HR: 0800h
AN: SM41A-1115    [Abstracts]
TI: Effect of Solar Wind Dynamic Pressure Enhancement on the Development of Ring Current Asymmetry
AU: * Shi, Y
EM: yongshi@atmos.ucla.edu
AF: UCLA Dept. of Atmospheric and Oceanic Sciences, 405 Hilgard Ave., Los Angeles, CA 90095 United States
AB: Our previous study has shown that solar wind dynamic pressure enhancement can further increase ring current asymmetry when it occurs during the main phase of a storm. We also found that pressure enhancement during the early recovery phase can slightly strengthen the asymmetry of a partially symmetric ring current, and that the pressure enhancement effect on ring current asymmetry is negligible during the late recovery phase. The effects therefore highly depend on storm phases and the state of the ring current at the time of the onset of a pressure enhancement. In this study, we statistically investigate the effect of a pressure enhancement on the ring current development under more general conditions, i.e. not necessarily occurring during a magnetic storm. We select pressure enhancement events occurring during the period of June 2003 to December 2003, during which we have magnetometer observations from the SAMBA and 210 chains, located approximately 180 degrees in longitude apart. Through examining the variations in the H and D components of the geomagnetic in those events, it is preliminarily found that pressure enhancements have significantly smaller effect on the development of ring current asymmetry during non-storm time than during storm time. The results also show that the orientation of IMF Bz plays a very important role in influencing ring current asymmetry during non-storm time, the effect being stronger for southward IMF Bz than for northward IMF Bz.
DE: 7800 SPACE PLASMA PHYSICS
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting