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| Titel |
A plasma flow vortex in the magnetotail and its related ionospheric signatures |
| VerfasserIn |
C. L. Tang |
| 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 ; 30, no. 3 ; Nr. 30, no. 3 (2012-03-16), S.537-544 |
| Datensatznummer |
250017199
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| Publikation (Nr.) |
 copernicus.org/angeo-30-537-2012.pdf |
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| Zusammenfassung |
| We presented a large-scale plasma flow vortex event that occurred on 1
March 2009 observed by Time History of Events and Macroscale
Interactions during Substorms (THEMIS) satellites. During the
interval, THEMIS satellites were located in the premidnight region
between 11 and 16 RE downtail. Dawnward-earthward plasma
flows were seen initially in the magnetotail, followed by
duskward-tailward flows. This suggests that a clockwise plasma
flow vortex (seen from above the equatorial plane) was observed on
the dawn side of the plasma sheet. Furthermore, high energy (>1 keV)
electrons were observed. Auroral images at 427.8 nm and
THEMIS white light all-sky imager (ASI) at Fort Smith showed a
discrete auroral patch formed at the poleward of the auroral oval,
it then intensified. It extended eastward and equatorward first
and followed by westward motion to form the clockwise auroral
vortex. The auroral feature corresponded to the ionospheric
signatures of the plasma flow vortex in the magnetotail when the
Alfvén transit time between the magnetotail and the ionosphere
was taken into account. We suggest that the large-scale clockwise
plasma flow vortex in association with the high energy (>1 keV)
electrons on the dawn side of the plasma sheet generated a downward
field-aligned current (FAC) that caused the related ionospheric
signatures. The plasma flow vortex had rotational flow speeds of
up to 300 km s−1. The current density associated with the plasma
flow vortex was estimated at 2.0 μA m−2, mapped to the
ionosphere. |
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