Auroral streamers implication for the substorm progression on September 14, 2004
Frey, H. U.; Kubyshkina, M. V.; Fu, S. Y.; Pu, Z. Y.; Zong, Q. G.; Du, A. M.; Xie, L.; Xiao, C. J.; Wang, X. G.; Cao, X.; Tian, S.; Mishin, V. M.
China, United States, Russia
Abstract
Magnetospheric substorms manifest a fundamental disturbance in geospace. Understanding of substorm progression is essential for solar terrestrial physics and space weather research. The auroral streamer and the bursty bulk flows (BBFs) were simultaneously observed by the IMAGE/WIC and the Cluster in the midtail (X∼-16RE), whose footprint was near the auroral streamer, respectively, during a substorm on September 14, 2004. The auroral poleward boundaries (APBs) are 2∼3° MLAT lower than the open-closed field line boundaries (OCBs) during the growth phase. After the expansion onset, streamer elongated poleward, and the location of APBs became coincident with OCBs. These observations are consistent with the scenario that substorm activations start from plasma sheet reconnection of closed field lines during growth phase; in the expansion phase the open field line in the lobes are involved in reconnection in tail.