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| Titel |
Low-frequency waves in the Earth's magnetosheath: present status |
| VerfasserIn |
S. J. Schwartz, D. Burgess, J. J. Moses |
| 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 ; 14, no. 11 ; Nr. 14, no. 11, S.1134-1150 |
| Datensatznummer |
250012465
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| Publikation (Nr.) |
 copernicus.org/angeo-14-1134-1996.pdf |
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| Zusammenfassung |
| The terrestrial magnetosheath contains a rich
variety of low-frequency (≲ proton gyrofrequency) fluctuations. Kinetic
and fluid-like processes at the bow shock, within the magnetosheath plasma, and
at the magnetopause all provide sources of wave energy. The dominance of kinetic
features such as temperature anisotropies, coupled with the high-β
conditions, complicates the wave dispersion and variety of instabilities to the
point where mode identification is difficult. We review here the observed
fluctuations and attempts to identify the dominant modes, along with the
identification tools. Alfvén/ion-cyclotron and mirror modes are generated by
T^/T∥>1
temperature anisotropies and dominate when the plasma β is low or
high, respectively. Slow modes may also be present within a transition layer
close to the subsolar magnetopause, although they are expected to suffer strong
damping. All mode identifications are based on linearized theory in a
homogeneous plasma and there are clear indications, in both the data and in
numerical simulations, that nonlinearity and/or inhomogeneity modify even the
most basic aspects of some modes. Additionally, the determination of the wave
vector remains an outstanding observational issue which, perhaps, the Cluster
mission will overcome. |
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