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| Titel |
Radial transport of radiation belt electrons due to stormtime Pc5 waves |
| VerfasserIn |
A. Y. Ukhorskiy, M. I. Sitnov, K. Takahashi, B. J. Anderson |
| 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 ; 27, no. 5 ; Nr. 27, no. 5 (2009-05-13), S.2173-2181 |
| Datensatznummer |
250016534
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2173-2009.pdf |
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| Zusammenfassung |
| During geomagnetic storms relativistic electron fluxes in the outer radiation
belt exhibit dynamic variability over multiple orders of magnitude. This
requires radial transport of electrons across their drift shells and implies
violation of their third adiabatic invariant. Radial transport is induced by
the interaction of the electron drift motion with electric and magnetic field
fluctuations in the ULF frequency range. It was previously shown that
solar-wind driven ULF waves have long azimuthal wave lengths and thus can
violate the third invariant of trapped electrons in the process of resonant
interaction with their gradient-curvature motion. However, the amplitude of
solar-wind driven ULF waves rapidly decreases with decreasing L. It is
therefore not clear what mechanisms are responsible for fast transport rates
observed inside the geosynchronous orbit. In this paper we investigate wether
stormtime Pc5 waves can contribute to this process. Stormtime Pc5s have short
azimuthal wave lengths and therefore cannot exhibit resonance with the the
electron drift motion. However we show that stormtime Pc5s can cause
localized random scattering of electron drift motion that violates the third
invariant. According to our results electron interaction with stormtime Pc5s
can produce rapid radial transport even as low as L≃4. Numerical
simulations show that electron transport can exhibit large deviations from
radial diffusion. The diffusion approximation is not valid for individual
storms but only applies to the statistically averaged response of the outer
belt to stormtime Pc5 waves. |
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