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Solar and seasonal dependence of ion frictional heating
journal contribution
posted on 2012-10-24, 09:05 authored by J. A. Davies, Mark Lester, I. W. McCreaIon frictional heating constitutes one of the principal mechanisms whereby energy, originating in the solar wind, is deposited into the Earth's ionosphere and ultimately the neutral atmosphere. Common programme observations by the EISCAT UHF radar system, spanning the years 1984 to 1995, provide the basis for a comprehensive statistical study of ion frictional heating, results of which are documented in this and a previous paper by the authors. In the present work, the authors demonstrate the solar and seasonal dependence of the universal time distribution of frictional heating, and explain these results with reference to corresponding dependences of the ion velocity. Although EISCAT observes a significant increase in the occurrence of enhanced ion velocities associated with increased solar activity, the latter characterised according to the prevailing 10.7 cm solar flux, this is not reflected to such an extent in the occurrence of frictional heating. It is suggested that this is a consequence of the decreased neutral atmosphere response times associated with active solar conditions, resulting from the higher ionospheric plasma densities present. Seasonal effects on the diurnal distribution of ion frictional heating are well explained by corresponding variations in ionospheric convection, the latter principally a result of geometrical factors. It is noted that, over the entire dataset, the variations in the unperturbed F-region ion temperature, required to implement the identification criterion for ion heating, are highly correlated with model values of thermospheric temperature.
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Citation
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1999, 17 (5), pp. 682-691Published in
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCESPublisher
European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)issn
0992-7689eissn
1432-0576Copyright date
1999Available date
2012-10-24Publisher DOI
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http://www.ann-geophys.net/17/682/1999/angeo-17-682-1999.htmlLanguage
EnglishAdministrator link
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Science & TechnologyPhysical SciencesAstronomy & AstrophysicsGeosciencesMultidisciplinaryMeteorology & Atmospheric SciencesGeologyionosphere (auroral ionosphereionosphere-atmosphere interactionsplasma temperature and density)HIGH-LATITUDE IONOSPHEREVELOCITY DISTRIBUTIONSF-REGIONTHERMOSPHERIC WINDSELECTRIC-FIELDSEISCATTEMPERATUREPLASMAMODEL
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