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| Titel |
Turbulence in a global magnetohydrodynamic simulation of the Earth's magnetosphere during northward and southward interplanetary magnetic field |
| VerfasserIn |
M. El-Alaoui, R. L. Richard, M. Ashour-Abdalla, R. J. Walker, M. L. Goldstein |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 19, no. 2 ; Nr. 19, no. 2 (2012-03-05), S.165-175 |
| Datensatznummer |
250014185
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| Publikation (Nr.) |
 copernicus.org/npg-19-165-2012.pdf |
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| Zusammenfassung |
| We report the results of MHD simulations of Earth's magnetosphere for
idealized steady solar wind plasma and interplanetary magnetic field (IMF)
conditions. The simulations feature purely northward and southward magnetic
fields and were designed to study turbulence in the magnetotail plasma
sheet. We found that the power spectral densities (PSDs) for both northward
and southward IMF had the characteristics of turbulent flow. In both cases,
the PSDs showed the three scale ranges expected from theory: the
energy-containing scale, the inertial range, and the dissipative range. The
results were generally consistent with in-situ observations and theoretical
predictions. While the two cases studied, northward and southward IMF, had
some similar characteristics, there were significant differences as well.
For southward IMF, localized reconnection was the main energy source for the
turbulence. For northward IMF, remnant reconnection contributed to driving
the turbulence. Boundary waves may also have contributed. In both cases, the
PSD slopes had spatial distributions in the dissipative range that reflected
the pattern of resistive dissipation. For southward IMF there was a trend
toward steeper slopes in the dissipative range with distance down the tail.
For northward IMF there was a marked dusk-dawn asymmetry with steeper slopes
on the dusk side of the tail. The inertial scale PSDs had a dusk-dawn
symmetry during the northward IMF interval with steeper slopes on the dawn
side. This asymmetry was not found in the distribution of inertial range
slopes for southward IMF. The inertial range PSD slopes were clustered
around values close to the theoretical expectation for both northward and
southward IMF. In the dissipative range, however, the slopes were broadly
distributed and the median values were significantly different, consistent
with a different distribution of resistivity. |
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