Magnetotail Flux Accumulation Leads to Substorm Current Wedge Formation: A Case Study

Reconnection-generated earthward flows, magnetic field dipolarizations, and auroral expansions are related to substorm current wedge (SCW) development. It has been suggested that field-aligned currents (FACs) within the SCW can be generated by flow vortices, pressure gradients, or both. Observations these generation mechanisms differ from one event another, due their different locations relative SCW's central meridian timing evolutionary state. A pattern of in situ observations consistent with yet emerge. Obtaining such a relies on satellite FAC driver regions, which hard determine because coincident magnetotail sparse. To solve this problem, an inversion technique was used model connections between magnetospheric ionospheric phenomena. Using technique, flux, parameter is relatively insensitive locations, analyzed during isolated February 13, 2008. We compared temporal variations accumulated flux caused dipolarization poleward boundary. found them good agreement transported flows. This suggests accumulation leads SCW, causing expansion. The amount positively correlated amplitudes substorm-related