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| Titel |
Day-to-day thermosphere parameter variation as deduced from Millstone Hill incoherent scatter radar observations during March 16-22, 1990 magnetic storm period |
| VerfasserIn |
A. V. Mikhailov, M. Forster |
| 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 ; 15, no. 11 ; Nr. 15, no. 11, S.1429-1438 |
| Datensatznummer |
250013006
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1429-1997.pdf |
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| Zusammenfassung |
| A self-consistent method for day-time
F2-region modelling was applied to the analysis of Millstone Hill incoherent
scatter observations during the storm period of March 16-22, 1990. The method
allows us to calculate in a self-consistent way neutral composition, temperature
and meridional wind as well as the ionized species height distribution.
Theoretically calculated Ne(h) profiles fit the observed
daytime ones with great accuracy in the whole range of heights above 150 km for
both quiet and disturbed days. The overall increase in Tex by
270 K from March 16 to March 22 reflects the increase of solar activity level
during the period in question. A 30% decrease in [O] and a two-fold increase in
[N2] are calculated for the disturbed day of March 22 relative
to quiet time prestorm conditions. Only a small reaction to the first
geomagnetic disturbance on March 18 and the initial phase of the second storm on
March 20 was found in [O] and [N2] variations. The meridional
neutral wind inferred from plasma vertical drift clearly demonstrates the
dependence on the geomagnetic activity level being more equatorward on disturbed
days. Small positive F2-layer storm effects on March 18 and 20 are totally
attributed to the decrease in the northward neutral wind but not to changes in
neutral composition. A moderate (by a factor of 1.5) O/N2
ratio decrease relative to the MSIS-83 model prediction is required to describe
the observed NmF2 decrease on the most disturbed day of March
22, but virtually no change of this ratio is needed for March 21. |
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