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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 110,
A12217,
doi:10.1029/2004JA010986,
2005
Overlap of the plasmasphere and ring current: Relation to subauroral ionospheric heating
C. Gurgiolo
Bitterroot Basic Research, Hamilton, Montana, USA
B. R. Sandel
Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
J. D. Perez
Physics Department, Auburn University, Auburn, Alabama, USA
D. G. Mitchell
John Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
C. J. Pollock
Southwest Research Institute, San Antonio, Texas, USA
B. A. Larsen
Department of Physics, Montana State University, Bozeman, Montana, USA
Abstract
The overlap of the ring current with the outer plasmasphere is thought to play a major role in storm-time related increases
in the subauroral ambient topside electron temperature. Instabilities generated within the overlap region, Coulomb collisions
of plasmaspheric electrons with the ring current ions, and charge exchange are all thought to work either individually or
together to generate a downward heat flux into the ionosphere to produce the increase in temperature. Analysis of IMAGE two-dimensional
ring current and plasmasphere density maps together with in situ DMSP ambient electron temperature data shows that the heating
generally occurs over a small radial extent within the plasmasphere/ring current overlap region and may be significantly earthward
of the plasmapause. This argues against collisional heat conduction as the source of the heat flux and for an instability-based
process. The finding that the heating occurs within well-defined ratios of the cold plasmasphere to hot ring current density
strengthens this supposition.
Received 20
December
2004;
accepted 5
October
2005;
published 16
December
2005.
Keywords: plasmasphere;
ring current;
ionosphere temperature;
EMIC waves.
Index Terms: 2768 Magnetospheric Physics: Plasmasphere; 2778 Magnetospheric Physics: Ring current; 2467 Ionosphere: Plasma temperature and density.
Read Full Article (file size: 1319641 bytes) Cited by
Citation: Gurgiolo, C., B. R. Sandel, J. D. Perez, D. G. Mitchell, C. J. Pollock, and B. A. Larsen
(2005),
Overlap of the plasmasphere and ring current: Relation to subauroral ionospheric heating,
J. Geophys. Res.,
110,
A12217,
doi:10.1029/2004JA010986.
Copyright 2005 by the American Geophysical Union.
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