Explosive Magnetotail Activity
Explosive Magnetotail Activity
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DOI：
10.1007/s11214-019-0599-5
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发表时间：
2019-05
影响因子：
10.3
通讯作者：
M. Sitnov;J. Birn;B. Ferdousi;E. Gordeev;Y. Khotyaintsev;V. Merkin;T. Motoba;A. Otto;E. Panov;P. Pritchett;F. Pucci;J. Raeder;A. Runov;V. Sergeev;M. Velli;Xuzhi Zhou
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文献类型：
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作者：
M. Sitnov;J. Birn;B. Ferdousi;E. Gordeev;Y. Khotyaintsev;V. Merkin;T. Motoba;A. Otto;E. Panov;P. Pritchett;F. Pucci;J. Raeder;A. Runov;V. Sergeev;M. Velli;Xuzhi Zhou
综述了地球磁尾爆炸活动的模式和表现，以及它的发生机制和关键的发生前条件。本文讨论了两种产生初始电流片的机制，即尾叶的磁通增加或其他高纬度扰动，以及与日侧重联有关的近地尾的磁通疏散。重新连接的开始可能需要将薄片拉伸和变薄到电子级。在赤道磁场向尾部倾斜的地区，它也可能以较厚的薄片开始；在这种情况下，它开始于理想的mhd不稳定，随后产生突发的大块流和双极化锋。事实上，遥感和全球MHD模型显示，尾部区域的形成增加了，容易发生磁重联、气球/交换和襟翼不稳定性。虽然交换不稳定性也可能在如此厚的薄片中发展，但与撕裂相比，它可能增长得更慢，并在黎明-黄昏方向局部引起二次重连。爆发后瞬态包括突发流和双极化锋，低混合漂移和哨声波的微不稳定性，以及近地区域的阻尼全球通量管振荡。它们将被拉伸的尾部磁场能量转化为体等离子体加速和无碰撞加热，激发等离子体波的广谱，以及电离层的碰撞耗散。无碰撞加热包括离子从锋面、费米、电子加速器以及其他非绝热机制的反射。讨论了其中一些磁尾现象的电离层表现。还讨论了实验室观测到的爆炸等离子体现象、日冕和太阳风。
Modes and manifestations of the explosive activity in the Earth’s magnetotail, as well as its onset mechanisms and key pre-onset conditions are reviewed. Two mechanisms for the generation of the pre-onset current sheet are discussed, namely magnetic flux addition to the tail lobes, or other high-latitude perturbations, and magnetic flux evacuation from the near-Earth tail associated with dayside reconnection. Reconnection onset may require stretching and thinning of the sheet down to electron scales. It may also start in thicker sheets in regions with a tailward gradient of the equatorial magnetic field; in this case it begins as an ideal-MHD instability followed by the generation of bursty bulk flows and dipolarization fronts. Indeed, remote sensing and global MHD modeling show the formation of tail regions with increased, prone to magnetic reconnection, ballooning/interchange and flapping instabilities. While interchange instability may also develop in such thicker sheets, it may grow more slowly compared to tearing and cause secondary reconnection locally in the dawn-dusk direction. Post-onset transients include bursty flows and dipolarization fronts, micro-instabilities of lower-hybrid-drift and whistler waves, as well as damped global flux tube oscillations in the near-Earth region. They convert the stretched tail magnetic field energy into bulk plasma acceleration and collisionless heating, excitation of a broad spectrum of plasma waves, and collisional dissipation in the ionosphere. Collisionless heating involves ion reflection from fronts, Fermi, betatron as well as other, non-adiabatic, mechanisms. Ionospheric manifestations of some of these magnetotail phenomena are discussed. Explosive plasma phenomena observed in the laboratory, the solar corona and solar wind are also discussed.