesize the current state of
  knowledge of the properties of CMEs, along with some specific observed
  characteristics that illuminate the physical processes occurring during
  CME eruption. These include the common three-part structures of CMEs,
  which is generally attributed to compressed material at the leading
  edge, a low-density magnetic bubble and dense prominence gas. Signatures
  of shock waves are seen, but the location of these shocks relative
  to the other structures and the occurrence rate at the heights where
  Solar Energetic Particles are produced remains controversial. The
  relationships among CMEs, Moreton waves, EIT waves, and EUV dimming
  are also cloudy. The close connection between CMEs and flares suggests
  that magnetic reconnection plays an important role in CME eruption
  and evolution. We discuss the evidence for reconnection in current
  sheets from white-light, X-ray, radio and UV observations. Finally, we
  summarize the requirements for future instrumentation that might answer
  the outstanding questions and the opportunities that new space-based
  and ground-based observatories will provide in the future.

Title: A study of the CME geometry
Authors: Dal Lago, A.; Schwenn, R.; Gonzalez, W. D.
Bibcode: 2006cosp...36.1157D
Altcode: 2006cosp.meet.1157D
  Coronal mass ejections are the main source of space weather disturbances
  thus understanding their evolution is a crussial point for forecasting
  their impacts at earth Near the sun 3 dimentional observations are not
  available thus the 3D geometry of CMEs are still under debate Based on
  2D observational parameters we investigate the possible 3D geometry
  of coronal mass ejections These parameters are the perpendicular
  expansion and the radial expansion Three cone models are annalized
  and their evolution studied If the geometry of CMEs is known and
  if it is possible to have a similar model for all CMEs this can be
  used to correct and interpret the meaning of the plane-of-sky speeds
  measured by coronagraph like SOHO LASCO This knowledge would improve
  the forecasting of CME arrival time at earth models

Title: Radial Speed for Slow CMEs
Authors: Munoz, G.; Schwenn, R.
Bibcode: 2006cosp...36.3369M
Altcode: 2006cosp.meet.3369M
  Coronal Mass Ejections CMEs have been registered since 1996 with The
  Solar and Heliospheric observatory SoHO The diversity and sensitivity
  of the instruments in SoHO have provided huge quantity of data for
  CMEs and related phenomena Dynamical parameters of CMEs are evaluated
  and published in the SoHO LASCO CME Catalogue A broad range of values
  for the plane of the sky speed of CMEs results from these observations
  in particular extremely slow events seem to be possible sim 40 km s
  In this work we analyzed slow CMEs speed 400 km s for events during
  2003 and 2004 using the expansion speed to determine the radial speed
  We evaluated the projection effects on the determination of speed and
  acceleration for these events The possible relation of these CMEs to
  flares and prominences is studied as well in order to present a wide
  panorama for slow CMEs

Title: KuaFu Mission: The scientific payload of KuaFu-B
Authors: Wang, J. -S.; Tu, C. -Y.; Schwenn, R.; Donovan, E.; Xia,
   L. -D.; Zhang, Y. -W.; Kuafu Team
Bibcode: 2006cosp...36.2742W
Altcode: 2006cosp.meet.2742W
  The KuaFu mission would consist an L1 satellite KuaFu-A and a polar
  satellite pair KuaFu B1 B2 The mission is designed to explore the whole
  cause-and-result chain in solar-terrestrial space The two KuaFu-Bs will
  have the same payload sets and fly on the same polar orbit plane but
  with a phase difference of half period The preferred perigee is 1 8
  Re and the apogee is 7 Re This orbit design will support a 24 times 7
  full-covered observation on the northern auroral oval by the onboard
  aurora cameras The suggested payloads consist of a Far Ultraviolet
  Auroral Monitoring Camera UVAMC a FUV Imaging Spectrometer FUVSI a Wide
  Field Auroral Imager WFAI a Fluxgate Magnetometer FGM a High Energy
  Charged Particle Experiment HECPE an Imaging energetic electron and
  proton instrument IEPS a Neutral Atom Imager on KuaFu NAIK a Fast
  Plasma Pitch Angle Instrument FPI an Ion Mass Spectrometer IMS FPI
  and IMS were suggested to merge and a Tri-Band Beacon TBB

Title: KuaFu Mission: The Scientific Payload of KuaFu-A
Authors: Xia, L. -D.; Tu, C. -Y.; Schwenn, R.; Donovan, E.; Wang,
   J. -S.; Zhang, Y. -W.
Bibcode: 2006cosp...36.2677X
Altcode: 2006cosp.meet.2677X
  The KuaFu mission would consist of three satellites KuaFu-A and
  KuaFu B1 and B2 KuaFu-A would be operated in the Sun-Earth L1 region
  while the satellite pair KuaFu-B1 and -B2 fly on identical Earth polar
  orbits The mission is designed to explore solar disturbances and their
  ultimate effects on the near-Earth space including solar flares CMEs
  interplanetary clouds shock waves and their respective geo-effects such
  as magnetospheric substorms magnetic storms and auroral activities The
  launch of KuaFu is suggested in 2012 KuaFu-A would be instrumented to
  continuously observe the solar disk in EUV FUV emission to register
  Coronal Mass Ejections CMEs in white light and Lyman-alpha radiation
  to trace CME propagation by radio wave measurements and to measure
  the local solar wind plasma and magnetic field and solar energetic
  particles Besides measurements of hard X-ray and Gamma-ray spectrum
  and solar irradiance would also be carried out on KuaFu-A In this
  poster we outline the payload of KuaFu-A and its scientific and space
  weather objectives

Title: Why KuaFu? The missing links in understanding Sun-Earth
    connections
Authors: Schwenn, R.
Bibcode: 2006cosp...36.1962S
Altcode: 2006cosp.meet.1962S
  Despite the enormous progress in recent years there is still a lack
  in understanding of several key links in the long chain of actions
  and reactions that connects our Earth to its parent star the Sun They
  concern 1 the origin of disturbances at the Sun flares and CMEs and
  our inability to forecast them 2 the propagation of their effects to
  the Earth 3 their capability of entering the Earth system and 4 the
  magnitude of the terrestrial effects I will review these processes
  and point out where the KuaFu mission is supposed to achieve better
  understanding in context with the Living With a Star program

Title: An introduction to KuaFu project (scientific goals, scientific
    payloads, historical events, present status and perspectives)
Authors: Tu, C. -Y.; Schwenn, R.; Donovan, E.; Wang, J. -S.; Xia,
   L. -D.; Zhang, Y. -W.; Kuafu Study Team
Bibcode: 2006cosp...36..984T
Altcode: 2006cosp.meet..984T
  KuaFu mission is composed of three spacecraft KuaFu-A and KuaFu B1 and
  B2 KuaFu-A will be located at the L1 Lagrangian point The satellite
  pair KuaFu-B1 B2 will fly on the same polar Earth orbit but with
  a phase difference of half-period KuaFu-A will be instrumented to
  continuously observe the solar disk in EUV including Lyman alpha
  emission to register Coronal Mass Ejections CMEs in white light
  and Lyman alpha radiation to trace CME propagation by radio wave
  measurements and to measure the local solar wind plasma and magnetic
  field and solar energetic particles Another remote sensing instrument
  will observe the hard X-ray and Gamma-ray spectrum KuaFu-B1 and -B2
  will carry out continuous 24 hours a day observation of the northern
  hemisphere auroral oval and the ring current as well as systematic
  conjugate aurora observations KuaFu-B will also carry a limited suite
  of in situ instruments including a fluxgate magnetometer and charged
  particle detectors The KuaFu project is now a space science mission
  selected by China National Space Administration CNSA The Comprehensive
  Study project already began in which careful review of scientific
  payload initial design of spacecraft platforms launch tracking and
  control and data transferring will be addressed The KuaFu mission may
  start at the next solar maximum launch in 2012 hopefully and with an
  initial mission lifetime of two to three years The KuaFu mission will
  be an essential element of the ILWS program The scientific goal is to
  study globally the Sun-Earth complex system The mission is

Title: In-situ data from Helios 1 and 2 on the web in preparation
    for STEREO
Authors: Schroeder, P.; Luhmann, J.; Schwenn, R.
Bibcode: 2006cosp...36.2112S
Altcode: 2006cosp.meet.2112S
  Although flown in the 1970 s the Helios mission continues to provide
  a unique science opportunity Not only were the twin Helios spacecraft
  s orbits unusual but the in-situ instruments were capable of probing
  heliospheric structures in a manner similar to the upcoming STEREO
  mission For the first time we make the electron data from the Helios
  Plasma Experiment readily available to the public We integrate this
  electron data with data already available for protons SEPs and the
  magnetic field from the Helios mission as well as in-situ data from the
  IMP-8 and ISEE-3 missions into a single user-customizable browser and
  make these data available for download and local analysis in a variety
  of formats Not only will analysis of the full Helios data set give new
  insights into the analysis of multi-point in-situ data in preparation
  for missions like STEREO but the full Helios data set provides an
  unprecedented opportunity to explore regions of the heliosphere that
  remain largely unexplored

Title: LASCO-C1 Spectral Data Analysis of the Slow Solar Wind
Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Podlipnik, B.;
   Stenborg, G.
Bibcode: 2005ESASP.600E..45M
Altcode: 2005dysu.confE..45M; 2005ESPM...11...45M
  No abstract at ADS

Title: The Relative Distribution of the Magnetic and Plasma Kinetic
    Energy Densities in the Inner Heliosphere (&lt;1 AU)
Authors: Leitner, M.; Farrygia, C. J.; Osherovich, V. A.; Biernat,
   H. K.; Ogilvie, K. W.; Schwenn, R.; Torbert, R.
Bibcode: 2005ESASP.592..743L
Altcode: 2005ESASP.592E.151L; 2005soho...16E.151L
  No abstract at ADS

Title: On the Thickness of the Sheath of Magnetic Clouds in the
Inner Heliosphere: A Helios   Wind Investigation
Authors: Leitner, M.; Farrugia, C. J.; Biernat, H. K.; Torbert, R.;
   Erkaev, N. V.; Ogilvie, K. W.; Schwenn, R.
Bibcode: 2005ESASP.592..739L
Altcode: 2005soho...16E.150L; 2005ESASP.592E.150L
  No abstract at ADS

Title: Evolution of Interplanetary Magnetic Clouds from 0.3 AU to
1 AU: A Joint Helios-Wind Investigation
Authors: Farrugia, C. J.; Leiter, M.; Biernat, H. K.; Schwenn, R.;
   Ogilvie, K. W.; Matsuil, H.; Kucharek, H.; Jordanova, V. K.; Lepping,
   R. P.
Bibcode: 2005ESASP.592..723F
Altcode: 2005ESASP.592E.146F; 2005soho...16E.146F
  No abstract at ADS

Title: The association of coronal mass ejections with their effects
    near the Earth
Authors: Schwenn, R.; dal Lago, A.; Huttunen, E.; Gonzalez, W. D.
Bibcode: 2005AnGeo..23.1033S
Altcode:
  To this day, the prediction of space weather effects near the Earth
  suffers from a fundamental problem: The radial propagation speed of
  "halo" CMEs (i.e. CMEs pointed along the Sun-Earth-line that are known
  to be the main drivers of space weather disturbances) towards the Earth
  cannot be measured directly because of the unfavorable geometry. From
  inspecting many limb CMEs observed by the LASCO coronagraphs on SOHO
  we found that there is usually a good correlation between the radial
  speed and the lateral expansion speed Vexp of CME clouds. This latter
  quantity can also be determined for earthward-pointed halo CMEs. Thus,
  Vexp may serve as a proxy for the otherwise inaccessible radial speed
  of halo CMEs. We studied this connection using data from both ends:
  solar data and interplanetary data obtained near the Earth, for a period
  from January 1997 to 15 April 2001. The data were primarily provided
  by the LASCO coronagraphs, plus additional information from the EIT
  instrument on SOHO. Solar wind data from the plasma instruments on
  the SOHO, ACE and Wind spacecraft were used to identify the arrivals
  of ICME signatures. Here, we use "ICME" as a generic term for all
  CME effects in interplanetary space, thus comprising not only ejecta
  themselves but also shocks as well. Among 181 front side or limb full
  or partial halo CMEs recorded by LASCO, on the one hand, and 187
  ICME events registered near the Earth, on the other hand, we found
  91 cases where CMEs were uniquely associated with ICME signatures in
  front of the Earth. Eighty ICMEs were associated with a shock, and
  for 75 of them both the halo expansion speed Vexp and the travel time
  Ttr of the shock could be determined. The function Ttr=203-20.77*ln
  (Vexp fits the data best. This empirical formula can be used for
  predicting further ICME arrivals, with a 95% error margin of about
  one day. Note, though, that in 15% of comparable cases, a full or
  partial halo CME does not cause any ICME signature at Earth at all;
  every fourth partial halo CME and every sixth limb halo CME does not
  hit the Earth (false alarms). Furthermore, every fifth transient shock
  or ICME or isolated geomagnetic storm is not caused by an identifiable
  partial or full halo CME on the front side (missing alarms).

Title: Properties and geoeffectiveness of magnetic clouds in the
    rising, maximum and early declining phases of solar cycle 23
Authors: Huttunen, K. E. J.; Schwenn, R.; Bothmer, V.; Koskinen,
   H. E. J.
Bibcode: 2005AnGeo..23..625H
Altcode:
  The magnetic structure and geomagnetic response of 73 magnetic clouds
  (MC) observed by the WIND and ACE satellites in solar cycle 23 are
  examined. The results have been compared with the surveys from the
  previous solar cycles. The preselected candidate MC events were
  investigated using the minimum variance analysis to determine if
  they have a flux-rope structure and to obtain the estimation for the
  axial orientation (θC, φC). Depending on the calculated inclination
  relative to the ecliptic we divided MCs into "bipolar" (θC&lt;45°)
  and "unipolar" (θC&gt;45°). The number of observed MCs was largest in
  the early rising phase, although the halo CME rate was still low. It
  is likely that near solar maximum we did not identify all MCs at 1AU,
  as they were crossed far from the axis or they had interacted strongly
  with the ambient solar wind or with other CMEs. The occurrence rate of
  MCs at 1AU is also modified by the migration of the filament sites on
  the Sun towards the poles near solar maximum and by the deflection of
  CMEs towards the equator due to the fast solar wind flow from large
  polar coronal holes near solar minimum. In the rising phase nearly
  all bipolar MCs were associated with the rotation of the magnetic
  field from the south at the leading edge to the north at the trailing
  edge. The results for solar cycles 21-22 showed that the direction
  of the magnetic field in the leading portion of the MC starts to
  reverse at solar maximum. At solar maximum and in the declining
  phase (2000-2003) we observed several MCs with the rotation from
  the north to the south. We observed unipolar (i.e. highly inclined)
  MCs frequently during the whole investigated period. For solar cycles
  21-22 the majority of MCs identified in the rising phase were bipolar
  while in the declining phase most MCs were unipolar. The geomagnetic
  response of a given MC depends greatly on its magnetic structure and the
  orientation of the sheath fields. For each event we distinguished the
  effect of the sheath fields and the MC fields. All unipolar MCs with
  magnetic field southward at the axis were geoeffective (Dst&lt;-50nT)
  while those with the field pointing northward did not cause magnetic
  storms at all. About half of the all identified MCs were not geoffective
  or the sheath fields preceding the MC caused the storm. MCs caused
  more intense magnetic storms (Dst&lt;-100nT) than moderate magnetic
  storms (-50nT ≥Dst≥-100nT). &lt;p style="line-height: 20px;"&gt;
  &lt;/td&gt; &lt;/tr&gt;

Title: What have we learned with SOHO?
Authors: Schwenn, Rainer
Bibcode: 2005IAUS..226...19S
Altcode:
  The Solar and Heliospheric Observatory (SOHO), a space mission of
  international collaboration between ESA and NASA, has been operating
  almost continuosly since early 1996. The Sun and the heliosphere went
  through both: the minimum and maxumum of solar activity in 1996 and
  2000, respectively. The perfectly working set of modern solar telescopes
  and insitu instrumentation has been producing an unprecedented set of
  most valuable observational data that are almost immediately available
  to the public via the Internet. A wealth of new results has been
  published in innumerable papers. For CME research in particular,
  SOHO has started a new era. CME evolution can now be studied from
  their initiation up to the arrival of the ejecta clouds at 1 AU. For
  the first time, helioseismological observations reveal flow vortices
  underneath sunspots, i.e., activity centers that are involved in
  subsequebt eruptions. Combined EUV disk observations and coronagraph
  images allow to differentiate between CMEs pointed towards to or away
  from the Earth. Thus, space weather predictions have achieved a new
  quality. The occurrence of "EIT waves" at CME onset was discovered, the
  internal structure of CMEs (including "disconnection", magnetic topology
  and helicity, etc.) was made visible, statitics about CME properties and
  their change with solar activity were refined. Spectacular CME images
  and animations have been attracting the public to an unexpected extent,
  to the benefit of solar research in general.

Title: SoHO/EIT Observation of a Coronal Inflow
Authors: Tripathi, D.; Bothmer, V.; Solanki, S. K.; Schwenn, R.;
   Mierla, M.; Stenborg, G.
Bibcode: 2005IAUS..226..133T
Altcode:
  A distinct coronal inflow has been discovered after ∼90 min
  of prominence eruption associated coronal mass ejection (CME) on
  05-Mar-2000 by EIT (Extreme ultraviolet Imaging Telescope) aboard SoHO
  (Solar and Heliospheric Observatory). Evolution of the prominence seen
  by EIT was tracked into the LASCO/C2 and C3 field-of-view (FOV; 4-10
  R<SUB>⊙</SUB>) where it developed as the core of a typical three-part
  CME. The speed of the inflow, which was only seen in EIT FOV, was 70-80
  km/s at a height between 1.5-1.2 R<SUB>⊙</SUB> coinciding with the
  deceleration phase of the core of the CME in LASCO/C2. In contrast to
  dark inflow structures observed earlier and interpreted as plasma void
  moving down, the inflow reported here was bright. The inflow showed a
  constant deceleration and followed a curved path suggesting the apex
  of a contracting magnetic loop sliding down along other field lines.

Title: Dynamics of the Solar Corona Using LASCO-C1 Spectral Data
Authors: Mierla, Marilena; Schwenn, Rainer; Teriaca, Luca; Stenborg,
   Guillermo; Podlipnik, Borut
Bibcode: 2005RoAJ...15..137M
Altcode:
  No abstract at ADS

Title: Using LASCO-C1 spectroscopy for coronal diagnostics
Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.;
   Podlipnik, B.
Bibcode: 2005AdSpR..35.2199M
Altcode:
  The LASCO-C1 telescope was designed to perform spectral analysis of
  coronal structures by means of a tunable Fabry-Pérot interferometer
  acquiring images at different wavelengths. Results from spectral
  scans of the Fe XIV 5303 Å green coronal emission line are
  presented. Physical quantities like the ion temperature (line widths),
  and the flow velocity along the line of sight (Doppler shifts) are
  obtained over the entire corona.

Title: Preparing for STEREO - Revisit Helios!
Authors: Schwenn, R.
Bibcode: 2004AGUFMSH21D..02S
Altcode:
  Exactly 30 years ago, the first Helios solar probe was launched into
  an elliptical heliocentric orbit, with a perihelion of 0.3 AU. It had
  a set of then modern particle and field instruments on board, but no
  imagers. One year later, an almost identical probe was put into a very
  similar orbit, approaching the Sun even a bit closer. For most of their
  common lifetime of 4 years, the two probes were separated in longitude
  by no more than about 30 degrees. Further, due to their special
  orbits, they spent many months above the Sun's limb (as seen from
  Earth). In conjunction with the Earth-orbiting IMP 7&amp;8 satellites
  and the Voyager 1&amp;2, and the Pioneer 10&amp;11 space probes, real
  multipoint studies covering large parts of the heliosphere could be
  performed successfully for the first time. The Helios mission resembled
  the upcoming STEREO mission in several respects and was indeed of good
  use for defining the STEREO science goals. For example, Helios could
  reveal details about the longitudinal and latitudinal solar wind stream
  structure, it allowed unique associations between limb CMEs and their
  radial propagation towards an in-situ observer, and the propagation
  of solar energetic particles could be studied. However, since then our
  understanding of the heliosphere has improved considerably, thanks to
  recent space missions (Ulysses, Yohkoh, SOHO, Wind, ACE) and to more
  and more refined theoretical models. In view of these new results,
  it appears worthwhile to revisit the huge Helios data sets since they
  certainly keep hiding some answers that future observations from STEREO
  might benefit from.

Title: The phase curve of cometary dust: Observations of comet
    96P/Machholz 1 at large phase angle with the SOHO LASCO C3 coronagraph
Authors: Grynko, Ye.; Jockers, K.; Schwenn, R.
Bibcode: 2004A&A...427..755G
Altcode:
  We have analyzed brightness and polarization data of comet 96P/Machholz,
  obtained with the SOHO-LASCO C3 coronagraph at phase angles up to
  167<SUP>°</SUP> and 157<SUP>°</SUP>, respectively. The polarization
  data are characteristic of a typical dusty comet. Within error limits
  the corresponding trigonometric fit describes the new data measured at
  larger phase angles as well as those of the previously known range. In
  the phase angle range from 110<SUP>°</SUP> to 167<SUP>°</SUP>
  the brightness increases almost linearly by about two orders of
  magnitude. The gradient is independent of wavelength. From the
  absence of a diffraction spike we conclude that the grains contributing
  significantly to the scattered light must have a size parameter x = 2π
  r/λ ≥20, i.e. have a radius larger than 1 μm. Fits of the data with
  Mie calculations of particles having a power law distribution of power
  index ≈ 2.5 provide a best fit refractive index m = 1.2 + i0.004. In
  the framework of effective medium theory and on the assumption of
  a particle porosity P= 0.5 this leads to a complex refractive index
  of the porous medium m = 1.43 + i0.009. A higher refractive index is
  possible for more porous grains with very low absorption. The large
  particle sizes are in qualitative agreement with findings derived
  from the analysis of the motion of cometary dust under solar radiation
  pressure (Fulle and coworkers, see \cite{fulle}; \cite{jockers} 1997)
  and with the in-situ measurements of the dust of Halley's comet.

Title: Comparison Between Halo cme Expansion Speeds Observed on the
    Sun, the Related Shock Transit Speeds to Earth and Corresponding
    Ejecta Speeds at 1 au
Authors: Dal Lago, A.; Vieira, L. E. A.; Echer, E.; Gonzalez, W. D.;
   de Gonzalez, A. L. C.; Guarnieri, F. L.; Schuch, N. J.; Schwenn, R.
Bibcode: 2004SoPh..222..323D
Altcode:
  We have compared characteristics of 38 halo coronal mass ejections
  observed on the Sun by the Large Angle and Spectrometric Coronagraph
  onboard SOHO with their corresponding counterparts observed near Earth
  by the magnetic field and plasma instruments onboard the ACE, WIND and
  SOHO satellites, in the period from January 1997 to April 2001. We only
  have selected events that have some associated interplanetary ejecta
  structure at 1 AU and we have compared the lateral expansion speeds
  of these halo CMEs and the corresponding ejecta speeds near Earth. We
  found that there is a high correlation between these two speeds. The
  results are very similar to the study done by Lindsay et al. (1999)
  using observations made by Solwind and SMM coronagraphs, and Helios-1
  and PVO plasma and interplanetary field data from the period of 1979
  to 1988. Also, we reviewed the relation between the CME-related shock
  transit speed to Earth and the ejecta speeds near Earth. This kind
  of relation is very important to estimate ejecta speeds of events for
  which no interplanetary observations are available.

Title: CMEs in the heliosphere
Authors: Schwenn, R.
Bibcode: 2004cosp...35.2442S
Altcode: 2004cosp.meet.2442S
  Since their discovery in the Skylab era, almost exactly 30 years
  ago, coronal mass ejections (CMEs) have been a fascinating topic in
  the vast field of solar system research. Several thousands of these
  spectacular bright gas clouds ejected spontaneously from the dynamic
  Sun were portraied from space-borne coronagraphs (OSO-7, Skylab, P78-1,
  SMM). Since 1996, a new generation of instruments on SOHO has kept
  the Sun under almost continuous surveillance. Images and animations
  are being made public in near real-time through the Internet and have
  thus stirred wide-spread interest. Some exceptionally dramatic CMEs in
  the recent past have emphasized the CMEs' key role in forming space
  weather near the Earth and throughout the heliosphere. No wonder
  that they have raised unprecedented attention even in the public
  media. Scientific exploration of CMEs has also made major progress,
  but some fundamental questions are still waiting to be answered.

Title: Plasma dynamics of a prominence associated coronal mass
    ejection
Authors: Tripathi, D.; Bothmer, V.; Solanki, S. K.; Schwenn, R.;
   Mierla, M.; Stenborg, G.
Bibcode: 2004IAUS..223..401T
Altcode: 2005IAUS..223..401T
  An erupting prominence seen by SOHO/EIT was tracked into the field of
  view of the LASCO C2 and C3 coronagraphs where it developed into the
  core of a structured CME. The erupting prominence was deflected by an
  angle of sim 20^{circ} towards the north pole whereas the consequent
  core of the CME and it's leading edge propagated in the outer corona at
  constant position angle. The prominence material underwent a constant
  acceleration phase until a height of sim1.5 solar radii before it
  started to decelerate up to a distance of 5.0 solar radii. An inflow
  of plasma with a speed of about 70-80 km/s was discovered in the EIT
  observations at a height of 1.5-1.2 solar radii in the course of the
  prominence eruption, matching in time the prominence deceleration
  phase. The downflowing material followed a curved path, suggestive
  of the apex of a contracting magnetic loop sliding down along other
  field lines.

Title: Structure of Solar Ejecta
Authors: Muñoz, G.; Cantó, J.; Lara, A.; González, R.; Schwenn, R.
Bibcode: 2004cosp...35.2642M
Altcode: 2004cosp.meet.2642M
  Solar Ejecta (SE) have been of interest in the last years,
  especially those which may reach Earth environment. It is possible
  to observe the SE early evolution, when they are in the field of
  view of coronagraphs. There are few indirect observations, as the
  case of interplanetary scintillation, of SEs in the interplanetary
  medium. Finally, we observe SEs in situ when they arrive at 1 AU.The SEs
  structure and evolution are important to understand the origin of these
  phenomena but to predict the possible effects in the space weather. It
  is of general acceptance that SEs are "Erupting Flux Ropes" traveling
  trough the Solar Wind. The "shapes" have been modeled as cylinders or as
  "ice cream cones" in order to represent the many different projections
  observed on Coronagraphs.We present a model of the SE evolution based
  on purely Hydrodynamic considerations. This model reproduces in good
  approximation some of the features observed in the images and in the
  measures of the shocks near Earth.

Title: Exploring the global shock scenario at multiple points
between Sun and Earth: the launch of solar transients on January 1
    and September 23, 1978.
Authors: Berdichevsky, Db; Reames, Dv; Wu, C. -C.; Schwenn, R.;
   Lepping, Rp; MacDowall, Rj; Farrugia, Cj; Bougeret, J. -L.; Ng, C.;
   Lazarus, Aj
Bibcode: 2004cosp...35.1774B
Altcode: 2004cosp.meet.1774B
  We revisit the transient events of January and September 1978. In
  the January event the ejecta (an interplanetary magnetic cloud, IMC)
  was studied using multiple spacecraft observations [Burlaga et al.,
  1981]. In the September event Reames et al., 1997 studied the spectral
  characteristics of the energetic particles of this big particle
  event with a driven shock passage observed at longitudes nearly 180°
  apart. Here we present a combined analysis of the overall solar wind
  and energetic particles (EP) features of the shock and the driver,
  observed at different locations in longitude. We further evaluate the
  Rankine-Hugoniot properties of the shock at the locations its passage is
  observed and add modeling of the driven shock using a three dimensional
  MHD code which, at this stage of the analysis, does not include the
  magnetic structure of the ejecta. For the study of the shock velocity
  we use remote type II radio burst observations from near Earth (the
  September event), and at different longitude locations we examine:
  (a) flux intensity of the energetic particles, (b) shock strength,
  (c) timing of the shock structure and the driver passage at each
  spacecraft to infer the possible location of the nose of the shock. A
  preliminary assessment on the connection between the global nature
  of the shock and the observed level of energetic particle flux will
  be presented. The data sets include the kilometric radio measurements
  on ISEE3, and the 3 to 80 MeV energetic proton flux data from IMP-8,
  and a similar energy range from Helios at wide longitudinal locations
  relative to Earth. For the solar wind parameters we use magnetic
  field and plasma parameters from instruments at Helios 1, and 2,
  Voyager 1 and 2, and ISEE3 and IMP-8. The data set is completed with
  the Dst index (Kyoto). We acknowledge partial support from NSF and
  NASA grants, and the NSSDC for on-line access to their space science
  data archives. Burlaga LF, E. Sittler, F. Mariani, and R. Schwenn,
  Magnetic loop behind an interplanetary shock: Voyager, Helios, and IMP-8
  observations, J. Geophys. Res., 86, 6673, 1981. Reames, DV, SW Kahler,
  , and CK Ng, Spatial and temporal invariance in the spectra of gradual
  particles in gradual solar events, Astrophys. J., 491, 414, 1997.

Title: The association of CMEs their counterparts near the Earth
Authors: Schwenn, R.; dal Lago, A.; Huttunen, E.; Gonzalez, W.
Bibcode: 2004cosp...35.2634S
Altcode: 2004cosp.meet.2634S
  The propagation speed of halo CMEs towards Earth cannot be measured
  directly because of the unfavorable geometry. From inspecting many limb
  CMEs observed by the LASCO coronagraphs on SOHO we found that there is
  a good correlation between the radial speed and the lateral expansion
  speed v<SUB>exp</SUB> of CME clouds. This latter quantity can also be
  determined for earthward-pointed ``halo'' CMEs. Thus, the expansion
  speed may serve as a proxy for the otherwise inaccessible radial speed
  of halo CMEs. We studied this connection using data from both ends:
  solar data and interplanetary data obtained near the Earth, for a
  period from January 1997 to April 15, 2001. The data were primarily
  provided by the LASCO coronagraphs, plus additional information from
  the EIT instrument. Solar wind data from the plasma instruments on
  the SOHO, ACE and Wind spacecraft were used to identify the arrivals
  of ICME signatures. Among 163 front side or limb full or partial halo
  CMEs we found 91 cases uniquely and another 48 possibly correlated
  with ICME signatures right in front of the Earth, that is a total
  of 85%. That also means that 15% of all these CMEs missed the Earth:
  False alarms! About 25 % of all 151 detected transient shocks and 40
  ICMEs without shocks were apparently not caused by an identifiable
  partial or full halo on the front side: Missing alarms! For 75 out of
  91 safe associations between CMEs and ICMEs we could determine both the
  expansion speed V<SUB>exp</SUB> near the Sun and the travel time of the
  associated shock towards the Earth. An empirical formula was derived
  which now allows to predict (for an isolated, undisturbed front side
  halo CME) the shock/ICME arrival time at the Earth. There is a 95 %
  probability that the shock will arrive within one day around that
  predicted time, except if it is one of the 15 % of ICMEs that never
  hit the Earth.

Title: Dynamic properties of the solar corona: SOHO/LASCO observations
Authors: Mierla, M.; Schwenn, R.; Stenborg, G.; Teriaca, L.;
   Podlipnik, B.
Bibcode: 2004cosp...35.2275M
Altcode: 2004cosp.meet.2275M
  With the launch of the SOHO spacecraft in December 1995, the quality of
  corona observations has improved significantly. The LASCO instruments
  with their field of view now extending from 1.1 Rs (C1) to 30 Rs (C3)
  offer sufficient sensitivity to make an almost continuous outflow in
  the streamer belt visible. We report on two different approaches to
  study the plasma motion, both in the plane of the sky and along the
  line of sight. 1. By means of a multi-resolution image processing
  technique based on wavelet packets the boundaries and the internal
  details of originally faint and diffuse structures are enhanced. This
  approach allows unambiguous image interpretation and provides a means
  for the quantification of stationary and dynamic coronal structures
  required for conducting morphological studies. 2. The LASCO/C1 telescope
  was designed to perform spectral analysis on coronal structures. The
  tunable Fabry-Perot interferometer allows to obtain images at different
  wavelengths. Results from spectral scans of the coronal green and
  red emission lines are presented. From the line profiles physical
  quantities like temperatures (from line widths), and flow velocities
  (from Doppler shifts) along the line of sight are deduced.

Title: Forecasting interplanetary ejecta arrival at 1 AU
Authors: dal Lago, A.; Vieira, L. E.; Echer, E.; Gonzalez, W. D.;
   Clua de Gonzalez, A. L.; Guarnieri, F. L.; Santos, J.; Schwenn, R.;
   Schuch, N. J.
Bibcode: 2004cosp...35.3045D
Altcode: 2004cosp.meet.3045D
  A big challenge in space weather forecasting is the prediction of
  arrival of an interplanetary disturbance at earth. Many attempts
  have been done, and some forecasting models have been proposed. We
  focus on the subset of solar-interplanetary events which have shown
  interplanetary ejecta at 1 AU. To identify interplanetary ejecta at 1 AU
  we use visual inspection of the cases, based on the criterion of intense
  and smooth magnetic field, observed by the Advanced Composition Explorer
  (ACE). For forecasting the arrival of the interplanetary ejecta at 1
  AU we used the lateral expansion speed of the coronal mass ejection,
  measured approximately perpendicular to the single plane-of-sky CME
  speed, as defined by Schwenn et al (2001), using observations from the
  Large Angle and Spectroscopic Coronagraph (LASCO), aboard the Solar
  and Heliospheric Observatory (SOHO). The data set is from January 1997
  to mid April 2001, and a number of 38 LASCO CMEs were identified to
  be correlated with interplanetary ejecta at 1 AU. Results indicate
  that forecasting the arrival at 1 AU of the sub set of interplanetary
  ejecta is very well done by LASCO CME speed observations, being much
  better than the predictions for the complete set of interplanetary
  disturbances, like shocks/sheath structures.

Title: Evolution of interplanetary magnetic clouds from 0.3 AU to
1 AU: A joint Helios-Wind Study
Authors: Biernat, H. K.; Farrugia, C. J.; Leitner, M.; Kucharek,
   H.; Schwenn, R.; Berdichevsky, D.; Osherovich, V.; Lepping, R. P.;
   Matsui, H.
Bibcode: 2003AGUFMSH42A0474B
Altcode:
  A class of interplanetary configurations which interact strongly
  with the Earth's magnetosphere are interplanetary magnetic clouds. A
  desideratum of space weather predictions is that they be made from data
  acquired by distant probes so as to guarantee as long a lead time as
  possible. For this to be viable, one must have accurate knowledge of
  how parameters evolve. To this end, we use observations of magnetic
  cloud made by the spacecraft Wind at 1 AU, and Helios 1 &amp; 2 between
  0.3 and 1 AU. A model is constructed, regarding the magnetic cloud as
  a cylindrically symmetric, force-free constant-alpha magnetic field
  configuration, i.e. the cylindrically symmetric solution of ∇ B =
  α B. We least--squares fit the model to the data and obtain model
  parameters, e.g. the magnetic field strength on the axis of the tube,
  the helicity, the orientation, the diameter, and its orientation. We
  adopt two approaches: In the first we obtain statistically the way these
  parameters evolve with distance from the Sun. In the second approach
  we focus on line-ups of the spacecraft and determine directly how
  parameters scale with distance. The two approaches are compared. This
  work is supported by NASA Living with a Star under grant NAG 5-10883.

Title: Global heliospheric disturbances near 1 AU caused by the
    launch of solar transients on January 1 and September 23, 1978.
Authors: Berdichevsky, D. B.; Reames, D. V.; Wu, C.; Schwenn, R.;
   Lepping, R. P.; Farrugia, C. J.; MacDowall, R. J.; Bougeret, J.; Ng,
   C. K.; Lazarus, A. J.; Richardson, I. G.
Bibcode: 2003AGUFMSM22A0219B
Altcode:
  We revisit the transient events of January and September 1978. In
  the January event the ejecta (an interplanetary magnetic cloud, IMC)
  was studied using multiple spacecraft observations [Burlaga et al.,
  1981]. In the September event Reames et al., 1997 studied the spectral
  characteristics of the energetic particles of this big particle
  event with a driven shock passage observed at longitudes nearly 180°
  apart. Here we present a combined analysis of the overall solar wind
  and energetic particles (EP) features of the shock and the driver,
  observed at different locations in longitude. We further evaluate the
  Rankine-Hugoniot properties of the shock at the locations its passage is
  observed and add modeling of the driven shock using a three dimensional
  MHD code which, at this stage of the analysis, does not include the
  magnetic structure of the ejecta. For the study of the shock velocity
  we use remote type II radio burst observations from near Earth (the
  September event), and at different longitude locations we examine:
  (a) flux intensity of the energetic particles, (b) shock strength,
  (c) timing of the shock structure and the driver passage at each
  spacecraft to infer the possible location of the nose of the shock. A
  preliminary assessment on the connection between the global nature
  of the shock and the observed level of energetic particle flux will
  be presented. The data sets include the kilometric radio measurements
  on ISEE3, and the 3 to 80 MeV energetic proton flux data from IMP-8,
  and a similar energy range from Helios at wide longitudinal locations
  relative to Earth. For the solar wind parameters we use magnetic field
  and plasma parameters from instruments at Helios 1, and 2, and ISEE3
  and IMP-8. The data set is completed with the Dst index (Kyoto). We
  acknowledge partial support from NSF and NASA grants, and the NSSDC
  for on-line access to their space science data archives. Burlaga
  LF, E. Sittler, F. Mariani, and R. Schwenn, Magnetic loop behind
  an interplanetary shock: Voyager, Helios, and IMP-8 observations,
  J. Geophys. Res., 86, 6673, 1981. Reames, DV, SW Kahler,, and CK Ng,
  Spatial and temporal invariance in the spectra of gradual particles
  in gradual solar events, Astrophys. J., 491, 414, 1997.

