Diffusive Plasma Transport by the Magnetopause Kelvin-Helmholtz Instability During Southward IMF
Diffusive Plasma Transport by the Magnetopause Kelvin-Helmholtz Instability During Southward IMF
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DOI：
10.3389/fspas.2021.809045
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
T. Nakamura;K. Blasl;Y. Liu;S. Peery
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文献类型：
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作者：
T. Nakamura;K. Blasl;Y. Liu;S. Peery
在地球低纬度磁层顶，开尔文-亥姆霍兹（KH）波是由穿过磁层顶的超阿尔弗尼速度切变驱动的，在向北的行星际磁场（IMF）期间经常被观测到，并被认为有助于有效地将太阳风等离子体输送到磁层中。另一方面，在向南的 IMF 时期，KH 波的特征观测到的频率要低得多，并且 KH 波如何促进太阳风传输尚未得到很好的探索。最近，磁层多尺度（MMS）任务在南向IMF期间成功探测到磁层顶黄昏侧翼附近的KH波特征。在本研究中，我们分析了一系列二维和三维全动力学模拟，对 MMS 事件进行建模。结果表明，KH波边缘层低密度（磁层）侧附近的低混合漂移不稳定性（LHDI）的湍流演化迅速扰乱了该层的结构，并导致等离子体跨层有效传输。获得的输送速率与北向IMF 的预测相当甚至更大。这些结果表明，KH波引起的扩散太阳风传输可能在南向IMF期间的侧翼至尾部磁层顶处活跃。
At the Earth’s low-latitude magnetopause, the Kelvin-Helmholtz (KH) waves, which are driven by the super-Alfvénic velocity shear across the magnetopause, have been frequently observed during periods of northward interplanetary-magnetic-field (IMF) and believed to contribute to efficiently transporting the solar wind plasmas into the magnetosphere. On the other hand, during southward IMF periods, the signatures of the KH waves are much less frequently observed and how the KH waves contribute to the solar wind transport has not been well explored. Recently, the Magnetospheric Multiscale (MMS) mission successfully detected signatures of the KH waves near the dusk-flank of the magnetopause during southward IMF. In this study, we analyzed a series of two- and three-dimensional fully kinetic simulations modeling this MMS event. The results show that a turbulent evolution of the lower-hybrid drift instability (LHDI) near the low-density (magnetospheric) side of the edge layer of the KH waves rapidly disturbs the structure of the layer and causes an effective transport of plasmas across the layer. The obtained transport rate is comparable to or even larger than that predicted for the northward IMF. These results indicate that the diffusive solar wind transport induced by the KH waves may be active at the flank-to-tail magnetopause during southward IMF.