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| Titel |
A modelling study of the latitudinal variations in the nighttime plasma temperatures of the equatorial topside ionosphere during northern winter at solar maximum |
| VerfasserIn |
G. J. Bailey, M. H. Denton, R. A. Heelis, S. Venkatraman |
| 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 ; 18, no. 11 ; Nr. 18, no. 11, S.1435-1446 |
| Datensatznummer |
250014092
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| Publikation (Nr.) |
 copernicus.org/angeo-18-1435-2000.pdf |
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| Zusammenfassung |
Latitudinal variations in the nighttime
plasma temperatures of the equatorial topside ionosphere during northern winter
at solar maximum have been examined by using values modelled by SUPIM (Sheffield
University Plasmasphere Ionosphere Model) and observations made by the DMSP F10
satellite at 21.00 LT near 800 km altitude. The modelled values confirm that the
crests observed near 15° latitude in the winter hemisphere are due to adiabatic
heating and the troughs observed near the magnetic equator are due to adiabatic
cooling as plasma is transported along the magnetic field lines from the summer
hemisphere to the winter hemisphere. The modelled values also confirm that the
interhemispheric plasma transport needed to produce the required adiabatic
heating/cooling can be induced by F-region neutral winds. It is shown that the
longitudinal variations in the observed troughs and crests arise mainly from the
longitudinal variations in the magnetic meridional wind. At longitudes where the
magnetic declination angle is positive the eastward geographic zonal wind
combines with the northward (summer hemisphere to winter hemisphere) geographic
meridional wind to enhance the northward magnetic meridional wind. This leads to
deeper troughs and enhanced crests. At longitudes where the magnetic declination
angle is negative the eastward geographic zonal wind opposes the northward
geographic meridional wind and the trough depth and crest values are reduced.
The characteristic features of the troughs and crests depend, in a complicated
manner, on the field-aligned flow of plasma, thermal conduction, and inter-gas
heat transfer. At the latitudes of the troughs/crests, the low/high plasma
temperatures lead to increased/decreased plasma concentrations.
Key words: Ionosphere (equatorial ionosphere;
ionosphere-atmosphere interactions) |
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