Electrodynamics of high-latitude auroral arcs
Abstract
We present an overview of the Finnish experiments with European Incoherent Scatter (EISCAT) radar on Svalbard, which were performed during 2004 - 2009 to study ionospheric electric fields and currents in a vicinity of high-latitude (around 75 deg. MLAT) auroral arcs. The most important parameter is the electric field component perpendicular to an arc, which was derived from the F-region ionospheric plasma flow observed by the radar. The radar observations occurred during polar winter and were accompanied by optical auroral observations. Commonly, high-latitude auroral arcs were generated as a response to changes of the interplanetary magnetic field. We have obtained typical patterns of electric fields and currents for various kinds of auroral arcs in both evening and morning sectors, including polar cap (Sun-aligned) arcs. The downward electron flux producing auroral luminosity is associated with an upward field-aligned current over the arc. This current is closed by a transverse Pedersen current in the ionospheric E region, and a return downward FAC flows adjacent to the arc. Strong transverse electric fields perpendicular to the arc, up to 50 mV/m and more, are frequently observed in the return field-aligned current area near the arc. Commonly, the arcs demonstrate double or multiple structure of the upward field-aligned current, which is similar for different kind arcs in different MLT sectors.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMSM11A1682S
- Keywords:
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- 2704 MAGNETOSPHERIC PHYSICS / Auroral phenomena