Open AccessSpatial distribution of average vorticity in the high‐latitude ionosphere and its variation with interplanetary magnetic field direction and season
Author(s) -
Chisham G.,
Freeman M. P.,
Abel G. A.,
Bristow W. A.,
Marchaudon A.,
Ruohoniemi J. M.,
Sofko G. J.
Publication year - 2009
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009ja014263
Subject(s) - ionosphere , vorticity , interplanetary magnetic field , earth's magnetic field , physics , geophysics , ionospheric dynamo region , geology , atmospheric sciences , magnetic field , meteorology , geomagnetic storm , vortex , solar wind , quantum mechanics
We present a technique to measure the magnetic field‐aligned vorticity of mesoscale 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 six 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.