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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 4
Ann. Geophys., 16, 450–459, 1998
© European Geosciences Union 1998
Ann. Geophys., 16, 450–459, 1998
© European Geosciences Union 1998

  30 Apr 1998

30 Apr 1998

Electron temperatures during rapid subauroral ion drift events

R. J. Moffett1, A. E. Ennis1, G. J. Bailey1, R. A. Heelis2, and L. H. Brace3 R. J. Moffett et al.
  • 1Upper Atmosphere Modelling Group, School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK
  • 2William B. Hanson Center for Space Sciences, University of Texas at Dallas, Richardson, TX 75083, USA
  • 3Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA

Abstract. Examples of data from DE-2 satellite instruments are presented. These illustrate the behaviour of plasma parameters in the F-region and adjacent topside ionosphere during rapid sub-auroral ion drift (SAID) events. In particular, a variety of behaviours of the electron temperature (Te) is demonstrated, both within and equatorward of the SAID region. The Sheffield University plasmasphere-ionosphere model (SUPIM) is used to perform calculations in which a model SAID is applied to a plasma flux tube. The model results indicate that strongly elevated ion temperature (a recognised signature of SAID events) is on occasion sufficient to raise Te to observed values by ion-electron heat transfer. On other occasions, an additional heat source is required. It is suggested that such a source for the electron gas may be due to interaction between the ring current and the plasmasphere at high altitudes. The magnitude of the downward heat flux is consistent with that necessary to produce sub-auroral red arcs. The resulting strongly heated electron gas causes vibrational excitation of molecular nitrogen in the thermosphere.

Key words. Electron temperature · Subauroral ion drift · Plasmasphere-ionosphere SUPIM

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