Development of the Substorm as a Manifestation of Convection Transient
Development of the Substorm as a Manifestation of Convection Transient
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DOI：
10.1029/2020ja028942
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
T. Tanaka;Y. Ebihara;M. Watanabe;M. Den;S. Fujita;T. Kikuchi;K. Hashimoto;R. Kataoka
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文献类型：
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作者：
T. Tanaka;Y. Ebihara;M. Watanabe;M. Den;S. Fujita;T. Kikuchi;K. Hashimoto;R. Kataoka
我们通过全球模拟再现了亚暴，并分析了发展阶段最后阶段的对流、切变、发电机和场向流（FAC）的发展。从这些调查中，我们表明，亚暴是全球流动动力学重构的表现。电离层对流可以从两个方面来理解。一种理解是作为由FAC产生的位场，另一种是作为磁层对流的投影。为了使两者重合，FAC必须与运动一起传输。因此，由此产生的对流必须是从磁层到电离层连续的。我们从切变图中看到这种联系，从而认识到亚暴是瞬变对流的投射过程。在生长阶段，导致静弧和Harang反转（HR）的对流剪切发生在沿着等离子体片表面的开/闭边界上，具有从磁层到电离层的连续流动结构。沿着等离子体片表面。发病始于近地中性线（NENL）引起的更局部的流动。窄切变从NENL的中尾开始，并延伸到电离层，以取代增长相切变。沿着一条与NENL相连的闭合磁力线，直接穿透流、挤压流、近地发电机、HR释放和FAC起始相继发生，从而引起地面起始。这种启动机制与采用电流楔的模型有很大的不同。
We reproduced the substorm by global simulation and analyzed the development of convection, shear, the dynamo, and the field‐aligned current (FAC) at the final stage of the growth phase. From these investigations, we show that the substorm is a manifestation of reconfiguration in global flow dynamics. Ionospheric convection can be understood from two aspects. One understanding is as the potential field generated by the FAC, and the other is as the projection of magnetospheric convection. In order for the two to coincide, the FAC must be transmitted together with the motion. As a consequence, the resulting convection must be continuous from the magnetosphere to the ionosphere. We see this connection from the drawing of shear to recognize that the substorm is the projection process of transient convection. In the growth phase, convective shear that causes the quiet arc and the Harang reversal (HR) occurs on the open/closed boundary along the surface of the plasma sheet with a continuous flow structure from the magnetosphere to the ionosphere. The onset starts from a more local flow that is induced by the near‐earth neutral line (NENL). A narrow shear commences from the NENL in the mid‐tail and extends to the ionosphere to replace growth phase shear. Along a closed magnetic field line connected to the NENL, direct penetration flow, squeezing flow, the near‐earth dynamo, release of the HR, and the onset FAC occur successively and consequently cause the ground onset. Such onset mechanism is quite different from the model adopting the current wedge.