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

Forsyth, C. and Lester, M. and Cowley, S. W. H. and Dandouras, I. and Fazakerley, A. N. and Fear, R. C. and Frey, H. U. and Grocott, A. and Kadokura, A. and Lucek, E. and Rème, H. and Milan, S. E. and Watermann, J. (2008) Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms. Annales Geophysicae, 26 (1). pp. 167-184. ISSN 0992-7689

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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 ~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 ~5 mA km−2. When projected into the ionosphere, these currents give ionospheric field-aligned currents of ~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.

Item Type:
Journal Article
Journal or Publication Title:
Annales Geophysicae
Additional Information:
© European Geosciences Union 2008
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
ID Code:
67143
Deposited By:
Deposited On:
11 Oct 2013 12:43
Refereed?:
Yes
Published?:
Published
Last Modified:
03 Jul 2020 01:08