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Observations of an active thin current sheet.
J GEOPHYS RES-SPACE
, Article A07S27. 10.1029/2007JA012685.
We analyze observations of magnetotail current sheet dynamics during a substorm between 2330 and 2400 UT on 28 August 2005 when Cluster was in the plasma sheet at [-17.2, -4.49, 0.03] R-E (GSM) with the foot points near the IMAGE ground-based network. Observations from the Cluster spacecraft, ground-based magnetometers, and the IMAGE satellite showed that the substorm started in a localized region near midnight, expanding azimuthally. A thin current sheet with a thickness of less than 900 km and current density of about 30 nA/m(2) was observed during 5 min around the substorm onset. The thinning of the current sheet was accompanied by tailward plasma flow at a velocity of -700 km/s and subsequent reversal to earthward flow at V-x approximate to 500 km/s coinciding with a B-z turning from -5 to + 10 nT. The analysis of magnetic and electric fields behavior and particle distributions reveals signatures of impulsive (with similar to 1 min timescale) activations of the thin current sheet. These observations were interpreted in the framework of transient reconnection, although the data analysis reveals serious disagreements with the classical 2.5-D X line model.
|Title:||Observations of an active thin current sheet|
|Keywords:||CENTRAL PLASMA SHEET, MAGNETIC RECONNECTION, BALLOONING INSTABILITY, EARTHS MAGNETOSPHERE, CLUSTER OBSERVATIONS, CURRENT DISRUPTION, ELECTRIC-FIELD, MAGNETOTAIL, SUBSTORM, DYNAMICS|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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