HR: 13:40h
AN: SM32C-01    [PDF]
TI: Numerical Simulations of the Interchange Instability in the Plasma Sheet
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: rawolf@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 R
EM: toffo@rice.edu
AF: Rice University, Physics and Astronomy Dept., MS-108, 6100 South Main St., Houston, TX 77005-1892 United States
AB: Although the plasma sheet of the Earth is usually stable with respect to interchange motion, it has been long known that, under appropriate conditions, interchange-like instabilities are possible even in the ideal MHD approximation. For example, such conditions may exist during periods of strong sunward convection when there are sharp and significant decreases in the plasma sheet density. Previously, we have used numerical simulations to show that the inner (L$<$6) magnetosphere can be interchange-unstable if we take particle fluxes measured by LANL geosynchronous spacecraft as inputs to the Rice Convection Model (RCM). In this paper, we present new results from RCM numerical simulations with the modeling region expanded to 20-25 Re in the magnetotail, to include the central plasma sheet region. In these simulations, a global time-dependent magnetic field model, as well as a time-dependent distribution of particle fluxes in the plasma sheet, are used as inputs to the model. First, we analyze under what geomagnetic conditions the plasma sheet may be interchange-unstable by using a number of different empirical models of the plasma sheet plasma distribution and several magnetic field configurations (both theoretical and data-based). We then present time-dependent simulations of magnetospheric global particle fluxes, field-aligned currents, and electric fields computed self-consistently with the RCM that show growth and evolution of the interchange instability. Based on these results, we address the previously-published idea that interchange-instability motions in the plasma sheet may be related to the formation of auroral arc structures.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2753 Numerical modeling
DE: 2760 Plasma convection
DE: 2764 Plasma sheet
DE: 2772 Plasma waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting