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| Titel |
Field-aligned chorus wave spectral power in Earth's outer radiation belt |
| VerfasserIn |
H. Breuillard, O. Agapitov, A. Artemyev, E. A. Kronberg, S. E. Haaland, P. W. Daly, V. V. Krasnoselskikh, D. Boscher, S. Bourdarie, Y. Zaliznyak, G. Rolland |
| 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 ; 33, no. 5 ; Nr. 33, no. 5 (2015-05-29), S.583-597 |
| Datensatznummer |
250121199
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| Publikation (Nr.) |
 copernicus.org/angeo-33-583-2015.pdf |
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| Zusammenfassung |
| Chorus-type whistler waves are one of the most intense electromagnetic waves
generated naturally in the magnetosphere. These waves have a substantial
impact on the radiation belt dynamics as they are thought to contribute to
electron acceleration and losses into the ionosphere through resonant
wave–particle interaction. Our study is devoted to the determination of
chorus wave power distribution on frequency in a wide range of magnetic
latitudes, from 0 to 40°. We use 10 years of magnetic and
electric field wave power measured by
STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus
wave spectral power, as well as PEACE and RAPID measurements to model the
properties of energetic electrons (~ 0.1–100 keV) in the outer radiation
belt. The dependence of this distribution upon latitude obtained from Cluster
STAFF-SA is then consistently reproduced along a certain L-shell range
(4 ≤ L ≤ 6.5), employing WHAMP-based ray tracing simulations in hot
plasma within a realistic inner magnetospheric model. We show here that, as
latitude increases, the chorus peak frequency is globally shifted towards
lower frequencies. Making use of our simulations, the peak frequency
variations can be explained mostly in terms of wave damping and
amplification, but also cross-L propagation. These results are in good
agreement with previous studies of chorus wave spectral extent using data
from different spacecraft (Cluster, POLAR and THEMIS). The chorus peak
frequency variations are then employed to calculate the pitch angle and
energy diffusion rates, resulting in more effective pitch angle electron
scattering (electron lifetime is halved) but less effective
acceleration. These peak frequency parameters can thus be used to improve the
accuracy of diffusion coefficient calculations. |
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