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| Titel |
O+ transport in the dayside magnetosheath and its dependence on the IMF direction |
| VerfasserIn |
R. Slapak, H. Nilsson, L. G. Westerberg, R. Larsson |
| 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 ; 33, no. 3 ; Nr. 33, no. 3 (2015-03-09), S.301-307 |
| Datensatznummer |
250121173
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| Publikation (Nr.) |
 copernicus.org/angeo-33-301-2015.pdf |
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| Zusammenfassung |
| Recent studies have shown that the escape of oxygen ions (O+) into the
magnetosheath along open magnetic field lines from the terrestrial cusp and
mantle is significant. We present a study of how O+ transport in the
dayside magnetosheath depends on the interplanetary magnetic field (IMF)
direction. There are clear asymmetries in the O+ flows for southward and
northward IMF. The asymmetries can be understood in terms of the different
magnetic topologies that arise due to differences in the location of the
reconnection site, which depends on the IMF direction. During southward IMF,
most of the observed magnetosheath O+ is transported downstream. In
contrast, for northward IMF we observe O+ flowing both downstream and
equatorward towards the opposite hemisphere. We observe evidence of dual-lobe
reconnection occasionally taking place during strong northward IMF
conditions, a mechanism that may trap O+ and bring it back into the
magnetosphere. Its effect on the overall escape is however small: we estimate
the upper limit of trapped O+ to be 5%, a small number considering that
ion flux calculations are rough estimates. The total O+ escape flux is
higher by about a factor of 2 during times of southward IMF, in agreement
with earlier studies of O+ cusp outflow. |
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