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| Titel |
Comparison of model electron densities and temperatures with Millstone Hill observations during undisturbed periods and the geomagnetic storms of 16-23 March and 6-12 April 1990 |
| VerfasserIn |
A. V. Pavlov, M. J. Buonsanto |
| 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. 3 ; Nr. 15, no. 3, S.327-344 |
| Datensatznummer |
250012669
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| Publikation (Nr.) |
 copernicus.org/angeo-15-327-1997.pdf |
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| Zusammenfassung |
| Measurements of F-region electron density and
temperature at Millstone Hill are compared with results from the IZMIRAN
time-dependent mathematical model of the Earth's ionosphere and plasmasphere
during the periods 16–23 March and 6–12 April 1990. Each of these two periods
included geomagnetically quiet intervals followed by major storms. Satisfactory
agreement between the model and the data is obtained during the quiet intervals,
provided that the recombination rate of O+(4S) ions was decreased by a factor of 1.5 at all altitudes during the
nighttime periods 17–18 March, 19–20 March, 6–8 April and 8–9 April in order to
increase the NmF2 at night better to match observations. Good model/data
agreement is also obtained during the storm periods when vibrationally excited
N2 brings about factor-of-2-4 reductions in daytime
NmF2. Model calculations are carried out using different expressions for the
O+ – O collision frequency for momentum transfer,
and the best agreement between the electron-density measurements and the model
results is obtained when the CEDAR interim standard formula for the O+ – O collision frequency is
used. Deviations from the Boltzmann distribution for
the ®rst ®ve vibrational levels of N2 collision frequency is used. Deviations from the
Boltzmann distribution for the first five vibrational levels of j were calculated. The calculated distribution is highly non-Boltzmann
at vibrational levels j > 2 and the Boltzmann distribution
assumption results in the increase of 10–30% in calculated NmF2 during the
storm-time periods. During the March storm at solar maximum the model results
obtained using the EUVAC solar flux model agree a little better with the
observations in comparison with the EUV94 solar flux model. For the April storm
period of moderate solar activity the EUV94X model results agree better with the
observations in comparison to the EUVAC model. |
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