Using patchy pulsating aurora to remote sense magnetospheric convection

Abstract

Five patchy pulsating aurora (PPA) patches have been identified in data obtained from the Gillam Time History of Events and Macroscale Interactions during Substorms (THEMIS) all-sky imager (ASI). We found that azimuthal velocities of five patches derived from THEMIS ASI data were close to the same value as the local convection velocities as obtained from analysis of Super Dual Auroral Radar Network data, consistent with the idea that the patch motion is primarily due to E×B convection. We argue that this means that we can infer 2-D maps of the time-evolving convection from time sequences of PPA. Further, given that the E×B convection is understood to be a projection of magnetospheric convection, this means that, provided auroral and viewing conditions cooperate, patch motion can be used for remote sensing magnetospheric convection over across-extended regions with fairly high time resolution. This is the first detailed demonstration of the equivalence of patch velocities and E×B convection. Key Points The motion of patches follows the E×B drift Suggest that the structure of PPA patches reflects cold plasma structures Infer 2-D maps of the time-evolving convection from time sequences of PPA.