Day-to-day thermosphere parameter variation as deduced from Millstone Hill incoherent scatter radar observations during March 16-22, 1990 magnetic storm period
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...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
1997-11-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/15/1429/1997/angeo-15-1429-1997.pdf |
| Summary: | 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 <i>N<sub>e</sub></i>(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 <i>T</i><sub>ex</sub> 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
[<i>N</i><sub>2</sub>] 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 [<i>N</i><sub>2</sub>] 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/<i>N</i><sub>2</sub>
ratio decrease relative to the MSIS-83 model prediction is required to describe
the observed <i>N<sub>m</sub>F</i>2 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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| ISSN: | 0992-7689 1432-0576 |