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NAM2012 - All Presentation Details

Record 442 of 756

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High latitude observations of magnetotail plasma-sheet plasma in conjunction with a transpolar arc

Author: Robert Fear

University of Leicester

Co-Authors: S. E. Milan (University of Leicester) & R. Maggiolo (Belgian Institute for Space Aeronomy)

Session: MST1: Magnetic Reconnection in Space and Astrophysical Plasmas

Presentation type: Poster      Poster Session B   


Transpolar arcs (TPAs) are auroral features which extend into the polar cap from the night side of the main auroral oval. A major candidate mechanism for TPA formation invokes the closure of lobe flux in a twisted magnetotail, where the closed flux is prevented from returning to the dayside as the twist causes the northern and southern hemisphere footprints of the closed field lines to straddle the midnight meridian. In this mechanism, closed flux builds up on the night side, so plasma similar to typical plasma sheet distributions should be observed at high latitudes embedded within the lobe. We present preliminary observations of three cases where the Cluster spacecraft observes plasma-sheet plasma embedded within the lobes, and at much higher latitudes than those at which the plasma sheet is usually observed. The locations of the spacecraft map to points on the TPA that are significantly poleward of the main auroral oval. These observations are consistent with TPAs being formed by the proposed reconnection/twisted magnetotail mechanism.

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