2D Maps of Convection Inferred from the Motion of Auroral Patches

Abstract:

Patchy Pulsating Aurora (PPA) is frequently observed in the evening and morning sector auroral oval. While the precipitating electrons span a wide range of energies, there is increasing evidence that the shape of the PPA patches is somehow controlled by structures in the near-equatorial cold plasma. One consequence of this is that PPA patches appear to move with convection. Given the tremendous (and rapidly increasing) amount of auroral image data from which the velocity of these patches can be inferred, it is timely to develop and implement techniques for automatic identification of PPA events in these data, and for automatic determination of the velocity of individual patches from that data. As a first step towards this, we have implemented an automatic technique for determining patch velocities from sequences of THEMIS All-Sky Imager (ASI) images, and applied it to a large number of PPA events. Here we demonstrate the use of this technique and present initial results including 2D ionospheric convection maps inferred from PPA data for different levels of magnetic activity. We discuss implications of this technique for remote sensing convection in the inner magnetosphere.