HR: 1340h
AN: SM23A-1173    [Abstracts]
TI: Substorm onset dynamics in the magnetotail: joint TC-1 and Cluster observation and SWMF simulation
AU: * Wang, H
EM: whui@umich.edu
AF: Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, United States
AU: * Wang, H
EM: whui@umich.edu
AF: College of Electronic Informatics, Wuhan University, Wuhan, HB 430079, China
AU: Ridley, A
EM: ridley@umich.edu
AF: Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, United States
AU: Luehr, H
EM: hluehr@gfz-potsdam.de
AF: GeoForshungsZentrum, Potsdam, Potsdam, D-14473, Germany
AU: Ma, S Y
EM: syma@whu.edu.cn
AF: College of Electronic Informatics, Wuhan University, Wuhan, HB 430079, China
AB: This study investigates two substorm onset events with favorable constellations of spacecraft, TC-1 and Cluster, near the current sheet separated by several Earth radius. The substorms have been identified in both auroral regions. One is believed to be triggered by a northward turning of the interplanetary magnetic field (IMF), while the other occurs under generally southward IMF. For both events, Cluster was located tailward of TC-1 and observed the dipolarization at earlier times. The timing difference of dipolarization at different positions could be explained by an earthward propagation of the field disturbances from midtail to the inner magnetotail. And the earthward dipolarization front was found in one case to bounce back and forth at TC-1. The earthward propagation was accompanied by a fast earthward flow for the 21 September 2005 event, while this was not the case for the 28 September 2004 event. This suggests that substorms can be quite different from case to case due to differences in the solar wind condition and magnetotail configuration. The space weather modeling framework (SWMF) can capture the general topology of the magnetotail during these two events. However, it has predicted one of the substorm onsets about 50 minutes earlier than observations while missed out the other substorm onset totally.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2753 Numerical modeling
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting