Large scale current systems developed from substorm onset:Global MHD results  

作　　者：TANG BinBin WANG Chi 

机构地区：[1]State Key Laboratory of Space Weather,National Space Science Center, Chinese Academy of Sciences

出　　处：《Science China(Technological Sciences)》2018年第3期389-396,共8页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41474145 and 41574159);the Specialized Research Fund for State Key Laboratories of China

摘　　要：We investigate the large-scale substorm current systems developed from its onset in an idealized substorm event simulated by global magnetohydrodynamic(MHD) models. Mainly three current systems(loops) are revealed:(1) the classical substorm current wedge, which is composed by the disputed cross-tail current in the magnetotail, the nightside westward electrojet in the high-latitude ionosphere and a pair of region 1 field-aligned currents(FAC);(2) the partial-ring current system, which is braced by two region 2 FACs; and(3) the meridional current system, which is formed by an equatorial radial current(outward/inward in the morning/evening sector), and region 1 and region 2 FACs at its two ends. The region 2 FAC connects with region 1 FAC by a latitudinal horizontal current at each morning/evening ionosphere to complete Loops 2 and 3. A quantitative study shows the significant enhancement of these current systems during the substorm expansion phase, while Loop 1 dominates, which can reach a magnitude of ~1 MA. Empirical relations among the ionospheric currents and the related magnetotail currents are established based on the simulation results, implying that the substonn current systems are not evolved locally or separately, but must be viewed from a global perspective. This knowledge of large-scale substorm current system would deepen our understanding of the substorm development and could be validated by observations in the future.

关 键 词：magnetospheric physics substorm current system magnetohydrodynamic（MHD） simulation 

分 类 号：P353[天文地球—空间物理学]