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Elsevier, Planetary and Space Science, 7(59), p. 517-525

DOI: 10.1016/j.pss.2010.06.006

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Dipolarization fronts in the magnetotail plasma sheet

This paper is available in a repository.
This paper is available in a repository.

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Data provided by SHERPA/RoMEO

Abstract

We present a THEMIS study of a dipolarization front associated with a bursty bulk flow (BBF) that was observed in the central plasma sheet sequentially at X=−20.1, −16.7, and −11.0RE. Simultaneously, the THEMIS ground network observed the formation of a north–south auroral form and intensification of westward auroral zone currents. Timing of the signatures in space suggests earthward propagation of the front at a velocity of 300 km/s. Spatial profiles of current and electron density on the front reveal a spatial scale of 500 km, comparable to an ion inertial length and an ion thermal gyroradius. This kinetic-scale structure traveled a macroscale distance of 10RE in about 4 min without loss of coherence. The dipolarization front, therefore, is an example of space plasma cross-scale coupling. THEMIS observations at different geocentric distances are similar to recent particle-in-cell simulations demonstrating the appearance of dipolarization fronts on the leading edge of plasma fast flows in the vicinity of a reconnection site. Dipolarization fronts, therefore, may be interpreted as remote signatures of transient reconnection.