HR: 0800h
AN: SM41A-1132    [Abstracts]
TI: Statistical Pitch Angle Properties of Substorm Injected Electron Clouds and Their Relation to Dawnside Energetic Electron Precipitation
AU: Aasnes, A
EM: Arne.Asnes@ift.uib.no
AF: Department of Bergen University of Bergen, Allegt. 55, Bergen, 5007 Norway
AU: * Friedel, R W
EM: friedel@lanl.gov
AF: Los Alamos National Laboratory, ISR-1 MS-D466, Los Alamos, NM 87545 United States
AU: Stadsnes, J
EM: Johan.Stadsnes@ift.uib.no
AF: Department of Bergen University of Bergen, Allegt. 55, Bergen, 5007 Norway
AU: Thomsen, M
EM: mthomsen@lanl.gov
AF: Los Alamos National Laboratory, ISR-1 MS-D466, Los Alamos, NM 87545 United States
AU: Ostgaard, N
EM: Nikolai.Ostgaard@ift.ui.no
AF: Department of Bergen University of Bergen, Allegt. 55, Bergen, 5007 Norway
AU: Cayton, T
EM: tcayton@lanl.gov
AF: Los Alamos National Laboratory, ISR-1 MS-D466, Los Alamos, NM 87545 United States
AB: Using the existing large database of geosynchronous orbit particle measurements from Los Alamos instruments, statistical properties of substorm injected electron clouds are investigated, with special focus on the pitch angle distribution (PAD). The equatorial plasma sheet at 6.6R$_E$ does in general show some anisotropy and its PADs are probably caused by the combined influence of drift orbits, different for each energy and pitch angle, and pitch angle diffusion due to waves. The statistical results of this paper indicate that the PADs during intervals of increased electron flux at energies greater than 10keV from midnight till noon are dominated by pitch angle diffusion by interaction with waves. The strength of the pitch angle diffusion is seen to initially limit the growth of anisotropy from differential drift speeds and orbits and later on to increase the anisotropy. After local noon we find evidence that pitch angle diffusion is no longer important and the PADs are evolving due to differential drift effects.
DE: 2716 Energetic particles, precipitating
DE: 2720 Energetic particles, trapped
DE: 2772 Plasma waves and instabilities
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting