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Geophysical Research Letters

Stopping flow bursts and their role in the generation of the substorm current wedge



During two flow burst events, earthward propagating dipolarization/injection fronts (DF) fortuitously stopped at ~9Re within a unique, compact multispacecraft constellation for the duration of a 30 min long substorm current wedge-related dipolarization. Observations inside and outside the halted flow burst indicate that it retained properties (including a narrow DF, a localized compression region ahead of it, and its structured, low density, low entropy (pV5/3) content) when arrived at its stopping point, where the entropy of the ambient plasma was nearly equal to that of the flow burst. We show that even short-duration flow bursts can significantly modify pressure and entropy distributions in the inner magnetosphere. The new distribution takes a long time to relax (a few tens of minutes, consistent with substorm recovery time scales). We argue that these pressure and entropy changes resulting from the incoming flow bursts can be responsible for the support/generation of a substorm current wedge.

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