Title: Long-distance Correlations of Interplanetary Parameters:
    A Case Study with HELIOS
Authors: Matsui, H.; Farrugia, C. J.; Kucharek, H.; Berdichevsky, D.;
   Torbert, R. B.; Jordanova, V. K.; Richardson, I. G.; Galvin, A. B.;
   Lepping, R. P.; Schwenn, R.
Bibcode: 2003AIPC..679..770M
Altcode:
  In recent work, promising agreement has been obtained between measured
  indices of geomagnetic activity (Dst, and cross-polar cap potential)
  and their predicted values using interplanetary input from probes in
  the inner heliosphere (~0.7 AU) when the probe was close to, (5), and
  even substantially displaced from, (4), the Earth-Sun line. Implicit in
  this agreement is a good correlation of, at least, the basic temporal
  profiles of the major interplanetary parameters at the two observing
  sites. In this work we discuss a case study using Helios 1 and 2 data
  when the spacecraft are lined - up and separated by an almost constant
  radial distance of 0.2 AU. In the period studied, the interplanetary
  medium consists of a fast stream being trailed by a magnetic cloud in
  a slower flow. Good correlation is found between the plasma and field
  observations at the two sites. Two lag times, reflecting the two types
  of major structures in the interval chosen, are determined. Evidence
  of evolutionary processes are briefly discussed. Spectral analysis
  confirms the results obtained from time series analysis.

Title: Solar-Heliospheric-Magnetospheric Observations on March
23-April 26, 2001: Similarities to Observations in April 1979
Authors: Berdichevsky, D. B.; Farrugia, C. J.; Lepping, R. P.;
   Richardson, I. G.; Galvin, A. B.; Schwenn, R.; Reames, D. V.; Ogilvie,
   K. W.; Kaiser, M. L.
Bibcode: 2003AIPC..679..758B
Altcode:
  We discuss the similarities and differences of two intervals of extreme
  interplanetary solar wind conditions, separated almost precisely by
  two solar cycles, in April 1979 and March-April 2001. The similarities
  extend to various data-sets: Energetic particles, solar wind plasma
  and interplanetary magnetic field. In April 1979 observations were made
  by three spacecraft covering a wide longitudinal range (~ 70°) in the
  heliosphere. Data are presented from Helios 2, located 28° East of the
  Sun-Earth line at ~ 2/3 AU, and from near the Earth. Observations of
  the 2001 interval are from Wind. We examine the geomagnetic activity
  during each interval.

Title: Launch of solar coronal mass ejections and submillimeter
    pulse bursts
Authors: Kaufmann, Pierre; GiméNez de Castro, C. Guillermo; Makhmutov,
   Vladimir S.; Raulin, Jean-Pierre; Schwenn, Rainer; Levato, H.;
   Rovira, M.
Bibcode: 2003JGRA..108.1280K
Altcode:
  The rapid solar spikes (100-500 ms) recently discovered at submillimeter
  waves bring new possibilities to investigate energetic processes near
  the solar surface that might have an important role in the launch and
  propelling of ionized mass away from the Sun. We present a study on
  the association between the launch time of coronal mass ejections
  (CMEs) observed by the LASCO instruments on the SOHO spacecraft
  and the onset of the new kind of rapid solar spikes (100-500 ms)
  observed at submillimetric waves (212 and 405 GHz) by the new Solar
  Submm-wave Telescope (SST). We investigated six submm-wave events,
  all found associated to CMEs. Seven related CME were identified. Five
  of them were associated with flares with large GOES class soft X-rays,
  presenting distinct time histories and associations at other energy
  ranges, and two of them were related to flares behind the solar limb,
  with simultaneous related activity observed in the visible solar
  disk. Ultraviolet images from EIT on SOHO show some kind of small
  or large-scale magnetic activity or brightening for all events. The
  extrapolation of apparent CME positions to the solar surface show that
  they occurred nearly coincident in time with the onset of submm-wave
  pulses for all six events. These results suggest that pulse bursts might
  be representative of an important early signature of CMEs, especially
  for events beginning near the center of the solar disk, sometimes
  identified as "halo" CMEs. They lead to several challenging questions
  relative to the physical nature of the pulses and its association to
  the launch and acceleration of coronal mass ejections. Although these
  evidences may favor multiple rapid energy releases at the origin near
  the solar surface, they require further research in order to better
  understand both diagnostics and model descriptions.

Title: Solar Pulsating Bursts at Submillimeter Wavelengths
Authors: Kaufmann, P.; Giménez de Castro, C. G.; Makhmutov, V. S.;
   Raulin, J. -P.; Schwenn, R.; Levato, H.; Rovira, M.
Bibcode: 2003EAEJA.....5652K
Altcode:
  We report some characteristics of trains of pulses that are
  frequently observed in the Sun at 212 and 405 GHz by the Solar
  Submillimeter Telescope operated at El Leoncito Astronomical Complex,
  Argentina Andes. Pulses time scales range typically from 100-500
  milliseconds. Although pulsed bursts are usually associated to optical
  flares or events at other energy ranges, there are various examples
  without connection to any important activity in the solar disk. In
  the submillimeter range of wavelength most pulsed bursts are detected
  without any bulk emission component. There is a significant association
  between the occurrence of submm-wave pulsed bursts and the launch
  times of coronal mass ejections (CMEs). Pulses bursts might turn out
  a reliable early signature of CME's, specially for those occurring
  near the center of the solar disk, which produce the most important
  geophysical effects. For solar event for which there are light curves
  measured at submm-waves or at higher energy ranges (X-, gamma-rays),
  there are qualitative indications that the time rate of pulse occurrence
  and pulses amplitudes are proportional to the energy release rate with
  time (fluxes). The submm-wave pulsed bursts might be representative
  of multiple energy releases in complex magnetic structures where many
  fast instabilities occur in small scale magnetic arcades or fluxules.

Title: A comparative analysis of the helios and istp era sun-earth
    connection during solar minimum
Authors: Berdichevsky, D.; Reames, D.; Schwenn, R.; Lepping, R.;
   Farrugia, C.; Richardson, I.; Wu, C. -C.
Bibcode: 2003EAEJA....13892B
Altcode:
  We discuss the similarities and differences of two intervals of extreme
  interplanetary solar wind conditions, separated almost precisely by
  two solar cycles, in Feb-Apr 1976 and Jan-Apr 2001. The similarities
  extend to various data-sets: Energetic particles, solar wind plasma
  and interplanetary magnetic field. In Jan-April 1979 observations were
  made by spacecraft at three locations covering a wide longitudinal range
  (from ~30 to 70°) in the heliosphere. Data are presented from Helios 2,
  Helios 1, and from near the Earth. Observations of the 1997 interval are
  from Wind, and solar conditions from SOHO. We examine the geomagnetic
  activity during each interval. This Study is partially supported by the
  following Grants: ATM-0208414 (NSF), and NASA NASW-02025 and NAG 5-10883

Title: On the solar origin of interplanetary disturbances observed
    in the vicinity of the Earth
Authors: Vilmer, N.; Pick, M.; Schwenn, R.; Ballatore, P.; Villain,
   J. P.
Bibcode: 2003AnGeo..21..847V
Altcode:
  The solar origin of 40 interplanetary disturbances observed in
  the vicinity of the Earth between January 1997 and June 1998 is
  investigated in this paper. Analysis starts with the establishment
  of a list of Interplanetary Mass Ejections or ICMEs (magnetic clouds,
  flux ropes and ejecta) and of Interplanetary Shocks measured at WIND
  for the period for which we had previously investigated the coupling
  of the interplanetary medium with the terrestrial ionospheric
  response. A search for associated coronal mass ejections (CMEs)
  observed by LASCO/SOHO is then performed, starting from an estimation
  of the transit time of the inter-planetary perturbation from the Sun
  to the Earth, assumed to be achieved at a constant speed (i.e. the
  speed measured at 1 AU). EIT/SOHO and Nançay Radioheliograph (NRH)
  observations are also used as proxies in this identification for the
  cases when LASCO observations do not allow one to firmly establish the
  association. The last part of the analysis concerns the identification
  of the solar source of the CMEs, performed using a large set of solar
  observations from X-ray to radio wavelengths. In the present study,
  this association is based on a careful examination of many data sets
  (EIT, NRH and H images and not on the use of catalogs and of Solar
  Geophysical Data reports). An association between inter-planetary
  disturbances and LASCO/CMEs or proxies on the disk is found for 36
  interplanetary events. For 32 events, the solar source of activity
  can also be identified. A large proportion of cases is found to be
  associated with a flare signature in an active region, not excluding of
  course the involvement of a filament. Conclusions are finally drawn on
  the propagation of the disturbances in the interplanetary medium, the
  preferential association of disturbances detected close to the Earth’s
  orbit with halos or wide CMEs and the location on the solar disk of
  solar sources of the interplanetary disturbances during that period.

Title: Continuous tracking of CMEs using MICA, and LASCO C2 and
    C3 coronagraphs
Authors: Balmaceda, L.; Dal Lago, A.; Stenborg, G.; Francile, C.;
   Gonzalez, W. D.; Schwenn, R.
Bibcode: 2003AdSpR..32.2625B
Altcode:
  In this work we have tracked coronal mass ejections observed with the
  ground based Mirror Coronagraph for Argentina (MICA) and the Large Angle
  and Spectroscopic Coronagraph (LASCO) C2 and C3 on board of the Solar
  and Heliospheric Observatory (SOHO). The MICA telescope is located at El
  Leoncito (31.8 S, 69.3 W), San Juan (Argentina), since 1997 as part of
  a bilateral scientific project between Germany and Argentina. SOHO is
  a project of international cooperation between ESA and NASA. Together
  these instruments are able to observe the solar corona ranging from
  1.05 to 32 solar radii. MICA images the Fe XIV emission line corona
  and LASCO coronagraphs observe the Thomson scattered white light
  corona. We have selected events for which there are observations from
  the three coronagraphs. Using the composite data we were able to obtain
  height-time diagrams for the corresponding dynamical coronal features
  traveling outwards in order to determine some of their kinematical
  properties, i.e., plane of sky velocity and acceleration.

Title: Relation between the radial speed and theexpansion speed of
    coronal mass ejections
Authors: Dal Lago, A.; Schwenn, R.; Gonzalez, W. D.
Bibcode: 2003AdSpR..32.2637D
Altcode:
  We have selected 57 limb coronal mass ejections observed by LASCO
  during the period of January1997 to April 2001. We used the related EIT
  activity close to the limb to define these CMEs as "limbs". We measured
  the radial speed of the leading edge close to the center of these CMEs
  and the lateral expansion speed of the structures. Comparison of both
  speeds revealed a high correlation between them, the radial speed being
  around 88% of the expansion speed of the CME. The expansion speed can
  also be measured for halo CMEs so that it can be used to infer their
  radial speed toward earth, which is otherwise inaccessible.

Title: Causes of major magnetic storms near the latest solar maximum
Authors: Huttunen, K. E. J.; Koskinen, H. E. J.; Schwenn, R.; dal
   Lago, A.
Bibcode: 2002ESASP.506..137H
Altcode: 2002svco.conf..137H; 2002ESPM...10..137H
  We have studied the nine most severe magnetic storms (Dst &lt; -200 nT)
  that occurred during the period from 1999 to the end of the year 2001
  i.e. near the last solar activity maximum. The investigated storms
  showed large variety both in their solar and solar wind causes. Only
  two of these storms were caused by a sheath region together with a
  well-defined magnetic cloud event. Distorted magnetic fields preceding
  the CME ejecta were the storm drivers in five cases.

Title: Variability of magnetospheric storms driven by different
    solar wind perturbations
Authors: Huttunen, K. Emilia J.; Koskinen, Hannu E. J.; Schwenn, Rainer
Bibcode: 2002JGRA..107.1121H
Altcode:
  We have investigated the solar wind drivers of magnetic storms during
  the rising phase of solar cycle 23 from January 1996 to December
  1999. We used observations of coronal mass ejections (CMEs) by the
  Large Angle and Spectrometric Coronagraph instrument on SOHO and in
  situ solar wind observations by Wind, IMP 8, and ACE spacecraft. The
  storms were determined from both the Dst and Kp indices, and the study
  was limited to storms with Dst &lt;= -50 nT or Kp &gt;= 5. We show
  examples of different behavior of Dst and Kp indices during magnetic
  storms caused by different types of solar wind drivers. Furthermore,
  we have investigated cross-correlation between peak Dst and Kp values
  of storms organized according to the associated solar wind driver. It
  makes a difference whether a sheath region or the following ejecta
  causes the storm. We found that almost all intense and stronger
  magnetic storms (Dst &lt;= -100 nT, or Kp &gt;= 7-) were associated
  with shocks and CMEs, but for moderate storms, driver statistics were
  different in different phases of the solar cycle. We found different
  behavior of the Kp and Dst indices during different types of solar wind
  drivers. Intense and short-time disturbances, like postshock streams
  and sheath regions, generated more Kp storms, and ejecta generated
  more Dst storms. Thus one should be careful when comparing studies
  based on any single activity index.

Title: A comparative study of Solar-Heliospheric Observations during
    very active Sun intervals in the 21st and 23rd solar cycles (April
    1979 and March-April, 2001)
Authors: Berdichevsky, D. B.; Farrugia, C. J.; Lepping, R. P.;
   Richardson, I. G.; Galvin, A. B.; Schwenn, R.; Reames, D. V.
Bibcode: 2002AGUSMSH51A..01B
Altcode:
  On March 24, 2001, the largest sun spot group in 10 years, consisting
  of three or more active regions (ARs) centered near AR 9393, emerged
  from behind the eastern limb of the Sun and began a 2-week passage
  across the visible hemisphere. During the same time, the Sun showed
  several other ARs so this period constituted a phase of unusually
  intense solar activity that continued almost 18 days beyond the
  disk passage of the largest sun spot group and included possibly
  the most energetic solar flare event in modern records (a &gt; X20
  flare in soft X-rays). We shall present an overview of the associated
  solar energetic particle events and an analysis of the thermodynamic
  characteristics of the shocks observed in the Earth's vicinity. The
  investigation includes cross-correlation analysis of interplanetary
  plasma and magnetic field observations at ACE (SWEPAM/MAG level-2 data)
  situated 250 Re upstream of Earth and at Wind (SWE/MFI data), which
  was ahead of Earth and executing a distant prograde orbit with large
  Y-coordinate. The interval under study bears a close resemblance to a
  similar active period during April 1979 (i.e., 2 solar cycles earlier)
  observed by the Helios 1/2 probes and Earth solar wind monitors (ISEE-3,
  IMP). The similarities and differences between the two intervals are
  examined further.

Title: Response of magnetic indices to different solar wind
    disturbances
Authors: Huttunen, K. Emilia J.; Koskinen, H. E. J.; Schwenn, R.
Bibcode: 2002ESASP.477..339H
Altcode: 2002scsw.conf..339H
  We have investigated the magnetic storms during the rising phase of
  the solar cycle 23 from January 1996 to December 1999. We determined
  the storm periods from both the Dst and Kp indices. Study was limited
  to storms with Dst &lt;= -50 nT or Kp &gt;= 5. We have investigated
  cross-correlation between the peak Dst and Kp values of storms
  organized according to the asscociated solar wind driver. It makes a
  difference whether the Earth's magnetosphere is hit by a CME ejecta
  or by a compressed and heated sheath region plasma. We found different
  behavior of the Kp and Dst indices during different types of solar wind
  drivers. Intense and short-time disturbances, like post-shock streams
  and sheath regions generated more Kp storms and ejecta generated more
  Dst storms. Thus one should be careful when comparing studies based
  on any single activity index.

Title: Interplanetary phenomena associated with very intense
    geomagnetic storms
Authors: Gonzalez, W. D.; Tsurutani, B. T.; Lepping, R. P.; Schwenn, R.
Bibcode: 2002JASTP..64..173G
Altcode: 2002JATP...64..173G
  The dominant interplanetary phenomena that are frequently associated
  with intense magnetic storms are the interplanetary manifestations of
  fast coronal mass ejections (CMEs). Two such interplanetary structures,
  involving an intense and long duration B<SUB>s</SUB> component of
  the IMF are: the sheath region behind a fast forward interplanetary
  shock, and the CME ejecta itself. Frequently, these structures lead
  to the development of intense storms with two-step growth in their
  main phases. These structures, when combined, lead sometimes to the
  development of very intense storms, especially when an additional
  interplanetary shock is found in the sheath plasma of the primary
  structure accompanying another stream. The second stream can also
  compress the primary cloud, intensifying the B<SUB>s</SUB> field, and
  bringing with it an additional B<SUB>s</SUB> structure. Thus, at times
  very intense storms are associated with three or more B<SUB>s</SUB>
  structures. Another aspect that can contribute to the development of
  very intense storms refers to the recent finding that magnetic clouds
  with very intense core magnetic fields tend to have large velocities,
  thus implying large amplitude interplanetary electric fields that can
  drive very intense magnetospheric energization.

Title: New insights on the onsets of coronal mass ejections from soho
Authors: Plunkett, S. P.; Michels, D. J.; Howard, R. A.; Brueckner,
   G. E.; St. Cyr, O. C.; Thompson, B. J.; Simnett, G. M.; Schwenn, R.;
   Lamy, P.
Bibcode: 2002AdSpR..29.1473P
Altcode:
  Coronal mass ejections (CMES) are among the most dramatic forms of
  transient activity occurring in the solar atmosphere. Despite over
  twenty years of research, many basic questions related to the physics
  of CMEs have remained unanswered. Observations with the LASCO and EIT
  experiments on SOHO, combined with recent theoretical modeling, have
  provided new insights on some of these outstanding questions and have
  also raised many new ones that need to be addressed in the future. In
  this paper, we present some of the new results from SOHO pertaining
  to the source regions and onsets of CMEs, and their evolution in the
  corona. We emphasize the important role that studies of CMEs will play
  in the International Solar Cycle Studies program.

Title: Comparison between halo CME expansion speeds observed on the
    sun, their average propagation speeds to earth and their corresponding
    counterparts near earth
Authors: dal Lago, A.; Schwenn, R.; Huttunen, K.; Gonzalez, W.;
   Gonzalez, A.; Vieira, L.; Echer, E.; Guarnieri, F.; Prestes, A.;
   Balmaceda, L.; Schuch, N.
Bibcode: 2002cosp...34E.827D
Altcode: 2002cosp.meetE.827D
  We have compared characteristics of 85 halo CMEs observed on the sun
  by the Large Angle and Spectroscopic Coronagraph on SOHO with their
  corresponding counterparts observed near earth by the magnetic field
  and plasma instruments on board of ACE, WIND and SOHO satellites, in
  the period from January 1997 to April 2001. First, we focussed on the
  comparison between the lateral expansion speeds of these halos and
  the corresponding ejecta speeds near earth. It is found that there
  is a relation between these two speeds, but the scatter is high. If
  one takes a subset from these data which includes only those CMEs that
  showed magnetic cloud structures near earth (21 cases), the correlation
  mentioned above increases. The results are very similar to the study
  done by Lindsay et al (1999) using observations made from Solwind and
  SMM coronagraphs, and Helios-1 and PVO plasma and interplanetary field
  data from the period of 1979 to 1988. Also, we reviewed the relations
  between the average CME propagation speed to earth and the ejecta
  speeds near earth. We found a relation for this set of data which
  differs from the relation derived by Cliver et al. (1990). This kind
  of relation is very important to estimate ejecta speeds of events for
  which no interplanetary observations are available.

Title: Relation between the radial speed and the expansion speed of
    coronal mass ejections
Authors: dal Lago, A.; Schwenn, R.; Gonzalez, W.
Bibcode: 2002cosp...34E.828D
Altcode: 2002cosp.meetE.828D
  We have selected 54 limb coronal mass ejections observed by LASCO
  during the period of January 1997 to April 2001. We used the related
  EIT activity close to the limbto define these CMEs as SlimbT CMEs. We
  measured the radial speed of the leading edge close to the center of
  these CMEs and the lateral expansion speed of the structures. Comparison
  of both speeds revealed a high correlation between them, the radial
  speed being around 88% of the expansion speed of the CME. The expansion
  speed can also be measured for halo CMEs so that it can be used to infer
  their radial speed toward earth which is otherwise unaccessible. The
  associations of CME expansion speeds and their travel speeds to earth on
  the one hand and the radial limb CME speeds and their measured travel
  time to Solwind and Helios-1 spacecraft on the other hand show a lot
  of similarities.

Title: The halo CME expansion speed as a tool for predicting their
travel time to earth: testing the tool.
Authors: dal Lago, A.; Schwenn, R.; Gonzalez, W.; Huttunnen, K.
Bibcode: 2002cosp...34E.826D
Altcode: 2002cosp.meetE.826D
  Expansions speeds of 94 halo coronal mass ejections were measured
  from LASCO C3 images obtained in the period of January 1997 to April
  2001. They have been found to be a very useful tool for predicting their
  travel time to earth. The expansion speed is defined by the expansion
  of oppositely directed portions of the halo CME front l. Only CMEs with
  unique interplanetary association were chosen, and their travel time
  was determined from the first CME appearance in the LASCO C2 field of
  view and the arrival of an interplanetary signature (shock or blob)
  near earth, as observed by ACE, WIND or SOHO instruments. An empirical
  model for CME propagation was developed based on these measurements
  which assumes that there is deceleration of CMEs proportional to their
  speed.This model allows to estimate the travel time to earth from the
  halo expansion speed. Recently, we had several opportunities to test
  this empirical model, and the predictions were usually very good.

Title: Continuous tracking of CME's using MICA and LASCO -C2 and
    -C3 coronagraphs
Authors: Balmaceda, L.; dal Lago, A.; Stenborg, G.; Francile, C.;
   Gonzalez, W.; Schwenn, R.
Bibcode: 2002cosp...34E1440B
Altcode: 2002cosp.meetE1440B
  In this work we have tracked coronal mass ejections observed with the
  ground based Mirror Coronagraph for Argentina (MICA) and the Large
  Angle Spectroscopic Coronagraph (LASCO) C2 and C3 on board of Solar
  and Heliospheric Observatory (SOHO). MICA telescope is located at
  El Leoncito, (San Juan, Argentina) since 1997 as part of a bilateral
  scientific project between Germany and Argentina and SOHO is a project
  of international cooperation between ESA and NASA. Together these
  instruments are able to observe the solar corona ranging from 1.05 to
  32 solar radii. MICA images the Fe XIV emission-line corona while LASCO
  coronagraphs observe the Thomsonscattered white light. We have selected
  events for which there are observations from the three coronagraphs
  in order to determine the outflow characteristics such as velocity,
  acceleration or deceleration. Using this composite data we were able
  to obtain height-time diagrams for coronal moving features.

Title: Major Storms During The Last Solar Activity Maximum: Solar
    and Interplanetary Causes
Authors: Huttunen, K. E. J.; Koskinen, H. E. J.; Schwenn, R.;
   Dallago, A.
Bibcode: 2002EGSGA..27.3428H
Altcode:
  During the solar maximum the prediction of the magnetic storms is
  more difficult than in the minimum as several CMEs may impart during
  a day interacting with the ambient solar wind and possibly with each
  other. We analyzed the eight most severe storms (Dst &lt; ­200 nT)
  occurring during the years 1999-2001, i.e. around the last so- lar
  maximum. For two of these storms the geoeffective structures (sheath
  region and well-defined magnetic cloud) were easily identifiable in
  the solar wind data, and it was possible to find unique associations
  to CMEs observed by SOHO/LASCO. The other six storms were caused
  by more complex solar wind structures. Four of these had more than
  one suitable CME association and were probably caused by the inter-
  action of multiple CMEs. One storm was caused by a very strong sheath
  region and one by the interaction of the CME ejecta with a high-speed
  stream. The prediction of the geoeffectivity for complex cases is more
  difficult as they have several solar source candidates. Also, due to
  their mutual interaction, they lack the simple magnetic cloud topology
  known from isolated CMEs. We have investigated the differences and sim-
  ilarities in solar events and solar wind conditions that led to these
  major storms and tried to identify the origin of the geoeffective
  structures, even for the complex cases.

Title: Improving space weather predictions - what is missing?
Authors: Schwenn, R.; Huttunen, E.; dal Lago, A.
Bibcode: 2002cosp...34E1361S
Altcode: 2002cosp.meetE1361S
  With the arrival of SOHO and its modern instrumentation, space
  weather predictions reached a new quality: 1) an almost continuous
  patrol service for detecting halo CMEs early on is now in service,
  2) simultaneous EUV disk observations allow to determine wheather a
  halo is pointed towards or away from Earth, i.e., wheather an impact
  at Earth is probable or not. Yet, the accurracy of actual predictions
  is still deplorably bad. The actual arrivals at Earth are usually off
  by many hours, about 10% of storms are not predicted at all, another
  10% of predictions are false alarms, and predicting the strength and
  exact timing of storms caused by the ICMEs seems to be that worthless
  that it is not even tried. From our experience over the years we
  pinpoint several issues where practical improvements appear feasible,
  both on short and on long term. In addition, basic research work
  remains indispensible, for finally identifying the warning signals of
  imminent solar transients and for pre-determininig their propagation
  characteristics using near-real-time computer models.

Title: Coronal mass ejection speeds measured in the solar corona
    using LASCO C2 and C3 images
Authors: dal Lago, A.; Schwenn, R.; Stenborg, G.; Gonzalez, W.
Bibcode: 2002cosp...34E.830D
Altcode: 2002cosp.meetE.830D
  In this work we present height-time diagrams of 3 halo coronal mass
  ejections, observed on July 25th,1999, September 28th,1997, and June
  29th,1999. The CMEs were observed by the Large Angle and Spectroscopic
  Coronagraph (LASCO) which is an instrument on board of the Solar and
  Heliospheric Observatory (SOHO observing the solar corona from 2 to 32
  solar radii. To obtain these diagrams we divide the LASCO images of a
  given sequence in angular slices, transform them into rectangular slices
  (their width chosen proportional to the time distance to the next image)
  and place them side by side. Thus, the speed profile of any pattern
  moving in the particular latitudinal slice can be derived. With this
  method we were able to identify even minor speed changes in several
  angular positions for the chosen events. This technique is particularly
  appropriate to identify acceleration or deceleration of structures in
  halo CMEs. This information may be used to improve predictions of CME
  travel times to earth. From the analysis of these 3 events we conclude
  that: (a) the CME observed on September 28th,1997, started very slowly,
  with initial speeds ranging from 107 to 178 km/s, and accelerated
  in the C2 field of view reaching final constant speeds of 352 to 400
  km/s in the C3 field of view; (b) the CMEs observed on July 25th,1999,
  and June 29th,1999 started with initial speeds from 310 to 650 km/s
  and 435 to 650 km/s, respectively. They decelerated smoothly in the
  C3 field of view and reached a variety of speeds ranging from 150 to
  330 km/s, depending on the direction around the sun.

Title: Solar orbiter, a high-resolution mission to the sun and
    inner heliosphere
Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.;
   Fleck, B.; Harrison, R.; Langevin, Y.; Marsden, R.; Pace, O.; Schwenn,
   R.; Vial, J. -C.
Bibcode: 2002AdSpR..29.2027M
Altcode:
  The scientific rationale of the Solar Orbiter is to provide, at high
  spatial (35 km pixel size) and temporal resolution, observations of the
  solar atmosphere and unexplored inner heliosphere. Novel observations
  will be made in the almost heliosynchronous segments of the orbits at
  heliocentric distances near 45 R⊙ and out of the ecliptic plane at
  the highest heliographic latitudes of 30° - 38°. The Solar Orbiter
  will achieve its wide-ranging aims with a suite of sophisticated
  instruments through an innovative design of the orbit. The first
  near-Sun interplanetary measurements together with concurrent remote
  observations of the Sun will permit us to determine and understand,
  through correlative studies, the characteristics of the solar wind
  and energetic particles in close linkage with the plasma and radiation
  conditions in their source regions on the Sun. Over extended periods
  the Solar Orbiter will deliver the first images of the polar regions
  and the side of the Sun invisible from the Earth.

Title: Solar Orbiter: a high-resolution mission to the sun and
    inner heliosphere
Authors: Fleck, Bernhard; Marsch, E.; Antonucci, Ester; Bochsler,
   Peter A.; Bougeret, J. L.; Harrison, R.; Marsden, R. P.; Coradini,
   M.; Pace, Oscar; Schwenn, Rainer; Vial, Jean-Claude
Bibcode: 2001SPIE.4498....1F
Altcode:
  The key mission objective of the Solar Orbiter is to study the Sun
  from close-up (45 solar radii, or 0.21 AU) in an orbit tuned to solar
  rotation in order to examine the solar surface and the space above from
  a co-rotating vantage point at high spatial resolution. Solar Orbiter
  will also provide images of the Sun's polar regions from heliographic
  latitudes as high as 38 degrees. The strawman payload encompasses
  two instrument packages: Solar remote-sensing instruments: EUV
  full-sun and high resolution imager, high-resolution EUV spectrometer,
  high-resolution and full-sun visible light telescope and magnetograph,
  EUV and visible-light coronagraphs, radiometers. Heliospheric
  instruments: solar wind analyzer, radio and plasma wave analyzer,
  magnetometer, energetic particle detectors, interplanetary dust
  detector, neutral particle detector, solar neutron detector. To
  reach its novel orbit, Solar Orbiter will make use of low-thrust
  solar electric propulsion (SEP) interleaved by Earth and Venus gravity
  assists. Solar Orbiter was selected by ESA's Science Programme Committee
  (SPC) in October 2000 as a Flexi-mission, to be implemented after the
  BepiColombo cornerstone mission to Mercury before 2013. This paper
  summarizes the science to be addressed with the Solar Orbiter, followed
  by brief descriptions of the strawman payload, the mission profile,
  and the spacecraft and ground segment designs.

Title: A Tool For Improved Space Weather Predictions: The CME
    Expansion Speed
Authors: Schwenn, R.; Dal Lago, A.; Gonzalez, W. D.; Huttunen, E.;
   St. Cyr, C. O.; Plunkett, S. P.
Bibcode: 2001AGUFMSH12A0739S
Altcode:
  From inspecting limb CMEs we found that there is usually a good
  correlation between the apparent radial speed and the lateral
  expansion speed of CME clouds. In case of halo CMEs, the radial speed
  is inaccessible because of the geometry, but the expansion speed can
  still be determined. Thus, the halos' radial speed can be inferred
  and their travel time to Earth be estimated and compared with the
  observed travel time. We studied this connection using solar and
  interplanetary data for a period from January 1997 to April 2001. The
  data were primarily provided by the LASCO coronagraphs on SOHO, plus
  additional information from the EIT instrument. Solar wind data from
  SOHO, ACE and Wind were used to identify the arrivals of CME effects
  at the earth. Out of 280 full and partial halo CMEs recorded by LASCO
  we found 102 cases uniquely correlated with ejecta signatures right
  in front of the earth. For 94 of them, both the halo expansion speed
  Vexp and the travel time Ttr could be determined. The function Ttr =
  220.8 - 22.75 * ln(Vexp) fits the data best.

Title: 3D Coronal Observations and Sun Earth Connections : from SOHO
    to STEREO data
Authors: Portier-Fozzani, F.; Inhester, B.; Schwenn, R.; Dal Lago,
   A.; Papadopoulo, T.
Bibcode: 2001AGUFMSH31B0715P
Altcode:
  Recent progress in 3D visualization and reconstruction made possible
  to follow the evolution of coronal plasma structures frozen by the
  magnetic field. As optically thin coronal emission lines introduce
  uncertainties on the reconstructions, it is needed to develop
  constraints on stereoscopic methods to be able to use them in the
  solar case. Basic geometric assumptions on structures made possible
  to determine the main parameters on loops - including their twists -,
  arcade loops structures or filament shapes, using the difference angle
  due to solar rotation with SOHO/EIT. Tomographic techniques are being
  adapted to coronagraphic data such as SOHO/LASCO. 3D analysis of flare
  formation on April 7th, 1997 shows emerging flux near a sigmoid loop
  with magnetic fields reconnection. October 13th, 1999 a twisted filament
  becomes instable and creates a limb CME. April 6-7th, 1998 at the limb,
  several ejections of twisted structures are observed. In all of these
  cases, the role of the helicity in these instabilities formations
  is analyzed. Consequences of the observed detwisting processes in
  ejections of material into the interplanetary space up to aurora
  formations are described. Then improvements expected in dynamical
  cases due to simultaneous observations at various angle, provided by
  the STEREO mission (launched in December 2004) are presented in the
  context of the space weather forecast.

Title: Dependence of Geoeffective Interplanetary Parameters on
Heliographic Longitude: A Case Study for March 1979
Authors: Lepping, R. P.; Farrugia, C. J.; Jordanova, V. K.;
   Berdichevsky, D. B.; Galvin, A.; Schwenn, R.; Richardson, I. G.
Bibcode: 2001AGUFMSH31A0703L
Altcode:
  We inquire into how much information content is lost in using
  interplanetary field and plasma parameters to predict the Dst index
  from monitors in the inner heliosphere (distance R &lt; 1 AU) and
  displaced from the Sun-Earth line. To this end, we selected a period
  in March, 1979, during which 2 major geomagnetic storms (Dst &lt; -100
  nT) occurred. Data are from ISEE 3, in orbit around the L1 Lagrangian
  point, and from Helios 2 situated at R ~ 0.8 AU and at a substantial
  separation from the Sun-Earth line are used. Scaling factors with
  R are the same as those in Lindsay et al. (1999), irrespective of
  interplanetary configuration. Previous investigations have recorded
  good overall agreement between the measured Dst and that predicted from
  Burton et al.'s formula (1975). However, there are occasional large
  discrepancies even when input interplanetary parameters are from probes
  near the Sun-Earth line. In computing the Dst in this study we shall
  therefore contrast predictions using two approaches. One is based on
  Burton et al.'s formula; the other is based on a numerical simulation
  with our kinetic ring current model [3] driven by a magnetopsheric
  electric field derived from the Weimer [2001] model. The twofold aim
  of the work is thus to answer the two questions: (1) which part of the
  Dst is still predicted from off the Sun-Earth line and what are the
  corresponding interplanetary configurations?; (2) Is prediction improved
  when the model of Weimer (2001) is used?. This work is supported by
  NASA Living with a Star grant NAG5-10883. 1. Lindsay, G. M., et al.,
  JGR, 104, 10,335, 1999. 2. Burton, R. K., et al., JGR, 80, 4204,
  1975. 3. Jordanova, V. K., et al., JGR, 103, 79, 1998. 4. Weimer,
  D. R., JGR, 106, 407, 2001.

Title: The eruptive events on September 30, 1998: 1. The jet
Authors: Bagalá, L. G.; Stenborg, G.; Schwenn, R.; Haerendel, G.
Bibcode: 2001JGR...10625239B
Altcode:
  The jet on September 30, 1998, is part of a complex event that
  involved also other eruptive phenomena. Changes in the coronal
  magnetic field topology were observed during the ejection of the
  jet, as deduced from the Fe XIV green line emission. The whole event
  was well observed by both the H-Alpha Solar Telescope for Argentina
  (HASTA) and the Mirror Coronagraph for Argentina (MICA), which are
  installed in the German-Argentinean Solar Observatory at El Leoncito,
  Argentina. The Soft X-ray Telescope (SXT) on board Yohkoh also observed
  the jet. In this work, observations of the first part of this complex
  event showing the evolution of the jet and release of blobs are
  presented. Certain features observed are interpreted as signatures
  of a magnetic reconnection process in the region. We conclude that
  existing theoretical and phenomenological models based on magnetic
  reconnection mechanisms could explain our observations, which span
  three temperature regimes far apart from each other.

Title: Solar Orbiter, a high-resolution mission to the Sun and
    inner heliosphere
Authors: Marsch, E.; Harrison, R.; Pace, O.; Antonucci, E.; Bochsler,
   P.; Bougeret, J. -L.; Fleck, B.; Langevin, Y.; Marsden, R.; Schwenn,
   R.; Vial, J. -C.
Bibcode: 2001ESASP.493D..11M
Altcode: 2001sefs.workD..11M
  Solar Orbiter will provide, at very high spatial (35 km pixel size)
  and temporal resolution, novel observations of the solar atmosphere
  and unexplored inner heliosphere. It will achieve its wide-ranging
  scientific aims with a suite of sophisticated instruments through an
  innovative orbit design. Unprecedented observations will be made in
  the heliosynchronous segments of the orbits at heliocentric distances
  near 45 R<SUB>solar</SUB> and out of the ecliptic plane at the highest
  heliographic latitudes of 30° - 38°. The first near-Sun interplanetary
  measurements together with concurrent remote-sensing observations of
  the Sun and its corona will permit us to determine and understand,
  through correlative studies, the characteristics of the solar wind
  and energetic particles in close linkage with the plasma and radiation
  conditions in the source regions on the Sun. Solar Orbiter will deliver
  the first images of the polar regions and the far side of the Sun
  invisible from the Earth.

Title: Ionization state and magnetic topology of coronal mass
    ejections
Authors: Henke, T.; Woch, J.; Schwenn, R.; Mall, U.; Gloeckler, G.;
   von Steiger, R.; Forsyth, R. J.; Balogh, A.
Bibcode: 2001JGR...10610597H
Altcode:
  Charge state distributions of heavy solar wind ions measured in
  interplanetary space can be used to probe the physical conditions
  in the solar corona. This paper presents a study of the charge state
  distributions and the magnetic topology of 56 coronal mass ejections
  (CMEs) observed in interplanetary space by the Ulysses spacecraft. The
  analysis of the data from the Solar Wind Ion Composition Spectrometer
  (SWICS) instrument and the Vector Helium Magnetometer (VHM) experiment
  onboard Ulysses shows a clear correlation between the charge state
  distributions and the magnetic topology of CMEs. Almost all CMEs whose
  charge state distributions are shifted to higher charge states with
  respect to the ambient solar wind have the structure of magnetic clouds,
  whereas CMEs with the same charge state distributions as the surrounding
  solar wind do not show magnetic cloud structure. This correlation
  is found for CMEs observed at low, mid, and high solar latitudes. On
  the basis of the numerical solution of the ionization/recombination
  equations for oxygen and silicon, it is investigated which changes of
  the electron temperature, electron density, and the speed of the ions
  in the source region of the CMEs can reproduce the observations. It is
  shown that the main reason for the observed enhancement of higher charge
  states in the cloud CMEs is an increased electron temperature. However,
  the evolution of the density and velocity of the CMEs before the charge
  states freeze in cannot be neglected.

