Determination of low latitude plasma drift speeds from FUV images

Thomas J. Immel, Stephen B. Mende, Harald U. Frey, Laura M. Peticolas
Space sciences Laboratory, University of California, Berkeley

Eiichi Sagawa
Communications Research Laboratory, Tokyo, Japan


Thousands of images of the nighttime equatorial airglow arcs have been obtained 
by the far-ultraviolet imager (FUV) on-board the NASA IMAGE satellite.  Imaging 
periods lasting several hours around the time of satellite apogee allow for the 
determination of the velocity of drifting plasma density depletions occurring 
within the airglow arcs.  These velocities reflect the ExB drift of low-latitude 
plasma under the influence of a vertical electric field.  A survey of several 
weeks of data produces information regarding the variation of drift speeds with 
solar 10.7-cm radio flux.  Comparisons to previous measurements by the Jicamarca 
radar show that the FUV-determined plasma drift speeds are 10-35% greater, 
particularly before 2100 local time.  This difference is attributed mainly to 
the different magnetic latitudes of the observations.

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Geophysical Research Letters, 30(18), 1945, doi:10.1029/2003GL0175732003