A statistical comparison of ion bulk properties at geosynchronous orbit during moderate and intense geomagnetic storms at solar minimum and maximum

HR: 15:50h
AN: SM44A-02 [Abstracts]
TI: A statistical comparison of ion bulk properties at geosynchronous orbit during moderate and intense geomagnetic storms at solar minimum and maximum
AU: * Zhang, J
EM: jichunz@umich.edu
AF: Space Physics Research Laboratory, University of Michigan, 2455 Hayward St., #1424, Ann Arbor, MI 48109-2143 United States
AU: Liemohn, M W
EM: liemohn@umich.edu
AF: Space Physics Research Laboratory, University of Michigan, 2455 Hayward St., #1424, Ann Arbor, MI 48109-2143 United States
AU: Thomsen, M F
EM: mthomsen@lanl.gov
AF: Los Alamos National Laboratory, MS D466, Los Alamos, NM 87545 United States
AU: Kozyra, J U
EM: jukozyra@umich.edu
AF: Space Physics Research Laboratory, University of Michigan, 2455 Hayward St., #1424, Ann Arbor, MI 48109-2143 United States
AB: Geosynchronous orbit plasma observations by the LANL MPAs before and during 42 intense storms and 111 moderate storms at solar minimum (January, 1995 - June, 1997) and at solar maximum (July, 1999 - June, 2002) are collected, categorized, and analyzed through the superposed epoch technique. The storms are defined by the pressure corrected Dst (Dst^*). IMF southward B_z (B_s ) from the Wind and ACE spacecrafts is also included in this study. The similarities and differences among the average variations of IMF B_s, four channel fluxes (with energies ~30 keV, ~18 keV, ~7 keV, and ~1 keV) and several derived bulk properties of ions at geosynchronous orbit, and Dst^* in the four storm categories are examined. It is found that both IMF B_s and plasma sheet density determine the intensity of the storm-time ring current. At geosynchronous orbit, hot-ion fluxes, density, and temperature vary with local time and are enhanced in high geomagnetic activity. It is also shown that hot ions are nearly isotropic in the central plasma sheet during storms. On the nightside, the storm-time temperature of hot ions at solar minimum is higher than that at solar maximum.
UR: http://www-personal.engin.umich.edu/~jichunz/
DE: 2700 MAGNETOSPHERIC PHYSICS
DE: 2730 Magnetosphere--inner
DE: 2740 Magnetospheric configuration and dynamics
DE: 2764 Plasma sheet
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly