A fresh perspective of the substorm current system and its dynamo

[1] The common view for the substorm current system is a current wedge involving principally an azimuthal current system. We first evaluate briefly previous studies that provide strong evidence for the dominance of a meridional current system (MCS) in substorms. Based on these clues, we propose the dynamo for the MCS to be a kinetic current disruption process such that dipolarization is achieved by magnetic field line slippage, thus producing the dynamo action of a tailward directed current with an earthward directed electric field. The total current strength is estimated to be similar to10 MA for an average substorm size, consistent with that obtained from the KRM algorithm.