Title: Large Doppler Shifts in X-Ray Plasma: An Explosive Start to
    Coronal Mass Ejection
Authors: Innes, D. E.; Curdt, W.; Schwenn, R.; Solanki, S.; Stenborg,
   G.; McKenzie, D. E.
Bibcode: 2001ApJ...549L.249I
Altcode:
  We report observations, taken with the Solar Ultraviolet Measurements
  of Emitted Radiation spectrometer, of spatially resolved high red and
  blue Doppler shifts (up to 650 km s<SUP>-1</SUP>) from X-ray-emitting
  plasma in the corona above a flare. The high Doppler shifts are seen
  minutes after a fast, faint optical front is seen racing through the
  same part of the corona in images taken with the Mirror Coronagraph
  for Argentina. The association of the large-scale fast optical emission
  front with soft X-ray emission and high Doppler shifts suggests plasma
  heating and acceleration in the wake of a shock.

Title: Solar Orbiter - A high resolution mission to the Sun and the
    inner heliosphere (Oral papers and posters which were given at the
    conference, but for which no manuscripts were submitted)
Authors: Marsch, E.; Fleck, B.; Schwenn, R.
Bibcode: 2001ohnf.conf..445M
Altcode:
  No abstract at ADS

Title: Solar Orbiter, a High-Resolution Mission to the Sun and
    Inner Heliosphere
Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.;
   Fleck, B.; Harrison, R.; Marsden, R.; Schwenn, R.; Vial, J. -C.
Bibcode: 2001IAUS..203..565M
Altcode:
  The scientific rationale of the Solar Orbiter (SO) is to provide,
  at high spatial and temporal resolution, observations of the solar
  atmosphere and unexplored inner heliosphere. The most interesting and
  novel observations will be made in the almost heliosynchronous segments
  of the orbits at heliocentric distances near 45 R<SUB>odot</SUB> and
  out-of-ecliptic at the highest heliographic latitudes of 38 degrees. The
  SO will achieve its many and varied aims with a suite of small and
  innovative instruments through a clever choice of orbits. The first
  near-Sun interplanetary measurements together with concurrent remote
  observations of the Sun will permit us to determine and understand,
  through correlative studies, the characteristics of the solar wind and
  energetic particles in close linkage with the plasma and radiation
  conditions in their source regions on the Sun. The SO will, during
  the high-latitude orbital passes, provide the first observations of
  the Sun's polar regions as seen from outside the ecliptic and also
  measure the magnetic field at the poles.

Title: Long-term variations of the flow direction and angular momentum
    of the solar wind observed by Helios
Authors: Scherer, K.; Marsch, E.; Schwenn, R.; Rosenbauer, H.
Bibcode: 2001A&A...366..331S
Altcode:
  The flow directions of solar wind protons were measured in situ by
  the Helios spacecraft. A long-term average of the velocity shows a
  systematic drift in the latitudinal flow angle of about +1<SUP>o</SUP>
  north observed with Helios 1 and -1<SUP>o</SUP> south observed onboard
  of Helios 2. The longitudinal flow angle migrates about +1<SUP>o</SUP>
  west over a period of almost 10 years for Helios 1 and 6 years for
  Helios 2. This systematic change with time of the plasma flow direction
  may be caused by solar-cycle variations of the orientation of the Sun's
  magnetic field which partially corotates with the Sun inside the Alfvén
  surface (varying in distance between 10 R<SUB>sun</SUB> over the poles
  and 30 R<SUB>sun</SUB> near the equator). These variations must have
  been imprinted on the solar wind flow when it detached from corotation
  with the Sun near the Alfvén point. The angular momentum of the wind
  is intimately connected with the flow and field directions. The gain of
  total angular momentum of the wind equals the loss of angular momentum
  of the Sun, which is caused by the torque exerted on the rotating
  Sun through the magnetic field of the expanding corona. Implications
  of the Helios observations for models of the magnetic fields of the
  Sun as well as the solar wind are discussed. We show evidence, that
  changes of the solar magnetic field inside the Alfvén surface are
  responsible for systematic drifts in the solar wind flow direction.

Title: Solar Wind: Global Properties
Authors: Schwenn, R.
Bibcode: 2000eaa..bookE2301S
Altcode:
  The most fundamental problem in solar system research is still unsolved:
  how can the Sun with a surface temperature of only 5800 K heat up its
  atmosphere to more than a million K? In fact, the solar atmosphere is
  so hot that not even the Sun's enormous gravity can contain it. Part
  of it is continuously evaporating into interplanetary space: the SOLAR
  WIND. As a highly ionized magnetized plasma it...

Title: First combined observations in the German-Argentinean solar
observatory: correlations in quiet and eruptive phenomena at the limb
Authors: Stenborg, G.; Bagalá, L. G.; Bauer, O. H.; Borda, R. F.;
   Francile, C.; Haerendel, G.; Rovira, M. G.; Schwenn, R.
Bibcode: 2000JASTP..62.1553S
Altcode: 2000JATP...62.1553S
  This is a first report of combined observations form the solar
  instruments at the recently inaugurated German-Argentinean
  Solar-Observatory at El Leoncito, San Juan, Argentina. The /Hα
  telescope (HASTA) and the mirror coronagraph (MICA) daily image the
  solar disk and the inner solar corona respectively with high temporal
  and spatial resolution. The excellent weather conditions for solar
  studies of the Observatory, and its south equatorial location allow a
  complementary summer-condition data with respect to the majority of the
  other observatories, mainly located in the northern hemisphere. In this
  paper, we present four events in order to study possible correlations
  between observations taken by both telescopes. Since each instrument
  records data in quite different temperature regimes, correlation between
  both set of data appears when the phenomena span a broad range of
  temperatures. This is explicitly shown for two of the four set of data
  presented here. On the other hand, the four cases are good examples
  of the contributions the two instruments can provide to the better
  understanding of the mechanisms at work in the inner solar atmosphere.

Title: The origin of the solar wind: an overview
Authors: Srivastava, Nandita; Schwenn, Rainer
Bibcode: 2000ohbp.conf...13S
Altcode:
  A tutorial review of the origin of the solar wind is presented in this
  chapter. At the outset, the concept of the solar wind is introduced and
  its various components and their charactertistics are discussed. Also
  outlined are some of the important space missions dedicated to the
  study of the solar wind and a review of their observations. The salient
  features of a three-dimensional model of the inner heliosphere are
  presented on the basis of the observations. From these space-based
  observations, it is now well established that there exists a close
  relation between the 3D heliosphere and the underlying coronal
  structure. Around solar activity minimum, large polar coronal holes
  dominate the major part of the heliosphere through which emanates
  the high-speed solar wind. On the other hand, another type of solar
  wind which is relatively slow, is restricted to a narrow equatorial
  belt of about ±30° width in latitude. The magnetic topology
  is dominated by strong multipole components and multiple current
  sheets in the upper corona and by a large-scale dipole field further
  outside, respectively. In this review, the emphasis is laid on the
  new observations and findings by several sophisticated instruments
  aboard SOHO which observe both, the inner and outer corona. These have
  revealed several clues to the solar origins or the source regions of the
  two types of solar wind, viz., the fast and the slow solar wind. The
  observations also unravel the finer details of the processes that are
  responsible for their generation. Finally, we summarize the present
  status of our knowledge on the origin of solar wind.

Title: Solar Orbiter --- A High Resolution Mission to the Sun and
    Inner Heliosphere
Authors: Fleck, B.; Marsch, E.; Schwenn, R.; Antonucci, E.; Bochsler,
   P.; Bougeret, J. -L.; Harrison, R. A.; Marsden, R.; Vial, J. -C.
Bibcode: 2000SPD....31.0296F
Altcode: 2000BAAS...32..828F
  The scientific rationale of the Solar Orbiter (SO) is to provide,
  at high spatial and temporal resolution, observations of the solar
  atmosphere and unexplored inner heliosphere. The most interesting and
  novel observations will be made in the almost heliosynchronous segments
  of the orbits at heliocentric distances near 45 R<SUB>sun</SUB> and
  out-of-ecliptic at heliographic latitudes of up to 38<SUP>o</SUP>. By
  going to 45 R<SUB>sun</SUB> the SO will allow remote sensing of the
  solar atmosphere with unprecedented spatial resolution, and the almost
  heliosynchronous orbit segments will permit us to disentangle spatial
  and temporal variations in the solar wind in close linkage with the
  plasma and radiation conditions in the source regions of the Sun. The
  strawman payload encompasses two instrument packages: Heliospheric
  Instruments --- high-res visible light telescope and magnetograph
  (&lt;40 km), high-res X-ray/EUV imager (&lt;30 km), high-res EUV
  spectrometer (&lt;100 km), EUV and visible-light coronagraphs, solar
  neutron and γ -ray detectors, radiometers. Heliospheric Instruments
  --- solar wind analyzer, magnetometer, energetic particle detectors, IP
  dust detector, plasma wave analyser, radio experiment, neutral particle
  detector. Using solar electric propulsion (SEP) in conjunction with
  multiple planet swing-by manoeuvres, it will take SO two years to reach
  a perihelion of 45 R<SUB>sun</SUB> at an orbital period of 149 days,
  with an inclination ranging from 6.7<SUP>o</SUP> to 23.4<SUP>o</SUP>
  w.r.t. the ecliptic. During an extended mission phase of about 2
  years the inclination will increase to 31.7<SUP>o</SUP>, leading to
  a maximum heliographic latitude of 38.3<SUP>o</SUP>. The SO was one
  of the about 40 responses to the Call for Proposals for the next two
  "flexi-missions" (F2 and F3) within ESA's Scientific Programme. At
  its meeting on 1 March 2000, ESA's Space Science Advisory Committee
  recommended the Solar Orbiter among 5 other proposals for an assessment
  study. Launch is expected by the end of the decade.

Title: Factors Related to the Origin of a Gradual Coronal Mass
    Ejection Associated with an Eruptive Prominence on 1998 June 21-22
Authors: Srivastava, Nandita; Schwenn, Rainer; Inhester, Bernd;
   Martin, Sara F.; Hanaoka, Yoichiro
Bibcode: 2000ApJ...534..468S
Altcode:
  We present observations of a coronal mass ejection (CME) associated
  with an eruptive prominence during 1998 June 21-22 by LASCO (Large
  Angle Spectroscopic Coronagraph) aboard SOHO (Solar and Heliospheric
  Observatory). Various features in the three-part structured, white-light
  CME as observed by LASCO-C2 and C3 coronagraphs were compared with
  features in the other wavelengths, for example, in Fe XIV and Fe X
  emission lines obtained from LASCO C1, in Hα from Helio-Research and
  at 17 GHz obtained from Nobeyama Radioheliograph. We have investigated
  conditions in several data sets to understand the eruptive and the
  pre-eruptive scenario of the CME. The CME and the eruptive prominence
  accelerate up to ~20 R<SUB>solar</SUB> and then decelerate to the
  velocity of the ambient slow solar wind. The analysis clearly shows
  that this particular CME is a typical case of a very slow or gradual
  CME for which it is difficult to define an exact onset time. The CME
  could be tracked for about 30 hours until it crossed a distance of
  30 R<SUB>solar</SUB> and disappeared from the field of view of the
  LASCO-C3 coronagraph. The height-time profiles of various features of
  this CME suggest that the leading edge of the CME and the top of the
  prominence or the core follow similar pattern, implying a common driver
  for both the CME and the eruptive prominence. The observations provide
  strong evidence that the CME and the prominence eruption resulted from
  a common cause which is the global restructuring of the magnetic field
  in the corona in an extensive volume of space near and including the
  CME. The restructuring in turn was a consequence of newly emerging
  flux regions near and within the neighboring active regions close to
  the base of the CME.

Title: Heliospheric 3d Structure and CME Propagation as Seen from
SOHO: Recent Lessons for Space Weather Predictions
Authors: Schwenn, R.
Bibcode: 2000AdSpR..26...43S
Altcode:
  Observations from Skylab, Helios, Ulysses, and SOHO have demonstrated
  how closely the 3D heliosphere is related to the underlying coronal
  structure. Around solar activity minimum, the large polar coronal holes
  dominate the major part of the heliosphere, through the high-speed
  solar wind streams emanating from them. A distinctively different
  type of solar wind is restricted to a narrow near-equatorial belt
  (about 30° in latitude). Its magnetic topology is dominated by strong
  multipole components and multiple current sheets. Owing to the new
  telescopes on SOHO, various effects of CME disturbances propagating
  through the heliosphere can now be observed in much greater detail:
  optically from the photosphere out to 32 R<SUB>s</SUB>, and later on by
  in situ spacecraft. It appears that the prediction reliability of space
  weather at Earth's orbit can be raised substantially in the near future

Title: Properties of coronal mass ejections: SOHO LASCO observations
    from January 1996 to June 1998
Authors: St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J.; Paswaters,
   S. E.; Koomen, M. J.; Simnett, G. M.; Thompson, B. J.; Gurman, J. B.;
   Schwenn, R.; Webb, D. F.; Hildner, E.; Lamy, P. L.
Bibcode: 2000JGR...10518169S
Altcode: 2000JGR...105.8169S; 2000JGRA..105.8169S
  We report the properties of all the 841 coronal mass ejections (CMEs)
  observed by the Solar and Heliospheric Observatory (SOHO) Large Angle
  Spectroscopic Coronagraph (LASCO) C2 and C3 white-light coronagraphs
  from January 1996 through June 1998, and we compare those properties to
  previous observations by other similar instruments. Both the CME rate
  and the distribution of apparent locations of CMEs varied during this
  period as expected based on previous solar cycles. The distribution
  of apparent speeds and the fraction of CMEs showing acceleration were
  also in agreement with earlier reports. The pointing stability provided
  by an L-1 orbit and the use of CCD detectors have resulted in superior
  brightness sensitivity for LASCO over earlier coronagraphs; however, we
  have not detected a significant population of fainter (i.e., low mass)
  CMEs. The general shape of the distribution of apparent sizes for LASCO
  CMEs is similar to those of earlier reports, but the average (median)
  apparent size of 72° (50°) is significantly larger. The larger
  average apparent size is predominantly the result of the detection of
  a population of partial and complete halo CMEs, at least some of which
  appear to be events with a significant longitudinal component directed
  along the Sun-Earth line, either toward or away from the Earth. Using
  full disk solar images obtained by the Extreme ultraviolet Imaging
  Telescope (EIT) on SOHO, we found that 40 out of 92 of these events
  might have been directed toward the Earth, and we compared the timing
  of those with the Kp geomagnetic storm index in the days following
  the CME. Although the ``false alarm'' rate was high, we found that 15
  out of 21 (71%) of the Kp&gt;=6 storms could be accounted for as SOHO
  LASCO/EIT frontside halo CMEs. If we eliminate three Kp storms that
  occurred following LASCO/EIT data gaps, then the possible association
  rate was 15 out of 18 (83%).

Title: Coupling Between High and Low Latitudes as Observed with
    Lasco in the Solar Corona and in Interplanetary Space
Authors: Schwenn, R.
Bibcode: 2000AdSpR..26..771S
Altcode:
  From Skylab, Helios and Ulysses observations we had learnt already
  how closely the 3D heliosphere is related to the underlying coronal
  structure. Around solar activity minimum, large polar coronal holes
  dominate the major part of the heliosphere, through the high-speed
  solar wind streams emanating from them. A different type of solar
  wind is restricted to a narrow near-equatorial belt (about 30
  degrees in latitude). The magnetic topology is dominated by strong
  multipole components and multiple current sheets in the upper corona,
  and by a large-scale dipole field further outside, respectively. New
  observations by LASCO on SOHO cover both regions and may reveal clues
  to the processes responsible for the generation of the different types
  of solar wind

Title: Coronal Mass Ejections and Large Scale Structure of the Corona
Authors: Maia, D.; Vourlidas, A.; Pick, M.; Howard, R.; Schwenn, R.;
   Lamy, P.
Bibcode: 2000AdSpR..25.1843M
Altcode:
  A comparative study of two events accompanied by both a flare and a
  CME has been performed. The data analysis has been made by comparing
  the observations of the LASCO/SOHO coronagraphs with those of the
  Nancay radioheliograph. The observations show a clear connection
  between coronal green and red line transient activity, burst radio
  emission and the CME development which is due to successive loop
  interactions. Signatures of these interactions are given by the radio
  emission. One can identify successive sequences in the evolution
  of the coronal restructuring leading to the full development of the
  CME. Identification and timing of these sequences result from the radio
  emission analysis. For flare-CME events , the evolution takes place
  in the low corona and is extremely fast of the order, on a few minutes

Title: Hot Cores in Coronal Filament Cavities
Authors: Hudson, H.; Schwenn, R.
Bibcode: 2000AdSpR..25.1859H
Altcode:
  Filaments represent cold intrusions in the corona, embedded in magnetic
  configurations termed ``filament cavities.'' Such cavities may occur
  without actually containing prominence material. A cavity then may
  erupt, leading to a coronal mass ejection (CME). Studies of Yohkoh
  soft X-ray images have previously shown that such eruptions may contain
  elongated high-temperature regions closely aligned with the Hα filament
  material. We report in this paper multi-wavelength observations of an
  extremely stable filament cavity, observed by Yohkoh and SOHO during
  July-September 1997. Hot multi-thermal structures persistently occupied
  the core of this large-scale polar-crown cavity

Title: Coronal structure and dynamics near solar activity
    minimum. Proceedings. E2.2 Symposium of COSPAR Scientific Commission
    E held during the 32nd COSPAR Scientific Assembly, Nagoya (Japan),
    12 - 19 Jul 1998.
Authors: Watanabe, T.; Schwenn, R.
Bibcode: 2000AdSpR..25.....W
Altcode:
  The solar minimum between solar cycles 22 and 23 was considered the
  first opportunity to investigate solar and heliospheric physics during
  the solar activity minimum via a set of major space-born instruments. In
  these proceedings the main results and their theoretical implications
  are presented.

Title: Multi-wavelength Observations of the September 30, 1998 Event
    at the German-Argentinian Solar Observatory
Authors: Bagalá, L. G.; Stenborg, G.; Schwenn, R.; Bauer, O. H.;
   Fernández Borda, R.; Haerendel, G.
Bibcode: 1999ESASP.448..959B
Altcode: 1999mfsp.conf..959B; 1999ESPM....9..959B
  No abstract at ADS

Title: On the Rotation Rate of the Emission Solar Corona
Authors: Stenborg, G.; Schwenn, R.; Inhester, B.; Srivastava, N.
Bibcode: 1999ESASP.448.1107S
Altcode: 1999mfsp.conf.1107S; 1999ESPM....9.1107S
  No abstract at ADS

Title: Comparative Study of Coronal Mass Ejections Associated with
    Eruptive prominences
Authors: Srivastava, Nandita; Schwenn, Rainer; Stenborg, Guillermo
Bibcode: 1999ESASP.446..621S
Altcode: 1999soho....8..621S
  Coronal mass ejections associated with eruptive prominences often
  display a classical 3-part structure in white light, viz., a bright
  leading edge followed by a dark cavity devoid of material and an
  embedded prominence or core. However, the initiation of such CMEs and
  nature of their acceleration as they propagate outward in the corona
  are some of the basic questions that remain unsolved. In particular, the
  question of role of the prominence in triggering or driving the CME has
  not been settled yet. In this paper, we report observations of coronal
  mass ejections (CMEs) associated with eruptive quiescent prominences
  that occurred on June 2,1998 and June 21-22, 1998. A comparative study
  based on multi-wavelength observations is presented. Various features
  in three part structured, white-light CME as observed by LASCO C2
  and C3 coronagraphs aboard SOHO were compared with features in other
  wavelengths, for example, in FeXIV green and FeX red emission lines
  by LASCO-C1 coronagraph. These observations were combined with other
  data-sets in H-alpha, X-ray and radio wavelengths. The comparison
  provides an important clue to the understanding, the origin or the
  initiation of the CMEs. Measurements of speed and acceleration of
  these CMEs have also been made in order to understand the nature
  of propagation of the CMEs in the outer corona and the driver that
  triggers the onset of the CMEs.

Title: MICA Observations of Coronal Transients
Authors: Stenborg, G.; Schwenn, R.; Srivastava, N.
Bibcode: 1999ESASP.446..627S
Altcode: 1999soho....8..627S
  Dynamical processes are well known to occur in the inner solar
  atmosphere, many of them giving origin to spectacular eruptions known as
  coronal mass ejections. The projected velocity of propagation of these
  events ranges from less than 100 km/sec to greater than 1200 km/sec. In
  order to study the initial evolution of the faster processes it is
  necessary to image the inner corona at a very high cadence. Although
  ground-based observations of the corona are strongly affected by
  sky conditions they allow imaging at a high temporal resolution as
  compared to coronagraphic observations from space. In the recently
  inaugurated German-Argentinean Solar-Observatory at El Leoncito, San
  Juan, Argentina, a mirror coronagraph (MICA) daily images the inner
  solar corona with high temporal and spatial resolution in two spectral
  ranges: the well known green (~1.8 MK) and red (~1.0 MK) coronal lines
  at 5303 A and 6374 A respectively. It is essentially similar in design
  to LASCO-C1 on board SOHO, its field-of-view ranging from 1.05 to 2.0
  solar radii from the sun center. Thus, it is ideally suited to observe
  the hot material and reveal the fast processes that occur in the coronal
  plasma. In the last year MICA has recorded several fast and not so fast
  green line transients at a high temporal resolution. In this work we
  will present observations of a few such events. This study would allow
  us to have a better understanding of the conditions that trigger the
  coronal mass ejections and their propagation in the inner solar corona.

Title: SOHO, der ungetrübte Blick auf die Sonne.
Authors: Schwenn, R.; Wilhelm, K.
Bibcode: 1999S&WSp...4...38S
Altcode:
  No abstract at ADS

Title: LASCO FeXIV and FeX observations of the solar coronal rotation
    during the recent solar activity minimum
Authors: Inhester, B.; Stenborg, G.; Schwenn, R.; Srivastava, N.;
   Podlipnik, B.
Bibcode: 1999AIPC..471..297I
Altcode: 1999sowi.conf..297I
  We investigate the periodicity and recurrence of FeXIV and FeX emission
  structures with heliospheric latitude and distance above the Sun's
  surface. The data was observed by the LASCO C1 coronagraph on board
  the SOHO spacecraft during the solar minimum activity from April 1996
  to March 1997. For the green FeXIV emission line, reliable estimates
  of the solar rotation period could be obtained between -60 and 60
  degrees in latitude and between 1.1 and 2 solar radii. Our investigation
  confirms the results of (3) of an almost ridgidly rotating equatorial
  streamer belt with a rotation period of about 27.5+/-0.5 days. Even
  coronal emissivity structures with a shorter life time between 14 and
  27 days do not seem to rotate differentially. The FeX observations
  on the other hand do yield some indication of a reduced rotation for
  coronal structures over the solar poles. However, the error of the
  derived rotation period estimates is considerable so that the analysis
  of the FeX data does not allow a definite conclusion.

Title: Recent observations of the solar corona with a new ground-based
    Coronagraph in Argentina (MICA)
Authors: Stenborg, G.; Schwenn, R.; Srivastava, N.; Inhester, B.;
   Podlipnik, B.; Rovira, M.; Francile, C.
Bibcode: 1999AIPC..471..561S
Altcode: 1999sowi.conf..561S
  As part of the new German-Argentinian Solar-Observatory in El Leoncito,
  San Juan, Argentina, a new ground-based solar telescope (MICA: Mirror
  Coronagraph for Argentina) began to operate in August 1997. MICA is an
  advanced mirror coronagraph, its design being an almost exact copy of
  the LASCO-C1 instrument. Since its installation, it has been imaging the
  inner solar corona (1.05 to 2.0 solar radii) in two spectral ranges,
  corresponding to the emission lines of the Fe XIV and Fe X ions. The
  instrument can image the corona as fast as every minute. Thus, it is
  ideally suited to study fast processes in the inner corona. In this
  way it is a good complement for the LASCO-C1 instrument. We present
  a brief review of the characteristics of the instrument, and some
  recent observations.

Title: Radio signatures of a fast coronal mass ejection development
    on November 6, 1997
Authors: Maia, D.; Vourlidas, A.; Pick, M.; Howard, R.; Schwenn, R.;
   Magalhães, A.
Bibcode: 1999JGR...10412507M
Altcode:
  The Oporto radiospectrograph and the Nançay radioheliograph recorded
  a radio event on November 6, 1997, closely related in time with a flare
  on National Oceanic and Atmospheric Administration (NOAA) active region
  8100. At the beginning of the event the radio sources are located on a
  rather small volume in the vicinity of the flare site. In a timescale of
  only a few minutes the radio emission sites spread over a large volume
  in the corona, covering a range of 100° in heliolatitude. During the
  period of the radio event the Large Angle and Spectrometric Coronagraph
  (LASCO) on board the Solar and Heliospheric Observatory (SOHO) observed
  an extremely fast coronal mass ejection (CME), with a velocity around
  2000 kms<SUP>-1</SUP>. This CME presents the particularity of having
  a fast lateral expansion, giving it a shape reminiscent of a ``coat
  hanger.'' There is a very good association between the latitudinal
  extent and time development of the CME seen by LASCO and the radio
  sources recorded by the radio instruments.

Title: Measurements of flow speeds and acceleration in gradually
    evolving solar mass ejections as observed by LASCO
Authors: Srivastava, Nandita; Schwenn, Rainer; Inhester, Bernd;
   Stenborg, Guillermo; Podlipnik, Borut
Bibcode: 1999AIPC..471..115S
Altcode: 1999sowi.conf..115S
  We present observations of slowly evolving, balloon-type solar mass
  ejections observed by the LASCO coronagraphs aboard SOHO. These
  mass ejections are typically observed to rise gradually in the solar
  corona for several hours (&gt;20 hours) as large loops or balloons
  crossing the entire field of view of the coronagraphs. Usually, their
  angular extent does not change much. Analysis of several such cases of
  balloon-type mass ejections show that they rise with very slow speeds
  (less than 50 km s-1) up to a distance of 2 R<SUB>solar</SUB> and then
  are accelerated to higher speeds until 5 R<SUB>solar</SUB>. From a
  distance of about 20 R<SUB>solar</SUB>, the mass ejecta attain almost a
  constant speed ranging between 300 and 500 km s-1. The speed profiles
  obtained for individual mass ejections indicate that they trace out
  the slow solar wind and, thus, provide an insight into the initiation
  and the propagation of the CMEs into the solar wind.

Title: Combined Ulysses solar wind and SOHO coronal observations of
    several west limb coronal mass ejections
Authors: Funsten, H. O.; Gosling, J. T.; Riley, P.; Cyr, O. C. St.;
   Forsyth, R. J.; Howard, R. A.; Schwenn, R.
Bibcode: 1999JGR...104.6679F
Altcode:
  From October 1996 to January 1997, Ulysses was situated roughly above
  the west limb of the Sun as observed from Earth at a heliocentric
  distance of about 4.6 AU and a latitude of about 25°. This presents the
  first opportunity to compare Solar and Heliospheric Observatory (SOHO)
  limb observations of coronal mass ejections (CMEs) directly with their
  solar wind counterparts far from the Sun using the Ulysses data. During
  this interval, large eruptive events were observed above the west
  limb of the Sun by the Large Angle Spectrometric Coronagraph (LASCO)
  on SOHO on October 5, November 28, and December 21-25, 1996. Using
  the combined plasma and magnetic field data from Ulysses, the October
  5 event was clearly identified by several distinguishing signatures
  as a CME. The November 28 event was also identified as a CME that
  trailed fast ambient solar wind, although it was identified only by
  an extended interval of counterstreaming suprathermal electrons. The
  December 21 event was apparently characterized by a 6-day interval
  of nearly radial field and a plasma rarefaction. For the numerous
  eruptive events observed by the LASCO coronagraph during December
  23-25, Ulysses showed no distinct, individual CMEs, perhaps because
  of intermingling of two or more of the eruptive events. By mapping the
  Ulysses observations back in time to the Sun assuming a constant flow
  speed, we have identified intervals of plasma that were accelerated
  or decelerated between the LASCO and Ulysses observations.

Title: LASCO observations of the coronal rotation
Authors: Lewis, D. J.; Simnett, G. M.; Brueckner, G. E.; Howard,
   R. A.; Lamy, P. L.; Schwenn, R.
Bibcode: 1999SoPh..184..297L
Altcode:
  The near-rigid rotation of the corona above the differential rotation
  of the photosphere has important implications for the form of the
  global coronal magnetic field. The magnetic reconfiguring associated
  with the shear region where the rigidly-rotating coronal field lines
  interface with the differentially-rotating photospheric field lines
  could provide an important energy source for coronal heating. We present
  data on coronal rotation as a function of altitude provided by the Large
  Angle Spectrometric Coronagraph (LASCO) instrument aboard the Solar and
  Heliospheric Observatory (SOHO) spacecraft. LASCO comprises of three
  coronagraphs (C1, C2, and C3) with nested fields-of-view spanning 1.1
  R⊙ to 30 R⊙. An asymmetry in brightness, both of the Fe xiv emission
  line corona and of the broad-band electron scattered corona, has been
  observed to be stable over at least a one-year period spanning May
  1996 to May 1997. This feature has presented a tracer for the coronal
  rotation and allowed period estimates to be made to beyond 15 R⊙,
  up to 5 times further than previously recorded for the white-light
  corona. The difficulty in determining the extent of differential motion
  in the outer corona is demonstrated and latitudinally averaged rates
  formed and determined as a function of distance from the Sun. The
  altitude extent of the low latitude closed coronal field region is
  inferred from the determined rotation periods which is important to the
  ability of the solar atmosphere to retain energetic particles. For the
  inner green line corona (&lt;2 R⊙) we determine a synodic rotation
  period of (27.4±0.1) days, whereas, for the outer white- light corona,
  (&gt;2.5 R⊙) we determine a rotation period of (27.7±0.1) days.

Title: The Rotation of the Fe XIV Solar Corona During the Recent
    Solar Activity Minimum
Authors: Inhester, B.; Stenborg, G.; Schwenn, R.; Srivastava, N.;
   Podlipnik, B.
Bibcode: 1999SSRv...87..211I
Altcode:
  We analyze data observed by the LASCO C1 coronagraph on board the
  SOHO spacecraft during the solar minimum activity from April 1996
  to March 1997. Using the phase dispersion technique, we investigate
  the periodicity and recurrence of Fe XIV emission structures with
  heliospheric latitude and distance above the Sun's surface with high
  spatial resolution. We find no significant deviation from a rigidly
  rotating Fe XIV corona with latitude or with distance from the Sun
  even on these small scales. In agreement with earlier work, the coronal
  rotation period at solar minimum is about 27.5 ± 1 days.

Title: MICA: The Mirror Coronagraph for Argentina
Authors: Stenborg, G.; Schwenn, R.; Srivastava, N.; Inhester, B.;
   Podlipnik, B.; Rovira, M.; Francile, C.
Bibcode: 1999SSRv...87..307S
Altcode:
  As part of the new German-Argentinian Solar Observatory in El Leoncito,
  San Juan, Argentina, a new ground-based solar telescope (MICA) began
  to operate in August 1997. MICA is an advanced mirror coronagraph, its
  design being an almost exact copy of the LASCO-C1 instrument. Since its
  installation, it has been imaging the inner solar corona (1.05 to 2.0
  solar radii) in two spectral ranges corresponding to the emission lines
  of the Fe XIV and Fe X ions. The instrument can image the corona as fast
  as every minute. Thus, it is ideally suited to study fast processes in
  the inner corona. In this way, it is a good complement for the LASCO-C1
  instrument. After a brief review of the instrument, we present some
  recent observations showing the capabilities of the instrument.

Title: Observaciones de la corona solar interior con un coronógrafo
    de espejo
Authors: Stenborg, G.; Schwenn, R.; Francile, C.; Rovira, M.
Bibcode: 1999BAAA...43...22S
Altcode:
  El plasma de la corona solar es un buen indicador de las líneas de
  fuerza del campo magnético. Por lo tanto, el análisis de estructuras
  coronales cuasiestacionarias en la corona da importante información
  sobre el campo magnético y la actividad asociada. Se trata de poner
  límites a los modelos teóricos existentes mediante el estudio
  de distintas estructuras en la corona interior. En agosto de 1997
  comenzó a operar el coronógrafo solar (MICA) en El Leoncito como
  parte del Observatorio Solar Alemán-Argentino. Desde su instalación
  obtiene imágenes de la corona solar (1.05 a 2.0 radios solares)
  en 2 líneas espectrales correspondientes a la emisión de Fe XIV y
  Fe X. El instrumento puede obtener imágenes cada minuto por lo que
  es ideal para estudiar procesos rápidos. Presentamos observaciones
  recientes que muestran la capacidad del coronógrafo así como la
  evolución de algunos eventos dinámicos observados por MICA.

Title: Acceleration Profile of the Slow Solar Wind as Inferred from
    Gradual Mass Ejections Observed by LASCO
Authors: Srivastava, Nandita; Schwenn, Rainer; Inhester, Bernd;
   Stenborg, Guillermo; Podlipnik, Borut
Bibcode: 1999SSRv...87..303S
Altcode:
  The slow solar wind (&lt; 400 km s<SUP>-1</SUP>) appears to initiate
  from the regions in the corona where magnetic fields are closed, or from
  the interface between streamers and other coronal regions. The nature
  of the acceleration of slow solar wind is not yet well known. LASCO
  observations of gradually evolving mass ejections offer us a good
  opportunity to study the speed and acceleration profiles of the slow
  solar wind from a distance of 1.1 up to 30 R<SUB>⊙</SUB>. We present
  speed and acceleration profiles of slow solar wind, derived on the
  basis of measurements of mass flows in several cases of gradual mass
  ejections and present them in perspective of earlier work.

Title: Differences in the O<SUP>7+</SUP>/O<SUP>6+</SUP> ratio of
    magnetic cloud and non-cloud coronal mass ejections
Authors: Henke, T.; Woch, J.; Mall, U.; Livi, S.; Wilken, B.; Schwenn,
   R.; Gloeckler, G.; von Steiger, R.; Forsyth, R. J.; Balogh, A.
Bibcode: 1998GeoRL..25.3465H
Altcode:
  On its trajectory to Jupiter and over the poles of the Sun
  the Ulysses spacecraft has observed a considerable number of
  Coronal Mass Ejection (CME) transients in slow and in fast solar
  wind streams. The analysis of the magnetic field topology and the
  O<SUP>7+</SUP>/O<SUP>6+</SUP> charge state ratio of 56 of these events
  has yielded strong evidence for a systematic connection between the
  two features. Coronal mass ejections with magnetic cloud structure
  have an increased O<SUP>7+</SUP>/O<SUP>6+</SUP> ratio with respect
  to the ambient solar wind whereas non-cloud CMEs do not show enhanced
  O<SUP>7+</SUP>/O<SUP>6+</SUP> ratios. We discuss possible mechanisms
  based on the freezing-in concept that can account for the observation.

Title: Die neue Aktivität der Sonne.
Authors: Schwenn, R.
Bibcode: 1998S&W....37..724S
Altcode:
  No abstract at ADS

Title: Joint Nancay Radioheliograph and LASCO Observations of Coronal
    Mass Ejections - II. The 9 July 1996 Event
Authors: Pick, M.; Maia, D.; Kerdraon, A.; Howard, R.; Brueckner,
   G. E.; Michels, D. J.; Paswaters, S.; Schwenn, R.; Lamy, P.; Llebaria,
   A.; Simnett, G.; Lanzerotti, L. J.; Aurass, H.
Bibcode: 1998SoPh..181..455P
Altcode:
  The development of a coronal mass ejection on 9 July 1996 has been
  analyzed by comparing the observations of the LASCO/SOHO coronagraphs
  with those of the Nancay radioheliograph. The spatial and temporal
  evolution of the associated radioburst is complex and involves a
  long-duration continuum. The analysis of the time sequence of the
  radio continuum reveals the existence of distinct phases associated
  with distinct reconnection processes and magnetic restructuring
  of the corona. Electrons are accelerated in association with these
  reconnection processes. An excellent spatial association is found
  between the position and extension of the radio source and the CME seen
  by LASCO. Furthermore, it is shown that the topology and evolution
  of the source of the radio continuum involve successive interactions
  between two systems of loops. These successive interactions lead to
  magnetic reconnection, then to a large scale coronal restructuring. Thus
  electrons of coronal origin may have access to the interplanetary
  medium in a large range of heliographic latitudes as revealed by the
  Ulysses observations.

Title: Geomagnetic storms caused by coronal mass ejections (CMEs):
    March 1996 through June 1997
Authors: Brueckner, G. E.; Delaboudiniere, J. -P.; Howard, R. A.;
   Paswaters, S. E.; St. Cyr, O. C.; Schwenn, R.; Lamy, P.; Simnett,
   G. M.; Thompson, B.; Wang, D.
Bibcode: 1998GeoRL..25.3019B
Altcode:
  (1) All but two geomagnetic storms with Kp ≥ 6 during the operating
  period (March 1996 through June 1997) of the Large Angle Spectroscopic
  Coronagraph (LASCO) experiment on the Solar and Heliospheric Observatory
  (SOHO) spacecraft can be traced to Coronal Mass Ejections (CMEs). (2)
  These geomagnetic storms are not related to high speed solar wind
  streams. (3) The CMEs which cause geomagnetic effects, can be classified
  into two categories: Halo events and toroidal CMEs. (4) The CMEs are
  accompanied by Coronal Shock Waves as seen in the Extreme Ultraviolet
  Imaging Telescope (EIT) Fe XII images. (5) Some CMEs are related to
  flares, others are not. (6) In many cases, the travel time between
  the explosion on the Sun and the maximum geomagnetic activity is about
  80 hours.

Title: The Solar Minimum Active Region 7978, Its X2.6/1B Flare, CME,
    and Interplanetary Shock Propagation of 9 July 1996
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Galvin,
   A. B.; Garcia, H.; Ipavich, F. M.; Karlický, M.; Kiplinger, A.;
   Klassen, A.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappin,
   S. J.; Thompson, B. J.; Watari, S. I.; Michels, D. J.; Brueckner,
   G. E.; Howard, R. A.; Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.;
   Schwenn, R.
Bibcode: 1998SoPh..181..159D
Altcode:
  The first X-class flare in four years occurred on 9 July 1996. This
  X2.6/1B flare reached its maximum at 09:11 UT and was located in active
  region 7978 (S10° W30°) which was an old-cycle sunspot polarity
  group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before
  and after this event together with Yohkoh SXT images of the flare,
  radio observations of the type II shock, and GOES disk-integrated soft
  X-ray flux during an extended period that included energy build-up in
  this active region.

