Plasma sheet changes caused by sudden enhancements of the solar wind pressure
Plasma sheet changes caused by sudden enhancements of the solar wind pressure
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DOI：
10.1029/2009ja014617
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发表时间：
2010-05
影响因子：
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通讯作者：
Y. Miyashita;K. Keika;K. Liou;S. Machida;Y. Kamide;Y. Miyoshi;Y. Matsumoto;I. Shinohara;Y. Saito;T. Mukai
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文献类型：
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作者：
Y. Miyashita;K. Keika;K. Liou;S. Machida;Y. Kamide;Y. Miyoshi;Y. Matsumoto;I. Shinohara;Y. Saito;T. Mukai
[1]利用磁尾资料，研究了磁尾等离子体片对太阳风压突然增强的响应。我们选择了三个事件，其中没有迹象表明亚暴膨胀周围相应的突然脉冲（SI）在地面上。结果表明，由于等离子体片的压缩，离子数密度和温度以及离子压力显著增加。等离子体片的比熵没有明显的变化，表明等离子体片的压缩是近绝热的。这种等离子体行为与非绝热亚暴相关过程相反。因此，检查数密度和温度之间的相关性，尤其是比熵，对于区分等离子体片的亚暴相关变化和SI相关变化至关重要。等离子体片中向北的磁场也会增加，或者至少不会减少，与压缩有关，这意味着横向磁尾压缩抑制了磁重联的触发，从而抑制了亚暴膨胀的发生。
[1] Using Geotail data, we have studied the response of the plasma sheet in the magnetotail to sudden enhancements of the solar wind pressure. We have selected three events in which there were no indications of substorm expansions around the corresponding sudden impulses (SIs) on the ground. It is shown that the ion number density and temperature, as well as the ion pressure, increase significantly due to the plasma sheet compression. The specific entropy does not significantly change, suggesting that the plasma sheet compression is nearly adiabatic. This plasma behavior is in contrast to the nonadiabatic substorm-associated processes. Hence examining the correlation between the number density and the temperature, and especially the specific entropy is critical for distinguishing between substorm-associated and SI-associated changes of the plasma sheet. The northward magnetic field in the plasma sheet also increases, or at least does not decrease, associated with the compression, implying that the lateral magnetotail compression suppresses the triggering of magnetic reconnection and therefore substorm expansion onsets.