First observations of the temporal/spatial variation of the sub‐auroral polarization stream from the SuperDARN Wallops HF radar

In this letter we present the first two‐dimensional observations of sub‐auroral ion drift (SAID) variability within the sub‐auroral polarization stream (SAPS) using a new mid‐latitude SuperDARN radar located at Wallops Island, VA. The radar data are complemented with observations from the DMSP F15, TIMED, and NOAA‐18 spacecraft to confirm that a backscatter feature observed at the equatorward edge of the auroral oval is a manifestation of SAPS/SAID. During a several hour long period on August 6, 2005, the velocity data indicate that significant changes in the SAPS flow occurred on time scales of a few minutes. The Wallops HF radar observations demonstrate that the SAPS phenomenon is a source of small‐scale irregularities extending over many hours of MLT and that the electric fields associated with SAID in particular are highly variable.