HR: 0800h
AN: SM21B-0383    [Abstracts]
TI: Field-Aligned Currents Observed by CHAMP During the Superstorms in 2003
AU: * Wang, H
EM: huiwang@gfz-potsdam.de, hui_wang2002@hotmail.com
AF: Inst. of Ionosphere and Magnetosphere, College of Electronic Information, Wuhan University, China, Luojia Hill, Wuchang District, Wuhan, HB 430079 China
AU: * Wang, H
EM: huiwang@gfz-potsdam.de, hui_wang2002@hotmail.com
AF: GeoforschungsZentrum, Potsdam, Germany, Telegrafenberg, Potsdam, D-14473 Germany
AU: Ma, S
EM: syma@whu.edu.cn
AF: Inst. of Ionosphere and Magnetosphere, College of Electronic Information, Wuhan University, China, Luojia Hill, Wuchang District, Wuhan, HB 430079 China
AU: Luehr, H
EM: hluehr@gfz-potsdam.de
AF: GeoforschungsZentrum, Potsdam, Germany, Telegrafenberg, Potsdam, D-14473 Germany
AU: Weygand, J
SM21B-0383 AF: Institute of Geophysics and Planetary Physics, Department of Earth and Space Sciences,University of California, USA, 3845 Slichter Hall Los Angeles, California , Los Angeles, CA 90095-1567 United States
AB: A study is made on the global characteristics of large-scale field-aligned currents (FACs) in the topside ionosphere during extreme storms, October 29-31 and November 20-22, 2003. High-precision magnetic field measurements on board of CHAMP register the dynamics of FACs during the super-storms, which are quite different from normal periods. The large scale FAC peak density is on average enhanced by about a factor of 5. On the dayside, the FAC densities on average are 2.5 times larger in the southern (summer) hemisphere than in the northern (winter), while they are quite comparable between the two hemispheres on the night-side. In addition to control of IMF Bz on the FAC intensity, solar wind dynamic pressure is also found to play an important role for the variation of the FAC strength. The latitudinal variations of the FACs' location are compared with the variation in IMF Bz, various solar wind-magnetosphere coupling parameters and Dst index in order to find the key parameters controlling the configuration of large-scale FACs in the polar region. It is found that (1) On the dayside, the IMF southward component controls directly the equatorward shift of FACs but there is a saturation of the displacement for large negative Bz, with a lower latitude cutoff in summer hemisphere than in winter. (2) The equatorward expansion of the nightside auroral oval, characterized by FAC, is delayed relative to the solar wind input. Then, its poleward recovery is slower than on the dayside. The Dst index can better describe the latitudinal variation of FAC on the nightside. (3) The latitude coverage of the FAC on the nightside near the main phase minimum of the storms can be as wide as 25 degree, with a multiple current sheet configuration.
UR: http://www.whu.edu.cn
DE: 2407 Auroral ionosphere (2704)
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2784 Solar wind/magnetosphere interactions
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005