Inferring the source regions of pulsating auroras

Abstract. The aurora is an essential tool for remote sensing the large-scale dynamics of the magnetosphere which are to difficult to observe in situ and impossible to recreate in a lab. Despite pulsating aurora being a common and widespread morning-sector phenomenon, the processes responsible for its differentiation are not understood. In situ measurements of the pulsating aurora source regions are difficult to associate with specific auroral features, yet such observations will be necessary for identifying the unique causes of pulsating auroras. This study reports a method of inferring when a spacecraft is passing through the source region of patchy aurora (PA) based on the structuring of chorus. The locations of longer-lived chorus packets are found to correspond to the region of PA occurrence reported by Grono et al. (2019b). This result constrains the region where the structuring mechanisms and conditions responsible for PA and patchy pulsating aurora (PPA) can exist.