HR: 0800h
AN: SM21A-0318    [Abstracts]
TI: The seasonal dependence of relativistic electron fluxes in the Earth's outer van Allen Belt
AU: * Kanekal, S G
EM: shri.kanekal@lasp.colorado.edu
AF: LASP, Univ. of Colorado, 1234 Innovation Drive, Boulder, CO 80303, United States
AU: Baker, D N
AF: LASP, Univ. of Colorado, 1234 Innovation Drive, Boulder, CO 80303, United States
AU: McPherron, R
AF: Department of Earth and Space Sciences University of California, Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095, United States
AB: It is well known that geomagnetic activity shows a marked seasonal dependence. This effect has been attributed to the seasonal variation of the Earth's dipole tilt angle exposing the magnetosphere to an increased southward component of the interplanetary field (the Russell-McPherron effect) or an increased solar wind velocity (the axial/equinoctial effect). We examine the seasonal dependence of relativistic electron fluxes in the Earth's outer Van Allen belt. An earlier investigation by Baker et. al., (1999) found that the relativistic electron fluxes do show a strong seasonal dependence with the equinoctial electron fluxes being almost three times higher than the solstitial fluxes. We extend this previous investigation using data obtained by sensors onboard SAMPEX. This study of the seasonal dependence is based on data with a higher time resolution as compared to the earlier study. The results of our analysis show that the peak electron fluxes are shifted in time from the nominal equinoctial times. We discuss some possible implications of our observations in the context of electron energization in the Earth's magnetosphere. Baker, D.N., S.G. Kanekal, T.I. Pulkkinen, and J.B. Blake, Equinoctial and solstitial averages of magnetospheric relativistic electrons: A strong semiannual modulation, Geophys. Res. Lett., 26, No. 20, 3193-3196, 1999.
DE: 2720 Energetic particles: trapped
DE: 2730 Magnetosphere: inner
DE: 2774 Radiation belts
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting