Midday sub‐auroral patches (MSPs) associated with interplanetary shocks
Midday sub‐auroral patches (MSPs) associated with interplanetary shocks
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DOI：
10.1029/2001gl014182
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发表时间：
2002-08
影响因子：
5.2
通讯作者：
K. Liou;C.-C. Wu-C.;R. Lepping;P. Newell;C. Meng
中科院分区：
文献类型：
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作者：
K. Liou;C.-C. Wu-C.;R. Lepping;P. Newell;C. Meng
我们使用极地航天器紫外线成像仪的极光图像数据报告了一类新的日侧极光瞬变现象。这种瞬变的特征是午间亚极光地带的极光斑块突然变亮，因此被称为午间亚极光斑块(MSP)。发现MSP与风暴的突然开始同时发生，以响应行星际激波对磁层的压缩。变亮后，MSP变宽和/或向赤道移动。MSP的纬度位置取决于激波下游的太阳风动压：动压越大，对应的纬度越低。MSP的寿命较短(∼为5-6分钟)。根据国防气象卫星计划从一次偶然事件中获得的粒子数据，MSPS的磁层源区是中央等离子体片(CPS)。激电冲击对地球磁场的突然压缩可能会改变预先存在的CPS粒子群的俯仰角，从而落入损失锥并产生极光发射。
We report a new category of dayside auroral transients using auroral image data from the Polar spacecraft Ultraviolet Imager. The transients are characterized by a sudden brightening of the auroral patch in the midday sub‐auroral zone, and thus are named midday sub‐auroral patches (MSPs). MSPs were found to occur concurrently with storm sudden commencements in response to the compression of the magnetosphere by interplanetary (IP) shocks. After brightening, the MSP widened and/or moved equatorward. The latitudinal location of an MSP depends on the solar wind dynamic pressure in the shock downstream: a larger dynamic pressure corresponds to a lower latitude. The lifetime of an MSP is short (∼5–6 min). The magnetospheric source region for the MSPs, as determined with the Defense Meteorological Satellite Program particle data from one fortuitous event, is the central plasma sheet (CPS). Sudden compression of the Earth's magnetic field due to the IP shock impact may change the pitch angles of a pre‐existing population of CPS particles, which consequently fall into the loss cone and produce auroral emission.