HR: 0800h
AN: SM31B-1232    [Abstracts]
TI: Convection and Auroral Electrojet Behavior deduced from a Simplified Magnetosphere: Is a Steady State possible when Curvature and Gradient Drifts are considered?
AU: * Atkinson, G
EM: atkinson@chem.ubc.ca
AF: Dept. Physics and Astronomy, University of British Columbia, 6224 Agricultural Rd, Vancouver, BC V6T1Z1 Canada
AB: A simplified model of the magnetosphere is used to study convection in the presence of reconnection and energetic particles. The latitude-limited band of magnetic flux which contains azimuthal convection from the nightside to the dayside is sandwiched between a high-latitude region, in which magnetic flux tubes are too tail-like to convect to the dayside, and a low-latitude region in which the plasma does not strongly affect convection. In order to include the effects of curvature and gradient drifts, the band of azimuthally-convecting flux is treated as two regions: the dawn convection channel (westward electrojet) and the dusk channel (eastward electrojet). The author has not been able to find a simple steady-state solution to the convection if the Harang discontinuity is a true discontinuity (variations only in the perpendicular direction). However, a time-dependent solution exists in which: (1) there is no flux transfer from the highest-latitude region into the convection channels, (2) the Harang discontinuity drifts westward with the eastern edge of energetic particles (partial ring current), (3) the convection channels become thinner with time, (4) the westward electrojet overlaps the eastward electrojet. If flux transfer from the highest latitude region into the convection channels occurs as sporadic events, each event would be expected to produce a new pair of electrojets similar to the above, and the pair would be added to the poleward edge of the pre-existing system. This would produce multiple current sheets and electrojets near midnight. The author has previously suggested that azimuthal convection from the nightside near-earth plasma sheet might play a major role in controlling dipolarization and reconnection events. If this is true, then the onset of the events will be related to the above behavior of the Harang discontinuity.
DE: 2700 MAGNETOSPHERIC PHYSICS
DE: 2708 Current systems (2409)
DE: 2712 Electric fields (2411)
DE: 2760 Plasma convection
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting