Coupling of dipolarization front flow bursts to substorm expansion phase phenomena within the magnetosphere and ionosphere

Recent THEMIS spacecraft observations have shown longitudinally narrow, earthward moving, plasma sheet flow channels with large, abrupt magnetic field dipolarizations that have been referred to as dipolarization fronts. We undertake a detailed study of the subset of these events that had good quality auroral imaging. We find that many occurred during the substorm expansion phase after onset (determined by auroral intensification) and were …