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| Titel |
Magnetic turbulence in the magnetospheric environment: highlights from multi-spacecraft missions |
| VerfasserIn |
Gaetano Zimbardo, Antonella Greco, Luca Sorriso-Valvo, Silvia Perri, Zoltan Voeroes, Giorgi Aburjania, Khatuna Chargazia, Olga Alexandrova |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052839
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| Zusammenfassung |
| Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere
and the interaction region between the magnetosphere and the solar wind. Recent
observations of magnetic turbulence in the ion foreshock, in the magnetosheath,
in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere
will be reviewed [1]. Many interesting features can be investigated with the use of
Geotail, Cluster, and THEMIS data. Indeed, multi-spacecraft missions allow to
assess the spatial structure and spatial evolution of the observed turbulence. It is
found that: 1. A large share of magnetic turbulence in the geospace environment is
generated locally, as due for instance to the reflected ion beams in the ion foreshock, to
temperature anisotropy in the magnetosheath and the polar cusp regions, and to
velocity shear in the magnetosheath and magnetotail. 2. Spectral indices close to the
Kolmogorov value can be recovered for low frequency turbulence when long enough
intervals at relatively constant flow speed are analyzed in the magnetotail, or when
fluctuations in the magnetosheath are considered far downstream from the bow shock. 3.
For high frequency turbulence, a spectral index α -ă 2.3 or larger is observed in
most geospace regions, in agreement with what is observed in the solar wind. 4.
Further studies are needed to gain an understanding of turbulence dissipation in the
geospace environment, also keeping in mind that the strong temperature anisotropies
which are observed show that wave particle interactions can be a source of wave
emission rather than of turbulence dissipation. 5. Coordinated multi-spacecraft
observations show the existence of conjugate vortices in the magnetotail and in the
ionosphere, so that they may have a primary role in the turbulent injection and
evolution.
The influence of such a turbulence on the plasma transport, dynamics, and energization
will be described, also using the results of numerical simulations.
[1] Zimbardo et al., Space Sci. Rev., DOI 10.1007/s11214-010-9692-5 |
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