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Spatial distribution of average vorticity in the high-latitude ionosphere and its variation with interplanetary magnetic field direction and season

Chisham, G.; Freeman, M.P.; Abel, G.A.; Bristow, W.A.; Marchaudon, A.; Ruohoniemi, J.M.; Sofko, G.J.. 2009 Spatial distribution of average vorticity in the high-latitude ionosphere and its variation with interplanetary magnetic field direction and season. Journal of Geophysical Research, 114, A09301. 14, pp. 10.1029/2009JA014263

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Abstract/Summary

We present a technique to measure the magnetic field-aligned vorticity of meso-scale plasma flows in the F-region ionosphere using line-of-sight velocity measurements made by the Super Dual Auroral Radar Network (SuperDARN). Vorticity is often used as a proxy for magnetic field-aligned current (FAC) intensity in the ionosphere but also provides information about turbulent processes in the ionosphere and magnetosphere. Using 6 years (2000-2005 inclusive) of vorticity measurements made by 6 SuperDARN radars in the northern hemisphere we have compiled, for the first time, maps of average vorticity across the northern polar ionosphere. These maps have been subdivided according to different seasonal and interplanetary magnetic field (IMF) conditions. The variations in the morphology of the vorticity maps with IMF direction match very closely those seen in maps of average FAC intensity (determined using different methods and instrumentation), suggesting that vorticity is a good proxy for FAC in an averaged sense. The variations in the morphology of the vorticity maps with season show differences from those seen in the FAC maps, illustrating that ionospheric conductance plays a major role in determining the differences between measurements of vorticity and FAC.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/2009JA014263
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Natural Complexity Programme
ISSN: 0148-0227
NORA Subject Terms: Space Sciences
Date made live: 11 Feb 2010 14:54
URI: http://nora.nerc.ac.uk/id/eprint/8003

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