HR: 0800h
AN: SM31A-1207    [Abstracts]
TI: Substorms During Prolonged Northward Interplanetary Magnetic Field
AU: * Miyashita, Y
EM: miyasita@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Wu, C
EM: wuc@cspar.uah.edu
AF: CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 United States
AU: Liou, K
EM: Kan.Liou@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AU: Kamide, Y
EM: kamide@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Ieda, A
EM: ieda@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, 442-8507 Japan
AU: Machida, S
EM: machida@kugi.kyoto-u.ac.jp
AF: Department of Geophysics, Kyoto University, Sakyo-ku, Kyoto, 606-8502 Japan
AU: Mukai, T
EM: mukai@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, 229-8510 Japan
AU: Saito, Y
EM: saito@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, 229-8510 Japan
AU: Meng, C
EM: Ching.Meng@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723 United States
AU: Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720 United States
AU: Creutzberg, F
EM: creutzberg@sp-agency.ca
AF: Keometrics, 9 Massey Ln, Ottawa,, ON K1J 6C7 Canada
AB: We have studied substorm events under a condition of prolonged northward interplanetary magnetic field (IMF). In substorms on January 19, 1998, a series of expansion onsets and intensifications was observed by Polar UVI. The IMF remained northward for more than 20 hours before the expansion onsets, except for several very short and small southward excursions. During this period, ionospheric convection was very weak. GEOTAIL observed total pressure increases in the magnetotail at $-25>X>-30$ $R_E$, probably caused by an enhancement in the solar wind dynamic pressure and the large IMF $B_y$ component. At the substorm onsets, GEOTAIL observed fast tailward flows and southward magnetic fields, associated with plasmoids, suggesting that magnetic reconnection occurred earthward of GEOTAIL. The GOES satellites observed dipolarizations. There were no large changes in the solar wind and the IMF around the onsets. On the basis of these observations, a possible substorm mechanism will be discussed.
DE: 2704 Auroral phenomena (2407)
DE: 2744 Magnetotail
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting