Increases in plasma sheet temperature with solar wind driving during substorm growth phases.
Increases in plasma sheet temperature with solar wind driving during substorm growth phases.
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DOI：
10.1002/2014gl062400
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发表时间：
2014-12-28
影响因子：
5.2
通讯作者：
Carr, C. M.
中科院分区：
文献类型：
--
作者：
Forsyth, C.;Watt, C. E. J.;Rae, I. J.;Fazakerley, A. N.;Kalmoni, N. M. E.;Freeman, M. P.;Boakes, P. D.;Nakamura, R.;Dandouras, I.;Kistler, L. M.;Jackman, C. M.;Coxon, J. C.;Carr, C. M.
在亚暴生长阶段，磁层顶的磁重联从太阳风中提取1015 J，然后存储在磁尾叶中。等离子体片压力增加以平衡叶中磁通密度的增加。在这里，我们使用9年的星团数据（> 316，000个数据点）来研究亚暴生长阶段的等离子体片压力，密度和温度。我们发现，等离子体片的压力和温度较高的生长阶段与较高的太阳风驱动，而密度是近似恒定的。我们还表明，发病前的等离子体片温度和最小的SuperMAG AL（SML）极光指数在随后的亚暴之间的弱相关性。我们讨论了发病前的等离子体片的热膨胀可能会导致绝热过程;如何热等离子体片可能会导致磁尾不稳定性，以及这与随后的亚暴膨胀阶段的发病和大小。
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 the minimum 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.