Computer Simulation of a Geomagnetic Substorm

A global two-dimensional simulation of a substormlike process occurring in Earth's magnetosphere is presented. The results are consistent with an empirical substorm model—the neutral-line model. Specifically, the introduction of a southward inter-planetary magnetic field forms an open magnetosphere. Subsequently, a substorm neutral line forms $\lesssim 15 R_E$ in the magnetotail, and plasma sheet thinning and plasma acceleration occur. Eventually the substorm neutral line moves tailward toward its presubstorm position.