HR: 14:25h
AN: SM53A-04    [Abstracts]
TI: Temporal Evolution of the Cross-polar-cap Potential After Sharp Enhancements in Solar Wind Dynamic Pressure
AU: * Boudouridis, A
EM: thanasis@atmos.ucla.edu
AF: University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, 405 Hilgard Avenue, 7127 Math Sciences, Los Angeles, CA 90095-1565 United States
AU: Zesta, E
EM: ezesta@atmos.ucla.edu
AF: University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, 405 Hilgard Avenue, 7127 Math Sciences, Los Angeles, CA 90095-1565 United States
AU: Lyons, L R
EM: larry@atmos.ucla.edu
AF: University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, 405 Hilgard Avenue, 7127 Math Sciences, Los Angeles, CA 90095-1565 United States
AU: Anderson, P C
EM: phillip.anderson1@utdallas.edu
AF: University of Texas at Dallas, Center for Space Sciences, 2601 North Floyd Road, PO Box 830688, Richardson, TX 75083-0688 United States
AB: It is well known that the Interplanetary Magnetic Field (IMF) is the major contributor to geomagnetic activity on Earth. Recent studies, however, have shown that solar wind dynamic pressure variations are also important and cause global effects when they encounter the terrestrial magnetosphere. In particular, it has been shown, using Defense Meteorological Satellite Program (DMSP) measurements, that solar wind dynamic pressure enhancements significantly increase the cross-polar-cap potential drop and the coupling efficiency between the solar wind and the Earth's magnetosphere. It was previously suggested, based on DMSP data, that solar wind dynamic pressure enhancements induce enhanced magnetotail reconnection. Furthermore, Super Dual Auroral Radar Network (SuperDARN) observations show that significantly enhanced ionospheric convection in the dayside ionosphere is associated with the impact of solar wind pressure fronts, implying an increase in dayside reconnection. Thus both enhanced dayside and magnetotail reconnection, and an increase in polar cap convection and the cross-polar-cap potential occur after a sharp increase in solar wind dynamic pressure. Case studies of long-lasting solar wind pressure steps indicate that the potential first rises in response to the increase in pressure, but gradually subsides a few hours later despite the solar wind pressure remaining high. However, the remaining potential is still higher than the pre-front value. We conduct a superposed epoch analysis of the potential temporal evolution after several long-lasting solar wind pressure fronts with similar characteristics and under similar IMF conditions. The results are discussed in relation to enhancements in magnetospheric reconnection induced by a solar wind pressure front.
DE: 2712 Electric fields (2411)
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2776 Polar cap phenomena
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005