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| Titel |
Radial diffusion simulations of the 20 September 2007 radiation belt dropout |
| VerfasserIn |
J. Albert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 32, no. 8 ; Nr. 32, no. 8 (2014-08-08), S.925-934 |
| Datensatznummer |
250121091
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| Publikation (Nr.) |
 copernicus.org/angeo-32-925-2014.pdf |
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| Zusammenfassung |
| This is a study of a dropout of radiation belt electrons, associated with an
isolated solar wind density pulse on 20 September 2007, as seen by the solid-state
telescopes (SST)
detectors on THEMIS (Time History of Events and Macroscale
Interactions during Substorms). Omnidirectional fluxes were converted to phase space
density at constant invariants M = 700 MeV G−1 and K = 0.014 RE G1/2, with the assumption of
local pitch angle α ≈ 80° and using the T04 magnetic field
model. The last closed drift shell, which was calculated throughout the time
interval, never came within the simulation outer boundary of L* = 6. It is
found, using several different models for diffusion rates, that radial
diffusion alone only allows the data-driven, time-dependent boundary values
at Lmax = 6 and Lmin = 3.7 to propagate a few tenths of an RE during
the simulation; far too slow to account for the dropout observed over the
broad range of L* = 4–5.5. Pitch angle diffusion via resonant
interactions with several types of waves (chorus, electromagnetic ion
cyclotron waves, and plasmaspheric and plume hiss) also seems problematic,
for several reasons which are discussed. |
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