HR: 14:45h
AN: SM53D-05    [Abstracts]
TI: Effects of Ionospheric Heating on Feedback-Unstable Electromagnetic Fields at High Latitudes
AU: * Streltsov, A V
EM: streltsov@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AU: Lotko, W
EM: wlotko@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755, United States
AB: Results from a numerical study of the nonlinear interaction between large-scale magnetic field-aligned currents (FACs) and the high-latitude ionosphere are presented. This study focuses on the dynamics of intense, small- scale electromagnetic structures generated in the ionosphere and low-altitude magnetosphere by the ionospheric feedback instability. The instability is caused by the large-scale electric field produced in the ionosphere where a large-scale, downward FAC depletes the ionospheric density and reduces the ionospheric conductivity. The novel aspect of this research is the evaluation of the effects of E-region electron and ion heating on the feedback instability. Anomalous electron heating can be attributed to nonlinearly saturated turbulence of the Farley-Buneman instability; the ion heating is mainly due to ion-neutral collisions. Electron heating increases the ionospheric conductivity by decreasing the recombination rate whereas ion heating tends to reduce the ionospheric conductivity by increasing the ion-neutral collision frequency. Numerical simulations based on a two- fluid MHD model describing coupling between ULF electromagnetic waves and the ionosphere are presented. In this study, we explore the parametric dependence of ion and electron heating on the feedback instability and the resulting plasma electrodynamics without fully treating the ion and electron energy dynamics.
DE: 2704 Auroral phenomena (2407)
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 2753 Numerical modeling
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting