MHD simulation of the magnetotail during the December 10, 1996, substorm

This paper presents results of a global MHD simulation of a substorm that o ccurred on December 10, 1996. We concentrate on the relationship between th e simulation results and the magnetotail observations during the growth and expansion phases of the substorm. In general, we find excellent agreement between the single point observations made by various spacecraft in both th e geosynchronous and mid-tail regions: the simulation accurately represente d the energy loading (lobe field increase), small-scale activations (partia l dipolarizations), and a global substorm onset (large dipolarizations and fast flows). The global view presented by the simulation shows complex seri es of discrete flow channels during the expansion phase prior to the onset of global reconnection. It is these flows channels that disrupt the thin cu rrent sheets present during the expansion phase of the substorm.