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| Titel |
Characterising electron butterfly pitch angle distributions in the magnetosphere through observations and simulations |
| VerfasserIn |
M. M. Klida, T. A. Fritz |
| 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. 2 ; Nr. 31, no. 2 (2013-02-22), S.305-314 |
| Datensatznummer |
250018992
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| Publikation (Nr.) |
 copernicus.org/angeo-31-305-2013.pdf |
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| Zusammenfassung |
| The Imaging Electron Spectrometer (IES) on the Polar satellite has measured
the average characteristics of the equatorial electron pitch angle
distributions (PADs) in the midnight sector as a function of radial distance
out to the 9 RE apogee of the Polar satellite. Depressions in
the observed fluxes of electrons occur with pitch angles around 90° in
the equatorial zone, while the more field-aligned electrons remain largely
unchanged. The orbital precessions of the satellite have allowed much of the
inner equatorial magnetosphere to be observed. Statistically, butterfly PADs
with different shapes are observed selectively in different regions, which
can provide insight to their source and possible history. Electron paths of
varied pitch angles were modelled using Runge-Kutta approximations of the
Lorentz force in a Tsyganenko (T96) simulated magnetosphere. The resulting
drift paths suggest that the process of magnetopause shadowing plays a
significant role in the loss of these electrons. Case studies of the drifting
patterns of electrons with varied pitch angles were simulated from Polar's
orbit when a butterfly PAD was observed on 3 October 2002 at an altitude near
9 RE and on 12 September 2000 at an altitude near 6 RE. These two locations represent regions on each side of the
boundary of stable trapping. The modelling effort strongly suggests that
magnetopause shadowing does play a significant role in the loss of
equatorially drifting electrons from the outer regions of the inner
magnetosphere. |
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