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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
A12216,
11 PP., 2006
doi:10.1029/2006JA011802
Observation of two distinct, rapid loss mechanisms during the 20 November 2003 radiation belt dropout event
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Space Sciences Department/Chantilly, The Aerospace Corporation, Chantilly, Virginia, USA
NOAA, Boulder, Colorado, USA
Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA
The relativistic electron dropout event on 20 November 2003 is studied using data from a number of satellites including SAMPEX, HEO, ACE, POES, and FAST. The observations suggest that the dropout may have been caused by two separate mechanisms that operate at high and low L-shells, respectively, with a separation at L ∼ 5. At high L-shells (L > 5), the dropout is approximately independent of energy and consistent with losses to the magnetopause aided by the Dst effect and outward radial diffusion which can deplete relativistic electrons down to lower L-shells. At low L-shells (L < 5), the dropout is strongly energy-dependent, with the higher-energy electrons being affected most. Moreover, large precipitation bands of both relativistic electrons and energetic protons are observed at low L-shells which are consistent with intense pitch angle scattering driven by electromagnetic ion cyclotron (EMIC) waves and may result in a rapid loss of relativistic electrons near the plasmapause in the dusk sector or in plumes of enhanced density.
Received 20 April 2006; accepted 18 October 2006; published 21 December 2006.
Citation: (2006), Observation of two distinct, rapid loss mechanisms during the 20 November 2003 radiation belt dropout event, J. Geophys. Res., 111, A12216, doi:10.1029/2006JA011802.
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