On the consistency of the SuperDARN radar velocity andE × Bplasma drift

Joint observations of the Rankin Inlet (RKN) and Inuvik (INV) Super Dual Auroral Radar Network (SuperDARN) HF radars and Resolute Bay incoherent scatter radar (RISR) are used to assess consistency in their plasma flow velocity measurements. The analysis covers more than 500 hours of successful concurrent measurements. We demonstrate that, overall, the radars show close velocities, though there were minor differences including SuperDARN velocity underestimation, in line with previous publications, and the persistent occurrence of measurements with a SuperDARN velocity magnitude above the RISR velocity magnitude. We argue that, for one event, the velocity overestimation occurs owing to echo detection from a laterally refracted RKN beam while, generally, the effect should be fairly wide-spread in SuperDARN data because of microstructures with enhanced electron density in the scattering volume that might have either weak irregularities or increased local electric fields. We estimate that the correction of RKN velocity data by considering the effect of the index of refraction improves RKN-RISR velocity agreement but only for 63% of points. This implies that care should be exersised when attempting to correct raw SuperDARN velocity data by the index of refraction.