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Increases in plasma sheet temperature with solar wind driving during substorm growth phases

Forsyth, C; Watt, CEJ; Rae, IJ; Fazakerley, AN; Kalmoni, NME; Freeman, MP; Boakes, PD; ... Carr, CM; + view all (2014) Increases in plasma sheet temperature with solar wind driving during substorm growth phases. GEOPHYSICAL RESEARCH LETTERS , 41 (24) 8713 - 8721. 10.1002/2014GL062400. Green open access

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Abstract

During substorm growth phases, magnetic reconnection at the magnetopause extracts ~1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and theminimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase.

Type: Article
Title: Increases in plasma sheet temperature with solar wind driving during substorm growth phases
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/2014GL062400
Publisher version: http://dx.doi.org/10.1002/2014GL062400
Additional information: © 2014. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: substorm, growth phase, plasma sheet, temperature
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/1459990
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