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| Titel |
A statistical study of ion frictional heating observed by EISCAT |
| VerfasserIn |
J. A. Davies, Mark Lester, I. W. McCrea |
| 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.1399-1411 |
| Datensatznummer |
250013003
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1399-1997.pdf |
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| Zusammenfassung |
| Results of a statistical survey of F-region
ion frictional heating are presented, a survey which is based on over 4000 h of
common programme observations taken by the European incoherent scatter (EISCAT)
UHF radar facility. The criterion adopted in this study for the identification
of ion frictional heating was that defined by McCrea et al., requiring an
enhancement in the F-region field-parallel ion temperature exceeding 100 K over
two consecutive integration periods, which was itself based on a selection
criterion for frictional heating derived for the study of high-latitude F-region
ion temperature observations from the Atmospheric Explorer-C satellite. In the
present study, the diurnal distribution of ion frictional heating observed by
EISCAT is established and, furthermore, its dependence on geomagnetic activity
and the orientation of the interplanetary magnetic field (IMF) is investigated;
results are interpreted with reference to corresponding distributions of
enhanced ion velocity, again derived from the extended set of EISCAT UHF common
programme observations. The radar, due to its location relative to the
large-scale convection pattern, observes ion frictional heating principally
during the night, although preferentially during the post-midnight hours where
there is reduced coupling between the ion and neutral populations. There is an
increased preponderance of frictional heating during intervals of high
geomagnetic activity and for a southward z component of the IMF and, moreover,
evidence of asymmetries introduced by the y component of the IMF. |
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