External triggering of substorms identified using modern optical versus geosynchronous particle data

Abstract. Previous works on substorm triggering have shown that more than 50% of the substorms are triggered by a northward turning of the IMF Bz; However, recent studies have found a much lower percentage. We have examined triggering using three different onset lists: The THEMIS All Sky Image (ASI) list, substorm onsets from IMAGE-FUV, and events with large geosynchronous injections. We analyzed these onset lists with three different …