Title: Joint Nançay Radioheliograph and LASCO Observations of
    Coronal Mass Ejections - I. The 1 July 1996 Event
Authors: Maia, D.; Pick, M.; Kerdraon, A.; Howard, R.; Brueckner,
   G. E.; Michels, D. J.; Paswaters, S.; Schwenn, R.; Lamy, P.; Llebaria,
   A.; Simnett, G.; Aurass, H.
Bibcode: 1998SoPh..181..121M
Altcode:
  The development of a coronal mass ejection on 1 July 1996 has been
  analyzed by comparing the observations of the LASCO/SOHO coronagraph
  with those of the Nançay radioheliograph. This comparison brings new
  insight and very useful diagnosis for the study of CME events. It
  is shown that the initial instability took place in a small volume
  located above an active region and that the occurrence of short radio
  type III bursts implies a triggering process due to magnetic field
  interactions. The subsequent spatial and temporal evolution of the
  radio emission strongly suggests that the large scale structure becomes
  unstable within the first minute of the event.

Title: LASCO observations of an Earth-directed coronal mass ejection
    on May 12, 1997
Authors: Plunkett, S. P.; Thompson, B. J.; Howard, R. A.; Michels,
   D. J.; St. Cyr, O. C.; Tappin, S. J.; Schwenn, R.; Lamy, P. L.
Bibcode: 1998GeoRL..25.2477P
Altcode:
  Coronal mass ejections (CMEs) that occur near the center of the
  solar disk are most likely to impact Earth. Detection of such
  events as ‘halos’ in white-light coronagraphs has been somewhat
  controversial in recent years. We present observations from the LASCO
  coronagraphs on SOHO that provide convincing evidence of the detection
  of an Earth-directed CME on May 12, 1997. The event began at about
  04:35 UT and propagated outwards from the Sun with a projected speed
  of around 250 km s<SUP>-1</SUP>. Using some reasonable assumptions
  about the geometry of the CME, we estimate the true speed to be around
  600 km s<SUP>-1</SUP>. The onset of the event in LASCO is coincident
  (to within measurement uncertainties) with an eruptive event detected
  in extreme ultraviolet observations of the solar disk by the SOHO
  EIT. This is the first reported observation of a halo CME at projected
  distances greater than 10 R<SUB>⊙</SUB>, with a clearly identifiable
  solar origin. We discuss the possibility that at least some of the
  enhanced brightness observed by LASCO may be due to a compressional
  wave propagating in the corona.

Title: Origin of Streamer Material in the Outer Corona
Authors: Wang, Y. -M.; Sheeley, N. R., Jr.; Walters, J. H.; Brueckner,
   G. E.; Howard, R. A.; Michels, D. J.; Lamy, P. L.; Schwenn, R.;
   Simnett, G. M.
Bibcode: 1998ApJ...498L.165W
Altcode:
  We investigate the nature and origin of the outward-moving density
  inhomogeneities (``blobs'') detected previously with the Large Angle and
  Spectrometric Coronagraph on the Solar and Heliospheric Observatory. The
  blobs are concentrated around the thin plasma layer that surrounds
  the heliospheric current sheet and that constitutes the outer streamer
  belt; they represent only a small, fluctuating component of the total
  density within the plasma sheet. As noted before in Sheeley et al.,
  blobs are characterized by low speeds and are continually emitted
  from the elongated tips of helmet streamers at 3-4 R<SUB>solar</SUB>
  from Sun center. We suggest that both the blobs and the plasma sheet
  itself represent closed-field material injected into the solar wind as
  a result of footpoint exchanges between the stretched helmet-streamer
  loops and neighboring open field lines. The plasma sheet is thus
  threaded by newly reconnected, open magnetic field lines, which lend
  the white-light streamer belt its filamentary appearance. Since in
  situ observations at 1 AU show that the slow wind (with speeds below
  500 km s<SUP>-1</SUP>) spreads over an angular extent much greater
  than the &lt;~3° width of the plasma sheet, we deduce that a major
  component of this wind must originate outside the helmet streamers
  (i.e., from just inside coronal holes).

Title: The November 6, 1997 event: Radio signatures of the CME
    development
Authors: Maia, D.; Vourlidas, A.; Pick, M.; Howard, R.; Schwenn, R.;
   Magalhaes, A.; Carneiro, J.; Agostinho, R.
Bibcode: 1998cee..workE..57M
Altcode:
  The analysis of the November 6, 1997 event has taken advantage of the
  new capabilities of the OPorto Radiospectrograph and of the Nanccay
  Radioheliograph. The evolution of this event shows successive phases
  in time scales of a fraction of a second. It is shown that the CME
  observed by the LASCO/SOHO coronograph is the result of successive
  interactions of multiple loop systems which occur over a latitude range
  of about 100<SUP>circ</SUP>. These magnetic loop interactions lead to
  the creation of several electron acceleration sites which are widely
  separated in the corona. There is a close correspondance between the
  evolution of the CME seen by LASCO and the extend of radio sources
  seen by the radioheliograph. The association with particles detected
  by in situ measurements in the interplanetary medium is also presented.

Title: Magnetic Reconnection Phenomena in Interplanetary Space
    (invited)
Authors: Wei, F. S.; Schwenn, R.; Hu, Q.
Bibcode: 1998asct.conf..279W
Altcode:
  No abstract at ADS

Title: European Plans for the Solar/Heliospheric Stereo Mission
Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.;
   Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.;
   Maltby, P.; Rust, D.; Schwenn, R.
Bibcode: 1998ESASP.417..145B
Altcode: 1998cesh.conf..145B
  No abstract at ADS

Title: The structure and origin of magnetic clouds in the solar wind
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1998AnGeo..16....1B
Altcode: 1998AnG....16....1B
  Plasma and magnetic field data from the Helios 1/2 spacecraft have
  been used to investigate the structure of magnetic clouds (MCs) in the
  inner heliosphere. 46 MCs were identified in the Helios data for the
  period 1974-1981 between 0.3 and 1 AU. 85% of the MCs were associated
  with fast-forward interplanetary shock waves, supporting the close
  association between MCs and SMEs (solar mass ejections). Seven MCs
  were identified as direct consequences of Helios-directed SMEs, and
  the passage of MCs agreed with that of interplanetary plasma clouds
  (IPCs) identified as white-light brightness enhancements in the Helios
  photometer data. The total (plasma and magnetic field) pressure in MCs
  was higher and the plasma-&lt;beta&gt; lower than in the surrounding
  solar wind. Minimum variance analysis (MVA) showed that MCs can best be
  described as large-scale quasi-cylindrical magnetic flux tubes. The axes
  of the flux tubes usually had a small inclination to the ecliptic plane,
  with their azimuthal direction close to the east-west direction. The
  large-scale flux tube model for MCs was validated by the analysis
  of multi-spacecraft observations. MCs were observed over a range
  of up to ~60° in solar longitude in the ecliptic having the same
  magnetic configuration. The Helios observations further showed that
  over-expansion is a common feature of MCs. From a combined study of
  Helios, Voyager and IMP data we found that the radial diameter of MCs
  increases between 0.3 and 4.2 AU proportional to the distance, R, from
  the Sun as R0.8 (R in AU). The density decrease inside MCs was found to
  be proportional to R-2.4, thus being stronger compared to the average
  solar wind. Four different magnetic configurations, as expected from
  the flux-tube concept, for MCs have been observed in situ by the Helios
  probes. MCs with left- and right-handed magnetic helicity occurred
  with about equal frequencies during 1974-1981, but surprisingly,
  the majority (74%) of the MCs had a south to north (SN) rotation of
  the magnetic field vector relative to the ecliptic. In contrast, an
  investigation of solar wind data obtained near Earth's orbit during
  1984-1991 showed a preference for NS-clouds. A direct correlation
  was found between MCs and large quiescent filament disappearances
  (disparition brusques, DBs). The magnetic configurations of the
  filaments, as inferred from the orientation of the prominence axis,
  the polarity of the overlying field lines and the hemispheric helicity
  pattern observed for filaments, agreed well with the in situ observed
  magnetic structure of the associated MCs. The results support the model
  of MCs as large-scale expanding quasi-cylindrical magnetic flux tubes in
  the solar wind, most likely caused by SMEs associated with eruptions of
  large quiescent filaments. We suggest that the hemispheric dependence
  of the magnetic helicity structure observed for solar filaments can
  explain the preferred orientation of MCs in interplanetary space as
  well as their solar cycle behavior. However, the white-light features
  of SMEs and the measured volumes of their interplanetary counterparts
  suggest that MCs may not simply be just H&lt;alpha&gt;-prominences,
  but that SMEs likely convect large-scale coronal loops overlying the
  prominence axis out of the solar atmosphere.

Title: Comparison of Observations of the Coronal FeXIV Emission and
    the Solar Surface Magnetic Field
Authors: Inhester, B.; Schwenn, R.
Bibcode: 1997ESASP.415...47I
Altcode: 1997cpsh.conf...47I
  No abstract at ADS

Title: The Dynamics of the Quiet Corona as Observed by the LASCO C2
    and C3 Coronagraphs
Authors: Andrews, M. D.; Morrill, J. S.; Howard, R. A.; Biesecker,
   D. A.; Schwenn, R.; Liebaria, A.
Bibcode: 1997ESASP.415..303A
Altcode: 1997cpsh.conf..303A
  No abstract at ADS

Title: Evidence of an Erupting Magnetic Flux Rope: LASCO Coronal
    Mass Ejection of 1997 April 13
Authors: Chen, J.; Howard, R. A.; Brueckner, G. E.; Santoro, R.;
   Krall, J.; Paswaters, S. E.; St. Cyr, O. C.; Schwenn, R.; Lamy, P.;
   Simnett, G. M.
Bibcode: 1997ApJ...490L.191C
Altcode:
  A coronal mass ejection (CME) observed by LASCO exhibits evidence
  that its magnetic field geometry is that of a flux rope. The dynamical
  properties throughout the fields of view of C2 and C3 telescopes are
  examined. The results are compared with theoretical predictions based
  on a model of solar flux ropes. It is shown that the LASCO observations
  are consistent with a two-dimensional projection of a three-dimensional
  magnetic flux rope with legs that remain connected to the Sun.

Title: White-Light Coronal Mass Ejections: A New Perspective from
    LASCO
Authors: St. Cyr, O. C.; Howard, R. A.; Simnett, G. M.; Gurman, J. B.;
   Plunkett, S. P.; Sheeley, N. R.; Schwenn, R.; Koomen, M. J.; Brueckner,
   G. E.; Michels, D. J.; Andrews, M.; Biesecker, D. A.; Cook, J.; Dere,
   K. P.; Duffin, R.; Einfalt, E.; Korendyke, C. M.; Lamy, P. L.; Lewis,
   D.; Llebaria, A.; Lyons, M.; Moses, J. D.; Moulton, N. E.; Newmark,
   J.; Paswaters, S. E.; Podlipnik, B.; Rich, N.; Schenk, K. M.; Socker,
   D. G.; Stezelberger, S. T.; Tappin, S. J.; Thompson, B.; Wang, D.
Bibcode: 1997ESASP.415..103S
Altcode: 1997cpsh.conf..103S
  No abstract at ADS

Title: LASCO Observations of Disconnected Magnetic Structures Out
    to Beyond 28 Solar Radii During Coronal Mass Ejections
Authors: Simnett, G. M.; Tappin, S. J.; Plunkett, S. P.; Bedford,
   D. K.; Eyles, C. J.; St. Cyr, O. C.; Howard, R. A.; Brueckner, G. E.;
   Michels, D. J.; Moses, J. D.; Socker, D.; Dere, K. P.; Korendyke,
   C. M.; Paswaters, S. E.; Wang, D.; Schwenn, R.; Lamy, P.; Llebaria,
   A.; Bout, M. V.
Bibcode: 1997SoPh..175..685S
Altcode:
  Two coronal mass ejections have been well observed by the LASCO
  coronagraphs to move out into the interplanetary medium as disconnected
  plasmoids. The first, on July 28, 1996, left the Sun above the west
  limb around 18:00 UT. As it moved out, a bright V-shaped structure
  was visible in the C2 coronagraph which moved into the field-of-view
  of C3 and could be observed out to beyond 28 solar radii. The derived
  average velocity in the plane of the sky was 110 ± 5 km s<SUP>-1</SUP>
  out to 5 solar radii, and above 15 solar radii the velocity was 269
  ± 10 km s<SUP>-1</SUP>. Thus there is evidence of some acceleration
  around 6 solar radii. The second event occurred on November 5, 1996
  and left the west limb around 04:00 UT. The event had an average
  velocity in the plane of the sky of ∼54 km s<SUP>-1</SUP> below
  4 R⊙, and it accelerated rapidly around 5 R⊙ up to 310 ± 10 km
  s<SUP>-1</SUP>. In both events the rising plasmoid is connected back
  to the Sun by a straight, bright ray, which is probably a signature of
  a neutral sheet. In the November event there is evidence for multiple
  plasmoid ejections. The acceleration of the plasmoids around a projected
  altitude of 5 solar radii is probably a manifestation of the source
  surface of the solar wind.

Title: First View of the Extended Green-Line Emission Corona At
    Solar Activity Minimum Using the Lasco-C1 Coronagraph on SOHO
Authors: Schwenn, R.; Inhester, B.; Plunkett, S. P.; Epple, A.;
   Podlipnik, B.; Bedford, D. K.; Eyles, C. J.; Simnett, G. M.; Tappin,
   S. J.; Bout, M. V.; Lamy, P. L.; Llebaria, A.; Brueckner, G. E.;
   Dere, K. P.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.; Michels,
   D. J.; Moses, J. D.; Moulton, N. E.; Paswaters, S. E.; Socker, D. G.;
   St. Cyr, O. C.; Wang, D.
Bibcode: 1997SoPh..175..667S
Altcode:
  The newly developed C1 coronagraph as part of the Large-Angle
  Spectroscopic Coronagraph (LASCO) on board the SOHO spacecraft has
  been operating since January 29, 1996. We present observations
  obtained in the first three months of operation. The green-line
  emission corona can be made visible throughout the instrument's full
  field of view, i.e., from 1.1 R⊙ out to 3.2 R⊙ (measured from Sun
  center). Quantitative evaluations based on calibrations cannot yet be
  performed, but some basic signatures show up even now: (1) There are
  often bright and apparently closed loop systems centered at latitudes
  of 30° to 45° in both hemispheres. Their helmet-like extensions
  are bent towards the equatorial plane. Farther out, they merge into
  one large equatorial `streamer sheet' clearly discernible out to 32
  R⊙. (2) At mid latitudes a more diffuse pattern is usually visible,
  well separated from the high-latitude loops and with very pronounced
  variability. (3) All high-latitude structures remain stable on time
  scales of several days, and no signature of transient disruption of
  high-latitude streamers was observed in these early data. (4) Within
  the first 4 months of observation, only one single `fast' feature was
  observed moving outward at a speed of 70 km s<SUP>-1</SUP> close to
  the equator. Faster events may have escaped attention because of data
  gaps. (5) The centers of high-latitude loops are usually found at the
  positions of magnetic neutral lines in photospheric magnetograms. The
  large-scale streamer structure follows the magnetic pattern fairly
  precisely. Based on our observations we conclude that the shape
  and stability of the heliospheric current sheet at solar activity
  minimum are probably due to high-latitude streamers rather than to
  the near-equatorial activity belt.

Title: The Relationship of Green-Line Transients to White-Light
    Coronal Mass Ejections
Authors: Plunkett, S. P.; Brueckner, G. E.; Dere, K. P.; Howard,
   R. A.; Koomen, M. J.; Korendyke, C. M.; Michels, D. J.; Moses, J. D.;
   Moulton, N. E.; Paswaters, S. E.; St. Cyr, O. C.; Socker, D. G.;
   Wang, D.; Simnett, G. M.; Bedford, D. K.; Biesecker, D. A.; Eyles,
   C. J.; Tappin, S. J.; Schwenn, R.; Lamy, P. L.; Llebaria, A.
Bibcode: 1997SoPh..175..699P
Altcode:
  We report observations by the Large Angle Spectrometric Coronagraph
  (LASCO) on the SOHO spacecraft of three coronal green-line transients
  that could be clearly associated with coronal mass ejections (CMEs)
  detected in Thomson-scattered white light. Two of these events, with
  speeds &gt;25 km s<SUP>-1</SUP>, may be classified as `whip-like'
  transients. They are associated with the core of the white-light
  CMEs, identified with erupting prominence material, rather than with
  the leading edge of the CMEs. The third green-line transient has a
  markedly different appearance and is more gradual than the other two,
  with a projected outward speed &lt;10 km s<SUP>-1</SUP>. This event
  corresponds to the leading edge of a `streamer blowout' type of CME. A
  dark void is left behind in the emission-line corona following each of
  the fast eruptions. Both fast emission-line transients start off as a
  loop structure rising up from close to the solar surface. We suggest
  that the driving mechanism for these events may be the emergence of new
  bipolar magnetic regions on the surface of the Sun, which destabilize
  the ambient corona and cause an eruption. The possible relationship of
  these events to recent X-ray observations of CMEs is briefly discussed.

Title: MHD Interpretation of LASCO Observations of a Coronal Mass
    Ejection as a Disconnected Magnetic Structure
Authors: Wu, S. T.; Guo, W. P.; Andrews, M. D.; Brueckner, G. E.;
   Howard, R. A.; Koomen, M. J.; Korendyke, C. M.; Michels, D. J.; Moses,
   J. D.; Socker, D. G.; Dere, K. P.; Lamy, P. L.; Llebaria, A.; Bout,
   M. V.; Schwenn, R.; Simnett, G. M.; Bedford, D. K.; Eyles, C. J.
Bibcode: 1997SoPh..175..719W
Altcode:
  We present a qualitative and quantitative comparison of a single
  coronal mass ejection (CME) as observed by LASCO (July 28-29, 1996)
  with the results of a three-dimensional axisymmetric time-dependent
  magnetohydrodynamic model of a flux rope interacting with a helmet
  streamer. The particular CME considered was selected based on the
  appearance of a distinct `tear-drop' shape visible in animations
  generated from both the data and the model.

Title: EIT and LASCO Observations of the Initiation of a Coronal
    Mass Ejection
Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.;
   Korendyke, C. M.; Kreplin, R. W.; Michels, D. J.; Moses, J. D.;
   Moulton, N. E.; Socker, D. G.; St. Cyr, O. C.; Delaboudinière, J. P.;
   Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Hochedez, J. F.; Millier,
   F.; Song, X. Y.; Chauvineau, J. P.; Marioge, J. P.; Defise, J. M.;
   Jamar, C.; Rochus, P.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.;
   Neupert, W.; Clette, F.; Cugnon, P.; Van Dessel, E. L.; Lamy, P. L.;
   Llebaria, A.; Schwenn, R.; Simnett, G. M.
Bibcode: 1997SoPh..175..601D
Altcode:
  We present the first observations of the initiation of a coronal mass
  ejection (CME) seen on the disk of the Sun. Observations with the EIT
  experiment on SOHO show that the CME began in a small volume and was
  initially associated with slow motions of prominence material and a
  small brightening at one end of the prominence. Shortly afterward,
  the prominence was accelerated to about 100 km s<SUP>-1</SUP> and
  was preceded by a bright loop-like structure, which surrounded an
  emission void, that traveled out into the corona at a velocity of
  200-400 km s<SUP>-1</SUP>. These three components, the prominence,
  the dark void, and the bright loops are typical of CMEs when seen at
  distance in the corona and here are shown to be present at the earliest
  stages of the CME. The event was later observed to traverse the LASCO
  coronagraphs fields of view from 1.1 to 30 R⊙. Of particular interest
  is the fact that this large-scale event, spanning as much as 70 deg in
  latitude, originated in a volume with dimensions of roughly 35" (2.5
  x 10<SUP>4</SUP> km). Further, a disturbance that propagated across
  the disk and a chain of activity near the limb may also be associated
  with this event as well as a considerable degree of activity near the
  west limb.

Title: Origin and Evolution of Coronal Streamer Structure During
    the 1996 Minimum Activity Phase
Authors: Wang, Y. -M.; Sheeley, N. R., Jr.; Howard, R. A.; Kraemer,
   J. R.; Rich, N. B.; Andrews, M. D.; Brueckner, G. E.; Dere, K. P.;
   Koomen, M. J.; Korendyke, C. M.; Michels, D. J.; Moses, J. D.;
   Paswaters, S. E.; Socker, D. G.; Wang, D.; Lamy, P. L.; Llebaria,
   A.; Vibert, D.; Schwenn, R.; Simnett, G. M.
Bibcode: 1997ApJ...485..875W
Altcode:
  We employ coronal extrapolations of solar magnetograph data to interpret
  observations of the white-light streamer structure made with the LASCO
  coronagraph in 1996. The topological appearance of the streamer belt
  during the present minimum activity phase is well described by a model
  in which the Thomson-scattering electrons are concentrated around a
  single, warped current sheet encircling the Sun. Projection effects
  give rise to bright, jet-like structures or spikes whenever the current
  sheet is viewed edge-on multiple spikes are seen if the current sheet is
  sufficiently wavy. The extreme narrowness of these features in polarized
  images indicates that the scattering layer is at most a few degrees
  wide. We model the evolution of the streamer belt from 1996 April to
  1996 September and show that the effect of photospheric activity on
  the streamer belt topology depends not just on the strength of the
  erupted magnetic flux, but also on its longitudinal phase relative
  to the background field. Using flux transport simulations, we also
  demonstrate how the streamer belt would evolve during a prolonged
  absence of activity.

Title: The Green Line Corona and Its Relation to the Photospheric
    Magnetic Field
Authors: Wang, Y. -M.; Sheeley, N. R., Jr.; Hawley, S. H.; Kraemer,
   J. R.; Brueckner, G. E.; Howard, R. A.; Korendyke, C. M.; Michels,
   D. J.; Moulton, N. E.; Socker, D. G.; Schwenn, R.
Bibcode: 1997ApJ...485..419W
Altcode:
  Images of the green line corona made with the LASCO C1 coronagraph
  on SOHO are analyzed by applying current-free extrapolations to the
  observed photospheric field. The Fe XIV λ5303 emission is shown to
  be closely related to the underlying photospheric field strength. By
  modeling the observed intensity patterns as a function of latitude and
  height above the solar limb, we derive an approximate scaling law of the
  form n<SUB>foot</SUB> ~ &lt;B<SUB>foot</SUB>&gt;<SUP>0.9</SUP>, where
  n<SUB>foot</SUB> is the density of the green line-emitting plasma and
  &lt;B<SUB>foot</SUB>&gt; is the average field strength at the footprints
  of the coronal loop. The observed high-latitude enhancements in the
  green line corona are attributed to the poleward concentration of the
  large-scale photospheric field. The strongest such enhancements occur
  where the high-latitude unipolar fields become reconnected to active
  region flux at lower latitudes; the global emission pattern rotates
  quasi-rigidly at the rate of the dominant active region complex. The
  validity of the current-free approximation is assessed by comparing
  the topology of the observed and simulated green line structures.

Title: Measurements of Flow Speeds in the Corona Between 2 and 30
    R<SUB>⊙</SUB>
Authors: Sheeley, N. R.; Wang, Y. -M.; Hawley, S. H.; Brueckner,
   G. E.; Dere, K. P.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.;
   Michels, D. J.; Paswaters, S. E.; Socker, D. G.; St. Cyr, O. C.;
   Wang, D.; Lamy, P. L.; Llebaria, A.; Schwenn, R.; Simnett, G. M.;
   Plunkett, S.; Biesecker, D. A.
Bibcode: 1997ApJ...484..472S
Altcode:
  Time-lapse sequences of white-light images, obtained during sunspot
  minimum conditions in 1996 by the Large Angle Spectrometric Coronagraph
  on the Solar and Heliospheric Observatory, give the impression of
  a continuous outflow of material in the streamer belt, as if we
  were observing Thomson scattering from inhomogeneities in the solar
  wind. Pursuing this idea, we have tracked the birth and outflow of
  50-100 of the most prominent moving coronal features and find that:
  <P />1. They originate about 3-4 R<SUB>⊙</SUB> from Sun center as
  radially elongated structures above the cusps of helmet streamers. Their
  initial sizes are about 1 R<SUB>⊙</SUB> in the radial direction and
  0.1 R<SUB>⊙</SUB> in the transverse direction. <P />2. They move
  radially outward, maintaining constant angular spans and increasing
  their lengths in rough accord with their speeds, which typically
  double from 150 km s<SUP>-1</SUP> near 5 R<SUB>⊙</SUB> to 300 km
  s<SUP>-1</SUP> near 25 R<SUB>⊙</SUB>. <P />3. Their individual speed
  profiles v(r) cluster around a nearly parabolic path characterized
  by a constant acceleration of about 4 m s<SUP>-2</SUP> through most
  of the 30 R<SUB>⊙</SUB> field of view. This profile is consistent
  with an isothermal solar wind expansion at a temperature of about
  1.1 MK and a sonic point near 5 R<SUB>⊙</SUB>. <P />Based on their
  relatively small initial sizes, low intensities, radial motions, slow
  but increasing speeds, and location in the streamer belt, we conclude
  that these moving features are passively tracing the outflow of the
  slow solar wind.

Title: Using LASCO Observations to Infer Solar Wind Flow Near the Sun
Authors: Sheeley, N. R., Jr.; Brueckner, G. E.; Dere, K. P.; Howard,
   R. A.; Korendyke, C. M.; Michels, D. J.; Socker, D. G.; Koomen, M. J.;
   Paswaters, S. E.; Wang, D.; Lamy, P. L.; Llebaria, A.; Schwenn, R.;
   St Cyr, O. C.; Simnett, G. M.; Plunkett, S.; Biesecker, D. A.
Bibcode: 1997SPD....28.0301S
Altcode: 1997BAAS...29..907S
  We have continued to track individual coronal features as they become
  detached from helmet streamers and move outward from the Sun. The
  composite speed profile for 50-100 features has a parabolic shape
  with a constant acceleration of about 4 m/s(2) over the 2-30 R field
  of view. This well-determined speed profile contrasts strongly with
  the nearly uniform scatterplot obtained for about 50 nominal coronal
  mass ejections (CMEs), and suggests that these detached bits of coronal
  ``debris'' are passively tracing the speed of the slow solar wind. We
  have also begun the more difficult task of tracking outflow along
  polar plumes and will summarize these results as of June 1997.

Title: Pressure enhancement associated with meridional flow in
high-speed solar wind: possible evidence for an interplanetary
    magnetic flux rope
Authors: Tu, C. -Y.; Marsch, E.; Ivory, K.; Schwenn, R.
Bibcode: 1997AnGeo..15..137T
Altcode: 1997AnG....15..137T
  A sizable total-pressure (magnetic pressure plus kinetic pressure)
  enhancement was found within the high-speed wind stream observed by
  Helios 2 in 1976 near 0.3 AU. The proton density and temperature and
  the magnetic magnitude simultaneously increased for about 6 h. This
  pressure rise was associated with a comparatively large southward
  flow velocity component (with Vz &lt;&gt;~&lt;&gt; -100 km · s-1)
  and magnetic-field rotation. The pressure enhancement was associated
  with unusual features in the electron distribution function. It shows a
  wide angular distribution of electron counting rates in the low-energy
  (57.8 eV) channel, while previous to the enhancement it exhibits a
  wide angular distribution of electron count rate in the high-energy
  (112, 221 and 309 eV) channels, perhaps indicating the mirroring of
  electrons in the converging field lines of the background magnetic
  field. These fluid and kinetic phenomena may be explained as resulting
  from an interplanetary magnetic flux rope which is not fully convected
  by the flow but moves against the background wind towards the Sun.

Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 1: Solar Data
Authors: Andrews, M. D.; Dryer, M.; Aurass, H.; DeForest, C.;
   Kiplinger, A. L.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappipn,
   S. J.; Thompson, B. J.; Watari, S. I.; Lamy, P.; Mann, G.; Schwenn,
   R.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M.
Bibcode: 1997ESASP.404..169A
Altcode: 1997cswn.conf..169A
  No abstract at ADS

Title: Characterisation of Polar Plumes from LASCO-C2 Images in
    Early 1996
Authors: Lamy, P.; Liebaria, A.; Koutchmy, S.; Reynet, P.; Molodensky,
   M.; Howard, R.; Schwenn, R.; Simnett, G.
Bibcode: 1997ESASP.404..487L
Altcode: 1997cswn.conf..487L
  No abstract at ADS

Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 2: Propagation
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Karlicky,
   M.; Kiplinger, A.; Klassen, A.; Meisner, R.; Ipavich, F. M.; Galvin,
   A. B.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.;
   Watari, S. -I.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.;
   Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.; Schwenn, R.
Bibcode: 1997ESASP.404..331D
Altcode: 1997cswn.conf..331D
  No abstract at ADS

Title: Acceleration of Coronal Mass Ejections in the Upper Corona:
    Observations from Lasco/Soho
Authors: Simnett, G. M.; Tappin, S. J.; Brueckner, G. E.; Howard,
   R. A.; Lamy, P.; Michels, D. J.; Schwenn, R.
Bibcode: 1997ICRC....1..181S
Altcode: 1997ICRC...25a.181S
  No abstract at ADS

Title: Dynamical Evolution of a Coronal Mass Ejection (CME) to
Magnetic Cloud: A Preliminary Analysis of the January 6-10, 1997
    CME Observed by LASCO/SOHO
Authors: Wu, S. T.; Guo, W. P.; Michels, D. J.; Andrews, M. D.;
   Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.;
   Moses, J. D.; Socker, D. G.; Dere, K. P.; Bougeret, Jean-Louis; Lamy,
   P. L.; Schwenn, R.; Simnett, G. M.
Bibcode: 1997ESASP.404..739W
Altcode: 1997cswn.conf..739W
  No abstract at ADS

Title: EIT and LASCO Observations of the Initiation of a Coronal
    Mass Ejection
Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.;
   Korendyke, C. M.; Michels, D. J.; Moses, J. D.; Moulton, N. E.; Socker,
   D. G.; Delaboudiniere, J. P.; Hochedez, J. F.; Lamy, P. L.; Schwenn,
   R.; Simnett, G. M.; Defise, J. M.; Catura, R. C.
Bibcode: 1997IAUJD..19E..18D
Altcode:
  We present the first observations of the initiation of a corona mass
  ejection (CME) seen on the disk of the Sun. Observations with the EIT
  and LASCO experiments on SOHO show that the CME starts in a small volume
  and is associated with slow motions of prominence material. At about
  the same time, a shock wave is created that travels out into the corona
  at a velocity of 400 km s^{-1} ahead of an eruptive prominence. This
  shock wave is clearly the event that is later seen as a classical CME
  when observed in the coronagraph above 1.5 solar radii. Although the
  CME clearly starts in a small region, a chain of activity near the
  limb may also be associated with this event.

Title: Mirror Coronograph for Argentina (MICA). Primera Luz
Authors: Stenborg, G.; Epple, A.; Schwenn, R.; Francile, C.; Rovira, M.
Bibcode: 1997BAAA...41..115S
Altcode:
  En Julio de 1997 se terminó con la primera parte de la instalación del
  ``Coronógrafo de Espejo para la Argentina'' en la estación de altura
  Carlos U. Cesco (El Leoncito), gracias al esfuerzo de la gente del Max
  Planck Institut für Aeronomie (Alemania), del OAFA y del IAFE. Dicho
  coronógrafo forma parte de un programa de ciencia bilateral entre
  Alemania y Argentina. El propósito del mismo, en conjunción con otros
  telescopios solares y terrestres, es contribuir a un mejor entendimiento
  de cuestiones fundamentales de la física solar. Para ello, ya está
  observando la corona de emisión en el verde (Fe XIV), rojo (Fe X)
  y Hα entre 1.05 y 2 radios solares aproximadamente. El diseño del
  instrumento, el cual fuera ya presentado en esta misma reunión en La
  Plata en 1996, es esencialmente similar al del telescopio LASCO-C1 a
  bordo del Solar Heliospheric Observatory (SOHO). La adquisición de
  datos se realiza con un CCD de 1280x1024 pixels, codificando en 12
  bits, pudiendo ser el mismo operado en forma remota. En esta reunión
  presentaremos algunas de las observaciones realizadas durante la puesta
  a punto del instrumento en el período julio-setiembre de 1997. Asimismo
  expondremos cómo y por qué sus resultados complementarán a los de
  su par en el espacio.

Title: Electronic Densities in Coronal Holes from LASCO-C2 Images
Authors: Lamy, P.; Quemerais, E.; Llebaria, A.; Bout, M.; Howard,
   R.; Schwenn, R.; Simnett, G.
Bibcode: 1997ESASP.404..491L
Altcode: 1997cswn.conf..491L
  No abstract at ADS

Title: Joint Radioheliograph and LASCO Observations of Coronal
    Mass Ejections
Authors: Pick, M.; Maia, D.; Howard, R.; Kerdraon, A.; Brueckner,
   G. E.; Lamy, P.; Schwenn, R.; Aurass, H.
Bibcode: 1997ESASP.404..601P
Altcode: 1997cswn.conf..601P
  No abstract at ADS

Title: Visibility of Earth-Directed Coronal Mass Ejections
Authors: Michels, D. J.; Howard, R. A.; Koomen, M. J.; Plunkett, S.;
   Brueckner, G. E.; Lamy, Ph.; Schwenn, R.; Biesecker, D. A.
Bibcode: 1997ESASP.404..567M
Altcode: 1997cswn.conf..567M
  No abstract at ADS

Title: Non-Thermal Weak Radio Bursts: X-ray and/or EUV Counterparts?
Authors: Crosby, N.; Vilmer, N.; Chiuderi Drago, F.; Pick, M.;
   Kerdraon, A.; Khan, J.; Schwenn, R.
Bibcode: 1997ESASP.404..299C
Altcode: 1997cswn.conf..299C
  No abstract at ADS

Title: Analysis of a High Latitude Slow CME with Travelling Ejecta
Authors: Boulade, S.; Delanné, C.; Koutchmy, S.; Lamy, P.; Llebaria,
   A.; Howard, R.; Schwenn, R.; Simnett, G.
Bibcode: 1997ESASP.404..217B
Altcode: 1997cswn.conf..217B
  No abstract at ADS

Title: Enhancing the Spatial Resolution of Solar Coronagraph
    Observations Using Dynamic Imaging
Authors: Zaccheo, T. S.; Karovska, M.; Cook, J. W.; Howard, R. A.;
   Brueckner, G. E.; Korendyke, C. M.; Schwenn, R.
Bibcode: 1996ApJ...471.1058Z
Altcode:
  The Large Angle Spectrometric Coronagraph (LASCO) Cl coronagraph on
  board the Solar and Heliospheric Observatory (SOHO) is designed to
  image the corona from 1.1 to 3.0 R<SUB>sun</SUB>. The resolution of
  C1 is defined by the size of its CCD pixels, which correspond to 5".6,
  and not by the diffraction limit of the optical system, which may be as
  small as 3". The resolution of Cl can be improved using the technique of
  "dynamic imaging" the process of acquiring successive images of the same
  scene using sub- pixel displacements of the steerable primary mirror. We
  developed a technique we call the fractional pixel restoration (F PR)
  algorithm that utilizes these observations to construct an image with
  improved resolution. Simulations were used to test this algorithm and
  to explore its limitations. We also applied the direct co-addition
  and FPR algorithms to laboratory preffight images of a wire mesh
  grid. These results show that the resolution of the C1 coronagraph can
  be significantly enhanced, even in the presence of noise and modest
  differences between successive images. In some cases, the results can
  even reach the diffraction limit of the telescope.

Title: LASCO spectrometric Lyot coronagraph tunable passband filter
Authors: Socker, Dennis G.; Brueckner, Guenter E.; Korendyke, Clarence
   M.; Lilley, D. N.; Steenson, James H.; Kohn, Preston M.; Lyons, Gail
   M.; Owens, Michael L.; Moulton, Norman E.; Moye, Robert W.; Schwenn,
   Rainer; Hemmerich, P.
Bibcode: 1996SPIE.2804..126S
Altcode:
  Spectrometric and spectropolarimetric aspects of the Lyot coronagraph
  flown aboard the ESA/NASA SOlar Heliospheric Observatory (SOHO) are
  presented. The coronagraph is one of the three channels comprising
  the LASCO coronagraph and the only channel with spectroradiometric
  capabilities. Among the primary science objectives assigned to the
  Lyot coronagraph are the determination of the mechanisms responsible
  for the acceleration of the solar wind and the heating of the
  corona. Spectrometric and spectropolarimetric coronal observations
  made with the Lyot coronagraph are used in support of these and
  other objectives. We describe the Lyot instrument design from the
  imaging coronal spectrometer perspective. The rationale for use
  of a tunable Fabry-Perot interferometer as the spectral resolving
  element is outlined. The relationships between spectral resolving
  power, interferometer diameter, telescope entrance stop diameter and
  coronal field of view as it applies to LASCO is reviewed. Performance
  requirements imposed on the interferometer by the coronal source and the
  science objectives are described. The optical, mechanical, electronic
  and semi-automated control designs as well as the interferometer
  modes of operation are summarized. The actual flight model Fabry-Perot
  interferometer performance allows the instrument to operate with high
  luminosity and with finesse values high enough to provide approximately
  optimal passband widths and reasonable tunable ranges about useful
  spectral features. We conclude with some early results indicative of
  the flight performance of the instrument.

