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Global storm time depletion of the outer electron belt.
Ukhorskiy, A Y; Sitnov, M I; Millan, R M; Kress, B T; Fennell, J F; Claudepierre, S G; Barnes, R J.
Afiliação
  • Ukhorskiy AY; Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA.
  • Sitnov MI; Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA.
  • Millan RM; Department of Physics and Astronomy Dartmouth College Hanover New Hampshire USA.
  • Kress BT; Cooperative Institute for Research in Environmental Sciences University of Colorado at Boulder Boulder Colorado USA.
  • Fennell JF; The Aerospace Corporation Los Angeles California USA.
  • Claudepierre SG; The Aerospace Corporation Los Angeles California USA.
  • Barnes RJ; Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA.
J Geophys Res Space Phys ; 120(4): 2543-2556, 2015 Apr.
Article em En | MEDLINE | ID: mdl-27656334
ABSTRACT
The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scales. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase depletions adiabatic inflation of electron drift orbits caused by the ring current growth, electron loss into the atmosphere, and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the adiabatic effect and magnetopause loss to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of 17 March 2013 storm. The intensities of >1 MeV electrons were depleted by more than an order of magnitude over the entire radial extent of the belt in less than 6 h after the sudden storm commencement. For the analysis we used three-dimensional test particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with an inductive electric field. Comparison of the simulation results with electron measurements from the Magnetic Electron Ion Spectrometer experiment shows that magnetopause loss accounts for most of the observed depletion at L>5, while at lower L shells the depletion is adiabatic. Both magnetopause loss and the adiabatic effect are controlled by the change in global configuration of the magnetic field due to storm time development of the ring current; a simulation of electron evolution without a ring current produces a much weaker depletion.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2015 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2015 Tipo de documento: Article