Search Publications
Comment on the abundances of rotational and tangential discontinuities in the solar wind
Neugebauer, M.
Several recent studies indicate that there are very few discontinuities in the solar wind that have both the small changes in field magnitude and the large components of the magnetic field normal to the discontinuity surface that are commonly assumed to be signatures of rotational discontinuities (RDs). Those results call into question the validit…
Evidence for newly closed magnetosheath field lines at the dayside magnetopause under northward IMF
Balogh, A.; Thomsen, M. F.; Lavraud, B. +7 more
We analyze the structure of the high-latitude magnetopause under steady interplanetary magnetic field (IMF). We use 56 magnetopause encounters of Cluster spacecraft from 2001 to 2003 to explore the statistical properties of the magnetosheath electron boundary layer, observed outside the high-latitude dayside magnetopause. We focus on the occurrenc…
Magnetically controlled structures in the ionosphere of Mars
Gurnett, D. A.; Persoon, A. M.; Averkamp, T. F. +5 more
The ionospheric sounding data obtained by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) instrument on the Mars Express spacecraft show that the dayside ionosphere has considerable structure over regions of strong crustal magnetic fields. This structure is typically seen as a hyperbola-shaped trace in a display of echo in…
Comparisons between MHD model calculations and observations of Cassini flybys of Titan
Dougherty, Michele K.; Hansen, Kenneth C.; Sokolov, Igor V. +6 more
The Cassini spacecraft passed by Titan on 26 October 2004 (Ta flyby) and 13 December 2004 (Tb flyby). In both cases the Cassini Orbiter entered Titan's ionosphere and flew through Titan's dynamic wake region. In this paper, we present our simulation results of these two flybys using our three-dimensional multispecies MHD model. This model is a sli…
Structure and dynamics of a new class of thin current sheets
Sitnov, M. I.; Runov, A.; Swisdak, M. +1 more
New results on a steady state Vlasov theory of current sheets, which generalizes the Harris (1962) model by assuming anisotropic and nongyrotropic plasmas and using the invariant of particle motion in regions of strong gradients, are presented with the aim to explain multiprobe observations of thin current sheets in the geomagnetotail and laborato…
Ion composition and pressure changes in storm time and nonstorm substorms in the vicinity of the near-Earth neutral line
Lundin, R.; Dandouras, I.; Lucek, E. +9 more
Using CLUSTER/CODIF data from close to ∼19 Re in the magnetotail, we have performed a superposed epoch analysis of storm time and nonstorm substorms to determine how the ion composition changes during a substorm. We find that the median O+ density and pressure in the plasma sheet are a factor of 5 higher during storm times than during n…
Titan's near magnetotail from magnetic field and electron plasma observations and modeling: Cassini flybys TA, TB, and T3
André, N.; Lewis, G. R.; Russell, C. T. +14 more
The first close Titan encounters TA, TB, and T3 of the Cassini mission at almost the same Saturnian local time ∼1030 and in the same spatial region downstream of Titan have enabled us to study the formation of the tail of its induced magnetosphere. The study is based on magnetic field and electron plasma observations as well as three-dimensional m…
Long-lived geomagnetic storms and coronal mass ejections
Gopalswamy, N.; Yashiro, S.; Lara, A. +3 more
Coronal mass ejections (CMEs) are major solar events that are known to cause large geomagnetic storms (Dst < -100 nT). Isolated geomagnetic storms typically have a main phase of 3-12 hours and a recovery phase of around 1 day. However, there are some storms with main and recovery phases exceeding ∼3 days. We trace the origin of these long-lived…
Thermodynamic structure of collision-dominated expanding plasma: Heating of interplanetary coronal mass ejections
Liu, Y.; Richardson, J. D.; Kasper, J. C. +2 more
We investigate the thermodynamic structure of interplanetary coronal mass ejections (ICMEs) using combined surveys of the ejecta between 0.3 and 20 AU. ICMEs are shown to have a moderate expansion in the solar wind compared with theoretical predictions. The expansion seems to be governed by a polytrope with γ ∼ 1.3 in this distance range. We find …
Effect of adiabatic cooling on the fitted parallel mean free path of solar energetic particles
Zhang, M.; Qin, G.; Dwyer, J. R.
The focused transport equation without adiabatic energy loss is widely used to model solar energetic particles' (SEP) interplanetary propagation by fitting spacecraft data. We incorporate the adiabatic energy loss effect, provided by the divergence of the solar wind flows, into the focused transport equation. The equation is then solved numericall…