Reproduction of Ground Magnetic Variations During the SC and the Substorm From the Global Simulation and Biot‐Savart's Law
Reproduction of Ground Magnetic Variations During the SC and the Substorm From the Global Simulation and Biot‐Savart's Law
复制标题
从全球模拟和毕奥-萨伐尔定律再现 SC 和亚暴期间的地磁变化
DOI：
10.1029/2019ja027172
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
R. Kataoka
中科院分区：
文献类型：
--
作者：
Takashi Tanaka;Yusuke Ebihara;Masakazu Watanabe;Mitsue Den;Shuji Fujita;Takashi Kikuchi;K. Hashimoto;R. Kataoka
本文根据全球模拟结果和毕奥-萨伐尔定律，确定了引起亚暴突然开始（SC）的海流、Au/AL指数和正海湾。被认为是引起这些地面磁场变化的候选电流是电离层霍尔电流、电离层彼得森电流、场向电流（FAC）和除FAC之外的其他磁层电流。在福岛定理的限制下，FAC效应和Pedersen电流效应一般相互抵消。例如，在SC期间，由于霍尔电流的剩余效应，中纬度初始正脉冲出现在中午前，中纬度初始反向脉冲（PRI）出现在中午后。然而，违反福岛定理也是常见的，如在赤道PRI，极光电喷流，和积极的海湾的情况下。赤道赤道PRI由Pedersen流引起，出现在午前和午后区域。在极光区，霍尔电流效应明显优于其它电流，它决定了Au/AL指数。在FAC的影响下，在夜面产生了中纬度正海湾。从这些不同的地面磁场变化的再现，进一步验证了全球模拟的磁层-电离层耦合过程的再现。
In this paper, currents causing the sudden commencement (SC), the AU/AL indices, and the positive bay during the substorm are identified from the global simulation and Biot‐Savart's law. Candidate currents assumed as causes of these ground magnetic variations are the ionospheric Hall current, the ionospheric Pedersen current, the field‐aligned current (FAC), and other magnetospheric currents than the FAC. In general, FAC effect and Pedersen current effect cancel out each other under the restriction of Fukushima's theorem. During the SC, for instance, the midlatitude preliminary positive impulse appears in the prenoon and midlatitude preliminary reverse impulse (PRI) appears in the postnoon, due to the remaining effect of the Hall current. However, violations of the Fukushima's theorem are also common such as in the cases of the equatorial PRI, the auroral electrojet, and the positive bay. The equatorial PRI caused by the Pedersen current appears both in the prenoon and postnoon regions. In the auroral region, the Hall current effect prevails over other currents so much and determines the AU/AL indices only from it regardless other currents. The midlatitude positive bay on the nightside is generated by the effect of the FAC. From these diverse reproduction of ground magnetic variations, a further verification is given for the global simulation in reproductions of the magnetosphere‐ionosphere coupling process.