COMPARISON OF PLASMA-FLOW VELOCITIES DETERMINED BY THE IONOSONDE DOPPLER DRIFT TECHNIQUE, SUPERDARN RADARS, AND PATCH MOTION

We compare measurements of polar cap ionospheric plasma flow over Reso lute Bay, Canada, made by a digital ionosonde using the Doppler drift technique with simultaneous measurements at the same location made by the first operational pair of SuperDARN HF radars. During the 3-hour c omparison interval the flow varied widely in direction and from 100 to 600 m/s in speed. The two measurement techniques show very good agree ment for both the speed and direction of flow for nearly all of the sa mples in the interval. The difference between the velocities determine d by the two techniques has a scatter of about +/- 35 degrees in direc tion and +/- 30% in speed, with no systematic difference above the lev el of the scatter. The few samples which strongly disagreed were usual ly associated with strong spatial structure in the flow pattern measur ed by SuperDARN in the vicinity of the comparison point. The drift spe ed measured by the ionosonde was independently verified by observing t he time taken for polar cap F layer ionization patches to drift betwee n ionosondes sited at Eureka and Resolute Bay. These results confirm t hat the speed and direction of the polar cap ionospheric convection ca n be reliably monitored by the ionosonde Doppler drift technique.