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

Forsyth, C., Watt, C. J. E., Rae, I. J., Fazakerley, A., Kalmoni, N. M. E., Freeman, M. P., Boakes, P. D., Nakamura, R., Dandouras, I., Kistler, L. M., Jackman, C. M., Coxon, J. C. and Carr, C. M. (2014) Increases in plasma sheet temperature with solar wind driving during substorm growth phases. Geophysical Research Letters, 41 (24). pp. 8713-8721. ISSN 0094-8276 doi: 10.1002/2014GL062400

Abstract/Summary

During the substorm growth phase, magnetic reconnection extracts ~10^15 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.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/38679
Identification Number/DOI	10.1002/2014GL062400
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Uncontrolled Keywords	substorm; growth phase; plasma sheet; temperature
Publisher	American Geophysical Union
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