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| Titel |
Spatial variation of eddy-diffusion coefficients in the turbulent plasma sheet during substorms |
| VerfasserIn |
M. Stepanova, E. E. Antonova, D. Paredes-Davis, I. L. Ovchinnikov, Y. I. Yermolaev |
| 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 ; 27, no. 4 ; Nr. 27, no. 4 (2009-04-01), S.1407-1411 |
| Datensatznummer |
250016466
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| Publikation (Nr.) |
 copernicus.org/angeo-27-1407-2009.pdf |
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| Zusammenfassung |
| Study of the plasma turbulence in the central plasma sheet was performed
using the Interball-Tail satellite data. Fluctuations of the plasma bulk
velocity in the plasma sheet were deduced from the measurements taken by the
Corall instrument for different levels of geomagnetic activity and different
locations inside the plasma sheet. The events that satisfied the following
criteria were selected for analysis: number density 0.1–10 cm−3, ion
temperature T≥0.3 keV, and average bulk velocity ≤100 km/s. It was
found that the plasma sheet flow generally appears to be strongly turbulent,
i.e. is dominated by fluctuations that are unpredictable. Corresponding
eddy-diffusion coefficients in Y- and Z-direction in the GSM coordinate
system were derived using the autocorrelation time and rms velocity.
Statistical studies of variation of the eddy-diffusion coefficients with the
location inside the plasma sheet showed a significant increase in these
coefficients in the tailward direction. During substorms this dependence
shows strong increase of eddy-diffusion in the central part of the plasma
sheet at the distances of 10–30 Earth's radii. This effect is much stronger
for Y-components of the eddy-diffusion coefficient, which could be related
to the geometry of the plasma sheet, allowing more room for development of
eddies in this direction. |
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