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| Titel |
Escape of high-energy oxygen ions through magnetopause reconnection under northward IMF |
| VerfasserIn |
S. Kasahara, H. Hasegawa, K. Keika, Y. Miyashita, M. N. Nishino, T. Sotirelis, Y. Saito, T. Mukai |
| 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. 12 ; Nr. 26, no. 12 (2008-12-05), S.3955-3966 |
| Datensatznummer |
250016322
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| Publikation (Nr.) |
 copernicus.org/angeo-26-3955-2008.pdf |
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| Zusammenfassung |
| During a storm recovery phase on 15 May 2005, the Geotail spacecraft
repeatedly observed high-energy (>180 keV) oxygen ions in the
dayside magnetosheath near the equatorial plane.
We focused on the time period from 11:20 UT to 13:00 UT, when
Geotail observed the oxygen ions and the interplanetary magnetic field (IMF)
was constantly northward.
The magnetic reconnection occurrence northward and duskward
of Geotail
is indicated by the Walén analysis
and convective flows in the magnetopause boundary layer.
Anisotropic pitch angle distributions of ions suggest that high-energy
oxygen ions escaped from
the northward of Geotail
along the reconnected magnetic field lines.
From the low-energy particle precipitation in the polar cap observed by DMSP,
which is consistent with magnetic reconnection occurring between
the magnetosheath field lines and the magnetospheric closed field lines,
we conclude that these oxygen ions are of ring current origin.
Our results thus suggest a new escape route of oxygen ions during
northward IMF. In the present event, this escape mechanism
is more dominant than the leakage via the finite Larmor radius effect
across the dayside equatorial magnetopause. |
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