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| Titel |
Quantifying the effect of magnetopause shadowing on electron radiation belt dropouts |
| VerfasserIn |
Y. Yu, J. Koller, S. K. Morley |
| 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 ; 31, no. 11 ; Nr. 31, no. 11 (2013-11-15), S.1929-1939 |
| Datensatznummer |
250086141
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1929-2013.pdf |
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| Zusammenfassung |
| Energetic radiation belt electron fluxes can undergo sudden dropouts in
response to different solar wind drivers. Many physical processes contribute
to the electron flux dropout, but their respective roles in the net electron
depletion remain a fundamental puzzle. Some previous studies have
qualitatively examined the importance of magnetopause shadowing in the sudden
dropouts either from observations or from simulations. While it is difficult
to directly measure the electron flux loss into the solar wind, radial
diffusion codes with a fixed boundary location (commonly utilized in the
literature) are not able to explicitly account for magnetopause shadowing.
The exact percentage of its contribution has therefore not yet been resolved.
To overcome these limitations and to determine the exact contribution in
percentage, we carry out radial diffusion simulations with the magnetopause
shadowing effect explicitly accounted for during a superposed solar wind
stream interface passage, and quantify the relative contribution of the
magnetopause shadowing coupled with outward radial diffusion by comparing
with GPS-observed total flux dropout. Results indicate that during high-speed
solar wind stream events, which are typically preceded by enhanced dynamic
pressure and hence a compressed magnetosphere, magnetopause shadowing coupled
with the outward radial diffusion can explain about 60–99% of the main-phase radiation belt electron depletion near the geosynchronous orbit. While
the outer region (L* > 5) can nearly be explained by the above
coupled mechanism, additional loss mechanisms are needed to fully explain the
energetic electron loss for the inner region (L* ≤ 5). While this
conclusion confirms earlier studies, our quantification study demonstrates its
relative importance with respect to other mechanisms at different locations. |
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