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| Titel |
Seasonal dependence of the longitudinal variations of nighttime ionospheric electron density and equivalent winds at southern midlatitudes |
| VerfasserIn |
X. Luan, X. Dou |
| 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. 10 ; Nr. 31, no. 10 (2013-10-15), S.1699-1708 |
| Datensatznummer |
250086122
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1699-2013.pdf |
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| Zusammenfassung |
| It has been indicated that the observed Weddell Sea anomaly (WSA) appeared to
be an extreme manifestation of the longitudinal variations in the Southern
Hemisphere, since the WSA is characterized by greater evening electron
density than the daytime density in the region near the Weddell Sea. In the
present study, the longitudinal variations of the nighttime F2-layer peak
electron density at southern midlatitudes are analyzed using the observations
of the Constellation Observing System for Meteorology, Ionosphere, and
Climate (COSMIC) satellites between 2006 and 2008. It is found that
significant longitudinal difference (> 150%) relative to
the minimum density at each local time prevails in all seasons, although the
WSA phenomenon is only evident in summer under this solar minimum condition.
Another interesting feature is that in summer, the maximum longitudinal
differences occur around midnight (~ 23:00–00:00 LT) rather than in
the evening (19:00–21:00 LT) in the evening, when the most prominent
electron density enhancement occurs for the WSA phenomenon. Thus the
seasonal–local time patterns of the electron density longitudinal variations
during nighttime at southern midlatitudes cannot be simply explained in terms
of the WSA. Meanwhile, the variations of the geomagnetic configuration and
the equivalent magnetic meridional winds/upward plasma drifts are analyzed to
explore their contributions to the longitudinal variations of the nighttime
electron density. The maximum longitudinal differences are associated with
the strongest wind-induced vertical plasma drifts after 21:00 LT in the
Western Hemisphere. Besides the magnetic declination–zonal wind effects, the
geographic meridional winds and the magnetic inclination also have
significant effects on the upward plasma drifts and the resultant electron
density. |
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