Cause of Plasmasphere Corotation Lag

J.L. Burch (Southwest Research Institute, San Antonio, TX 78228), J. Goldstein, 
and B. R. Sandel

It is hypothesized that the recently observed plasmasphere corotation lag is
caused by a corresponding corotation lag in the upper ionosphere. Rotation
rates of long-lived plasmaspheric notches are compared to ionospheric drifts
observed on DMSP spacecraft in the same longitude sectors. Good agreement
between the two observations is found, and the cause of the corotation lag is
identified as the ionospheric disturbance dynamo. The observed corotation lag
will have to be accounted for in future magnetospheric convection models,
which until now have assumed strict plasmasphere corotation.

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Presentation at the Yosemite Conference of Inner Magnetospheric Interactions,
3 - 6 February 2004, Yosemite, California, USA