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| Titel |
Case study of the mesospheric and lower thermospheric effects of solar X-ray flares: coupled ion-neutral modelling and comparison with EISCAT and riometer measurements |
| VerfasserIn |
C.-F. Enell, P. T. Verronen, M. J. Beharrell, J. P. Vierinen, A. Kero, A. Seppälä, F. Honary, T. Ulich, E. Turunen |
| 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 ; 26, no. 8 ; Nr. 26, no. 8 (2008-08-05), S.2311-2321 |
| Datensatznummer |
250016190
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2311-2008.pdf |
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| Zusammenfassung |
Two case studies of upper mesospheric and lower thermospheric (UMLT)
high-latitude effects of solar X-ray flares are presented.
Sodankylä Ion-neutral Chemistry Model (SIC) electron density
profiles agree with D-region EISCAT and riometer observations,
provided that the profiles of the most variable ionisable component,
nitric oxide, are adjusted to compensate for NOx production
during preceding geomagnetically active periods. For the M6-class
flare of 27 April 2006, following a quiet period, the agreement with
cosmic noise absorption observed by the Sodankylä riometers was
within reasonable limits without adjustment of the [NO]
profile. For the major (X17-class) event of 28 October 2003, following
high auroral activity and solar proton events, the NO
concentration had to be increased up to on the order of
108 cm−3 at the D-region minimum. Thus [NO] can
in principle be measured by combining SIC with observations, if the
solar spectral irradiance and particle precipitation are adequately
known.
As the two case events were short and modelled for high latitudes,
the resulting neutral chemical changes are insignificant. However,
changes in the model ion chemistry occur, including enhancements of
water cluster ions. |
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