HR: 1340h
AN: SM13B-1316    [Abstracts]
TI: Responses of the Magnetosphere-Ionosphere System to A Sudden Pressure Commencement
AU: * Yu, Y
EM: yiqunyu@umich.edu
AF: University of Michigan, Space Research Building, 2455 Hayward str., Ann Arbor, MI 48109, United States
AU: Ridley, A
EM: ridley@umich.edu
AF: University of Michigan, Space Research Building, 2455 Hayward str., Ann Arbor, MI 48109, United States
AU: Liemohn, M
EM: liemohn@umich.edu
AF: University of Michigan, Space Research Building, 2455 Hayward str., Ann Arbor, MI 48109, United States
AB: The magnetospheric response to a sudden step increase of the solar wind dynamic pressure when interplanetary magnetic field is northward is studied using the University of Michigan MHD code. Two responses in the ionosphere are observed in terms of cross polar cap potential (CPCP) as well as travelling convection vortices (TCVs). The first response right after the high pressure commencement hits the dayside magnetopause is associated with a pair of NBZ-like high-latitude cells, set up by a dusk-to-dawn electric field in the dayside magnetopause carried by the fast mode compressional wave, mapped to the ionosphere along the field lines. A subsequent pair of TCVs appears at relatively low latitude on the dayside, with the opposite sense than the previous set, resulting from field-aligned currents driven by the magnetospheric vortices in the equatorial plane that are mainly driven by pressure gradients. These vortices are located inside the magnetopause, implying the positions of this Region-1-like field-aligned current is not from the magnetopause. The final CPCP for the new compressed configuration of the system is found to be higher than the prefront value, which appears to be a result of the higher pressure around the Earth.
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting