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| Titel |
Modelling substorm chorus events in terms of dispersive azimuthal drift |
| VerfasserIn |
A. B. Collier, A. R. W. Hughes |
| 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 ; 22, no. 12 ; Nr. 22, no. 12 (2004-12-22), S.4311-4327 |
| Datensatznummer |
250015093
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| Publikation (Nr.) |
 copernicus.org/angeo-22-4311-2004.pdf |
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| Zusammenfassung |
| The Substorm Chorus Event (SCE) is a radio phenomenon observed on the ground
after the onset of the substorm expansion phase. It consists of a band of VLF
chorus with rising upper and lower cutoff frequencies. These emissions are
thought to result from Doppler-shifted cyclotron resonance between whistler
mode waves and energetic electrons which drift into a ground station's field
of view from an injection site around midnight. The increasing frequency of
the emission envelope has been attributed to the combined effects of energy
dispersion due to gradient and curvature drifts, and the modification of
resonance conditions and variation of the half-gyrofrequency cutoff resulting
from the radial component of the ExB drift.
A model is presented which accounts for the observed features of the SCE in
terms of the growth rate of whistler mode waves due to anisotropy in the
electron distribution. This model provides an explanation for the increasing
frequency of the SCE lower cutoff, as well as reproducing the general
frequency-time signature of the event. In addition, the results place some
restrictions on the injected particle source distribution which might lead to
a SCE.
Key words. Space plasma physics (Wave-particle interaction)
– Magnetospheric physics (Plasma waves and instabilities;
Storms and substorms) |
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