Observation of magnetospheric relativistic electrons accelerated by Pc-5 ULF waves

Author/Creator ORCID

Date

2004-07-20

Department

Program

Citation of Original Publication

Tan, Lun C.; Fung, Shing F.; Shao, Xi; Observation of magnetospheric relativistic electrons accelerated by Pc-5 ULF waves; Geophysical Research Letters, 31, 14, 20 July, 2004; https://doi.org/10.1029/2004GL019459

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.

Subjects

Abstract

Magnetic field, electric field and energetic electron measurements from CRRES, GOES-6 and -7 satellites are used to investigate the production of up to 2 MeV electron fluxes through a storm sudden commencement (SSC) event on August 27, 1991. Strong Pc-5 oscillations, whose electric field is mainly along the radial direction, and up to an order-of-magnitude enhancement in relativistic electron fluxes occurred simultaneously in a two-hour period. The enhanced electron fluxes are found to have a pancake-like pitch angle distribution, which is consistent with the fluxes being accelerated near the equatorial plane. The electron acceleration is shown to result from drift-resonant interactions with the toroidal-mode Pc-5 ULF waves having wave frequencies three times the electron drift frequency. In view of the L-variation of ULF wave frequencies, electron acceleration to relativistic energies becomes more effective in the geosynchronous region.