Title: STEREO: a solar terrestrial event observer mission concept
Authors: Socker, Dennis G.; Antiochos, S. K.; Brueckner, Guenter E.;
   Cook, John W.; Dere, Kenneth P.; Howard, Russell A.; Karpen, J. T.;
   Klimchuk, J. A.; Korendyke, Clarence M.; Michels, Donald J.; Moses,
   J. Daniel; Prinz, Dianne K.; Sheely, N. R.; Wu, Shi T.; Buffington,
   Andrew; Jackson, Bernard V.; Labonte, Barry; Lamy, Philippe L.;
   Rosenbauer, H.; Schwenn, Rainer; Burlaga, L.; Davila, Joseph M.; Davis,
   John M.; Goldstein, Barry; Harris, H.; Liewer, Paulett C.; Neugebauer,
   Marcia; Hildner, E.; Pizzo, Victor J.; Moulton, Norman E.; Linker,
   J. A.; Mikic, Z.
Bibcode: 1996SPIE.2804...50S
Altcode:
  A STEREO mission concept requiring only a single new spacecraft has been
  proposed. The mission would place the new spacecraft in a heliocentric
  orbit and well off the Sun- Earth line, where it can simultaneously view
  both the solar source of heliospheric disturbances and their propagation
  through the heliosphere all the way to the earth. Joint observations,
  utilizing the new spacecraft and existing solar spacecraft in earth
  orbit or L1 orbit would provide a stereographic data set. The new
  and unique aspect of this mission lies in the vantage point of the
  new spacecraft, which is far enough from Sun-Earth line to allow an
  entirely new way of studying the structure of the solar corona, the
  heliosphere and solar-terrestrial interactions. The mission science
  objectives have been selected to take maximum advantage of this new
  vantage point. They fall into two classes: those possible with the
  new spacecraft alone and those possible with joint measurements using
  the new and existing spacecraft. The instrument complement on the new
  spacecraft supporting the mission science objectives includes a soft
  x-ray imager, a coronagraph and a sun-earth imager. Telemetry rate
  appears to be the main performance determinant. The spacecraft could
  be launched with the new Med-Lite system.

Title: A method for shock determination and classification
Authors: Liu, Shuhui; Marsch, E.; Schwenn, R.; Rosenbauer, H.
Bibcode: 1996AIPC..382..376L
Altcode:
  A new method to present, to determine and to classify shocks from in
  situ measurements is developed, using normalized velocities up- and
  down-stream in a velocity V<SUB>1</SUB>-V<SUB>2</SUB> diagram. With
  this method one can show how the observed shock solutions vary with
  different time averages over the data from the up- and down-stream
  region. Some shock events have been analyzed. The Helios measurements
  show, that the solutions for the fast forward shock are confined well
  in the 1--&gt;2 region. The different solutions, obtained by means of
  straightforward averages with different time intervals, are somewhat
  distributed in the normalized V<SUB>1</SUB>-V<SUB>2</SUB> diagram. But
  only the shock solutions which are consistent with the Rankine-Hugoniot
  relations and an entropy increase really define a particular shock.

Title: Mass ejections from the sun and their interplanetary
    counterparts
Authors: Schwenn, R.
Bibcode: 1996AIPC..382..426S
Altcode:
  Since the first observations of solar mass ejection events in the early
  seventies by OSO 7 and Skylab, a few thousand of these remarkable
  dynamic incidents have been observed, covering about two full solar
  activity cycles. The mass ejecta mainly include hot coronal plasma and
  cold prominence material in variable amounts. This is the reason why the
  often used term CME (for coronal mass ejection) should be replaced by
  the more neutral term SME (solar mass ejection). The ejecta are often
  recognized in the form of interplanetary plasma clouds detected in the
  distant solar wind by appropriately located spacecraft. Clouds which
  have been energetic enough to drive large scale interplanetary shock
  waves can be identified most readily, but clouds without associated
  shocks do also occur. Plasma clouds can be characterized by a variety
  of signatures, indicating that they actually originate from injections
  of different material into the ambient solar wind. Quite a few crucial
  problems still remain to be addressed by the upcoming SOHO mission.

Title: LASCO Observations of the 03Feb96 Streamer Blow-out
Authors: Andrews, M. D.; Korendyke, C. M.; Koomen, M. J.; Brueckner,
   G. E.; Cook, J. W.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Moses,
   J. D.; Morrill, J. S.; Moulton, N. E.; Paswaters, S. E.; Socker, D. G.;
   St. Cyr, O. C. St.; Wang, D.; Lamy, P. L.; Llebaria, A.; Bout, M. V.;
   Schwenn, R.; Podlipnik, B.; Bedford, D. K.; Biesecker, D. A.; Eyles,
   C. J.; Plunkett, S.; Simnett, G. M.
Bibcode: 1996AAS...188.3716A
Altcode: 1996BAAS...28..880A
  The C2 and C3 telescopes on the Large Angle Spectrometric Coronograph
  (LASCO) have recorded images of a Streamer Blow-out which occured
  on 03Feb96. We will present a series of images produces by combining
  data from the 2 coronographs. These images show a rapid evolution of
  the coronal streamer belt over projected distances of 2 to 20 solar
  radii. The streamer belt shows a dramatic brightening, which is seen to
  propagate outward. A bubble-like structure is seen to move away from
  the Sun and expand. At the end of this event, the equatorial corona
  is significantly less bright than prior to the event.

Title: LASCO Observations of the Solar Corona to 32 R<SUB>sun</SUB>
Authors: Cook, J. W.; Koomen, M. J.; Korendyke, C. M.; Brueckner,
   G. E.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Morrill, J. S.;
   Moses, J. D.; Socker, D. G.; Paswaters, S. E.; Wang, D.; Moulton,
   N. E.; Cyr, O. C. St.; Andrews, M. D.; Schwenn, R.; Podlipnik, B.;
   Lamy, P. L.; Llebaria, A.; Bout, M. V.; Simnett, G. M.; Bedford,
   D. K.; Eyles, C. J.; Plunkett, S.; Biesecker, D. A.
Bibcode: 1996AAS...188.3717C
Altcode: 1996BAAS...28..880C
  The Large Angle Spectrometric Coronagraph (LASCO) was launched on
  board the SOHO satellite on 2 December 1995. The C3 externally-occulted
  coronagraph of LASCO observes the solar corona over a field from 3.7-32
  R_ ⊙, using a 1024x1024 CCD detector with a pixel size corresponding
  to 56 arc sec. Observations can be made using color filters ranging
  from the blue (420-520 nm) to the near-IR (860-1050 nm), and through
  polarizing filters. We report on early observations of the solar corona
  out to 32 R<SUB>sun</SUB>.

Title: Preliminary Photometric Calibration of LASCO C3 Coronagraph
    Images using Pre-Flight Laboratory Images of Standard Sources and
    In-Flight Images of Standard Stars
Authors: Korendyke, C. M.; Koomen, M. J.; Andrews, M. D.; Brueckner,
   G. E.; Cook, J. W.; Dere, K. P.; Howard, R. A.; Michels, D. J.;
   Moses, J. D.; Morrill, J. S.; Moulton, N. E.; Paswaters, S. E.;
   Socker, D. G.; St. Cyr, O. C.; Wang, D.; Lamy, P. L.; Llebaria, A.;
   Bout, M. V.; Schwenn, R.; Podlipnik, B.; Bedford, D. K.; Biesecker,
   D. A.; Eyles, C. J.; Plunkett, S.; Simnett, G. M.
Bibcode: 1996AAS...188.3621K
Altcode: 1996BAAS...28..876K
  The C3 coronagraph is a wide field (+/-8.0 degrees), externally
  occulted, white light coronagraph. The instrument is one of three
  coronagraphs comprising the Large Angle Spectrometric COronagraph
  (LASCO) experiment mounted on the Solar Heliospheric Observatory
  satellite. The satellite was launched on Dec. 2, 1996; C3 observations
  began in early Jan. 1997. The coronagraph optical train includes a set
  of five broadband color filters mounted in a wheel. Prior to flight,
  an image was obtained through each color filter of a well characterized,
  rear-illuminated, opal glass diffusing screen. The C3 in-flight images,
  in addition to the coronal structures, also contain several hundred
  bright stars. We present a comparison of the photometric calibration
  derived from standard stars with the laboratory measurements. The
  resulting calibration is then used to examine color variations in the
  white light corona over the field of view. The LASCO experiment was
  developed by a scientific consortium of members from NRL (USA), MPAe
  (Germany), LAS (France) and U. Birmingham (United Kingdom).

Title: Signatures of fast CMEs in interplanetary space
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1996AdSpR..17d.319B
Altcode: 1996AdSpR..17..319B
  While fast coronal mass ejections (CMEs) have been uniquely identified
  as sources of transient shock-disturbances in interplanetary space,
  it is less understood why different kinds of plasma and magnetic field
  signatures are found in the individual post-shock flows. It is an
  open question if CMEs can produce various types of solar wind ejecta,
  e.g. magnetic flux ropes or flows without highly ordered internal
  fields. To help further clarify the consequences of fast CMEs in
  interplanetary space we have examined shock events measured by the
  Helios 1 spacecraft during the years 1979-1981 for which the associated
  CME has been directly observed with the coronagraph onboard the P78/1
  satellite. Seventeen (68%) out of 25 shock-disturbances were followed
  by clearly discernible driver gas signatures, but only 7 (41%) of the
  driver gases were magnetic clouds.

Title: An Essay on Terminology, Myths and Known Facts: Solar Transient
    - Flare - CME - Driver Gas - Piston - BDE - Magnetic Cloud - Shock
    Wave - Geomagnetic Storm
Authors: Schwenn, Rainer
Bibcode: 1996Ap&SS.243..187S
Altcode: 1996IAUCo.154..187S
  In the field of solar-terrestrial relations a clear and unique
  terminology is needed in order to abolish and avoid unnecessary
  confusion between the scientists from several involved disciplines. For
  example, the widely used abbreviationCME (for coronal mass ejection)
  has turned out to be somewhat misleading. Early on it had been known
  that other than coronal material is often involved in such events. The
  discoverers observed transient events of mass ejections from the sun,
  which could be observed in the corona owing to the newly available
  coronagraphs. This article is meant to clarify the terminology,
  with emphasis on giving credit to the original discoverers and the
  terms they introduced. With this aim in mind I suggest some minor
  modifications of the terminology.

Title: Descripción del coronógrafo a ser instalado en Argentina
    (MICA)
Authors: Stenborg, G.; Francile, C.; Schwenn, R.; Epple, A.; Rovira, M.
Bibcode: 1996BAAA...40R..42S
Altcode:
  El ``Coronógrafo de espejo para Argentina'' es un telescopio solar
  terrestre a ser colocado en el Observatorio Astronómico Félix Aguilar
  (El Leoncito), antes de finalizar 1996, como parte de un programa de
  ciencia bilateral entre Alemania y Argentina. Eclipses fotográficos
  de alta resolución han revelado que la corona solar es altamente
  estructurada y variable. De hecho, está contínuamente deformada y
  moldeada por los movimientos convectivos de los extremos de los arcos
  magnéticos en la fotosfera, estando, en muchas oportunidades, afectada
  por explosivas liberaciones de energía. MICA, en conjunción con otros
  telescopios solares espaciales y terrestres, tratará de contribuir al
  entendimiento de cuestiones fundamentales de la física solar. Entre
  ellas: cómo la corona está siendo calentada, dónde y cómo el
  viento solar es acelerado, qué causa los transitorios coronales,
  etc. Para ello investigará la distribución de los parámetros del
  plasma y su evolución con el tiempo, la estructura espacial de la
  corona en fina y gran escala, procesos que ocurren en los transitorios
  coronales y factores que los disparan, etc. Para responder a estas
  cuestiones MICA observará la atmósfera solar por sobre el limbo
  entre 1.1 y 2 radios solares aproximadamente, usando un nuevo tipo
  de sistema coronográfico que permite suprimir el brillo del disco
  solar suficientemente bien, tomando las imágenes con una cámara CCD
  de 1024x1024 pixels, codificada en 12 bits, pudiendo el mismo ser
  operado en forma remota. En la presente exposición describiremos
  las características del instrumento, cómo será controlado y
  qué esperamos observar basados en las imágenes obtenidas por los
  telescopios de similares características LASCO C1 a bordo del SOHO
  y PICO (ubicado en el Observatorio de Pic du Midi, Francia).

Title: Observations of the comet Hyakutake by the LASCO coronagraph
    on the SOHO satellite.
Authors: Andrews, M. D.; Paswaters, S. E.; Brueckner, G. E.; Korendyke,
   C. M.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Moses, J. D.;
   Morril, J. S.; Moulton, N. E.; Socker, D. G.; St. Cyr, O. C.; Wang,
   D.; Lamy, P. L.; Llebaria, A.; Bout, M. V.; Schwenn, R.; Podlipnik,
   B.; Bedford, D. K.; Biesecker, D. A.; Eyles, C. J.; Plunket, S.;
   Simnet, G. M.
Bibcode: 1996BAAS...28.1195A
Altcode:
  No abstract at ADS

Title: The Large Angle Spectroscopic Coronagraph (LASCO)
Authors: Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke,
   C. M.; Michels, D. J.; Moses, J. D.; Socker, D. G.; Dere, K. P.;
   Lamy, P. L.; Llebaria, A.; Bout, M. V.; Schwenn, R.; Simnett, G. M.;
   Bedford, D. K.; Eyles, C. J.
Bibcode: 1995SoPh..162..357B
Altcode:
  The Large Angle Spectroscopic Coronagraph (LASCO) is a three
  coronagraph package which has been jointly developed for the Solar
  and Heliospheric Observatory (SOHO) mission by the Naval Research
  Laboratory (USA), the Laboratoire d'Astronomie Spatiale (France),
  the Max-Planck-Institut für Aeronomie (Germany), and the University
  of Birmingham (UK). LASCO comprises three coronagraphs, C1, C2, and C3,
  that together image the solar corona from 1.1 to 30 R<SUB>⊙</SUB> (C1:
  1.1 - 3 R<SUB>⊙</SUB>, C2: 1.5 - 6 R<SUB>⊙</SUB>, and C3: 3.7 - 30
  R<SUB>⊙</SUB>). The C1 coronagraph is a newly developed mirror version
  of the classic internally-occulted Lyot coronagraph, while the C2 and
  C3 coronagraphs are externally occulted instruments. High-resolution
  imaging spectroscopy of the corona from 1.1 to 3 R<SUB>⊙</SUB> can
  be performed with the Fabry-Perot interferometer in C1. High-volume
  memories and a high-speed microprocessor enable extensive on-board image
  processing. Image compression by a factor of about 10 will result in
  the transmission of 10 full images per hour.

Title: Particle fluxes observed in the magnetic pileup regions of
    comets Halley and Grigg-Skjellerup
Authors: Kirsch, E.; McKenna-Lawlor, S.; Korth, A.; Schwenn, R.
Bibcode: 1995AdSpR..16d..29K
Altcode: 1995AdSpR..16...29K
  Energetic particles (E_H_2_O &gt;= 60 keV) as well as plasma ions of a
  few KeV in energy have been measured in the magnetic pileup region and
  in the cavity of comet Halley (13/14 March 1986) by the instruments
  EPA/EPONA, RPA and IMS. The Pileup region of comet Grigg-Skjellerup
  (G-S) was traversed on 10 July 1992. Similarities and diversities in
  the encounter conditions, particle fluxes and acceleration processes
  at both comets are discussed.

Title: Mass ejections from the sun and their interplanetary
    counterparts
Authors: Schwenn, R.
Bibcode: 1995sowi.confR..45S
Altcode:
  Since the first observations of solar mass ejection events in the early
  seventies from OSO 7 and Skylab a few thousand of these remarkable
  dynamic incidents have been observed by now, covering about two full
  solar activity cycles. The mass ejecta include mainly hot coronal
  plasma, plus cold prominence material in variable amounts. The
  ejecta are often recognised in the form of interplanetary plasma
  clouds detected in the distant solar wind by appropriately located
  spacecraft. Clouds which have been energetic enough to drive large
  scale interplanetary shock waves can be identified most readily, but
  clouds without associated shocks do also occur. The plasma clouds
  are characterized by a variety of signatures indicating that they
  actually originate from injections of different material into the
  ambient solar wind. Usually only a few of the signatures are found
  simultaneously. Apparently the bidirectional streaming of halo electrons
  is a most reliable criterion, indicating a magnetic bottle or plasmoid
  topology of the clouds. The discussion of the most recent discoveries
  in this context will show that quite a few crucial problems still
  remain to be addressed by the upcoming SOHO mission.

Title: Statistical analysis of interplanetary shock waves observed
    during a complete solar activity cycle
Authors: Khalisi, E.; Schwenn, R.
Bibcode: 1995sowi.conf...99K
Altcode:
  During the Helios mission a total of 391 fast forward non-corotating
  interplanetary shock waves was identified. For most of the 12 years
  between 1974 and 1986 unique shock detection was possible for more than
  80 % of the time. The occurrence rate (in shocks per day) varied from
  0.02 at activity minimum in 1976 to 0.17 in 1979 and 0.22 in 1982 with
  a significant drop to 0.13 in 1980, i.e. right at activity maximum. The
  average properties of all events as functions of solar distance. phase
  in the solar cycle, heliographic and -magnetic latitude and others
  are discussed.

Title: Ground-based observations of the corona in the visible and
    NIR spectral ranges
Authors: Epple, Alexander; Schwenn, Rainer
Bibcode: 1995sowi.conf...60E
Altcode:
  Since late 1993 we have been using a mirror coronagraph on Pic du Midi
  (PICO) to observe the solar emission corona in several spectral lines
  of (FE-X), (FE-XIII), and (FE-XIV). For good meteorological conditions
  the diffuse corona and coronal holes in between can be seen out to
  1.2 solar mass for sun center. Active regions can be mapped to bond
  1.5 solar mass in the green and infrared lines. Recent observations
  of PICO are presented.

Title: PICO - A Mirror Coronagraph on Pic Du Midi
Authors: Epple, A.; Schwenn, R.
Bibcode: 1995itsa.conf..233E
Altcode:
  No abstract at ADS

Title: PICO - a mirror coronograph on Pic Du Midi
Authors: Epple, A.; Schwenn, R.
Bibcode: 1994ESASP.373..399E
Altcode: 1994soho....3..399E
  No abstract at ADS

Title: Eruptive prominences as sources of magnetic clouds in the
    solar wind
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1994SSRv...70..215B
Altcode:
  Large amounts of coronal material are propelled outward into
  interplanetary space by Coronal Mass Ejections (CMEs). Thus one might
  expect to find evidence for expanding flux ropes in the solar wind
  as well. To prove this assumption magnetic clouds were analyzed and
  correlated with Hα-observations of disappearing filaments. When clouds
  were found to be directly associated with a disappearing filament,
  the magnetic structure of the cloud was compared with that of the
  associated filament. Additionally the expansion of magnetic clouds
  was examined over a wide range of the heliosphere and compared with
  the expansion observed for erupting prominences.

Title: Book-Review - Physics of the Inner Heliosphere - V.2 -
    Particles Waves and Turbulence
Authors: Schwenn, R.; Marsch, E.; Schwartz, S. J.
Bibcode: 1993SSRv...64..371S
Altcode:
  No abstract at ADS

Title: Comparison of CMEs, magnetic clouds, and bidirectionally
    streaming proton events in the heliosphere using helios data
Authors: Webb, D.; Jackson, B.; Hick, P.; Schwenn, R.; Bothmer, V.;
   Reames, D.
Bibcode: 1993AdSpR..13i..71W
Altcode: 1993AdSpR..13...71W
  Coronal Mass Ejections (CMEs) are large, energetic expulsions of mass
  and magnetic fields from the Sun; they can significantly affect large
  volumes of the heliosphere and appear to be a key cause of geomagnetic
  storms. We have compiled a list of all significant CMEs detected by
  the HELIOS white light photometers from 1975-1982. We are studying the
  characteristics of these CMEs, and present preliminary results of their
  associations with in-situ features, especially magnetic ``clouds'' and
  periods of bidirectionally streaming ions, two classes of structures
  considered indicative of interplanetary loops. Advantages of this data
  set include reliable association in the interplanetary medium of the
  white light CME plasma with the in-situ features, and observations of
  a large number of events over a long time base.

Title: Status of the LASCO Instrument Development Program
Authors: Moses, D.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.;
   Korendyke, C. M.; Michels, D. J.; Socker, D. G.; Lamy, P.; Schwenn,
   R.; Simnett, G. M.
Bibcode: 1993BAAS...25.1192M
Altcode:
  No abstract at ADS

Title: Book-Review - Solar Wind Seven
Authors: Marsch, E.; Schwenn, R.; Woan, G.
Bibcode: 1993Obs...113..151M
Altcode:
  No abstract at ADS

Title: Book-Review - Physics of the Inner Heliosphere - Part Two -
    Particles Waves and Turbulence
Authors: Schwenn, R.; Marsch, E.; Jackson, B. V.
Bibcode: 1993SoPh..145R.405S
Altcode:
  No abstract at ADS

Title: Book-Review - Physics of the Inner Heliosphere - Part One -
    Largescale Phenomena
Authors: Schwenn, R.; Marsch, E.; Jackson, B. V.
Bibcode: 1993SoPh..145Q.405S
Altcode:
  No abstract at ADS

Title: Books-Received - Solar Wind Seven
Authors: Marsch, E.; Schwenn, R.
Bibcode: 1993Sci...259.1634M
Altcode:
  No abstract at ADS

Title: Analysis of Comet Halley's Heavy Ion- and Micro-Dust Fluxes
    and Discussion of Possible Acceleration Processes
Authors: Kirsch, E.; McKenna-Lawlor, S.; Thompson, A.; O'Sullivan,
   D.; Korth, A.; Schwenn, R.; Wenzel, K. -P.
Bibcode: 1993penp.conf...89K
Altcode:
  No abstract at ADS

Title: Landolt-Börnstein: Numerical Data and Functional Relationships
    in Science and Technology - New Series " Gruppe/Group 6 Astronomy and
Astrophysics " Volume 3 Voigt: Astronomy and Astrophysics. Extension
    and Supplement to Volume 2 " Instruments, Methods, Solar System
Authors: Baars, J. W.; Beer, H.; Durrant, C. J.; Graser, U.; Guinot,
   B.; Hoffmann, M.; Hopp, U.; Ip, W. -H.; Jessberger, E. K.; Klecker, B.;
   Lemke, D.; Meisenheimer, K.; Möbius, E.; Palme, H.; Rahe, J.; Röser,
   H. J.; Schubart, J.; Schwenn, R.; Solf, J.; Soltau, G.; Staubert,
   R.; Stewart, R.; Trümper, J.; Vanysek, V.; Weigelt, G.; Wolf, R.
Bibcode: 1993lbor.book.....B
Altcode:
  No abstract at ADS

Title: Quiet Sun and Quiet Solar Wind (Abstract)
Authors: Schwenn, R.
Bibcode: 1993stp2.conf...90S
Altcode:
  No abstract at ADS

Title: The Large Angle Spectroscopic Coronagraph (LASCO): visible
    light coronal imaging and spectroscopy.
Authors: Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke,
   C.; Michels, D. J.; Socker, D. G.; Lamy, P.; Llebaria, A.; Maucherat,
   J.; Schwenn, R.; Simnett, G. M.; Bedford, D. K.; Eyles, C. J.
Bibcode: 1992ESASP.348...27B
Altcode: 1992cscl.work...27B
  The Large Angle Spectroscopic Coronagraph (LASCO) is a triple
  coronagraph being jointly developed for the SOlar and Heliospheric
  Observatory (SOHO) mission by the Naval Research Laboratory (USA),
  the Laboratoire d'Astronomie Spatiale (France), the Max Planck
  Institut für Aeronomie (Germany), and the University of Birmingham
  (UK). LASCO comprises three nested coronagraphs (C1, C2, and C3)
  that image the solar corona from 1.1 R<SUB><SUB>sun</SUB></SUB> to
  30 R<SUB><SUB>sun</SUB></SUB>.

Title: Origin of the solar wind and coronal mass ejections.
Authors: Schwenn, Rainer
Bibcode: 1992ESASP.346..205S
Altcode: 1992ssts.rept..205S
  Theories on the origin of solar wind, theories that are derived from
  Parker's first theory on the existence and evolution of solar wind, are
  discussed. It is suggested that knowledge on how the corona is heated
  would lead to insight into the problem of solar wind acceleration. From
  observations of solar wind stream structure through almost three
  solar activity cycles, four different types of solar wind and their
  respective coronal sources have been discerned. Each of these are
  discussed: high speed wind in highspeed streams, low speed wind of the
  'interstream' type, low speed wind of the 'maximum' type, and coronal
  mass ejecta following interplanetary shocks. For each type of solar
  wind, the following parameters are given: high speed, low density,
  low particle flux, helium content, and source. A list of the most
  urgent questions in context with the solar wind origin is given.

Title: LASCO - Large Angle Spectrometric Coronagraph for SOHO
Authors: Howard, R. A.; Brueckner, G. E.; Dere, K. P.; Korendyke,
   C. M.; Koomen, M. J.; Michels, D. J.; Moses, D.; Socker, D. G.;
   Schwenn, R.; Inhester, B.; Lamy, P.; Maucherat, A.; Simnett, G. M.;
   Eyles, C.
Bibcode: 1992AAS...180.3307H
Altcode: 1992BAAS...24..781H
  No abstract at ADS

Title: Observations of Plasma Dynamics in the Coma of P/Halley by
    the Giotto Ion Mass Spectrometer
Authors: Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Fuselier,
   S. A.; Shelley, E. G.; Balsiger, H.; Kettmann, G.; Ip, W. -H.;
   Rosenbauer, H.; Schwenn, R.
Bibcode: 1992JGR....97.4121G
Altcode:
  Observations in the coma of P/Halley by the Giotto ion mass spectrometer
  (IMS) are reported. The high-energy range spectrometer (HERS) of
  the IMS obtained measurements of protons and alpha particles from
  the far upstream region to the near ionopause region and of ions
  of mass 12-32 at distances of about 250,000 to 40,000 km from the
  nucleus. Plasma parameters from the high-intensity spectrometer (HIS)
  of the IMS obtained between 150,000 and 5000 km from the nucleus
  are also discussed. The distribution functions of water group ions
  (``water group'' will be used to refer to ions of 16-18 m/q, where m
  is in atomic mass units and q is in unit charges) are observed to be
  spherically symmetric in velocity space, indicating strong pitch angle
  scattering. The discontinuity known as the magnetic pileup boundary
  (MPB) is apparent only in Proton, alpha particle, and magnetometer
  data, indicating that it is a tangential discontinuity of solar wind
  origin. HERS observations show no significant change in the properties
  of the heavy ions across the MPB. The issue of whether a cometopause
  was unambiguously observed at comet Halley is discussed; it is concluded
  that the observations do not convincingly support the idea of a boundary
  due to internal cometary processes (as opposed to convected solar wind
  discontinuities). A comparison of the observations to MHD models is
  made. The plasma flow directions at all distances greater than 30,000
  km from the nucleus are in agreement with MHD calculations. However,
  despite the agreement in flow direction, within 200,000 km of the
  nucleus the magnitude of the velocity is lower than predicted by MHD
  models, and the density is much larger (a factor of 5 or more for
  distances 60,000-160,000 km from the comet). Within 30,000 km of the
  nucleus there are large theoretical differences between the MHD model
  flow calculations for the plane containing the magnetic field and for
  the plane perpendicular to the magnetic field. The observations agreed
  much better with the pattern calculated for the plane perpendicular to
  the magnetic field. The data obtained by the HERS that are published
  herein have also been provided to the International Halley Watch
  archive.

Title: Magnetic cloud observations by the HELIOS spacecraft
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1992sws..coll..599B
Altcode:
  A possible interpretation for the observed characteristics of an
  interplanetary magnetic cloud is the passage of a magnetic flux
  rope. For simplification the flux rope might be considered as a
  cylindrically symmetric structure with the magnetic field lines being
  directed parallel to the axis at its center and circular at its outer
  edges. Near the center of this flux rope the magnetic field strength
  would be strongest. The minimum variance technique was applied to
  several magnetic clouds observed by the Helios spacecraft between 0.3
  and 1 AU in order to determine the orientations of the magnetic flux
  rope axis. The calculated orientations are examined with respect to the
  global solar wind stream structure, the surrounding solar wind flow,
  the radial distance to the sun and their solar origin.

Title: Solar Wind Seven; Proceedings of the 3rd COSPAR Colloquium,
    Goslar, Germany, Sept. 16-20, 1991
Authors: Marsch, E.; Schwenn, R.
Bibcode: 1992sws..coll.....M
Altcode:
  The present conference discusses topics in coronal heating and solar
  wind acceleration, the large-scale structure of the interplanetary
  medium, minor ions and cosmic rays in the heliosphere, solar wind
  kinetics and turbulence, and heliospheric dynamic phenomena. Attention
  is given to the origin of high speed solar wind streams, density and
  temperature structure of a coronal hole, a two-fluid model of the solar
  wind, solar wind temperature observations in the outer heliosphere,
  the solar wind transonic region, and the spectral structure evolution
  of interplanetary medium parameters. Also discussed are MHD modeling
  of the heliospheric interface, the magnetic field in the heliosheath,
  radioastronomy of travelling interplanetary disturbances, Bernstein
  waves in the solar wind, multifractals in the solar wind, solar
  MHD turbulence, surface and body waves in solar wind flow tubes,
  magnetospheric LF nonresonant ion-beam turbulence, nearly incompressible
  fluid dynamics, and the interaction of intense magnetic clouds with
  ambient solar wind streams.

Title: Magnetic structures at sector boundaries in the inner
    heliosphere
Authors: Bothmer, V.; Schwenn, R.
Bibcode: 1992sws..coll..151B
Altcode:
  The strong deflections of the IMF out of the ecliptic plane that
  have been noted at sector boundaries, and are therefore related to
  the heliospheric current sheet, have north-to-south turnings in the
  case of magnetic field deflections at sector boundaries that point
  to an origin for this phenomenon in magnetic field lines that remain
  parallel to the inclined current sheet. The plasma and magnetic field
  properties at sector boundaries closer to the sun may show interesting
  coronal streamer belt features.

Title: Synoptic maps of heliospheric Thomson scattering brightness
    from 1974-1985 as observed by the HELIOS photometers
Authors: Hick, P.; Jackson, B. V.; Schwenn, R.
Bibcode: 1992sws..coll..187H
Altcode:
  We display the electron Thomson scattering intensity of the inner
  heliosphere as observed by the zodiacal light photometers on board
  the Helios spacecraft in the form of synoptic maps. The technique
  extrapolates the brightness information from each photometer sector
  near the Sun and constructs a latitude/longitude map at a given solar
  height. These data are unique in that they give a determination
  of heliospheric structures out of the ecliptic above the primary
  region of solar wind acceleration. The spatial extent of bright,
  co-rotating heliospheric structures is readily observed in the data
  north and south of the ecliptic plane where the Helios photometer
  coverage is most complete. Because the technique has been used on the
  complete Helios data set from 1974 to 1985, we observe the change in
  our synoptic maps with solar cycle. Bright structures are concentrated
  near the heliospheric equator at solar minimum, while at solar maximum
  bright structures are found at far higher heliographic latitudes. A
  comparison of these maps with other forms of synoptic data are shown
  for two available intervals.

Title: Comparison of Doppler scintillation and in situ spacecraft
    plasma measurements of interplanetary disturbances
Authors: Woo, Richard; Schwenn, Rainer
Bibcode: 1991JGR....9621227W
Altcode:
  Results are presented of detailed comparisons between Doppler
  scintillation and in situ plasma measurements to improve the
  understanding of Doppler scintillation transients. During a combined
  observing period of nearly 3 mo in 1981-1982 near solar maximum,
  22 transients were observed by the Pioneer Venus Orbiter spacecraft
  and 23 shocks were observed by Helios 1. It is found that at least
  84 percent of the transients are shocks, while at least 90 percent of
  the shocks are transients. Although the temporal profiles of Doppler
  scintillation and mass flux density are similar, the magnitudes of
  the Doppler scintillation transients may not simply reflect those
  of mass flux density. Only one pronounced solar wind event that was
  observed in the mass flux density measurements showed no signature
  in the scintillation data; field and particle measurements by Helios
  1 suggest that it is a noncompressive density enhancement and/or a
  magnetic cloud. It is shown that Doppler scintillation measurements
  can now be used by themselves to detect and locate interplanetary
  shocks near the sun with a relatively high degree of certainty.

Title: Heavy ions and micro dust fluxes recorded during the
    Giotto-Halley flyby
Authors: Kirsch, E.; McKenna-Lawlor, S.; Korth, A.; Schwenn, R.;
   O'Sullivan, D.; Thompson, A.
Bibcode: 1991ICRC....3..370K
Altcode: 1991ICRC...22c.370K
  No abstract at ADS

Title: Synoptic maps for the heliospheric Thomson scattering
    brightness as observed by the HELIOS photometers
Authors: Hick, P.; Jackson, B. V.; Schwenn, R.
Bibcode: 1991A&A...244..242H
Altcode:
  A method for displaying the electron Thomson scattering intensity in the
  inner heliosphere as observed by the zodiacal light photometers on board
  the Helios spacecraft in the form of synoptic maps is presented. The
  method is based on the assumption that the bulk of the scattering
  electrons along the line of sight is located near the point closest to
  the sun. Inner-heliospheric structures will generally be represented
  properly in these synoptic maps only if they are sufficiently long-lived
  (that is, a significant fraction of a solar rotation period). The
  examples of Helios synoptic maps discussed (from data in April 1976 and
  November 1978), indicate that it is possible to identify large-scale,
  long-lived density enhancements in the inner heliosphere. It is expected
  that the Helios synoptic maps will be particularly useful in the study
  of corotating structures (e.g., streamers), and the maps will be most
  reliable during periods when few transient featurs are present in the
  corona, i.e., during solar minimum.

Title: Observations of plasma dynamics in the coma of P/Halley by
    the Giotto Ion Mass Spectrometer
Authors: Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Fuselier,
   S. A.; Shelley, E. G.; Balsiger, H.; Kettmann, G.; Ip, W. -H.;
   Rosenbauer, H.; Schwenn, R.
Bibcode: 1991sicd.reptQ....G
Altcode:
  Observations in the coma of P/Halley by the Giotto Ion Mass Spectrometer
  (IMS) are reported. The High Energy Range Spectrometer (HERS) of the
  IMS obtained measurements of protons and alpha particles from the
  far upstream region to the near ionopause region and of ions from
  mass 12 to 32 at distances of about 250,000 to 40,000 km from the
  nucleus. Plasma parameters from the High Intensity Spectrometer (HIS)
  of the IMS obtained between 150,000 to 5000 km from the nucleus are
  also discussed. The distribution functions of water group ions (water
  group will be used to refer to ions of 16 to 18 m/q, where m is in AMU
  and q is in unit charges) are observed to be spherically symmetric
  in velocity space, indicating strong pitch angle scattering. The
  discontinuity known as the magnetic pile-up boundary (MPB) is apparent
  only in proton, alpha, and magnetometer data, indicating that it is a
  tangential discontinuity of solar wind origin. HERS observations show
  no significant change in the properties of the heavy ions across the
  MPB. A comparison of the observations to an MHD model is made. The
  plasma flow directions at all distances greater than 30,000 km from
  the nucleus are in agreement with MHD calculations. However, despite
  the agreement in flow direction, within 200,000 km of the nucleus the
  magnitude of the velocity is lower than predicted by the MHD model and
  the density is much larger (a factor of 4). Within 30,000 km of the
  nucleus there are large theoretical differences between the MHD model
  flow calculations for the plane containing the magnetic field and for
  the plane perpendicular to the magnetic field. The observations agreed
  much better with the pattern calculated for the plane perpendicular
  to the magnetic field. The data obtained by the High Energy Range
  Spectrometer (HERS) of the IMS that are published herein were provided
  to the International Halley Watch archive.

Title: Book-Review - Physics of the Inner Heliosphere - Part One -
    Largescale Phenomena
Authors: Schwenn, R.; Marsch, E.
Bibcode: 1991Sci...251..578S
Altcode:
  No abstract at ADS

Title: Physics of the Inner Heliosphere II. Particles, Waves and
    Turbulence
Authors: Schwenn, Rainer; Marsch, Eckart
Bibcode: 1991pihp.book.....S
Altcode: 1991PCS....21.....S
  No abstract at ADS

Title: Synoptic maps constructed from brightness observations of
    Thomson scattering by heliospheric electrons
Authors: Hick, P.; Jackson, B.; Schwenn, R.
Bibcode: 1991AdSpR..11a..61H
Altcode: 1991AdSpR..11Q..61H
  Observations of the Thomson scattering brightness by electrons in the
  inner heliosphere provide a means of probing the heliospheric electron
  distribution. An extensive data base of Thomson scattering observations,
  stretching over many years, is available from the zodiacal light
  photometers on board the two Helios spacecraft. A survey of these
  data is in progress, presenting these scattering intensities in the
  form of synoptic maps for successive Carrington rotations. The Thomson
  scattering maps reflect conditions at typically several tenths of an
  astronomical unit from the Sun. We discuss some representative examples
  from the survey in comparison with other solar/heliospheric data,
  such as in situ observations from the Helios plasma experiment and
  synoptic maps constructed from magnetic field, Hα and K-coronameter
  data. The comparison will provide some information about the extension
  of solar surface features into the inner heliosphere.

Title: Spatial structures in high-speed streams as signatures of
    fine structures in coronal holes.
Authors: Thieme, K. M.; Marsch, E.; Schwenn, R.
Bibcode: 1990AnGeo...8..713T
Altcode: 1990AnG.....8..713T
  During solar eclipses one can observe fine ray-like structures in
  coronal holes. In order to determine whether these structures might
  be preserved in the evolving interplanetary high-speed solar wind the
  authors used plasma and magnetic field data obtained by the two Helios
  solar probes. For the time period from 1974 till 1977 they analysed
  41 high-speed solar wind streams which were measured between 0.3 and 1
  AU. They investigated the velocity of protons and α-particles as well
  as the combined gas pressure of protons, α-particles, and electrons,
  the magnetic pressure, and the total pressure. The authors found many
  time periods with a strong anticorrelation between the variations in
  the gas pressure and the magnetic pressure while the total pressure
  was roughly constant. They interpret these features as structural
  relics of coronal origin. To get an estimation of the mean angular
  diameter of these structures they did a statistical analysis with the
  entire set of 41 high-speed solar wind streams. The resulting data
  show characteristic variations on an angular scale being of the same
  order as the angular size of the structures in the coronal holes.

Title: New technology mirror coronagraph with extended applications
Authors: Smartt, Raymond N.; Koutchmy, Serge L.; Colley, Stephen A.;
   Caron, R.; Schwenn, Rainer; Restaino, Sergio R.
Bibcode: 1990SPIE.1236..206S
Altcode:
  General design considerations of objective-mirror coronagraphs are
  presented. A 1-m-focal-length prototype reflecting coronagraph based on
  a 5.5-cm aperture spherical superpolished silicon mirror objective is
  described. The design is simple off-axis reflection from the objective
  to a conventional coronagraph optical system (occulting disk, field
  lens, Lyot stop, and imaging system). This instrument has produced the
  first images of the emission corona using a ground-based reflecting
  coronagraph. A second prototype instrument based on a 15-cm aperture
  superpolished fused-silica mirror is also described.

Title: Large-scale variations of thermal electron parameters in the
    solar wind between 0.3 and 1 AU.
Authors: Pilipp, W. G.; Muehlhaeuser, K. -H.; Miggenrieder, H.;
   Rosenbauer, H.; Schwenn, R.
Bibcode: 1990JGR....95.6305P
Altcode:
  Variations of thermal electron parameters in the solar wind are
  investigated using data obtained from the Helios probes in the years
  from 1974 to 1976, shortly before solar minimum, at heliocentric
  distances ranging from 0.3 to 1 AU. The main part of the present
  analysis is based on Helios 2 data obtained in 1976. Variations across
  the sector structure of the interplanetary magnetic field (IMF) and
  across the plasma stream structures are studied. These studies support
  the hypothesis that the thermal electron properties, i.e., the electron
  temperatures, the core temperatures, the heat flux, and the normalized
  heat flux, are strongly correlated with the distance from the neutral
  sheet in the IMF (implying also a correlation with the plasma stream
  structures). The results do not indicate significant electron heating
  in compression regions. Also, power laws for the variations of the
  electron parameters with distance from the Sun as well as polytrope laws
  are derived for different solar wind structures and distance ranges.

Title: Giotto IMS measurements of the production rate of hydrogen
    cyanide in the coma of comet Halley.
Authors: Ip, W. -H.; Rosenbauer, H.; Schwenn, R.; Balsiger, H.;
   Geiss, J.; Meier, A.; Goldstein, B. E.; Lazarus, A. J.; Shelley, E.;
   Kettmann, G.
Bibcode: 1990AnGeo...8..319I
Altcode: 1990AnG.....8..319I
  The ion composition measurements in the ionosphere of comet Halley by
  the ion mass spectrometer (IMS) experiment on the Giotto spacecraft are
  used to estimate the relative abundance of HCN. From a comparison of the
  normalized number density of ions with mass-to-charge (M/q) ratio of
  28 AMU/e with steady-state photochemical models, it can be determined
  that the production rate of HCN directly from the central nucleus is
  Q(HCN) ⪉ 2×10<SUP>-4</SUP>Q(H<SUB>2</SUB>O) at the time of Giotto
  encounter. The related photochemical model calculations also indicate
  that Q(NH<SUB>3</SUB>)/Q(H<SUB>2</SUB>O) ≡ 5×10<SUP>-3</SUP> in
  agreement with recent determinations from ground-based observations. The
  estimated value of Q(HCN) is lower than the relative abundance of
  Q(HCN)/Q(H<SUB>2</SUB>O) ≍ 10<SUP>-3</SUP> as derived from radio
  observations of the 88.6 GHz emission of the J = 1-0 transition of
  HCN. The difference may be the result of time-variations of the coma
  deposition and dynamics as well as other model-dependent effects.

Title: First results of measurements of ions of Martian origin and
    the discovery of a plasma sheet in the Martian magnetosphere in the
    TAUS experiment on Phobos-2
Authors: Rosenbauer, H.; Shutte, N.; Apathy, I.; Verigin, M.; Witte,
   M.; Galeev, A.; Gringaus, K.; Grunwaldt, H.; Jockers, K.; Kiraly,
   P.; Kotova, G.; Livi, S.; Marsch, E.; Remizov, A.; Richter, A.;
   Riedler, W.; Szego, K.; Hemmerich, P.; Schwenn, R.; Schwingenschuh,
   K.; Steller, M.
Bibcode: 1990PAZh...16..368R
Altcode:
  TAUS measurements showed that the Martian magnetosphere is considerably
  filled with fluxes of heavy ions originating from the planetary
  atmosphere. A plasma sheet was found in the magnetotail, which also
  consisted mainly of heavy ions. The flux of heavy ions leaving Mars
  through the tail is tentatively estimated to be (0.5-2) x 10 to the
  25th per sec.

Title: First Measurements of Ions of Martian Origin and Observation
    of a Plasma Layer in the Magnetosphere of Mars - the TAUS Experiment
    on the Spacecraft PHOBOS-2
Authors: Rosenbauer, H.; Shutte, N.; Apathy, I.; Verigin, M.; Witte,
   M.; Galeev, A.; Gringauz, K.; Grunwaldt, H.; Jockers, K.; Kiraly,
   P.; Kotova, G.; Livi, S.; Marsch, E.; Remizov, A.; Richter, A.;
   Riedler, W.; Szego, K.; Hemmerich, P.; Schwenn, R.; Schwingenschuh,
   K.; Steller, M.
Bibcode: 1990SvAL...16..156R
Altcode:
  No abstract at ADS

Title: On Representing the Large-scale Structure of the Inner
    Heliosphere in Synoptic Maps
Authors: Hick, P.; Jackson, B. V.; Schwenn, R.
Bibcode: 1990BAAS...22..810H
Altcode:
  No abstract at ADS

Title: Cometary ion flow variations at comet P/Halley as observed
    by the Giotto IMS experiments.
Authors: Kettmann, G.; Ip, W. -H.; Rosenbauer, H.; Schwenn, R.;
   Balsiger, H.; Meier, A.; Goldstein, B. E.; Shelley, E. G.
Bibcode: 1990AnGeo...8..229K
Altcode: 1990AnG.....8..229K
  Using the combined data sets from the angle analyzer and the mass
  analyzer of the Giotto IMS-HIS experiment, the authors have derived
  the three-dimensional plasma flow properties of cometary ions for
  masses ≥12 AMU. The results are in agreement with the theoretical
  model of charge exchange loss of the hot cometary ions.

Title: Introduction
Authors: Marsch, E.; Schwenn, R.
Bibcode: 1990pihl.book....1M
Altcode:
  No abstract at ADS

Title: Large-Scale Structure of the Interplanetary Medium
Authors: Schwenn, R.
Bibcode: 1990pihl.book...99S
Altcode:
  No abstract at ADS

Title: Physics of the Inner Heliosphere I. Large-Scale Phenomena.
Authors: Schwenn, Rainer; Marsch, Eckart
Bibcode: 1990pihl.book.....S
Altcode: 1990PCS....20.....S
  Physics of the Inner Heliosphere gives for the first time a
  comprehensive and complete summary of our knowledge of the inner solar
  system. Using data collected over more than 11 years by the HELIOS
  twin solar probes, one of the most successful ventures in unmanned
  space exploration, the authors have compiled 10 extensive reviews of
  the physical processes of the inner heliosphere and their connections
  to the solar atmosphere. Researchers and advanced students in space and
  plasma physics, astronomy, and solar physics will be surprised to see
  just how closely the heliosphere is tied to the sun and how sensitively
  it depends on our star. The four chapters of Volume I of the work deal
  with large-scale phenomena: - observations of the solar corona - the
  structure of the interplanetary medium - the interplanetary magnetic
  field - interplanetary dust.

Title: Observations of a shock and a recombination layer at the
    contact surface of comet Halley
Authors: Goldstein, B. E.; Altwegg, K.; Balsiger, H.; Fuselier, S. A.;
   Ip, W. -H.; Meier, A.; Neugebauer, M.; Rosenbauer, H.; Schwenn, R.
Bibcode: 1989JGR....9417251G
Altcode:
  Observations in the vicinity of the contact surface (ionopause)
  of comet Halley obtained by the Giotto ion mass spectrometer (IMS)
  are reported. Two specific events in this region were observed on the
  inbound pass. Two seconds before the contact surface was encountered,
  a burst of energized ions (about 20 eV, much greater than thermal
  energies) was detected by the angle analyzer; the flux of these ions
  decreased as the contact surface was approached. The burst of energized
  ions coincided with a pulse in magnetic field strength interpreted by
  Neubauer (1988) as a fast mode shock traveling away from the contact
  surface. At the contact surface, a sharp spike in ion densities was
  observed by the mass analyzer. This pileup region was at least 0.75
  s in duration (about 47 km in width); there may also have been a
  region of less enhanced densities extending inward another 47 km. The
  spike in densities was centered approximately at the inner edge of
  the magnetically determined contact surface. The exact magnitude of
  the density increase is uncertain due to instrumental limitations,
  but the increase above the ambient external density appears to have
  been at least a factor of 3.5, and appears to have been more than an
  order of magnitude for some species. The sharp spike in ion density
  is interpreted as a boundary layer into which the radial ionospheric
  flow enters, piles up, and in which the density increase is limited
  by recombination.

Title: Ions of martian origin and plasma sheet in the martian
magnetosphere: initial results of the TAUS experiment
Authors: Rosenbauer, H.; Shutte, N.; Apáthy, I.; Galeev, A.; Gringauz,
   K.; Grünwaldt, H.; Hemmerich, P.; Jockers, K.; Király, P.; Kotova,
   G.; Livi, S.; Marsch, E.; Richter, A.; Riedler, W.; Remizov, T.;
   Schwenn, R.; Schwingenschuh, K.; Steller, M.; Szegö, K.; Verigin,
   M.; Witte, M.
Bibcode: 1989Natur.341..612R
Altcode:
  UNLIKE plasma instruments used on previous space missions to Mars,
  the TAUS instrument on Phobos 2 was designed so that the energy per
  charge and angular spectra of three species of ions could be measured
  separately. These species were H<SUP>+</SUP> and He<SUP>2+</SUP>
  characteristic of the solar wind, and 'heavy ions' collected in
  one integral channel covering the mass per charge (M/q) range 3 to
  infinite, which we anticipated to find predominantly in the near-martian
  regime. In all spacecraft orbits around Mars we found a sharp boundary,
  separating the shocked solar wind from the martian magnetosphere which
  was characterized by the absence of solar-wind-like plasma. As the
  plasma inside the magnetosphere, and particularly in the tail, was
  dominated by heavy ions with number densities orders of magnitude
  higher than found in the solar wind, we assumed it was mainly of
  martian origin. Typically, heavy ions of low tailward flow velocity
  were seen near the boundary of the magnetotail, whereas high-speed
  tailward plasma flows of such ions were detected deeper inside the
  tail, a region not investigated before. Near the centre of the martian
  magnetotail a plasma regime, comparable to the terrestrial as well
  as the venusian1 plasma sheet, was detected, characterized by highly
  supersonic tailward streams of heavy ions. The flux of planetary ions
  leaving Mars through its magnetotail is tentatively estimated to be
  of the order of a few times 10<SUP>25</SUP> s<SUP>-1</SUP>. Such loss
  rates would be significant for the dissipation of the martian atmosphere
  on cosmological timescales.

Title: Large-scale propagation properties of interplanetary
    disturbances revealed from IPS and spacecraft observations
Authors: Watanabe, Takashi; Schwenn, Rainer
Bibcode: 1989SSRv...51..147W
Altcode:
  Interplanetary scintillation (IPS) observations may be used to study
  large-scale propagation properties of transient interplanetary
  disturbances in a three-dimensional manner, although current IPS
  observations have several limitations, e.g., poor time resolution and
  line-of-sight integration. Comparative studies with spacecraft solar
  wind and white-light coronal mass ejection (CME) observations are
  quite helpful in interpretation of IPS observations. An interplanetary
  disturbance apparently in association with a disappearing solar
  filament, which took place near the central meridian of the Sun on
  late 22 April, 1979, is discussed to examine previous deductions from
  IPS observations. Three-station IPS observations of the flow speed and
  spacecraft observations suggest that a quasi-spherical interplanetary
  disturbance was formed around the Sun-Earth line, whereas the center
  of the disturbance derived from the distribution of enhanced IPS across
  the sky (g-maps) is located to the east of the Sun-Earth line.

Title: Large-scale propagation properties of an interplanetary
    disturbance in association with a 'halo' coronal mass ejection on
    27 November 1979
Authors: Schwenn, Rainer; Watanabe, Takashio; Kakinuma, Takakiyo;
   Kojima, Masayoshi
Bibcode: 1989NURIA..36...11S
Altcode:
  Propagation properties of an interplanetary disturbance in association
  with a halo coronal mass ejection (CME), which was observed with the
  Solwind coronagraph from 08:22 to 09:58 UT on November 27, 1979,
  are examined utilizing IPS and spacecraft observations. Detailed
  model-fitting showed that a dip of the propagation speed of the
  disturbance was situated in the radial direction of the heliospheric
  current sheet. Quick deceleration of the disturbance along the current
  sheet is suggested.

Title: Ground-Based Mirror Coronograph: First Results
Authors: Smartt, R. N.; Koutchmy, S.; Schwenn, R.
Bibcode: 1989BAAS...21..848S
Altcode:
  No abstract at ADS

Title: Interplanetary Solar Wind Brightness Synoptic Maps from the
    HELIOS Zodiacal Light Photometers
Authors: Hick, P. L.; Jackson, B. V.; Schwenn, R.
Bibcode: 1989BAAS...21..858H
Altcode:
  No abstract at ADS

Title: The density of cometary protons upstream of comet Halley's
    bow shock
Authors: Neugebauer, M.; Goldstein, B. E.; Balsiger, H.; Neubauer,
   F. M.; Schwenn, R.; Shelley, E. G.
Bibcode: 1989JGR....94.1261N
Altcode:
  Cometary protons picked up by the solar wind were detected by the
  high energy range spectrometer of the Giotto ion mass spectrometer
  starting at a cometocentric distance of ~12×10<SUP>6</SUP> km. On the
  average, the density of cometary protons varied approximately as the
  inverse square of the cometocentric distance, reaching a value of 0.11
  cm<SUP>-</SUP><SUP>3</SUP> just outside the bow shock. The data can be
  successfully fit to models that include substantial amounts of both slow
  (~1 km/s) and fast (&gt;=8 km/s) H atoms beyond the bow shock. Large
  local variations in the density of picked-up protons can be explained on
  the basis of variations in the direction of the interplanetary magnetic
  field in upstream regions where pitch angle scattering was weak.

Title: Coronal mass ejections and their manifestation in the three
    dimensional heliosphere
Authors: Schwenn, R.
Bibcode: 1989AdSpR...9d.268S
Altcode: 1989AdSpR...9..268S
  No abstract at ADS

Title: Transport of Energy and Mass to the Outer Boundary of the
    Earth System
Authors: Schwenn, R.
Bibcode: 1989step.conf...13S
Altcode:
  No abstract at ADS

Title: Type II Interplanetary Radio Bursts and Electron Plasma
    Oscillations Associated with Interplanetary Shocks, Superthermal
    Electrons, and Low/Medium Energy Protons
Authors: Kikuchi, H.; Gurnett, D. A.; Anderson, R. R.; Keppler, E.;
   Richter, A. K.; Schwenn, R.; Marsch, E.; Pilipp, W. G.; Richter, K.;
   Rosenbauer, H.
Bibcode: 1989lsp..conf..415K
Altcode:
  No abstract at ADS

Title: Relationship of Coronal Transients to Interplanetary Shocks:
    3D Aspects
Authors: Schwenn, R.
Bibcode: 1989lsp..conf..369S
Altcode:
  No abstract at ADS

Title: Are structures in high-speed streams signatures of coronal
    fine structures?
Authors: Thieme, K. M.; Schwenn, R.; Marsch, E.
Bibcode: 1989AdSpR...9d.127T
Altcode: 1989AdSpR...9..127T
  Interplanetary plasma and magnetic field data were measured by the
  two Helios solar probes from 1974 until 1986 and from 1976 until 1980,
  respectively, between 0.3 and 1 AU. We used these data to investigate
  plasma parameters of high-speed streams, especially velocities,
  densities, and temperatures of protons and α-particles. The possibility
  is discussed that the variability in these parameters is due to spatial
  structures which are remnants of the underlying coronal structures
  (supergranulation cells) preserved in the outflowing solar wind.

Title: Ion Temperature and Flow Profiles in Comet Halley's Close
    Environment
Authors: Schwenn, R.; Ip, W. -H.; Rosenbauer, H.; Balsiger, H.;
   Buhler, F.; Goldstein, R.; Meier, A.; Shelley, E. G.
Bibcode: 1989lsp..conf..583S
Altcode:
  No abstract at ADS

Title: LASCO: A wide-field white light and spectrometric coronagraph
    for SOHO
Authors: Michels, D. J.; Schwenn, R.; Howard, R. A.; Bartoe, J. -D. F.;
   Antiochos, S. K.; Brueckner, G. E.; Cheng, C. -C.; Dere, K. P.;
   Doschek, G. A.; Mariska, J. T.
Bibcode: 1988sohi.rept...55M
Altcode:
  The scientific objectives of the LASCO (light and spectrometric
  coronagraph) project in the SOHO (solar and heliospheric observatory)
  mission are described. These include investigation of mechanisms
  for heating of the corona and acceleration of the solar wind, causes
  of coronal transients, and their role in development of large scale
  coronal patterns and interplanetary disturbances. The distribution
  and properties of dust particles, including those released from
  sun-grazing comets are investigated. Interactions of coronal plasma
  with the dust are studied. The corona is analyzed spectroscopically
  by a high-resolution scanning, imaging interferometer. The spectral
  profiles of three emission lines and one Fraunhofer line are measured
  for each picture point, giving temperatures, velocities, turbulent
  motions and volume densities. Polarization analysis yields the direction
  of coronal magnetic fields.

Title: Chemical Composition and Ionisation States of the Solar Wind -
    Plasma as Characteristics of Solar Phenomena.
Authors: Schwenn, R.
Bibcode: 1988RvMA....1..179S
Altcode:
  No abstract at ADS

Title: An Interpretation of the Ion Pile-Up Region Outside the
    Ionospheric Contact Surface
Authors: Ip, W. H.; Schwenn, R.; Rosenbauer, H.; Balsiger, H.;
   Neugebauer, M.; Shelley, E. G.
Bibcode: 1987A&A...187..132I
Altcode:
  An analysis interrelating some of the results of plasma measurements
  by the Giotto spacecraft in the inner coma of comet P/Halley suggests
  that the formation of the plasma pile-up region at a distance of 10,000
  km - 30,000 km may be the result of accumulation of ion density in
  a stagnant flow region with a sharp electron temperature transition
  forming a recombination front at about 10,000 km.

Title: The Composition and Dynamics of Cometary Ions in the Outer
    Coma of Comet p/ Halley
Authors: Balsiger, H.; Altwegg, K.; Buhler, F.; Fuselier, S. A.;
   Geiss, J.; Goldstein, B. E.; Goldstein, R.; Huntress, W. T.; Ip,
   W. H.; Lazarus, A. J.; Meier, A.; Neugebauer, M.; Rettenmund, U.;
   Rosenbauer, H.; Schwenn, R.; Shelley, E. G.; Ungstrup, E.; Young, D. T.
Bibcode: 1987A&A...187..163B
Altcode:
  During its flyby at comet Halley, the Giotto spacecraft encountered
  high densities of cometary ions inside approximately 200000 km from
  the nucleus. Their properties changed drastically as the comet was
  approached. We present here density profiles of solar wind alpha
  particles and of the major cometary ions as obtained by the IMS-HERS
  sensor between 340000 km and 60000 km from the nucleus. Typical mass
  spectra at various distances are presented and angular and velocity
  distributions of the cometary ions are discussed.

Title: Ion Temperature and Flow Profiles in Comet p/ Halley's Close
    Environment
Authors: Schwenn, R.; Ip, W. H.; Rosenbauer, H.; Balsiger, H.; Buhler,
   F.; Goldstein, R.; Meier, A.; Shelley, E. G.
Bibcode: 1987A&A...187..160S
Altcode:
  The HIS instrument of the ion mass spectrometer on board the Giotto
  spacecraft identified the contact surface at 4800 km distance from
  the comet nucleus. This boundary is clearly seen by a drastic drop
  in the temperatures of different ion species from about 2000 K
  outside to values as low as 300 K inside. Also, inside the contact
  surface an outflow speed of &gt;1 km s<SUP>-1</SUP> was measured,
  in contrast to a value around zero right outside. We discuss how
  these numbers might be affected by a potential charge-up of the
  spacecraft. Outside the contact surface, the ion temperature rises
  gradually with increasing distance. Between 9000 and 10000 km distance
  the ion density increases by a factor of 4. This "ion pile-up" is not
  yet explained uniquely. Between 25000 and 28000 km distance there is
  again a rather abrupt jump to significantly higher temperatures and
  higher outflow speeds.

Title: Giotto / IMS Observations of Ion Flow Velocities and
    Temperatures Outside the Magnetic Cavity of Comet p/ Halley
Authors: Goldstein, B. E.; Neugebauer, M.; Balsiger, H.; Drake, J.;
   Fuselier, S. A.; Goldstein, R.; Ip, W. H.; Rettenmund, U.; Rosenbauer,
   H.; Schwenn, R.; Shelley, E. G.
Bibcode: 1987A&A...187..174G
Altcode:
  Fluid parameters for He<SUP>2+</SUP> ions obtained from the Giotto
  Ion Mass Spectrometer HERS sensor are presented; also investigated
  are proton densities and velocities and thermal speeds of protons,
  alpha particles, and heavy ions in the hour before closest approach. A
  bow shock transition lasting ten minutes is observed. A region of
  enhanced He<SUP>2+</SUP> ion densities, and velocity, and decreased
  temperature is observed from 20:26 to 21:45. Sharp decreases in the
  proton density are observed at 23:30 and at 23:41; there are also
  sharp drops in alpha particle density and temperature at 23:30. There
  is a relative flow velocity between alpha particles and oxygen ions of
  approximately 20 km s<SUP>-1</SUP> during a period roughly from 22:55
  to 23:10; by 23:30 the difference in flow velocity is less than the
  experimental uncertainities.

Title: The variation of protons, alpha particles, and the magnetic
    field across the bow shock of comet Halley
Authors: Neugebauer, M.; Neubauer, F. M.; Balsiger, H.; Fuselier,
   S. A.; Goldstein, B. E.; Goldstein, R.; Mariani, F.; Rosenbauer, H.;
   Schwenn, R.; Shelley, E. G.
Bibcode: 1987GeoRL..14..995N
Altcode:
  Data from the Ion Mass Spectrometer and the magnetometer on the Giotto
  spacecraft are used to examine the structure of the inbound crossing
  of the comet Halley bow shock on March 13, 1986. It is found that the
  velocity decrease, the field strength increase, and the heating of
  picked up cometary protons occurred over a broad region corresponding
  to several heavy-ion gyroradii. The solar-wind protons and alphas,
  on the other hand, were compressed and heated at a narrow structure,
  which might be called a subshock, on the leading edge of the broad
  shock region. The electrostatic potential difference across the shock
  was less than 40 V.

Title: Solar activity and heliosphere-wide cosmic ray modulation
    in mid-1982
Authors: Cliver, E. W.; Mihalov, J. D.; Sheeley, N. R., Jr.; Howard,
   R. A.; Koomen, M. J.; Schwenn, R.
Bibcode: 1987JGR....92.8487C
Altcode:
  A major episode of flare activity in June and July 1982 was accompanied
  by a pair of heliosphere-wide cosmic ray modulation events. In each
  case, a large Forbush decrease (FD) at earth was followed in turn
  by apparently related decreases at Pioneer 11 (P11) and Pioneer 10
  (P10). The Pioneer spacecraft were separated by ~155° in ecliptic
  longitude. We reviewed white light coronagraph and near-sun (&lt;=1 AU)
  satellite data to identify plausible solar origins of these modulation
  events. The first widespread intensity decrease (FD 1) can be attributed
  to the combined effects of a backside flare on June 3 from solar active
  region 18382/18383, located 23° in ecliptic longitude from Pioneer 10,
  and a visible disk flare from 18405 on June 6, when this region was
  9° from Pioneer 11. The second widespread modulation event during this
  period (FD 2) may be linked to flares from active region 18474 on July
  12 and 22. The July 12 flare was located 34° in azimuth from Pioneer
  11, and the July 22 flare was 24° from Pioneer 10. Since even fast
  shocks would take ~1 month to propagate to Pioneer 11 (12 AU) and ~2
  months to reach Pioneer 10 (28 AU) in mid-1982, these ``one-to-one''
  associations must be regarded with caution. The processes of entrainment
  and coalescence can cause a given traveling interplanetary disturbance
  to lose its identify enroute to the outer heliosphere. The fact that
  we were able to identify plausible solar flare candidates for each of
  the four Forbushlike decreases observed at the Pioneer satellites (two
  each at P10 and P11), however, removes the need to invoke a chock from
  a single flare as the sole cause of either FD 1 (at both P10 and P11)
  or FD 2. Such single-flare scenarios have recently been suggested by
  several investigators to account for the widespread intensity decreases
  in mid-1982. Instead, the heliosphere-wide modulation during this
  period appears to result primarily from a sustained episode of powerful
  flares from a relatively narrow range of active solar longitude. <P />A
  significant fraction (1/2 to 3/4) of the major coronal mass ejections
  (CMEs) and near-sun shocks observed during June and July 1982 originated
  in flares occurring in a 45° band of Carrington longitude. Because
  of solar rotation these flares occur over the full range of ecliptic
  longitude and can generate an outward propagating shell of CMEs and
  shocks that encompasses the sun to produce the observed azimuthal
  symmetry in the cosmic ray modulation. The prolonged high-speed wind
  stream at P10 in the second half of 1982 may have resulted, at least
  in part, from the coalescence of a series of fast transient streams
  directed toward that distant spacecraft into an extended compound
  stream.

Title: The ion mass spectrometer on Giotto
Authors: Balsiger, H.; Altwegg, K.; Benson, J.; Buhler, F.; Fischer,
   J.; Geiss, J.; Goldstein, B. E.; Goldstein, R.; Hemmerich, P.;
   Kulzer, G.; Lazarus, A. J.; Meier, A.; Neugebauer, M.; Rettenmund,
   U.; Rosenbauer, H.; Sager, K.; Sanders, T.; Schwenn, R.; Shelley,
   E. G.; Simpson, D.; Young, D. T.
Bibcode: 1987JPhE...20..759B
Altcode:
  The design of the Giotto ion mass spectrometer (IMS) system, its
  calibration, and the initial flight performance are discussed. The IMS
  system consists of two sensors: one optimized for the outer coma, the
  other for the inner coma, with each sensor obtaining complementary
  information in the region for which it was not optimized. Both
  sensors feature mass-imaging characteristics, permitting simultaneous
  measurements of several ion species by means of multi-detector arrays,
  with resultant mass per charge resolution of not less than 20. In
  addition to mass per charge, the energy per charge and the elevation
  and azimuth of the incident ions were measured during the Giotto flight.

Title: The solar wind
Authors: Schwenn, R.
Bibcode: 1987ESASP.268..131S
Altcode: 1987sass.conf..131S
  Parker's theoretical model of the solar wind, i.e., a continuous
  outflow of particles from the solar corona is found to be in basic
  agreement with observations. More sophisticated models and more
  detailed measurements reveal significant gaps in understanding. The
  high values of flow speed in high speed streams cannot be explained,
  and identifying coronal sources of the slow solar wind reveals severe
  topological problems. It appears as if there are basic differences in
  the acceleration mechanism for slow and fast solar wind. The variation
  of the average solar wind during the solar activity cycle is only
  a minor effect. Modulation of galactic cosmic radiation by solar
  activity is probably due to transient effects on the Sun. Coronal mass
  ejections in association with solar flares or eruptive prominences
  drive interplanetary shock waves into the solar wind throughout the
  heliosphere. However, there are gaps in understanding of reactions
  between the Sun's surface and the outer solar system.

Title: The pick-up of cometary protons by the solar wind
Authors: Neugebauer, M.; Lazarus, A. J.; Altwegg, K.; Balsiger, H.;
   Goldstein, B. E.; Goldstein, R.; Neubauer, F. M.; Rosenbauer, H.;
   Schwenn, R.; Shelley, E. G.
Bibcode: 1987STIN...8719342N
Altcode:
  The High Energy Range Spectrometer (HERS) of the Ion Mass Spectrometer
  on the Giotto spacecraft measured the 3-dimensional distribution of
  picked-up cometary protons over a distance of approximately 8 million km
  upstream of the bow shock of Comet Halley. The protons were observed to
  be elastically scattered out of their original cycloidal trajectories
  such that they were nonuniformly distributed over a spherical shell
  in velocity space. The shell radius (relative to its expected radius)
  and thickness increased as the bow shock was approached. Downstream
  of the shock, the cometary protons could not be distinguished from
  the heated solar wind protons.

Title: Unusual electron distribution functions in the solar wind
derived from the Helios plasma experiment: Double-strahl distributions
    and distributions with an extremely anisotropic core
Authors: Pilipp, W. G.; Miggenrieder, H.; Montgomery, M. D.;
   Mühlhäuser, K. -H.; Rosenbauer, H.; Schwenn, R.
Bibcode: 1987JGR....92.1093P
Altcode:
  Electron distribution functions with unusual features, which have been
  observed on rare occasions in the solar wind by the Helios probes,
  are presented. Two examples show a strong symmetric bidirectional
  anisotropy in the energy regime of the halo up to particle energies of
  800 eV (double-strahl distributions). Another example shows an unusually
  strong bidirectional anisotropy in the energy regime of the core (below
  150 eV). The infrequently observed double-strahl distributions provide
  evidence that magnetic field loops can exist in the solar wind where
  electrons are trapped. In addition, they provide evidence that in the
  case of electrons trapped in closed magnetic field structures the break
  in the energy spectrum separating the core from the halo is produced
  only by collisions. On the other hand, the class of distribution
  functions with strongly anisotropic cores indicates that in the case
  of ``open'' magnetic field lines the break between core and halo is
  largely determined both by the interplanetary electrostatic potential
  and by collisions.

Title: Characteristics of electron velocity distribution functions
    in the solar wind derived from the helios plasma experiment
Authors: Pilipp, W. G.; Miggenrieder, H.; Montgomery, M. D.;
   Mühlhäuser, K. -H.; Rosenbauer, H.; Schwenn, R.
Bibcode: 1987JGR....92.1075P
Altcode:
  The shapes of three typical examples of electron distribution functions,
  which have been observed by Helios 2 in the solar wind, are analyzed and
  compared with theoretical predictions. We have considered a distribution
  function with a ``narrow strahl'' (narrow beam), which is extremely
  anisotropic and skewed with respect to the magnetic field direction
  at particle energies above 100 eV, a distribution function with a
  ``broad strahl'' (broad beam), which is less anisotropic and skewed,
  and finally a nearly isotropic distribution function which, however,
  shows a slight bidirectional anisotropy. <P />The main results are
  as follows: (1) For each distribution function we may discern a
  ``break,'' i.e., a sudden change in the slope of the distribution
  function, separating the ``core'' at lower energies from the ``halo''
  at larger energies. For the anisotropic distributions a significant
  break is observed in velocity directions opposite to the strahl and
  perpendicular to it but not along the strahl. Here the energy of the
  break (breakpoint energy) may be determined both by the interplanetary
  electrostatic potential and by collisions. In contrast, for the nearly
  isotropic distribution function, a significant break is observed for
  all velocity directions, and the breakpoint energy may be determined
  by collisions only. (2) The strahl observed at larger energies in the
  anisotropic distribution functions can be qualitatively explained by
  existing theoretical approaches describing the propagation of electrons
  in the solar wind. However, at least for the distribution function
  with the broad strahl as well as for the nearly isotropic distribution
  function, the halo electrons should be scattered by unknown anomalous
  scattering processes, which do not show a strong energy dependence. (3)
  For the anisotropic distribution functions we find a velocity shift
  between the peak of each distribution function and the solar wind
  bulk velocity, which is typically 100 kms<SUP>-</SUP><SUP>1</SUP>
  to 300 kms<SUP>-</SUP><SUP>1</SUP>. This shift is drastically reduced
  compared to the shift predicted by exospheric theory, indicating strong
  frictional processes between electrons and ions. <P />However the
  results do not settle the question whether this friction is provided by
  the combined action at wave-particle interactions and Coulomb collisions
  or by Coulomb collisions only. For the nearly isotropic distribution
  function this shift is probably not significantly different from
  zero. In this scae it may be determined by some anomalous processes
  and/or trapping in closed magnetic field structures. (4) For the
  anisotropic distribution functions the heat flux is carried mainly by
  the strahl. For the nearly isotropic distribution function most of the
  heat flux is carried by the core electrons. For this distribution, part
  of the halo electrons carry heat flux in the opposite direction, and the
  total heat flux is probably not significantly different from zero. (5)
  The pitch angle distribution in the energy regime of the halo may
  provide some indications for the global structure of the magnetic field.

Title: Variations of electron distribution functions in the solar wind
Authors: Pilipp, W. G.; Miggenrieder, H.; Mühlhaüser, K. -H.;
   Rosenbauer, H.; Schwenn, R.; Neubauer, F. M.
Bibcode: 1987JGR....92.1103P
Altcode:
  Variations of electron distribution functions in the solar wind have
  been investigated using the electron data observed aboard Helios 2
  during the first four months of its mission in 1976 in the distance
  range between 0.3 and 1 AU. In particular, variations across the sector
  structure of interplanetary magnetic field and across the plasma stream
  structures have been studied. It has been found that there is a strong
  correlation between the electron properties and the sector structure
  of the magnetic field. Within the interior of magnetic sectors the
  electron distribution functions are extremely anisotropic and skewed
  with respect to the magnetic field direction at high particle energies
  (above 100 eV); i.e., the distribution functions have a narrow strahl
  (beam) directed along the magnetic field away from the sun. Often
  a slight indication of a second strahl directed along the magnetic
  field toward the sun has been found. Toward sector boundaries the
  electron distribution functions become less anisotropic and less
  skewed. Right at sector boundaries the electrons are relatively cool,
  and their distributions are nearly isotropic, often showing a slight
  bidirectional anisotropy. These observations have been interpreted to
  indicate that scattering of electrons with energies above 100 eV is
  weak within the interior of magnetic sectors but anomalous scattering
  increases drastically toward sector boundaries for all energies in
  the halo regime up to several hyndred eV. There is evidence for closed
  magnetic field structures, probably occurring frequently in the solar
  wind, where the magnetic field lines should usually be connected to
  the sun outside sector boundaries but may or may not be disconnected
  from the sun at sector boundaries.

Title: Relationship between Structures in the Solar Wind and Their
    Source Regions in the Corona
Authors: Thieme, K. M.; Marsch, E.; Schwenn, R.
Bibcode: 1987sowi.conf..317T
Altcode:
  No abstract at ADS

Title: Doppler Scintillation Observations of Interplanetary
    Disturbances within 0.3 AU
Authors: Woo, R.; Armstrong, J. W.; Schwenn, R.
Bibcode: 1987sowi.conf..266W
Altcode:
  No abstract at ADS

Title: An interpretation of the ion pile-up region outside the
    ionospheric contact surface
Authors: Ip, Wing-H.; Schwenn, R.; Rosenbauer, H.; Balsiger, H.;
   Neugebauer, M.; Shelley, E. G.
Bibcode: 1986ESASP.250a.219I
Altcode: 1986ehc1.conf..219I
  An analysis inter-relating some of the published results of the plasma
  measurements by the Giotto spacecraft in the inner coma of comet Halley
  suggests that the formation of the plasma pile-up region at a distance
  of 10,000 km - 30,000 km may be the result of accumulation of ion
  density in a stagnant flow region with a sharp electron temperature
  transition forming a recombination front at about 10,000 km.

Title: Ion temperature and flow profiles in Comet Halley's close
    environment
Authors: Schwenn, R.; Ip, Wing-H.; Rosenbauer, H.; Balsiger, H.;
   Buehler, F.; Goldstein, R.; Meier, A.; Shelley, E. G.
Bibcode: 1986ESASP.250a.225S
Altcode: 1986ehc1.conf..225S
  The HIS instrument of the ion mass spectrometer on board the GIOTTO
  spacecraft identified the contact surface in 4800 km distance from
  the comet nucleus. This boundary is clearly seen by a drastic drop
  in the temperatures of different ion species from about 2000K outside
  to values as low as 300K inside. Also, inside the contact surface an
  outflow speed of &gt;1 km s<SUP>-1</SUP> was measured, in contrast to a
  value around zero right outside. The authors discuss how these numbers
  might be affected by a potential charge-up of the spacecraft. Outside
  the contact surface, the ion temperature rises gradually with increasing
  distance. Between 9000 and 10,000 km distance the ion density increases
  by a factor of 4. This "ion pile-up" is not yet explained uniquely. At
  27,000 km distance there is again a rather abrupt jump to significantly
  higher temperatures, higher outflow speeds and lower densities.

Title: Giotto-IMS observations of ion flow velocities and temperatures
    outside the contact surface of Comet Halley
Authors: Goldstein, B. E.; Neugebauer, M.; Balsiger, H.; Drake,
   J.; Fuselier, S. A.; Goldstein, R.; Ip, Wing-H.; Rettenmund, U.;
   Rosenbauer, H.; Schwenn, R.
Bibcode: 1986ESASP.250a.229G
Altcode: 1986ehc1.conf..229G
  Fluid parameters for He<SUP>++</SUP> ions obtained from the GIOTTO
  ion mass spectrometer HERS sensor are presented; also investigated
  are proton densities and velocities and thermal speeds of protons,
  alpha particles, and heavy ions in the hour before closest appraoch. A
  region of enhanced He<SUP>++</SUP> ion densities, and velocity, and
  decreased temperature is observed from 20:26 to 21:45. Sharp decreases
  in the proton density are observed at 23:30 and at 23:41. There is
  a relative flow velocity between alpha particles and oxygen ions of
  approximately 30 km/sec during a period roughly from 22:55 to 23:10;
  by 23:30 the difference in flow velocity is less than the experimental
  uncertainties. The flow properties of protons observed during this
  period are also discussed.

Title: Tangential discontinuities in the solar wind: Correlated
    field and velocity changes in the Kelvin-Helmholtz Instability
Authors: Neugebauer, M.; Alexander, C. J.; Schwenn, R.; Richter, A. K.
Bibcode: 1986JGR....9113694N
Altcode:
  Three-dimensional Helios plasma and field data are used to investigate
  the relative changes in direction of the velocity and magnetic
  field vectors across tangential discontinuities, (TDs) in the solar
  wind at solar distances of 0.29-0.50 AU. It is found for tangential
  discontinuities with both Δv and ΔB/B large that Δv and ΔB are
  closely aligned with each other, in agreement with the unexpected
  results of previous studies of tangential discontinuities observed at
  1 AU and beyond. It is shown that this effect probably results from
  the destruction by the Kelvin-Helmholtz instability of TDs for which
  Δv and ΔB are not aligned. The observed decrease in the number of
  interplanetary discontinuities with increasing solar distance may be
  associated with the growth of the Kelvin-Helmholtz instability with
  decreasing Alfvén speed.

Title: Formation of a compound stream between 0.85 AU and 6.2 AU
    and its effects on solar energetic particles and galactic cosmic rays
Authors: Burlaga, L. F.; McDonald, F. B.; Schwenn, R.
Bibcode: 1986JGR....9113331B
Altcode:
  During September 1979, Helios B (HB) and Voyager 1 (V1) were near
  0.85 AU and 6.2 AU, respectively, and they were radially aligned
  with respect to the sun within 20°. A slow transient stream, two
  corotating streams, and two unusually fast transient streams passed
  HB during a 17-day interval in that order. (A stream is defined here
  as a flow in which the speed is always greater than 475 km/s.) As the
  streams moved outward from HB to V1, they coalesced to form a single
  large ``compound stream'' which moved past V1 in 20 days. The compound
  stream was produced by motion of fast plasma away from slower plasma
  behind and by the interaction of the fast streams with slower streams
  ahead. The maximum speed observed was 1270 km/s at HB and 860 km/s at
  V1. <P />Closely associated with this compound stream was one of the
  largest solar energetic particle events (protons 0.4-69 MeV) observed
  beyond 5 AU. The maximum intensity was in the region of increasing
  speed. The intensity-time profile of the solar energetic particles was
  closely related to the speed profile. There is evidence of channeling
  and trapping of particles in a region following the highest speeds,
  where the magnetic field was strong and the magnetic field lines were
  nearly radial. The high-energy protons (&gt;150 MeV) and MeV electrons
  are believed to be accelerated in solar flare events. Interplanetary
  acceleration appears to play a major role in the low-energy particle
  population. The galactic cosmic ray intensity remained low throughout
  the passage of the compound stream, recovering slowly as the speed
  decreased. The long ``recovery time'' is thus related to the large
  extent of the flow.

Title: Hot ions observed by the Giotto ion mass spectrometer inside
    the Comet Halley contact surface
Authors: Goldstein, R.; Young, D. T.; Balsiger, H.; Buehler, F.;
   Goldstein, B. E.; Neugebauer, M.; Rosenbauer, H.; Schwenn, R.; Shelly,
   E. G.
Bibcode: 1986ESASP.250a.207G
Altcode: 1986ehc1.conf..207G
  Just inside the contact surface (approx. 4700 km) the High Energy
  Range Spectrometer (HERS) sensor of the Giotto ion mass spectrometer
  detected a sudden, intense burst of ions that lasted until the HERS
  sensor ceased transmitting data at a distance 3000 km from comet
  Halley. During this interval ions with M/Q=1, 2, 12, 14, 16, 19, 24 and
  28 were observed. The heavier ions appear in two populations (in the
  S/C frame): a very low energy, almost omnidirectional distribution,
  and a more energetic (approx. &lt; ram speed) population coming from
  the ram direction. The low energy ions may belong to the natural
  Halley environment or be generated at the spacecraft by dust and
  gas bombardment. The ions may also be related to spacecraft charging
  processes on Giotto.

Title: The pick-up of cometary protons by the solar wind
Authors: Neugebauer, M.; Lazarus, A. J.; Altwegg, K.; Balsiger, H.;
   Goldstein, B. E.; Goldstein, R.; Neubauer, F. M.; Rosenbauer, H.;
   Schwenn, R.; Shelley, E. G.
Bibcode: 1986ESASP.250a..19N
Altcode: 1986ehc1.conf...19N
  The HERS detector of the Ion Mass Spectrometer on the Giotto spacecraft
  measured the 3-dimensional distribution of picked-up cometary
  protons over a distance of 6 million km upstream of the bow shock. The
  protons were observed to be elastically scattered out of their original
  cycloidal trajectories such that they were nonuniformly distributed over
  a spherical shell in velocity space. The shell thickness increased as
  the bow shock was approached. Inside the shock, the cometary protons
  were difficult to distinguish from the heated solar wind protons.

Title: Relationship of Coronal Transients to Interplanetary Shocks -
    3d Aspects
Authors: Schwenn, R.
Bibcode: 1986SSRv...44..139S
Altcode:
  More than 1000 coronal mass ejections (CMEs) caused by different
  types of coronal transients have been analyzed up to now, based on
  the images from white light coronagraphs on board the OSO 7, Skylab,
  P78-1, and SMM spacecraft. In many cases, the CME images lead us to
  the impression of loop-like, more planar structures, similar to those
  of prominence structures often seen in H<SUB>α</SUB> pictures. There
  is increasing evidence, though, for a three-dimensional bubble- or
  cloud-like structure of CMEs. In several cases, CMEs directed toward the
  earth (or away from it) were identified, as their outer fronts emerged
  on all sides of the coronagraph's occulting disk, thus suggesting a
  bubble-like appearance. There now appears to be unanimity about the
  crucial role that magnetic reconnection plays during the transient
  process. Recently, direct evidence was found for the ‘pinch-off of
  CMEs, both from optical observations and from in situ measurements of
  isolated ‘magnetic clouds' following transient shock waves. However,
  the detailed sequence of events during the generation of a CME is
  still unclear. Interplanetary shock waves associated with the CMEs are
  usually restricted in latitudinal extent to about the angular width
  of the optically observed CMEs. They may be somewhat less restricted
  in longitudinal extent. A nearly 1 ∶ 1 association between CMEs and
  shock waves measured in situ from spacecraft (Helios 1 and 2, IMP 7
  and 8, ISEE 3, Pioneer Venus) can be established, provided the CME and
  the spacecraft were in the same longitudinal and latitudinal range and
  the CME speed exceeds ∼ 400 km s<SUP>-1</SUP>. Around the past solar
  activity minimum all CMEs observed were centered at solar latitudes of
  less than 60°. Around solar maximum, a significant fraction of CMEs
  also originated from the polar regions. Thus, there is a good chance
  that the Ulysses spaceprobe will encounter many shocks caused by both
  low- and high-latitude CMEs, when it finally starts its journey over
  the Sun's poles.

Title: Ion composition and dynamics at comet Halley
Authors: Balsiger, H.; Altwegg, K.; Buhler, F.; Geiss, J.; Ghielmetti,
   A. G.; Goldstein, B. E.; Goldstein, R.; Huntress, W. T.; Ip, W. -H.;
   Lazarus, A. J.; Meier, A.; Neugebauer, M.; Rettenmund, U.; Rosenbauer,
   H.; Schwenn, R.; Sharp, R. D.; Shelly, E. G.; Ungstrup, E.; Young,
   D. T.
Bibcode: 1986Natur.321..330B
Altcode:
  The ion mass spectrometer aboard the Giotto spacecraft measured the
  composition and velocity distributions of cometary ions at distances
  of ~7.5×l0<SUP>6</SUP> to ~1,300 km from the nucleus of comet
  Halley. Well outside the bow shock, pick-up cometary H<SUP>+</SUP>
  ions were found in a diffuse shell-like distribution. Heavier ions
  (C<SUP>+</SUP>, H<SUB>2</SUB>O<SUP>+</SUP>-group, CO<SUP>+</SUP>
  and S<SUP>+</SUP>) with similar distributions have been identified
  at &lt;=3×l0<SUP>5</SUP> km. Solar-wind He<SUP>2+</SUP> was found
  throughout the coma to as close as ~5,000 km; He<SUP>+</SUP> produced
  by charge exchange was seen inside ~2×10<SUP>5</SUP> km. Deeper
  within the coma the main cometary hot-ion species identified were
  H<SUP>+</SUP>, H<SUB>2</SUB><SUP>+</SUP>, C<SUP>+</SUP>, O<SUP>+</SUP>,
  OH<SUP>+</SUP>, H<SUB>2</SUB>O<SUP>+</SUP>, H<SUB>3</SUB>O<SUP>+</SUP>,
  CO<SUP>+</SUP> and S<SUP>+</SUP>. A pile-up of heavy cometary ions
  was found at ~10<SUP>4</SUP> km from the nucleus. Giotto crossed the
  contact surface at ~4,600 km, based on changes in ion flow velocity
  and temperature. Inside, ion temperatures as low as ~340 K and outflow
  velocities of ~1 km s<SUP>-1</SUP> were found. Outside the contact
  surface ion densities vary as r<SUP>-2</SUP>, with a transition to an
  r<SUP>-l</SUP> dependence approximately at the contact surface. A large
  C<SUP>+</SUP> abundance throughout the coma indicates an unexpected
  direct source of atomic carbon. The nitrogen abundance, on the other
  hand, is relatively low.

Title: In-Situ Observations of the Latitudinal Gradients of the
    Solar Wind Parameters during 1976 and 1977
Authors: Bruno, R.; Villante, U.; Bavassano, B.; Schwenn, R.;
   Mariani, F.
Bibcode: 1986SoPh..104..431B
Altcode:
  Interplanetary observations from Helios 1, Helios 2, and IMP-8
  spacecraft during 1976 and 1977, namely the early portion of solar
  cycle 21, have been used to investigate the latitudinal gradients of the
  solar wind parameters with respect to the angular displacement from the
  current sheet inferred from synoptic HAO white-light maps of the solar
  corona at 1.75 solar radii. A latitudinal belt of ±25 deg around the
  current sheet has been investigated. Large gradients for solar wind
  flow speed, proton density and temperature have been found. Smoother
  gradients were also found for particle flux, kinetic, gravitational
  and thermal energy density flux. All these gradients revealed to become
  smoother going towards the solar cycle's maximum. Neither latitudinal
  nor temporal variations were identified for magnetic and thermal
  energy density. A remarkable result of this study is that the momentum
  flux density and the total energy flux density which other authors
  found to be independent of any longitudinal stream structure were
  also found to be independent of any latitudinal structure. Moreover,
  these two parameters did not show any temporal variation during the
  period of interest.

Title: The Giotto ion mass spectrometer
Authors: Balsiger, H.; Altwegg, K.; Buehler, F.; Fischer, J.;
   Geiss, J.; Meier, A.; Rettenmund, U.; Rosenbauer, H.; Schwenn, R.;
   Neugebauer, M.
Bibcode: 1986gmis.rept..129B
Altcode:
  The Giotto Ion Mass Spectrometer (IMS) consists of two sensors: one
  optimized for the outer and the other for the inner coma, with each
  obtaining complementary information in the region for which it is not
  optimized. The outer coma is characterized by the interaction between
  solar wind and comentary plasmas, the inner coma by the outflow of
  cometary neutrals and their ionization products. Both sensors feature
  mass imaging characteristics, permitting simultaneous measurements of
  several ion species by multidetector arrays. Resultant mass-per-charge
  resolution is greater than or = 20. Energy per charge, and the elevation
  and aximuth of incident ions are measured. Calibration and in-flight
  solar-wind data show that the IMS will meet its scientific goals for
  the Halley encounter.

Title: Cosmic ray variations and turbulent flow systems: 0.3-1.0
    AU; 1977-1980
Authors: Burlaga, L. F.; Goldstein, M. L.; McDonald, F. B.; Lazarus,
   A. J.; Mariani, F.; Neubauer, F. M.; Schwenn, R.
Bibcode: 1986JGR....91.2917B
Altcode:
  Relations among the relative counting rates of cosmic ray protons
  and the magnetic fields and flows observed by Helios 1 between
  0.3 AU and 1 AU in the period January 1977 to August 1980 are
  discussed. Isolated corotating or transient flows are associated with
  short-term depressions in cosmic ray intensity, but the effects are
  localized in longitude. Systems of corotating streams do not produce a
  long-term modulation effect, although temporary, short-term depressions
  in cosmic ray intensity are associated with individual streams and
  interaction regions. Spectra of fluctuations of the magnetic field and
  magnetic helicity for systems of corotating flows often do not have the
  form f<SUP>-</SUP><SUP>5</SUP><SUP>/</SUP><SUP>3</SUP> at frequencies
  &gt;=10<SUP>-</SUP><SUP>5</SUP> Hz, and accordingly, the hydromagnetic
  fluctuations in corotating streams near the sun do not appear to
  represent fully developed turbulence at low frequencies. Systems of
  transient streams containing shocks that might encircle the sun are
  associated with long-lasting decreases in cosmic ray intensity. The
  magnetic field fluctuations in such flow systems are often turbulent,
  with f<SUP>-</SUP><SUP>5</SUP><SUP>/</SUP><SUP>3</SUP> spectra extending
  from below 10<SUP>-</SUP><SUP>5</SUP> Hz to the Nyquist frequency
  of the data. The turbulence is likely to be confined to sheets with
  thickness of the order of 0.1 AU, possibly associated with shocks. We
  conclude that long-term modulation of cosmic rays inside 1 AU is
  associated with turbulence in transient disturbances that probably
  encompass a large longitudinal extent around the sun. In mixed flow
  systems the effects are intermediate between those of corotating and
  transient systems. The net modulation may be relatively small, with
  large short-term variations associated with individual streams.

Title: The Giotto Ion Mass Spectrometer.
Authors: Balsiger, H.; Altwegg, K.; Bühler, F.; Fischer, J.; Geiss,
   J.; Meier, A.; Rettenmund, U.; Rosenbauer, H.; Schwenn, R.; Benson,
   J.; Hemmerich, P.; Säger, K.; Kulzer, G.; Neugebauer, M.; Goldstein,
   B. E.; Goldstein, R.; Shelley, E. G.; Sanders, T.; Simpson, D.;
   Lazarus, A. J.; Young, D. T.
Bibcode: 1986ESASP1070..129B
Altcode:
  The Giotto Ion Mass Spectrometer (IMS) consists of two sensors: one
  optimised for the outer and the other for the inner coma of Halley's
  comet. Both sensors feature mass imaging characteristics, thereby
  permitting simultaneous measurements of several ion species by means
  of multi-detector arrays. Resultant mass-per-charge resolution is
  ≥20. In addition to mass per charge, the energy per charge, the
  elevation and azimuth of incident ions are measured.

Title: Relationship of Coronal Transients to Interplanetary Shocks:
    3-D Aspects
Authors: Schwenn, R.
Bibcode: 1986shtd.symp..119S
Altcode:
  No abstract at ADS

Title: Shock and Statistical Acceleration of Energetic Particles in
    the Interplanetary Medium
Authors: Valdes-Galicia, J. F.; Moussas, X.; Quenby, J. J.; Neubauer,
   F. M.; Schwenn, R.
Bibcode: 1985ICRC....4..162V
Altcode: 1985ICRC...19d.162V
  Definite evidence for particle acceleration in the solar wind came
  around a decade ago. Two likely sources are known to exist: particles
  may be accelerated by the turbulence resulting from the superposition
  of Alfven and Magnetosonic waves (Statistical Acceleration) or they may
  be accelerated directly at shock fronts formed by the interaction of
  fast and slow solar wind (CIR's) or by traveling shocks due to sporadic
  coronal mass ejections. Naurally both mechanisms may be operative. In
  this work the acceleration problem was tackled numerically using Helios
  1 and 2 data to create a realistic representation of the Heliospheric
  plasma. Two 24 hour samples were used: one where there are only wave
  like fluctuations of the field (Day 90 Helios 1) and another with
  a shock present in it (Day 92 of Helios 2) both in 1976 during the
  STIP 2 interval. Transport coefficients in energy space have been
  calculated for particles injected in each sample and the effect of
  the shock studied in detail.

Title: Origin of the Solar Wind
Authors: Gabriel, A.; Schwenn, R.
Bibcode: 1985ESASP.235..231G
Altcode: 1985fmsh.work..231G
  No abstract at ADS

Title: Latitudinal gradients of the solar wind parameters during
1976 and 1977: HELIOS 1, 2 and IMP in-situ observations
Authors: Bruno, R.; Villante, V.; Bavassano, B.; Schwenn, R.
Bibcode: 1985STIN...8628902B
Altcode:
  Interplanetary observations from Helios 1, Helios 2 and IMP spacecraft
  during the early portion of solar cycle 21 were used to investigate
  the latitudinal gradients of solar wind parameters with respect to the
  angular displacement from the current sheet inferred from synoptic
  white-light maps of the solar corona at 1.75 solar radii. Large
  latitudinal gradients for solar wind flow speed, proton density, and
  temperature are found. All these gradients become smoother towards
  the solar cycle maximum. Neither latitudinal nor temporal variations
  for magnetic flow and thermal energy density are identified.

Title: Doppler scintillation observations of interplanetary shocks
    within 0.3 AU
Authors: Woo, Richard; Armstrong, J. W.; Sheeley, N. R.; Howard,
   R. A.; Koomen, M. J.; Michels, D. J.; Schwenn, R.
Bibcode: 1985JGR....90..154W
Altcode:
  Near-sun spacecraft Doppler scintillation observations have been
  combined with Solwind coronagraph and Helios 1 plasma measurements to
  provide more definitive measurements of the evolution and propagation
  of interplanetary shock waves between the sun and earth orbit than
  have been available from previous observations. This study shows that
  substantial deceleration of fast shocks (shock speeds exceeding 1000 km
  s<SUP>-</SUP><SUP>1</SUP>) takes place near the sun and that the amount
  of deceleration increases with shock speed. This is consistent with
  the significantly lower and rather narrow range of shock velocities
  observed by direct spacecraft near earth orbit. When coronal mass
  ejection (CME) speeds are available for the fast shocks, they are
  considerably lower than the speeds measured farther out but near the
  sun. This implies that either the fast shocks first accelerate before
  decelerating on their way out from the sun (assuming the CME front
  is identified with the shock) or the CME speeds do not represent and
  substantially underestimate the shock speeds in the outer corona. If
  the CME speeds underestimate the shock speeds of the fast shocks, they
  do not appear to do so for the slow shocks. If the shocks are being
  driven over distances indicated by the acceleration region or to the
  point where deceleration begins, then their velocity profiles imply
  that the slower shocks are being driven farther out than the faster
  shocks. The analysis of one piston-driven shock shows the velocity of
  the contact surface is about 0.58 that of the shock front velocity.

Title: Coronal mass ejections and interplanetary shocks
Authors: Sheeley, N. R., Jr.; Howard, R. A.; Michels, D. J.; Koomen,
   M. J.; Schwenn, R.; Muehlhaeuser, K. H.; Rosenbauer, H.
Bibcode: 1985JGR....90..163S
Altcode:
  A comparison between Solwind observations of coronal mass ejections
  (CME's) and Helios 1 observations of interplanetary shocks during
  1979-1982 indicates that 72% of the shocks were associated with large,
  low-latitude mass ejections on the nearby limb. Most of the associated
  CME's has speeds in excess of 500 km/s, but some of them had speeds in
  the range 200-400 km/s. An additional 26% of the shocks may have been
  associated with CME's, but we were less confident of these associations
  because the sizes and locations of the CME's did not seem appreciably
  different from those of the numerous CME's without Helios shocks. Only
  2% of the shocks clearly lacked CME's. As the average level of sunspot
  activity declined during 1982, the shock frequency also declined, but
  the observed shocks and some of their associated CME's had unusually
  high speeds well in excess of 1000 km/s.

Title: Review of interplanetary shock phenomena near and within 1 AU
Authors: Richter, A. K.; Hsieh, K. C.; Luttrell, A. H.; Marsch, E.;
   Schwenn, R.
Bibcode: 1985GMS....35...33R
Altcode:
  A review of the more recent observations regarding interplanetary shock
  waves and shock-related phenomena near and within 1 AU is presented. In
  particular, the observations of interplanetary fast mode shocks are
  summarized in terms of (1) their solar and interplanetary origin,
  (2) their observed characteristics with respect to the solar cycle,
  (3) the solar wind stream-structure, and (4) the heliocentric radial
  distance; and in terms of (5) their three-dimensional propagation
  properties in the inner part of the heliosphere. Postshock large-scale
  flows and structures and some recent 'field and particle' observations
  associated with interplanetary fast shocks are also reviewed.

Title: Interplanetary flow systems associated with cosmic ray
    modulation in 1977-1980
Authors: Burlaga, L. F.; McDonald, F. B.; Ness, N. F.; Schwenn, R.;
   Lazarus, A. J.; Mariani, F.
Bibcode: 1984JGR....89.6579B
Altcode:
  The hydromagnetic flow configurations associated with the cosmic ray
  modulation in 1977-1980 were determined using solar wind plasma and
  magnetic field data from Voyager 1 and 2 and Helios 1. The modulation
  was related to two types of large-scale systems of flows: one containing
  a number of transients such as shocks and postshock flows, the other
  consisting primarily of a series of quasistationary flows following
  interaction regions containing a stream interface and often bounded
  by a forward-reverse shock pair. Each of three major episodes of
  cosmic ray modulation was associated with the passage of a system of
  transient flows. Plateaus in the cosmic ray intensity-time profile
  were associated with the passage of systems of corotating streams.

Title: Mean free paths and diffusion coefficients for energetic
    protons at small heliodistances calculated using HELIOS 1 and 2 data
Authors: Valdes Galicia, J. F.; Moussas, X.; Quenby, J. J.; Neubauer,
   F. M.; Schwenn, R.
Bibcode: 1984SoPh...91..399V
Altcode:
  Pitch angle scattering of energetic particles (100 MeV) in the
  interplanetary medium are studied using Helios 1 and 2 magnetometer
  and plasma data during 1976 near the minimum of solar activity. An
  IMF configuration was used in the computer experiments which allowed
  the pitch angle diffusion coefficient, D<SUB>μμ</SUB> and hence the
  parallel mean free path, λ<SUB>∥</SUB>, to be determined. The radial
  mean free path was found to vary as λ<SUB>r</SUB> ≡ r<SUP>-0.9</SUP>
  between 0.4 and 1 AU, but between 0.3 and 0.4 AU it decreases
  significantly. To reconcile the authors' value of λ<SUB>r</SUB> at
  1 AU, lying between 0.01 and 0.02 AU, with the average prompt solar
  proton event profile an increasing value of λ<SUB>r</SUB> at lower
  radial distances would be required.

Title: Solar Radio Burst and In-Situ Determination of Interplanetary
    Electron Density
Authors: Bougeret, J. -L.; King, J. H.; Schwenn, R.
Bibcode: 1984SoPh...90..401B
Altcode:
  We review and discuss a few interplanetary electron density scales
  which have been derived from the analysis of interplanetary solar
  radio bursts, and we compare them to a model derived from 1974-1980
  Helios 1 and 2 in situ density observations made in the 0.3-1.0
  AU range. The Helios densities were normalized to 1976 with the
  aid of IMP and ISEE data at 1 AU, and were then sorted into 0.1
  AU bins and logarithmically averaged within each bin. The best
  fit to these 1976-normalized, bin averages is N(R<SUB>AU</SUB>) =
  6.1R<SUP>-2.10</SUP> cm<SUP>-3</SUP>. This model is in rather good
  agreement with the solar burst determination if the radiation is assumed
  to be on the second harmonic of the plasma frequency. This analysis
  also suggests that the radio emissions tend to be produced in regions
  denser than the average where the density gradient decreases faster
  with distance than the observed R<SUP>-2.10</SUP>.

Title: Report of ESA's topical team on solar and heliospheric physics.
Authors: Christensen-Dalsgaard, J.; Delache, P.; Hoyng, P.; Priest,
   E. R.; Schwenn, R.; Stenflo, J. O.
Bibcode: 1984ESASP1070...26C
Altcode:
  No abstract at ADS

Title: Synoptic observations of coronal transients and their
    interplanetary consequences
Authors: Michels, D. J.; Sheeley, N. R., Jr.; Howard, R. A.; Koomen,
   M. J.; Schwenn, R.; Mulhauser, K. H.; Rosenbauer, H.
Bibcode: 1984AdSpR...4g.311M
Altcode: 1984AdSpR...4..311M
  A small coronagraph has been placed in orbit to monitor the sun's
  outer corona from 2.5 to 10.0 solar radii, and five years of nearly
  continuous synoptic observations have now been completed. Rapid and
  sensitive image processing techniques have been developed to screen
  the data for transient phenomena, particularly coronal mass ejections
  (CMEs). About 50,000 coronal images have been examined, out of a
  five-year total of 68,000, and a standardized listing of more than 1,200
  coronal transients for the period 1979-1982 has been prepared. These
  data have been analysed in the light of other available information,
  particularly on conditions in the interplanetary plasma. The dynamical
  characteristics of the active corona, as they are beginning to emerge
  from the data, are presented. We find that coronal mass ejections
  exercise significant influence on the interplanetary solar wind. They
  are the source of disturbances that are frequent and energetic,
  that tend to be somewhat focussed, that often reach shock intensity,
  and that propagate to large heliocentric distances, sometimes causing
  major geomagnetic storms.

Title: Ten years solar wind experiments on HELIOS 1 and HELIOS 2
Authors: Schwenn, R.; Rosenbauer, H.
Bibcode: 1984GeCAS.......66S
Altcode:
  The Helios solar wind experiment is reviewed. The experiment measures
  low energy ions and electrons which run through an electrostatic or
  electrodynamic deflection system. A stepwise registration of energy
  spectra is performed, and the direction of particle arrival is also
  determined. Velocity distribution functions for the different particle
  species are used to deduce solar wind properties. The instruments
  operate without any major malfunctions. The long life of Helios 1
  allowed it to collect a set of solar plasma data of almost identical
  quality over a full solar activity cycle.

Title: Data analyis of electron measurements of the Plasma Experiment
    aboardthe Helios probes.
Authors: Philipp, W. G.; Miggenrieder, H.; Mühlhäuser, K. -H.;
   Rosenbauer, H.; Schwenn, R.
Bibcode: 1984MPERp.185.....P
Altcode:
  The methods to derive distribution functions for solar wind electrons
  from the measurements of the "Plasma Experiment" aboard the Helios
  probes are outlined. Electrons are measured in the energy range from 0.5
  to 1660 eV with a one-dimensional angular resolution along the ecliptic
  plane. From these measurements electron distribution functions with
  high time resolution (typically 18 s) but poor angular resolution in
  velocity space (45 degrees) and electron distribution functions with
  high angular resolution (better than 5 to 10 degrees) but poor time
  resolution (typically several minutes to few hours) have been derived.

Title: Interplanetary flow systems associated with cosmic ray
    modulation in 1977 - 1980
Authors: Burlaga, L. F.; McDonald, F. B.; Ness, N. F.; Schwenn, R.;
   Lazarus, A. J.; Mariani, F.
Bibcode: 1983STIN...8418149B
Altcode:
  The hydromagnetic flow configurations associated with cosmic ray
  modulation in 1977 to 1980 were determined using solar wind plasma and
  magnetic field data from Voyagers 1 and 2 and Helios 1. The modulation
  was related to two types of large scale systems of flows: one containing
  a number of transients such as shocks, post shock flows and magnetic
  clouds; the other consisting primarily of a series of quasi-stationary
  flows following interaction regions containing a stream interface and
  often bounded by a forward reverse shock pair. Each of the three major
  episodes of cosmic ray modulation was characterized by the passage of
  the system of transient flows. Plateaus in the cosmic ray intensity
  time profile were associated with the passage of systems of corotating
  streams.

Title: Associations between coronal mass ejections and interplanetary
    shocks.
Authors: Sheeley, N. R., Jr.; Howard, R. A.; Koomen, M. J.; Michels,
   D. J.; Schwenn, R.; Muhlhauser, K. H.; Rosenbauer, H.
Bibcode: 1983NASCP.2280.693S
Altcode: 1983sowi.conf..693S
  The authors are in the process of comparing nearly continuous
  complementary coronal observations and interplanetary plasma
  measurements for the years 1979 - 1982. Their preliminary results
  show that almost all low-latitude high-speed coronal mass ejections
  (CME's) were associated with shocks at HELIOS 1. Some suitably directed
  low-speed CME's were clearly associated with shocks while others may
  have been associated with disturbed plasma (such as NCDE's) without
  shocks. A few opposite-hemisphere CME's associated with great flares
  also seemed to have been associated with shocks at HELIOS.

Title: The "average" solar wind in the inner heliosphere: structures
    and slow variations.
Authors: Schwenn, R.
Bibcode: 1983NASCP.2280.489S
Altcode: 1983sowi.conf..489S
  Measurements from the HELIOS solar probes indicated that apart
  from solar activity related disturbances there exist two states
  of the solar wind which might result from basic differences in the
  acceleration process: the fast solar wind (v 600 kms(-)1) emanating
  from magnetically open regions in the solar corona and the "slow" solar
  wind (v 400 kms(-)1) correlated with the more active regions and its
  mainly closed magnetic structures. In a comprehensive study using all
  HELIOS data taken between 1974 and 1982 the average behavior of the
  basic plasma parameters were analyzed as functions of the solar wind
  speed. The long term variations of the solar wind parameters along the
  solar cycle were also determined and numerical estimates given. These
  modulations appear to be distinct though only minor. In agreement
  with earlier studies it was concluded that the major modulations are
  in the number and size of high speed streams and in the number of
  interplanetary shock waves caused by coronal transients. The latter
  ones usually cause huge deviations from the averages of all parameters.

Title: Dynamical evolution of interplanetary magnetic fields and
flows between 0.3 AU and 8.5 AU: entrainment.
Authors: Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.
Bibcode: 1983NASCP2280..729B
Altcode:
  No abstract at ADS

Title: Solar radio burst and in situ determination of interplanetary
    electron density
Authors: Bougeret, J. L.; King, J. H.; Schwenn, R.
Bibcode: 1983STIN...8335989B
Altcode:
  A few interplanetary electron density scales which were derived from the
  analysis of interplanetary solar radio burst are discussed and compared
  to a model derived from 1974 to 1980 Helios 1 and 2 in situ density
  observations made in the 0.3 to 1.0 AU range. The Helios densities were
  normalized to 1976 with the aid of IMP and ISEE data at 1 AU, and were
  then sorted into 0.1 AU bins and logarithmically averaged within each
  bin. The best fit to these 1976-normalized, bin averages is N(R(AU))
  = 6.1 R(-2.10)/cu cm. This model is in rather good agreement with the
  solar burst determination if the radiation is assumed to be on the
  second harmonic of the plasma frequency. This analysis also suggests
  that the radio emissions tend to be produced in regions denser than
  the average where the density gradient decreases faster with distance
  than the observed R(-2.10).

Title: Acceleration and spatial diffusion of energetic particles
    obtained with Helios data.
Authors: Valdes-Galicia, J. F.; Mousas, X.; Quenby, J. J.; Neubauer,
   F.; Schwenn, R. S.
Bibcode: 1983ICRC...10..104V
Altcode: 1983ICRC...18j.104V
  Numerical simulations have been performed to evaluate the transport
  coefficients for energetic particles in the interplanetary medium
  using Helios 1/2 IMF data at distances from 0.3 to 0.67 AU from the
  sun, and the results are reported. The data are also used to obtain
  the statistical acceleration of these particles.

Title: Determination of the solar wind angular momentum flux from
    the HELIOS data - an observational test of the Weber and Davis theory
Authors: Pizzo, V.; Schwenn, R.; Marsch, E.; Rosenbauer, H.;
   Muehlhaeuser, K. -H.; Neubauer, F. M.
Bibcode: 1983ApJ...271..335P
Altcode:
  In situ attempts to measure the sun's angular momentum loss in the
  solar wind and thereby to test the Weber and Davis description of the
  magnetic coupling between stellar rotation and winds have thus far
  produced widely divergent and inconclusive results. A new estimate
  for the solar loss rate in the ecliptic plane has been derived from
  the Helios spacecraft data. By intercomparing measurements made by
  the twin probes over the full 0.3-1.0 AU baseline of their orbits,
  it is possible to eliminate the systematic instrumental offsets from
  the true radial direction that have plagued previous efforts. The main
  observational findings are that (1) the total angular momentum flux
  loss rate (field + particles) near the solar equator is ∼0.2-0.3
  × 10<SUP>30</SUP> dyn cm sr<SUP>-1</SUP>, about one-quarter the
  Weber and Davis prediction and much lower than previous spacecraft
  estimates, and (2) the distribution of that flux between particles
  and field stresses is very near the 1:3 ratio of the model, when
  an important contribution from the heretofore neglected solar wind
  α-particles is accounted for. Though few by number in the solar wind,
  the α-particles' flow speed and direction in general differ from that
  of the protons, largely offsetting the latters' angular momentum content
  (+0.15-0.2 × 10<SUP>30</SUP> for the protons, -0.1 × 10<SUP>30</SUP>
  for the α-particles, plus being in the direction of corotation with
  the Sun). As to the small value reported for the total flux, theory
  and observation can be reconciled by moving the mean Alfvén radius,
  r<SUB>A</SUB>, in to 12 R<SUB>sun</SUB>, a figure that is consistent
  with coronal models more realistic than the single polytrope formulation
  used by Weber and Davis. There is a distinct tendency for slow solar
  wind to carry positive total flux and for fast wind, negative; this
  can probably be explained in terms of stream-interaction dynamics in
  the super-Alfvénic region. It thus appears that the Weber and Davis
  theory adequately describes angular momentum loss in solar-type winds,
  insofar as simple magnetic stresses are taken as the dominant coupling
  mechanism. However, in the general astrophysical application, it is
  suggested that a more accurate treatment of coronal acceleration be
  incorporated to properly locate r<SUB>A</SUB> (and hence fix the total
  loss rate) and that some allowance for three-dimensional effects be
  made. Also, should large speed differentials between α-particles and
  protons occur well inside r<SUB>A</SUB>, a three-fluid version of the
  Weber and Davis model may be in order.

Title: Dynamical evolution of interplanetary magnetic fields and
flows between 0.3 AU and 8.5 AU: Entrainment
Authors: Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.
Bibcode: 1983GeoRL..10..413B
Altcode: 1983STIN...8319667B
  The radial evolution of interplanetary flows and associated magnetic
  fields between 0.3 AU and 8.5 AU was analyzed using data from Helios 1
  and Voyager 1, respectively. During a 70-day interval in 1980 Voyager
  1 observed two streams which appeared to be recurrent and which had
  little fine structure. The corresponding flows observed by Helios 1
  were much more complex, showing numerous small streams, transient
  flows and shocks as well as a few large corotating streams. It is
  suggested that in moving to 8 AU the largest corotating streams swept
  up the slower flows (transient and/or corotating streams) and shocks
  into a relatively thin region in which they coalesced to form a single
  large-amplitude compression wave. We refer to this combined process of
  sweeping and coalescence as "entrainment". The resulting large-amplitude
  compression wave is different from that formed by the steepening of a
  corotating stream from a coronal hole, because different flows from
  distinct sources, with possibly different composition and magnetic
  polarity, are brought together to form a single new structure. As a
  result of entrainment, memory of the sources and flow configurations
  near the sun is lost. Small-scale features are erased as the flows move
  outward and energy is transferred from small scales to large scales
  by entrainment. Thus in the outer solar system the structure of the
  solar wind may be dominated by large scale pressure waves (compressions
  followed by rarefactions) separated by several AU. Beyond several AU
  most of the compression waves are no longer driven by streams, and
  the compression waves expand freely. At large distances (≳ 25 AU)
  they will have interacted extensively with one another producing yet
  another state of the solar wind, with fewer large-scale non-uniformities
  and more small-scale non-uniformities.

Title: On the equaton of state of solar wind ions derived from
    Helios measurements
Authors: Marsch, E.; Muehlhaeuser, K. H.; Rosenbauer, H.; Schwenn, R.
Bibcode: 1983JGR....88.2982M
Altcode:
  Observations of solar wind ion velocity distributions made by the Helios
  spacecraft between 0.3 and 1 AU are used to study the radial evolution
  of the so-called adiabatic invariants, for example, the ion magnetic
  moments. Significant differences between the parameters of protons and
  α particles have been found in dependence on the wind velocity. On
  the average, adiabaticity is observed to be violated. We interpret this
  violation of adiabatic invariance as evidence that protons are heated
  perpendicular to the field in fast streams and, with less statistical
  significance, that α particles are cooled more strongly than for
  adiabatic expansion parallel to the magnetic field. The contribution
  of the differential streaming energy to the total internal energy of
  the ions is briefly investigated. Also, average heliocentric radial
  profiles for the ion heat fluxes are presented, and the possible
  role of the ion heat flux in supplying thermal energy during the
  radial expansion of the wind is examined. Our findings suggest that
  wave-particle interactions and (or) Coulomb collisions (or other yet
  unknown processes) have to be invoked in order to explain the thermal
  energy state of solar wind ions and their radial temperature profiles.

