Longitudinal propagation of thin auroral arcs

Abstract:

Substorm auroral dynamics is very complicated.In a previous study, we used Rice Convection Model to simulate the generation and movement of auroral arcs. The simulation shows that when it travels through the middle plasma sheet along the Sun-Earth direction, the plasma-sheet bubble leads to a north-south-aligned auroral streamer, and when it arrives at the magnetic transition region, the bubble leads to an east-west-elongated thin arc. In order to verify the model prediction of the longitudinal propagation speed of the arcs, we analyze a number of events using THEMIS All-Sky-Imager data. We find that the calculated propagation speed of the leading edge of auroral arcs is ~0.5–3.5 km/s, roughly consistent with our simulations.