HR: 09:30h
AN: SM21C-07    [Abstracts]
TI: Nonlinear Electron Heating and Pedersen Conductivity Enhancements in the Evolution of Dispersive Field Line Resonances
AU: * Rankin, R
EM: rankin@phys.ualberta.ca
AF: University of Alberta, Department of Physics, University of Alberta, Edmonton, AB T6G 2J1 Canada
AU: Lu, J
EM: jlu@space.ualberta.ca
AF: University of Alberta, Department of Physics, University of Alberta, Edmonton, AB T6G 2J1 Canada
AU: Marchand, R
AF: University of Alberta, Department of Physics, University of Alberta, Edmonton, AB T6G 2J1 Canada
AU: Kabin, K
AF: University of Alberta, Department of Physics, University of Alberta, Edmonton, AB T6G 2J1 Canada
AU: Tikhonchuk, V
AF: Universite Bordeaux 1, Centre Lasers Intenses et Applications, 33405 Talence Cedex, Bordeaux, 33405 France
AB: We examine the effect of ionospheric electron heating by resonant standing shear Alfven waves in Earth's magnetosphere. It is demonstrated that for realistic parameters of dispersive field line resonances, heated electrons cause ionization that changes the Pedersen conductivity of the ionosphere by a large factor. We show that this leads to a strong feedback effect on the FLR amplitude and resulting dynamics. Our simulations using a 2D finite element code indicate that the primary mechanisms responsible for the variation in the electron temperature, are Ohmic heating by the electron component of the Pedersen current, and electron cooling due to ionization losses and collisions with neutrals. The Pedersen conductivity is also spatially modulated, influencing the electric field and the FLR dissipation. These effects are found to be quantitatively more important than those associated with direct collisional ionization produced by precipitating electrons. In particular, the latter can only reduce the initial ionospheric dissipation by at most a factor of two.
DE: 7807 Charged particle motion and acceleration
DE: 7823 Ionization processes
DE: 7843 Numerical simulation studies
DE: 7871 Waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting