HR: 0800h
AN: SM41C-1193    [Abstracts]
TI: Ionospheric Current Systems Under Magnetic Cloud Condition
AU: * Zhou, X
EM: xiaoyan.zhou@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Rostoker, G
EM: rostoker@space.ualberta.ca
AF: University of Alberta, Edmonton, Canada T6G 2J1, Edmonton, T6G 2J1 Canada
AU: Sun, W
EM: sun@jupiter.gi.alaska.edu
AF: University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Du, A
EM: amdu@mail.iggcas.ac.cn
AF: Institute of Geology and Geophysics, 19 W. Bei Tu Cheng Road , Beijing, 100029 China
AU: Lui, T
EM: Tony.Lui@jhuapl.edu
AF: Applied Physics Laboratory, 11100 Johns Hopkins Road , Laurel, MD 20723 United States
AB: During magnetic clouds the solar wind has properties of low plasma beta, intense magnetic field, smooth north-south (or south-north) magnetic field polarity reversals, and a general absence of Alfv‚n waves and discontinuities. The earth's magnetospheric and ionospheric convection velocities significantly increase during periods of southward IMF within magnetic clouds. At high latitudes, a two-cell convection pattern develops that can be quantitatively described by the DP2 equivalent current system. Under certain circumstances, "sawtooth" events occur featuring quasi-periodic substorm expansion phase activity in which westward electrojets (i.e., equivalent DP1 current) appear in the midnight sector in association with each substorm expansion phase. By studying the April 18, 2002 "sawtooth" event, we show how the DP2 and DP1 current systems develop during a smooth southward IMF interval within the magnetic cloud. With an absence of external triggering, the occurrence of quasi-periodic substorm expansion onsets suggests that this "sawtooth" event may be a result of magnetospheric self-regulation. We also discuss the corresponding energy transfer from the magnetotail where the tail magnetic field intensity is seen to vary quasi-periodically.
DE: 2407 Auroral ionosphere (2704)
DE: 2409 Current systems (2721)
DE: 2475 Polar cap ionosphere
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005