Determining the source region of auroral emissions in the prenoon oval using coordinated polar BEAR UV‐imaging and DMSP particle measurements

Abstract

The Polar Beacon Experiment and Auroral Research (Polar BEAR) satellite included the capability for imaging the dayside auroral oval in full sunlight at several wavelengths. We compare particle observations from the DMSP F7 satellite during dayside auroral oval crossings with approximately simultaneous Polar BEAR 1356‐Å images to determine the magnetospheric source region of the dayside auroral oval. The source region is determined from the Defense Meteorological Satellite Program (DMSP) particle data, according to recent work concerning the classification and identification of precipitation source regions. The close DMSP/Polar BEAR coincidences all occur when the former satellite is located between 0945 and 1000 MLT. We found instances of auroral arcs mapping to each of several different regions, including the boundary plasma sheet, the low‐latitude boundary layer, and the plasma mantle. However, our results indicate that about half the time the most prominent auroral arcs are located at the interfaces between distinct plasma regions, at least at the local time studied here.