Velocity of auroral arcs drifting equatorward from the polar cap

The drift velocity of an auroral arc is compared with the component of F-region plasma velocity in the same direction for ten cases where the arc is seen to move steadily equatorward for several minutes without any major change in appearance or orientation. In most cases the two velocities are c...

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Bibliographic Details
Main Authors: P. J. S. Williams, C. F. del Pozo, I. Hiscock, R. Fallows
Format: Article
Language:English
Published: Copernicus Publications 1998-10-01
Series:Annales Geophysicae
Online Access:https://www.ann-geophys.net/16/1322/1998/angeo-16-1322-1998.pdf
Description
Summary:The drift velocity of an auroral arc is compared with the component of F-region plasma velocity in the same direction for ten cases where the arc is seen to move steadily equatorward for several minutes without any major change in appearance or orientation. In most cases the two velocities are close, but on two occasions the drift velocity of the arc is much higher than the plasma velocity. From the cases studied it appears that during the growth and recovery phase of the substorm cycle the arc moves with a velocity close to the convection velocity, but during the expansion phase this is not the case.<br><br><b>Key words.</b> Magnetospheric physics (auroral phenomena; electric fields; plasma convection)</p>
ISSN:0992-7689
1432-0576