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Dipolarization fronts in the magnetotail plasma sheet |
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| Authors: | A Runov V Angelopoulos VA Sergeev Y Nishimura HU Frey D Larson K-H Glassmeier M Connors CT Russell |
| Institution: | a Institute of Geophysics and Planetary Physics, University of California, Los Angeles, USA b Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA c St. Petersburg State University, St. Petersburg, Russia d Space Research Institute Austrian Academy of Sciences, Graz, Austria e Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA f Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan g Space Science Laboratory, University of California, Berkeley, CA, USA h Institute of Geophysics and Extraterrestrial Physics, Technical University Braunschweig, Germany i NOAA Space Weather Prediction Center, Boulder, CO, USA j Athabasca University, Edmonton, AB, Canada |
| 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. |
| Keywords: | Planetary magnetosphere Plasma sheet Reconnection |
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