HR: 0830h
AN: SM21B-0202    [PDF]
TI: Comparative modeling of the magnetotail ion population for northward and southward IMF orientations
AU: Zelenyi, L M
EM: lzelenyi@iki.rssi.ru
AF: Space Research Institute, Profsoynaia Str 84/32, Moscow, 117997 Russian Federation
AU: * Peroomian, V
EM: vahe@igpp.ucla.edu
AF: UCLA-IGPP, Box 951567, Los Angeles, CA 90095-1567 United States
AB: We have investigated the mechanisms by which solar wind ions enter the magnetosphere and populate the magnetotail for northward and southward orientations of the interplanetary magnetic field (IMF). We have done so by tracing particle orbits in time-dependent electric and magnetic fields obtained from a three-dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere which includes both IMF orientations. We found that during northward IMF, solar wind ion entry occurs predominantly through the high-latitude reconnection regions and the dawn side low-latitude boundary layer. Some ions accelerated in the reconnection regions gain access to the plasma sheet at large downtail distances. The population of the plasma sheet for southward IMF is complicated by the dynamic nature of the plasma sheet for this IMF orientation. During this time, the MHD simulation contains an X-line at x $\sim$ -25 R$_E$ downtail. Because of this, the bulk of the plasma mantle finds itself accessing the plasma sheet tailward of the x-line and is lost down the tail. As expected, the plasma mantle is much more robust in particle content and in spatial extent for southward IMF compared to northward IMF. A new feature, however, is the population of the near-Earth (earthward of the x-line) plasma sheet by solar wind ions that are slowed down during their crossing of the magnetopause. Because of their small tailward drift speed, these ions are convected into the near-Earth plasma sheet where they are nonadiabatically accelerated up to tens of keV in energy.
DE: 2744 Magnetotail
DE: 2760 Plasma convection
DE: 2764 Plasma sheet
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting