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Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms

Forsyth, C; Lester, M; Cowley, SWH; Dandouras, I; Fazakerley, AN; Fear, RC; ... Watermann, J; + view all (2008) Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms. Annales Geophysicae , 26 (1) 167 - 184. 10.5194/angeo-26-167-2008. Green and gold open access

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Abstract

We present a multi-instrument study of a substorm bursty bulk flow (BBF) and auroral streamer. During a substorm on 25 August 2003, which was one of a series of substorms that occurred between 00:00 and 05:00 UT, the Cluster spacecraft encountered a BBF event travelling Earthwards and duskwards with a velocity of similar to 500 km s(-1) some nine minutes after the onset of the substorm. Coincident with this event the IMAGE spacecraft detected an auroral streamer in the substorm auroral bulge in the Southern Hemisphere near the footpoints of the Cluster spacecraft. Using FluxGate Magnetometer (FGM) data from the four Cluster spacecraft, we determine the field-aligned currents in the BBF, using the curlometer technique, to have been similar to 5 mA km(2). When projected into the ionosphere, these currents give ionospheric field-aligned currents of similar to 18 A km(2), which is comparable with previously observed ionospheric field-aligned currents associated with BBFs and auroral streamers. The observations of the BBF are consistent with the plasma 'bubble' model of Chen and Wolf (1993). Furthermore, we show that the observations of the BBF are consistent with the creation of the BBF by the reconnection of open field lines Earthward of a substorm associated near-Earth neutral line.

Type:Article
Title:Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms
Open access status:An open access publication. A version is also available from UCL Discovery.
DOI:10.5194/angeo-26-167-2008
Publisher version:http://dx.doi.org/10.5194/angeo-26-167-2008
Language:English
Additional information:© European Geosciences Union 2008
Keywords:Magnetosphere, Auroral phenomena, Current systems, Storms and substorms, Interplanetary magnetic-field, Hall conductance distribution, Advanced composition explorer, Plasma sheet, Image spacecraft, Electric-field, Ionosphere, Model, Magnetosphere, Convection
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics

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