Title: Direct Correlations Between Coronal Transients and
    Interplanetary Disturbances
Authors: Schwenn, R.
Bibcode: 1983SSRv...34...85S
Altcode:
  Major interplanetary shock waves have often been successfully associated
  with major solar flares. The interplanetary response to weaker solar
  events, e.g., eruptive prominences (EP) and slow coronal transients,
  is far less pronounced. Recently, progress has been made by combining
  the newly-available data of white-light-coronagraph measurements from
  the earth-orbiting satellite P78/1 (these data show the development of
  coronal transients between 2.5 and 10 R <SUB>bd</SUB>, in-situ plasma
  measurements from the HELIOS solar probes positioned mostly above
  the Sun's limb at solar distances between 60 and 200 R <SUB>bd</SUB>
  (showing the reactions of the interplanetary plasma), ground based
  Hα-coronagraphs (showing in a few cases the evolution of EP's from
  the Sun's limb up to 1.5 A<SUB>bd</SUB>). In the years 1979 to 1981
  about 25 uniquely associated events were identified, 19 of which
  allow some detailed analysis. The events can be sorted into three main
  categories: <P />The ‘flare-type’: 13 events, probably all of them
  flare-related, transient speeds v <SUB> t </SUB> from 560 to 1460 km
  s<SUP>-1</SUP>, no evidence for post-acceleration of the transient
  (indicating impulsive injection), all transients followed by drastic
  interplanetary shock waves, some of them probably involving magnetic
  clouds. <P />The ‘EP-type’: 4 events, none of them flare-related,
  at least one was observed as an Hα-EP, transient speed from 200 to
  410 km s<SUP>-1</SUP>, all post-accelerated (indicating ‘driven’
  injection), all followed by shocks with at least one magnetic cloud,
  one showing presence of He<SUP>+</SUP> and O<SUP>2+</SUP> behind
  the shock. <P />The ‘NCDE-type’: 2 events, one observed as an
  Hα-EP, the other without known solar source, v <SUB> t </SUB>, = 130
  and 470 km s<SUP>-1</SUP>, one post-accelerated, the other one not,
  considerable density increase in interplanetary plasma (however, in
  pressure equilibrium with surroundings), one event including shock, the
  other not. These two events may not belong to the same category. Our
  results are not completely consistent with previous work which is
  mainly based on data from the Skylab era, 1973/74. This could be due
  to the different phase in the solar cycle. The study is being continued.

Title: A magnetic cloud and a coronal mass ejection
Authors: Burlaga, L. F.; Klein, L.; Sheeley, N. R., Jr.; Michels,
   D. J.; Howard, R. A.; Koomen, M. J.; Schwenn, R.; Rosenbauer, H.
Bibcode: 1982GeoRL...9.1317B
Altcode:
  An interplanetary magnetic cloud observed by the Helios 1 spacecraft
  was found to be associated with a coronal mass ejection observed by the
  NRL Solwind coronagraph on the spacecraft P78-1. The magnetic cloud was
  observed on June 20, 1980 when Helios 1 was at 0.54 AU and nearly 90°
  west of the earth-sun line. This was associated with a large loop-like
  coronal mass ejection observed over the west limb on June 18, 1980,
  moving toward Helios 1. The speed of the front of the event at Helios
  1 was (470 ± 10) km/s, which is close to the mean transit speed (∽
  500 km/s). The magnetic cloud was similar to others described in the
  literature: The magnetic field strength was higher than average; the
  density was relatively low; the magnetic pressure greatly exceeded
  the ion thermal pressure; and the magnetic field direction changed
  through the cloud by rotating parallel to a plane which was highly
  inclined with respect to the ecliptic.

Title: Processing and evaluation of the data from the plasma
    experiment onboard the HELIOS solar probes
Authors: Schwenn, R.; Rosenbauer, H.
Bibcode: 1982mpia.rept.....S
Altcode:
  The data processing and evaluation procedure for the plasma experiment
  on board the HELIOS solar probes is described. The instruments of
  the HELIOS plasma experiment investigate the interplanetary plasma
  characteristics. Most of the intermediate data processing steps are
  explained and the resulting data plots are shown in their various
  forms. The most important computer programs are enclosed, together
  with basic explanations.

Title: Observation of flare-generated shock waves by Helios-2 near
    the sun
Authors: Volkmer, P. M.; Neubauer, F. M.; Schwenn, R.
Bibcode: 1982SSRv...32..131V
Altcode:
  We present the observation of three flare generated shock waves
  which were measured by Helios-2 at a radial distance from the Sun
  of 0.476 AU, 0.444 AU, and 0.297 AU. These results show that two of
  the shocks fulfill the classification scheme of ‘F-events’ stated
  in the past while the third shock profile is that of a ‘R-event’
  being interpreted as a driven wave. Because of the close distance to
  the Sun a flare-association was possible. Only in one case there is
  some evidence for a piston in the downstream region of the shock. One
  of the shocks is characterized by a distinct hole in the frequency
  distribution of directional discontinuities in the downstream region.

Title: Solar wind protons: Three-dimensional velocity distributions
    and derived plasma parameters measured between 0.3 and 1 AU
Authors: Marsch, E.; Schwenn, R.; Rosenbauer, H.; Muehlhaeuser,
   K. -H.; Pilipp, W.; Neubauer, F. M.
Bibcode: 1982JGR....87...52M
Altcode:
  A survey of solar wind three-dimensional proton velocity
  distributions as measured by the Helios solar probes between
  0.3 and 1 AU is presented. A variety of nonthermal features like
  temperature anisotropies, heat fluxes, or proton double streams has
  been observed. The relative speed of the second proton component
  increases on the average with increasing wind speed and decreasing
  heliocentric radial distance and shows a correlation with the local
  Alfvén speed. A marked anisotropy in the core of proton distributions
  with a temperature larger perpendicular than parallel to the magnetic
  field (T<SUB>∥c</SUB>&lt;T<SUB>⊥c</SUB>) is a persistent feature
  of high speed streams and becomes most pronounced in the perihelion
  (~0.3 AU). Fairly isotropic distributions have only been measured
  very close to and directly at magnetic sector boundaries. Low and
  intermediate speed distributions usually show a total temperature
  anisotropy T<SUB>∥p</SUB>/T<SUB>⊥p</SUB>&gt;1 frequently caused by
  'high-energy shoulders' or a resolved second proton component. No clear
  radial gradient of the temperature anisotropy could be established
  in these cases. The average dependence of the proton temperature on
  heliocentric radial distance is given by a power law R<SUP>-α</SUP>,
  where α~1 for T<SUB>⊥p</SUB> and 0.7&lt;α&lt;1 for T<SUB>⊥p</SUB>
  are compatible neither with isothermal nor adiabatic expansion. Flattest
  radial temperature profiles are obtained in high-speed streams. These
  observations indicate that local heating or considerable proton heat
  conduction occurs in the solar wind. Some consequences of nonthermal
  features of proton distributions for plasma instabilities are discussed
  as well as kinetic processes that may shape the observed distributions.

Title: Solar wind helium ions: obsevations of the Helios solar probes
    between 0.3 and 1 AU
Authors: Marsch, E.; Rosenbauer, H.; Schwenn, R.; Muehlhaeuser,
   K. -H.; Neubauer, F. M.
Bibcode: 1982JGR....87...35M
Altcode:
  A survey of solar wind helium ion velocity distributions and
  derived parameters as measured by the Helios solar probes between
  0.3 and 1 AU is presented. Nonthermal features like heat flux or
  He<SUP>2+</SUP> double streams and temperature anisotropies have been
  frequently observed. Fairly isotropic distributions have only been
  measured close to sector boundaries of the interplanetary magnetic
  field. At times in slow solar wind, persistent double-humped
  helium ion distributions constituting a temperature anisotropy
  T<SUB>∥α</SUB>/T<SUB>⊥α</SUB>&gt; have been reliably
  identified. Distributions in high-speed wind generally have small
  total anisotropies (T<SUB>∥α</SUB>/T<SUB>⊥α</SUB>&gt;1)
  with a slight indication that in the core part the temperatures
  are larger parallel than perpendicular to the magnetic field, in
  contrast to simultaneous proton observations. The anisotropy tends to
  increase with increasing heliocentric radial distance. The average
  dependence of helium ion temperatures on radial distance from the
  sun is described by a power law ~R<SUP>-β</SUP> with 0.7&lt;~1.2 for
  T<SUB>∥α</SUB> and 0.87&lt;~β&lt;~1.4 for T<SUB>⊥α</SUB>. In
  fast solar wind the T<SUB>⊥α</SUB> profile is compatible with
  nearly cooling. Pronounced differential ion speeds Δv<SUB>αp</SUB>
  have been observed with values of more than 150 km/s near perihelion
  (0.3 AU). In fast streams Δv<SUB>αp</SUB> tends to approach the local
  Alfvén velocity v<SUB>A</SUB>, whereas in slow plasma values around
  zero are obtained. Generally, the differential speed increases with
  increasing proton bulk speed and (with the exception of slow plasma)
  with increasing heliocentric radial distance. The role of Coulomb
  collisions in limiting Δv<SUB>αp</SUB> and the ion temperature ratio
  T<SUB>α</SUB>/T<SUB>p</SUB> is investigated. Collisions are shown to
  play a negligible role in fast solar wind, possibly a minor role in
  intermediate speed solar wind and a distinct role in low-speed wind
  in limiting the differential ion velocity and temperature.

Title: Pronounced proton core temperature anisotropy, ion differential
    speed, and simultaneous Alfvén wave activity in slow solar wind at
    0.3 AU
Authors: Marsch, E.; Rosenbauer, H.; Schwenn, R.; Muehlhaeuser,
   K. -H.; Denskat, K. U.
Bibcode: 1981JGR....86.9199M
Altcode:
  In the Helios 2 perihelion (0.3 AU) im May 1978, pronounced ion
  differential speeds Δv<SUB>op</SUB>&gt;0 and large proton temperature
  anisotropies T<SUB>∥p</SUB>/T<SUB>⊥p</SUB>&lt;1 have been observed
  in slow solar wind, in distinct contrast to earlier observations during
  the phase of solar activity minimum. These features of ion distributions
  occurred simultaneously with high Alfvénic wave activity. Coulomb
  friction between the two ion species can be shown to play a minor role,
  thus obviously favouring the establishment of a large differential ion
  speed by preferentially accelerating wave forces. The observations
  may also indicate that strong waves sometimes only heat the protons
  without creating a fast solar wind.

Title: The instruments of the plasma experiment onboard the HELIOS
    solar probe
Authors: Rosenbauer, H.; Schwenn, R.; Miggenrieder, H.; Meyer, B.;
   Gruenwaldt, H.; Muehlhaeuser, K. H.; Pellkofer, H.; Wolfe, J. H.
Bibcode: 1981mpia.reptQ....R
Altcode:
  The plasma experiment on board the solar probe HELIOS, consisting of
  four instruments designed to investigate the interplanetary plasma,
  or solar wind, is discussed. The velocity distribution functions of the
  different kinds of particles are measured. Hydrodynamic parameters of
  the solar wind plasma can then be derived. Three instruments analyze
  the positive component of the solar wind (protons and heavier ions
  with energy-per-charge values from 0.155 to 15.32 kV). Two of them
  permit an angular resolution in both directions of incidence. One
  instrument measures electrons in the energy range from 0.5 to 1660 eV
  with a one-dimensional angular resolution.

Title: Magnetic loop behind an interplanetary shock: Voyager, Helios,
    and IMP 8 observations
Authors: Burlaga, L.; Sittler, E.; Mariani, F.; Schwenn, R.
Bibcode: 1981JGR....86.6673B
Altcode: 1981STIN...8125009B
  Magnetic field and plasma data from five spacecraft (Voyager 1 and 2,
  Helios 1 and 2, and IMP 8) were used to analyze the flow behind an
  interplanetary shock. The shock was followed by a turbulent sheath
  in which there were large fluctuations in both the strength and
  the direction of the magnetic field. This in turn was followed by
  a region (magnetic cloud) in which the magnetic field vectors were
  observed to change by rotating nearly parallel to a plane, consistent
  with the passage of a magnetic loop. This loop extended at least
  30° in longitude between 1 and 2 AU, and its radical dimension was
  approximately 0.5 AU. In the cloud the field strength was high, and
  the density and temperature were relatively low. Thus the dominant
  pressure in the cloud was that of the magnetic field. The total
  pressure inside the cloud was higher than outside, implying that the
  cloud was expanding as it moved outward, even at the distance of 2
  AU. The momentum flux of the cloud at 2 AU was not higher than that
  of the preshock plasma, indicating that the cloud was not driving
  the shock at this distance. It is possible, however, that the shock
  was driven by the cloud closer to the sun where the cloud may have
  moved faster. An extraordinary filament was observed at the rear of
  the cloud. It was bounded by current sheets whose orientations were
  preserved over at least 0.12 AU and which were related to the plane
  of maximum variance of the magnetic field in the cloud.

Title: The Giotto Ion Mass Spectrometer
Authors: Balsiger, H.; Geiss, J.; Young, D. T.; Rosenbauer, H.;
   Schwenn, R.; Ip, W. -H.; Ungstrup, E.; Neugebauer, M.; Goldstein,
   R.; Goldstein, B. E.; Huntress, W. T.; Shelley, E. G.; Sharp, R. D.;
   Johnson, R. G.; Lazarus, A. J.; Bridge, H. S.
Bibcode: 1981giot.proc...93B
Altcode:
  No abstract at ADS

Title: Two States of the Solar Wind at the Time of Solar Activity
    Minimum - Part One - Boundary Layers Between Fast and Slow Streams
Authors: Schwenn, R.; Mohlhauser, K. H.; Rosenbauer, H.
Bibcode: 1981sowi.conf..118S
Altcode:
  No abstract at ADS

Title: Some Characteristics of Proton Velocity Distributions in the
    Solar Wind as Observed by the HELIOS Solar Probes
Authors: Marsch, E.; Pilipp, W. G.; Schwenn, R.; Mohlhauser, K. H.;
   Rosenbauer, H.
Bibcode: 1981sowi.conf..273M
Altcode:
  No abstract at ADS

Title: Solar wind and its interaction with the magnetosphere:
    measured parameters.
Authors: Schwenn, R.
Bibcode: 1981meth.conf....3S
Altcode:
  No abstract at ADS

Title: Correlation of solar radio bursts associated with electron
    plasma oscillations, solar particles and shock waves
Authors: Kikuchi, H.; Gurnett, D. A.; Keppler, E.; Richter, A. K.;
   Schwenn, R.; Rosenbauer, H.
Bibcode: 1981ICRC...10....1K
Altcode: 1982ICRC...10....1K; 1981ICRC...17j...1K
  A model for the generation mechanism of type III solar radio bursts
  (SRB) was originally proposed by Ginzburg-Zhelenznyakov (1958),
  and consists of a two-step process. The first process causes local
  electron plasma oscillations at the electron plasma frequency. During
  the second process, these electron plasma oscillations (EPO) are
  converted to electromagnetic radiation. Concerning the first process,
  the question arises, whether all of the electron plasma oscillation
  events be caused by nonthermal solar flare electrons ejected directly
  from the sun. Correlating EPO-SRB events with solar particle and shock
  wave observations, the present investigation indicates that there are a
  considerable number of EPO-SRB events which are not correlated with low
  energy electrons, but some of them are correlated with interplanetary
  shocks and/or low energy electrons.

Title: Solar wind and its interaction with the magnetosphere:
    Measured parameters
Authors: Schwenn, R.
Bibcode: 1981AdSpR...1l...3S
Altcode: 1981AdSpR...1....3S
  The earth's magnetosphere absorbs only a minor fraction (~
  10<SUP>-3</SUP>) of the incident solar wind energy. Variations of
  the solar wind can often cause lively reactions in the earth's close
  environment. However, the physical mechanisms involved are not yet
  understood. It appears now that the combined action of the solar
  wind momentum flux, the direction of the interplanetary magnetic
  field as well as its fluctuations might play the dominant role. The
  behaviour of these parameters is governed in some characteristic way
  by the solar wind stream structure which reflects the condition of
  the solar corona and its magnetic field topology. Transients in the
  sun's atmosphere associated with solar activity cause reactions in
  the interplanetary medium which also show some typical, though very
  different, signatures. Taking into account the interdependence of the
  solar wind parameters in context with the underlying solar phenomena,
  we may be able to pinpoint the mechanism which controls the action of
  the solar wind on the magnetosphere.

Title: Properties of Alfvenic Fluctuations Near the Sun - HELIOS-1
    and HELIOS-2
Authors: Denskat, K. U.; Neubauer, F. M.; Schwenn, R.
Bibcode: 1981sowi.conf..392D
Altcode:
  No abstract at ADS

Title: HELIOS - Indications of Resonant Wave-Particle Interaction
    in Fast Stream Solar Wind Ion Distributions
Authors: Rosenbauer, H.; Marsch, E.; Mohlhauser, K. H.; Pilipp, W.;
   Schwenn, R.
Bibcode: 1981sowi.conf..353R
Altcode:
  No abstract at ADS

Title: Two States of the Solar Wind at the Time of Solar Activity
    Minimum - Part Two - Radial Gradients of Plasma Parameters in Fast
    and Slow Streams
Authors: Schwenn, R.; Mohlhauser, K. H.; Marsch, E.; Rosenbauer, H.
Bibcode: 1981sowi.conf..126S
Altcode:
  No abstract at ADS

Title: Kalte Schauer von der Sonne.
Authors: Schwenn, R.
Bibcode: 1981Umsch..81..438S
Altcode:
  No abstract at ADS

Title: Initial Results on Solar Wind Alpha Particle Distributions
    as Measured by HELIOS Between 0.3AU and 1AU
Authors: Marsch, E.; Mohlhauser, K. H.; Pilipp, W.; Schwenn, R.;
   Rosenbauer, H.
Bibcode: 1981sowi.conf..443M
Altcode:
  No abstract at ADS

Title: Electron Characteristics in the Solar Wind as Deduced from
    HELIOS Observations
Authors: Pilipp, W. G.; Schwenn, R.; Marsch, E.; Molhauser, K. H.;
   Rosenbauer, H.
Bibcode: 1981sowi.conf..241P
Altcode:
  No abstract at ADS

Title: The Solar Origin of An Interplanetary Shock
Authors: Sheeley, N. R., Jr.; Howard, R. A.; Koomen, M. J.; Michels,
   D. J.; Rompolt, B.; Schwenn, R. W.; Mihalov, J. D.
Bibcode: 1980BAAS...12..920S
Altcode:
  No abstract at ADS

Title: Interplanetary particles and fields, November 22 to December 6,
1977: helios, voyager, and imp observations between 0.6 and 1.6 AU
Authors: Burlaga, L.; Lepping, R.; Weber, R.; Armstrong, T.; Goodrich,
   C.; Sullivan, J.; Gurnett, D.; Kellogg, P.; Keppler, E.; Mariani,
   F.; Neubauer, F.; Rosenbauer, H.; Schwenn, R.
Bibcode: 1980JGR....85.2227B
Altcode:
  In the period November 22 to December 6, 1977, three types
  of interplanetary flows were observed: a corotating stream, a
  flare-associated shock wave, and a shock wave driven by ejecta. Helios
  2, Imp 7, 8, and Voyager 1, 2 were nearly radially aligned at ?0.6, 1,
  and 1.6 AU, respectively, while Helios 1 was at ?0.6 AU and 35° east of
  Helios 2. The instruments on these spacecraft provided an exceptionally
  complete description of the particles and fields associated with the
  three flows and corresponding solar events. Analysis of these data
  revealed the following results. (1) A corotating stream associated
  with a coronal hole was observed at 0.6 and 1 AU, but not at 1.6
  AU. The stream interface corotated and persisted with little change
  in structure even though the stream disappeared. A forward shock was
  observed ahead of the interface and moved from Helios 2 at 0.6 AU to
  Voyager 1, 2 and 1.6 AU; although the shock was ahead of a corotating
  stream and interface, the shock was not stationary. (2) An exceptionally
  intense type III burst was observed in association with a 2B flare of
  November 22, The exciter of this burst (a beam of energetic electrons)
  and plasma oscillations (presumably caused by the electron beam)
  were observed by Helios 2. (3) A nonspherical shock was observed
  in association with the November 22 flare. This shock interacted
  with another shock between 0.6 and 1 AU, and they coalesced to form
  a single shock that was identified at 1 and at 1.6 AU. (4) A shock
  driven by ejecta was studied. In the ejecta the density and temperature
  were unusually low, and the magnetic field intensity was relatively
  high. This regio was preceded by a directional discontinuity at which
  the magnetic field intensity dropped appreciably. The shock appeared to
  move globally at a uniform speed, but locally, there were fluctuations
  in speed and direction of up to 100 km/s and 40°, respectively. (5)
  Three types of electrostatic waves were observed at the shocks, in
  different combinations. The detailed wave profiles differed greatly
  among the shocks, even for spacecraft separations of &lt;~0.2 AU,
  indicating a strong dependence on local conditions. However, the same
  types of fluctuations were observed at 0.6 and at 1.6 AU. (6) energetic
  (50-200 keV) protons were accelerated by the shocks. The intensities
  and durations of the fluxes varied by a factor of 12 over longitudinal
  distances of ?0.2 AU. The intensities were higher, and the duratjions
  were lower, at 1.6 than at 0.6 AU, suggesting a cumulative effect. (7)
  Energetic (?50 keV) protons from the November 22 flare were observed
  by all the spacecraft. During the decay, Helios 1 observed no change
  in intensity when the interface moved past the spacecraft, indicating
  that particles were injected and moved uniformly on both sides of the
  interface. Helios 2 observed an increase in flux not seen by Helios 1,
  reaching maximum at the time that a shock arrived at Helios 2. The
  intensity dropped abruptly when the interface moved past Helios 2,
  indicating that the 'extra' particles seen by Helios 2 did not penetrate
  the interface.

Title: Singly-ionized helium in the driver gas of an interplanetary
    shock wave
Authors: Schwenn, R.; Rosenbauer, H.; Muehlhaeuser, K. -H.
Bibcode: 1980GeoRL...7..201S
Altcode:
  The interplanetary shock wave observed on Jan. 29, 1977 by the HELIOS-1
  plasma instruments shows an unusual feature: In the cold tenuous
  piston plasma following this shock, there appears a third peak in the
  energy per charge (E/q) spectra, in addition to the normal proton
  and α-particle peaks. The peak is located at E/q = 4 and persists
  for about 14 hours, with slowly varying intensities. Independent
  simultaneous measurement of these particles’ charge yields a value
  of ≈ 1. These ions are thought to be <SUP>4</SUP>He<SUP>+</SUP>
  ions travelling with the same speed as protons and α-particles. The
  occurrence of <SUP>4</SUP>He<SUP>+</SUP> indicates the possibility
  that during eruptive prominences or other solar transients “cold”
  chromosperic plasma might escape from the sun without undergoing the
  normal coronal heating process.

Title: The plasma experiment on Helios (E 1).
Authors: Rosenbauer, H.; Schwenn, R.; Meyer, B.; Miggenrieder, H.;
   Wolfe, J.
Bibcode: 1980hsp..conf....6R
Altcode:
  No abstract at ADS

Title: Ion acoustic waves and related plasma observations in the
    solar wind
Authors: Gurnett, D. A.; Marsch, E.; Pilipp, W.; Schwenn, R.;
   Rosenbauer, H.
Bibcode: 1979JGR....84.2029G
Altcode:
  This paper presents an investigation of solar wind ion acoustic
  waves and their relationship to the macroscopic and microscopic
  characteristics of the solar wind plasma. Comparisons with the
  overall solar wind corotational structure show that the most
  intense ion acoustic waves usually occur in the low-velocity
  regions ahead of high-speed solar wind streams. Of the detailed
  plasma parameters investigated, the ion acoustic wave intensities
  are found to be most closely correlated with the electron to
  proton temperature ratio T<SUB>e</SUB>/T<SUB>p</SUB> and with the
  electron heat flux. Investigations of the detailed electron and
  proton distribution functions also show that the ion acoustic waves
  usually occur in regions with highly non-Maxwellian distributions
  characteristic of double-proton streams. The distribution functions
  for the double-proton streams are usually not resolved into two
  clearly defined peaks, but rather they appear as a broad shoulder on
  the main proton distribution. Two main mechanisms, an electron heat
  flux instability and a double-ion beam instability, are considered
  for generating the ion-acoustic-like waves observed in the solar
  wind. Both mechanisms have favorable and unfavorable features. The
  electron heat flux mechanism can account for the observed waves
  at moderate to large ratios of T<SUB>e</SUB>/T<SUB>p</SUB> but has
  problems when T<SUB>e</SUB>/T<SUB>p</SUB> is small, as sometimes
  occurs. The ion beam instability appears to provide more flexibility on
  the T<SUB>e</SUB>/T<SUB>p</SUB> ratio; however detailed comparisons
  using observed distribution functions indicate that the ion beam
  mode is usually stable. Possible resolutions of these difficulties
  are discussed.

Title: Plasma wave turbulence associated with an interplanetary shock
Authors: Gurnett, D. A.; Neubauer, F. M.; Schwenn, R.
Bibcode: 1979JGR....84..541G
Altcode:
  In this paper we give a brief summary of the interplanetary shocks
  detected and analyzed to date from the Helios 1 and 2 spacecraft and
  present a detailed analysis of the plasma wave turbulence associated
  with one particular shock, on March 30, 1976. This event was selected
  becaused a very clearly defined burst of plasma wave turbulence occurs
  at the shock with otherwise quiet conditions in the solar wind upstream
  and downstream of the shock. The shock is an oblique shock and the
  upstream parameters are characterized by a low Mach number, a low
  beta, and an unusually large electron to ion temperature ratio. Three
  types of plasma waves are detected in association with this shock
  (1) electron plasma oscillations, (2) electrostatic ion-acoustic or
  Buneman mode turbulence from about 1 to 30 kHz, and (3) whistler-mode
  magnetic noise. Because of the high velocity of the shock and the quiet
  conditions in the solar wind this event provides a particularly good
  determination of the scale size and characteristics of the precursor
  waves upstream of the shock and the electric magnetic field turbulence
  in the wake behind the shock. The primary burst of electric and magnetic
  field noise at the shock occurs a few seconds after the jump in the
  magnetic field, with a broad maximum in the electric field intensities
  at about 3 kHz and a monotonically decreasing magnetic field spectrum
  below about 1 kHz. Many of the characteristics of this shock are found
  to be closely similar to, and are compared with, previous observations
  of plasma wave turbulence associated with the earth's bow shock.

Title: Acceleration of ≥ 80 KEV Ions by Interplanetary Shocks
Between 0.3 - 1 AU Observed by HELIOS 1/2: a Survey
Authors: Richter, A. K.; Keppler, E.; Schwenn, R.; Hsieh, K. C.;
   Denskat, K. U.
Bibcode: 1979ICRC....5...56R
Altcode: 1980ICRC....5...56R; 1979ICRC...16e..56R
  Fifteen interplanetary shocks were observed by the Helios 1 and 2
  spaceprobes between 0.3-1 AU during their primary missions in 1974/75
  and 1976, respectively. By the use of plasma and magnetic field data
  these shocks are analyzed and classified according to the theory of
  collisionless shocks. Variations in intensity of greater than or equal
  to 80 keV ions are then examined in relation to these shocks. Results
  are compared with existing theories on particle acceleration by
  interplanetary shocks.

Title: Energetic Particles at Interplanetary Shock Waves: the April
    29 1978 Event
Authors: Richter, A. K.; Hsieh, K. C.; Keppler, E.; Schwenn, R.;
   Van Hollebeke, M. A. I.; McDonald, F. B.; Denskat, K. U.
Bibcode: 1979ICRC...12..312R
Altcode: 1980ICRC...12..312R; 1979ICRC...16l.312R
  On April 29, 1978 a low-energetic particle event originating from a
  3B flare at N22 E38 was observed by HELIOS 1 at 0.31 AU and W 38 and
  by HELIOS 2 at 0.29 AU and W 67 simultaneously with an interplanetary
  shock wave. Using plasma and magnetic field data these shocks were
  classified; the time variations were examined along with the angular
  and spectral distributions in the ecliptic plane of the intensities
  of 80 or more keV ions.

Title: On the radial expansion of the solar wind plasma between 0.3
    and 1.0 astronomical units.
Authors: Cuperman, S.; Levush, B.; Dryer, M.; Rosenbauer, H.;
   Schwenn, R.
Bibcode: 1978ApJ...226.1120C
Altcode:
  This paper is concerned with the clarification of the radial
  expansion-within 1 AU heliocentric distance-of the extended solar
  corona. The work has been stimulated by the recent availability of
  solar wind measurements by the Helios 1 solar probe for the period 1974
  December-1975 April covering (for the first time) the interplanetary
  medium between 1 and 0.3 AU. The first part of the work analyzes these
  data from a theoretical point of view. Thus, in order to classify the
  plasma states represented by the data, the particle fluxes J =- nvr2
  are calculated by using measured proton densities, n (r), and streaming
  velocities, v (r), and are correlated with heliocentric distances
  as well as with density and streaming velocity fluctuations, An and
  AVp, respectively. The quantity J has been chosen as a classifying
  criterion because its constancy represents the necessary condition for
  the validity of theoretical models assuming steady-state spherically
  symmetric flow. The results of these calculations indicate that (i)
  the normalized particle flux J = JIJE (E indicates 1 AU heliocentric
  distance) varies by a factor of 10 (between 0.5 and 5) over the
  interplanetary range explored by Helios 1; (ii) the strong deviations
  from the value 1 are found only for states with streaming velocities
  below about 500 km s -`, while for the high-speed states J 1; (iii)
  the deviations AJ found for low-speed states are strongly correlated
  with particle density fluctuations and moderately anticorrelated
  with streaming velocity fluctuations; and (iv) time-dependent andlor
  additional processes could play a significant role. In the second part
  of the work we use all observational data representing high-speed flows
  (i.e., satisfying the condition V &gt; 600 km s -`) in conjunction with
  the fluid equations for a twocomponent plasma (protons + electrons)
  in order to estimate unknown properties of the solar wind. Thus, using
  best fits to the observed n (r), v (r), and T (r) values, by the aid
  of the momentum equation one obtains the electron temperature profile,
  Te(r). Subject heading: Sun: solar wind

Title: Magnetic fields and flows between 1 and 0.3 AU during the
    primary mission of Helios 1
Authors: Burlaga, L. F.; Ness, N. F.; Mariani, F.; Bavassano, B.;
   Villante, U.; Rosenbauer, H.; Schwenn, R.; Harvey, J.
Bibcode: 1978JGR....83.5167B
Altcode:
  Helios 1 moved from 1 AU on December 10, 1974, to 0.31 AU on March
  15, 1975, and the sun rotated beneath the spacecraft nearly 4 times
  during the interval. Recurrent high-speed streams with uniform magnetic
  polarity were observed, and they were associated with coronal holes of
  the same polarity. Although they were recurrent, the streams and their
  magnetic field patterns were not stationary, because the coronal holes
  which produced them changed in shape and latitude from one rotation to
  the next. We estimated that the magnetic field intensity of open field
  lines in some of these holes was of the order 10-20 G. Recurrent slow
  flows were also observed. The magnetic field polarity and intensity in
  these flows were irregular, and they changed from one rotation to the
  next. Cold magnetic enhancements (CME's) characterized by a twofold
  to threefold enhancement of magnetic field intensity and a fivefold to
  sevenfold depression of proton temperature relative to conditions ahead
  of the CME's were observed in some slow flows. Some of these CME's were
  contiguous with interaction regions of streams. At perihelion, Helios
  observed a recurrent stream which was associated with a lobe of the
  south polar coronal hole. The longitudinal width of the stream was three
  times that of the hole. We estimate that the width of the eastern and
  western boundaries of the streams at the coronal holes was only 2.5°
  +/- 1.5°, and we infer that the width at the northern boundary of the
  stream was &lt;~5°. We conclude that between the sun and 0.3 AU there
  was a diverging stream surrounded by a thin boundary layer in which
  there was a large velocity shear. There is evidence for compression of
  the magnetic field in the western boundary layer (interaction region),
  presumably due to steepening of the stream within 0.31 AU.

Title: The prediction of fast stream front arrivals at the earth on
    the basis of solar wind measurements at smaller solar distances
Authors: Rosenbauer, H.; Schwenn, R.; Bame, S. J.
Bibcode: 1978omap....1R....R
Altcode:
  The problems involved in the prediction of the arrival of fast
  solar wind streams at the earth on the basis of measurements made by
  space probes in the region between 0.3 and 1 AU are discussed. It is
  shown that arrival time predictions accurate to within a few hours
  that can be made at least as long as the large scale conditions
  on the Sun are relatively stationary as observed near the time of
  solar minimum. However, the latitudinal extent of the respective
  high speed streams is found to be important for making quantitative
  predictions. Coronal data sufficient for locating the sources of high
  speed streams can improve the precision of these predictions.

Title: Direct observation of the latitudinal extent of a high-speed
    stream in the solar wind
Authors: Schwenn, R.; Montgomery, M. D.; Rosenbauer, H.; Miggenrieder,
   H.; Muehlhaeuser, K. H.; Bame, S. J.; Feldman, W. C.; Hansen, R. T.
Bibcode: 1978JGR....83.1011S
Altcode:
  Solar wind speeds measured from the Helios 1 solar probe between
  0.31 and 1 AU and the earth-orbiting Imp 7/8 satellites have been
  correlated with coronal holes as determined from K coronal brightness
  measurements. In March 1975 during perihelion passage, Helios 1
  traversed the range of heliographic latitudes from -6° to +6° in
  a period of only 20 days. During that time the space probe crossed
  the northern boundary of the high-speed stream associated with an
  equatorward extension of the south polar coronal hole. While this same
  stream continued to be observed by Imp satellites at -5° latitude, it
  was no longer observable from Helios 1 at +5° latitude. The conclusion
  is that sharp boundaries separate high-speed flows from the surrounding
  solar wind. The thickness of the boundary in latitude appears to be
  narrower than about 10°. The local latitudinal gradient in flow speed
  is at least 30 kms<SUP>-1</SUP> deg<SUP>-1</SUP>. With less confidence
  it can be deduced from the Helios 1 data that the actual gradients at
  0.31 AU might even exceed 100 kms<SUP>-1</SUP> deg<SUP>-1</SUP>.

Title: The prediction of fast stream front arrivals at the earth on
    the basis of solar wind measurements at smaller solar distances.
Authors: Rosenbauer, H.; Schwenn, R.; Bame, S. J.
Bibcode: 1978omap.conf...32R
Altcode:
  No abstract at ADS

Title: A survey on initial results of the HELIOS plasma experiment
Authors: Rosenbauer, H.; Schwenn, R.; Marsch, E.; Meyer, B.;
   Miggenrieder, H.; Montgomery, M. D.; Muehlhaeuser, K. H.; Pilipp,
   W.; Voges, W.; Zink, S. M.
Bibcode: 1977JGZG...42..561R
Altcode:
  The reported results are mainly based on data obtained during the
  first part of the Helios-1 mission. The sun was very quiet during
  the considered period. The data are, therefore, representative
  for comparatively stationary conditions in the solar corona. Data
  obtained concerning the protons were evaluated by means of a special
  computer routine. The significance of the data is discussed, taking
  into account the status of the corona and the interplanetary plasma
  during the considered part of the Helios-1 mission, fast stream
  structures in the region between 0.3 and 1 AU, radial gradients
  of fast and slow solar wind, and the separation of proton double
  streams and alpha-particles. Attention is also given to the 'strahl'
  in the electron distribution, differences between fast streams and
  slow plasma on the basis of the observed electron distributions,
  and radial gradients in the case of solar wind electron parameters.

Title: Preliminary results of the Helios plasma measurements.
Authors: Rosenbauer, H.; Miggenrieder, H.; Montgomery, M.; Schwenn, R.
Bibcode: 1976pspe.proc..319R
Altcode: 1976pspe.conf..319R
  The instrumentation aboard the sun-probes Helios A/B is described. The
  quiet interplanetary 'weather' during the first year of the Helios
  mission permitted the study of the development of fast stream
  characteristics with respect to the radial distance from the Sun. The
  changes of plasma velocity with solar longitude were found to be more
  abrupt not only at the trailing edges but also at the front sides of
  fast streams at smaller distances from the sun. A pronounced narrow
  'beam' of fast electrons traveling outward from the sun along the
  magnetic field lines was detected. The meaning of this newly discovered
  part of the distribution function and its relation to the 'core' and
  'halo' regions are discussed.

Title: Preliminary results of the Helios plasma experiment.
Authors: Schwenn, R.; Rosenbauer, H.; Miggenrieder, H.; Meyer, B.
Bibcode: 1976spre.conf..671S
Altcode: 1976spre.proc..671S
  The instruments used in the plasma experiment aboard the Helios
  space probe are described, and some preliminary results from the
  solar-wind ion instruments are presented. Proton bulk velocities and
  proton temperatures are plotted as functions of solar longitude with
  respect to the probe. It is shown that the first three solar rotations
  monitored by Helios were characterized by two high-speed solar-wind
  streams with a velocity rise time of about 2 days, a constant velocity
  of about 700 to 800 km/s for some days, and a slow decrease for several
  other days. Only the temperatures seemed to increase slightly during
  the third rotation. Helios passed perihelion during the fourth rotation
  and observed significant changes in stream structure, with decreased
  velocities and temperatures increased to as high as 1 million K. It is
  suggested that there may be rather sharp transitions between different
  regions in the solar-wind plasma, implying very sharply separated
  sources of different streams in the corona, or that the abrupt changes
  in solar-wind parameters might be due to time variations.

Title: Das Plasmaexperiment auf Helios (E1).
Authors: Schwenn, R.; Rosenbauer, H.; Miggenrieder, H.
Bibcode: 1975RF.....19..226S
Altcode:
  The solar probe Helios carries four independent instruments designed
  for solar wind measurements. Three instruments analyze the positive
  component (protons and heavier ions) of the solar wind. One instrument
  measures electrons in the energy range from 0.5 to 1660 eV with a
  one-dimensional angular resolution. With these instruments the velocity
  distribution functions of the various particles can be measured. Onboard
  data processing techniques and the High-Data-Mode measurement program
  are discussed.

Title: Preliminary Results of the Helios Plasma Experiment. (Abstract)
Authors: Rosenbauer, H.; Meyer, B.; Miggenrieder, H.; Montgomery,
   M.; Schwenn, R.
Bibcode: 1975ICRC....5.1857R
Altcode: 1975ICRC...14.1857R
  No abstract at ADS

Title: Radial gradients in solar wind plasma
Authors: Schwenn, R.
Bibcode: 1974hsde.rept...30S
Altcode:
  The Helios experiment 1 is described, and possible applications to
  radial solar wind velocity gradient measurements are indicated. This
  experiment measures ion and electron velocity spectra of the solar
  wind plasma. The usefulness of line-up of other active interplanetary
  spacecraft with intact plasma instruments for correlation purposes is
  discussed. It should be possible to determine the radial gradient of
  the solar wind azimuthal velocity, the corotation of the solar wind,
  since the ratio between the bulk velocity and the azimuthal velocity
  is lower than at the earth's orbit.

