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

Colin Forsyth, Clare J. E. Watt, Iain J. Rae, Andrew Fazakerley, Nadine M. E. Kalmoni, Mervyn P. Freeman, Peter D. Boakes, Rumi Nakamura, Iannis Dandouras, Lynn M. Kistler, Caitriona M. Jackman, John C. Coxon, Christopher M. Carr

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)
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Abstract

During the substorm growth phase, magnetic reconnection extracts 2610 15 J from the solar wind through magnetic reconnection at the magnetopause, which is then stored in the magnetotail lobes. Plasma sheet pressure then increases to balance magnetic flux density increases in the lobes. We examine plasma sheet pressure, density and temperature during substorm growth phases using nine 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 the minimum SuperMAG 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.
Original languageEnglish
Pages (from-to)8713-8721
Number of pages9
JournalGeophysical Research Letters
Volume41
Issue number24
DOIs
Publication statusPublished - 1 Dec 2014

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