HR: 0830h
AN: SM41B-0572    [PDF]
TI: Energy Budget of Alfven Wave Interactions with the Auroral Acceleration Region
AU: Pilipenko, V
EM: pilipenk@augsburg.edu
AF: Space Research Institute, Profsojuznaja 84/32, Moscow, 117997 Russian Federation
AU: Fedorov, E
AF: Institute of the Physics of the Earth, Bolshaya Gruzinskaya 10, Moscow, 123995 Russian Federation
AU: * Engebretson, M J
EM: engebret@augsburg.edu
AF: Augsburg College, 2211 Riverside Avenue, Minneapolis, MN 55454 United States
AB: Recent Polar satellite observations of intense Alfven ULF bursts over auroral arcs prompted researchers to suggest that ULF wave activity does provide energy to the auroral arc intensification. However, to provide physical grounds for this suggestion, it is important to know possible bounds on the rate of the ULF wave energy transfer into electron acceleration. To estimate the power dissipated in the ionosphere and that transferred into electron acceleration, we consider the interaction of magnetospheric Alfven waves with the auroral ionosphere, comprising the auroral acceleration region (AAR). The AAR is characterized by a mirror resistance to the field-aligned upward current that can provide the potential drop and the acceleration of electrons. Analytical treatment of the interaction of Alfven waves with the combined magnetosphere-AAR-topside ionosphere-E-layer system has been made within the "thin" AAR approximation, which is valid for small-scale disturbances. The input of Alfven waves into the energy balance of the AAR depends critically on their transverse scale. Only waves with scales comparable to the Alfven transit scale, that is $k_\perp \lambda_A \simeq 1$, will provide energy into electron acceleration. This process is expected to be more effective above a conductive ionosphere. These theoretical predictions could be verified with the multi-satellite measurements in the Cluster-2 mission.
DE: 2704 Auroral phenomena (2407)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2752 MHD waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting