HR: 0800h
AN: SA51B-0250    [Abstracts]
TI: Seasonal and Solar-Cycle Variation of Polar Cap Patches
AU: * Demars, H G
EM: howard@aros.net
AF: Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405 United States
AU: Schunk, R W
EM: schunk@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences, 4405 Old Main Hill, Logan, UT 84322-4405 United States
AB: Polar cap patches are regions of enhanced plasma density that form in the dayside cusp or equatorward of the cusp during periods of southward IMF and then convect in an antisunward direction across the polar cap. The density enhancement in a patch relative to the background ionospheric density varies over a wide range, from a few percent to a factor of 100. A horizontal cross-section of a polar cap patch can appear roughly circular or cigar-shaped, and patches are typically from about 200 to 1000 km across. We have used a time-dependent, 3-dimensional, fluid model of the coupled ionosphere-polar wind system to model the evolution of a representative polar cap patch and to study its effect on the polar wind for a range of seasonal and solar-cycle conditions. This model calculates the plasma dynamics in a large number (about 1500) of flux tubes as they move horizontally across the polar region under the influence of corotational and magnetospheric convection electric fields. The large number of flux tubes included in a simulation makes it possible to model mesoscale features of the ionosphere, such as plasma patches.
DE: 7843 Numerical simulation studies
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2439 Ionospheric irregularities
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting