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| Titel |
Identification of broad-band waves above the auroral acceleration region: Cluster observations |
| VerfasserIn |
M. Backrud, M. André, A. Balogh, S. Buchert, N. Cornilleau-Wehrlin, A. Vaivads |
| 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.4203-4216 |
| Datensatznummer |
250015085
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| Publikation (Nr.) |
 copernicus.org/angeo-22-4203-2004.pdf |
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| Zusammenfassung |
| We investigate broad-band emissions at frequencies above the ion
gyrofrequency on auroral field lines at geocentric distances of
about 4.5 Earth radii. Observations by the Cluster satellites are used to study the
wave characteristics and to determine the wave modes involved. All events
include some bursts of broad-band emissions with a substantial component of
the electric field parallel to the geomagnetic field. Studying the
polarization of the emissions we find that linear waves in a homogeneous
plasma can be used to theoretically describe the observations.
The broad-band emissions include short bursts of ion acoustic waves, and
longer periods of ion Bernstein and Electrostatic Ion Cyclotron (EIC) waves.
All waves occur during the same event within a few seconds, with EIC waves
as the most common. Theoretically, there is no sharp limit between these wave
modes and they can be described by the same dispersion surface. These
emissions are closely associated with low-frequency Alfvén waves,
indicating a possible generation mechanism.
Key words. Magnetospheric physics (auroral phenomena;
electric fields; plasma waves and instabilities) |
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