A statistical study of ion frictional heating observed by EISCAT
journal contributionposted on 24.10.2012, 09:07 by J. A. Davies, M. Lester, I. W. McCrea
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.
CitationANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1997, 15 (11), pp. 1399-1411
Published inANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES
PublisherEuropean Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)
Science & TechnologyPhysical SciencesAstronomy & AstrophysicsGeosciencesMultidisciplinaryMeteorology & Atmospheric SciencesGeologyINTERPLANETARY MAGNETIC-FIELDINCOHERENT-SCATTER OBSERVATIONSCONVECTION ELECTRIC-FIELDSHIGH-LATITUDE IONOSPHEREDEPENDENT PLASMA-FLOWAURORAL F-REGIONVELOCITY DISTRIBUTIONSTEMPERATURE ANISOTROPYDAYSIDE MAGNETOSPHERETHERMOSPHERIC WINDS