HR: 10:30h
AN: SA12A-01 INVITED     [Abstracts]
TI: Dynamics of Magnetosphere-Ionosphere Coupling at Low Latitudes: How Well do we Understand it?
AU: * Sazykin, S
EM: sazykin@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AU: Wolf, R A
EM: rawofl@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AU: Spiro, R W
EM: spiro@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AU: Toffoletto, F
EM: toffo@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AU: Xing, X
EM: xyxing@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AU: Garner, T
EM: garner@arlut.utexas.edu
AF: Univ. of Texas, Applied Research Lab, F0252, 10000 Burnet Rd., Austin, TX 78713 United States
AB: Based on theoretical considerations and an array of numerical simulations, we review the physics of the electrodynamic link via field-aligned region-2 currents between the inner magnetosphere and the ionosphere of Earth. In the canonical picture, high-latitude convection is a source electric field for the ionosphere. Region-2 field-aligned currents related to plasma pressure gradients in the near-Earth plasma sheet and ring current create an electric field that opposes and partially cancels the convection electric field at latitudes equatorward of the diffuse aurora. Region-2 currents can be thought of as a time-dependent gate that allows a fraction of the convection electric field to penetrate to the subauroral and low-latitude ionosphere. The characteristic lifetimes of this penetration are determined by the time history of the source electric field, the bulk properties of the plasma sheet and plasma distribution, the magnetic field configuration, and by the distribution of auroral/subauroral conductivites. The fraction of the penetrating electric potential drop is controlled by these and by the strength of the source. Ionospheric electric fields at latitudes away from the auroral oval are dependent, in a self-consistent manner, on ionospheric plasma density distributions. The specific focus of this paper is on how the density and temperature of the plasma sheet and the magnetospheric magnetic field configuration control the shielding capability of region-2 currents. We conclude by discussing how this relatively simple picture is affected by uncertainty about how plasma is transported in the plasma sheet, particularly when the solar-wind driver is changing in time.
DE: 2708 Current systems (2409)
DE: 2712 Electric fields (2411)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2740 Magnetospheric configuration and dynamics
DE: 2753 Numerical modeling
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly