Drift motions of small‐scale irregularities in the high‐latitude <i>F</i> region: An experimental comparison with plasma drift motions

Abstract

On the evening of January 6, 1986, coordinated observations were carried out with the Johns Hopkins University Applied Physics Laboratory HF coherent scatter radar at Goose Bay, Labrador, and the SRI International incoherent scatter radar at Sondre Stromfjord, Greenland. The common field of view comprised a section of high‐latitude F region ionosphere centered on the great circle plane between the radar sites. Over a 40‐min period, the HF radar observed strong backscatter from small‐scale (13.9 m) field‐aligned irregularities. The bulk line‐of‐sight drift velocity of the irregularities is deduced from the backscatter data. The returns collected simultaneously with the incoherent scatter radar are processed for estimates of the mean line‐of‐sight ion velocity. Approximately 100 distinct comparisons are possible between the two sets of velocity estimates. Reversals exceeding 1000 m/s are present in both. In this paper, we demonstrate a correspondence between the measured irregularity and ion drifts that is consistent with the supposition that the motion of the irregularities is dominated by convective drift of the ambient plasma. This indicates that the small‐scale irregularities detected by HF radars in the high‐latitude F region can serve as tracers of ionospheric convective drift.