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| Titel |
Correlation length of magnetosheath fluctuations: Cluster statistics |
| VerfasserIn |
O. Gutynska, J. Safrankova, Z. Nemecek |
| 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 ; 26, no. 9 ; Nr. 26, no. 9 (2008-09-01), S.2503-2513 |
| Datensatznummer |
250016206
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2503-2008.pdf |
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| Zusammenfassung |
Magnetosheath parameters are usually described by gasdynamic or magnetohydrodynamic (MHD)
models but these models cannot account for one of the most important sources of magnetosheath
fluctuations – the foreshock. Earlier statistical processing of a large amount of
magnetosheath observations
has shown that the magnetosheath magnetic field and plasma flow fluctuations downstream of
the quasiparallel shock are much larger than those at the opposite flank. These studies were
based on the observations of a single spacecraft and thus they could not provide full information
on propagation of the fluctuations through the magnetosheath.
We present the results of a statistical survey of the magnetosheath magnetic field fluctuations
using two years of Cluster observations. We discuss the dependence of the cross-correlation
coefficients between different spacecraft pairs on the orientation of the separation
vector with respect to the average magnetic field and plasma flow vectors and
other parameters. We have found that the correlation length does not exceed
~1 RE in the analyzed frequency range (0.001–0.125 Hz) and does not
depend significantly on the magnetic field or plasma flow direction. A close
connection of cross-correlation coefficients computed in the magnetosheath
with the cross-correlation coefficients between a solar wind monitor and a
magnetosheath spacecraft suggests that solar wind structures persist on the
background of magnetosheath fluctuations. |
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