Author/Authors :
Runov، نويسنده , , A. and Angelopoulos، نويسنده , , V. and Sitnov، نويسنده , , M. A. Sergeev ، نويسنده , , V.A. and Nakamura، نويسنده , , R. and Nishimura، نويسنده , , Y. and Frey، نويسنده , , H.U. and McFadden، نويسنده , , J.P. and Larson، نويسنده , , Bryan D. and Bonnell، نويسنده , , J. and Glassmeier، نويسنده , , K.-H. and Auster، نويسنده , , U. and Connors، نويسنده , , M. and Russell، نويسنده , , C.T. and Singer، نويسنده , , H.J.، نويسنده ,
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.
