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| Titel |
Comparison between vortices created and evolving during fixed and dynamic solar wind conditions |
| VerfasserIn |
Y. M. Collado-Vega, R. L. Kessel, D. G. Sibeck, V. L. Kalb, R. A. Boller, L. Rastaetter |
| 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 ; 31, no. 8 ; Nr. 31, no. 8 (2013-08-30), S.1463-1483 |
| Datensatznummer |
250086099
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1463-2013.pdf |
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| Zusammenfassung |
| We employ Magnetohydrodynamic (MHD) simulations to examine the creation and evolution of
plasma vortices within the Earth's magnetosphere for steady solar wind plasma
conditions. Very few vortices form during intervals of such solar wind
conditions. Those that do remain in fixed positions for long periods
(often hours) and exhibit rotation axes that point primarily in the x or
y
direction, parallel (or antiparallel) to the local magnetospheric magnetic
field direction. Occasionally, the orientation of the axes rotates from the
x direction to another direction. We compare our results with simulations
previously done for unsteady solar wind conditions. By contrast, these
vortices that form during intervals of varying solar wind conditions exhibit
durations ranging from seconds (in the case of those with axes in the x or
y
direction) to minutes (in the case of those with axes in the z direction) and
convect antisunward. The local-time dependent sense of rotation seen in
these previously reported vortices suggests an interpretation in terms of the
Kelvin–Helmholtz instability. For steady conditions, the biggest vortices
developed on the dayside (about 6 RE in diameter), had their
rotation axes aligned with the y direction and had the longest periods of
duration. We attribute these vortices to the flows set up by reconnection on
the high-latitude magnetopause during intervals of northward Interplanetary Magnetic Field (IMF) orientation.
This is the first time that vortices due to high-latitude reconnection have
been visualized. The model also successfully predicts the principal
characteristics of previously reported plasma vortices within the
magnetosphere, namely their dimension, flow velocities, and durations. |
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