HR: 0800h
AN: SM21A-0324    [Abstracts]
TI: Sawtooth Events at GPS Orbit
AU: * Varotsou, A
EM: athina@lanl.gov
AF: Los Alamos National Laboratory, ISR-1, P.O. Box 1663, MS D466, Los Alamos, NM 87545, United States
AU: Henderson, M G
EM: mghenderson@lanl.gov
AF: Los Alamos National Laboratory, ISR-1, P.O. Box 1663, MS D466, Los Alamos, NM 87545, United States
AU: Friedel, R H
EM: rfriedel@lanl.gov
AF: Los Alamos National Laboratory, ISR-1, P.O. Box 1663, MS D466, Los Alamos, NM 87545, United States
AU: Cayton, T E
EM: tcayton@lanl.gov
AF: Los Alamos National Laboratory, ISR-1, P.O. Box 1663, MS D466, Los Alamos, NM 87545, United States
AB: Sawtooth events have been identified as large-amplitude quasi-periodic oscillations of the energetic particle fluxes at geosynchronous orbit. The sharp flux increase and gradual decrease of each tooth are associated with strong dipolarization and stretching, respectively, of the magnetic field at geosynchronous orbit. Sawtooth events occur during storm intervals and have a characteristic periodicity of 2-4 hours. They are particularly prominent in the energetic proton fluxes but can also be seen in the energetic electron fluxes. Here we examine the effect of these events inside geosynchronous orbit (L<6.6) using relativistic electron flux data from the GPS satellite constellation (since the proton energy channels do not correspond to the correct energy for sawtooth observations). We find that, in some cases, relativistic electron fluxes near L=4 show substantial increases associated with a depolarization during a sawtooth event. Our goal is to determine whether these events are consistent with true particle injections deep into the radiation belts or whether the flux variations seen at GPS can be accounted for by adiabatic variations alone (due to the extreme field stretching and dipolarization effects that accompany sawtooth events). To exclude adiabatic effects, the L* value of the satellites is estimated using the Tsyganenko 2001 storm magnetic field model and also an event oriented magnetic field model that fits observed satellite magnetic field data.
DE: 2720 Energetic particles: trapped
DE: 2730 Magnetosphere: inner
DE: 2774 Radiation belts
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting