Coupling of magnetospheric and field-aligned currents by satellite-based observations

近赤道磁层（L-4 - 9 R_E）中的电流由两个基本成分组成：方位电流和径向电流。方位流绕地球向西流动。径向电流在深夜至午夜前流向地球，在午夜至凌晨流向地球，磁层径向电流的存在与极光纬度电离层Pedersen电流在磁层赤道面上的逆电流一致，方位电流和径向电流的不均匀性与场向电流（FAC）相关联，形成三维电流环，分别在亚暴生长阶段，由降水粒子推断出的离子等离子体片由核芯部分和裂隙状部分组成。在离子芯部分域中，增强的向西方位角电流回路关联区域2-感测FAC，并且此外径向电流回路导致区域2加上区域1-感测FAC成对。在类离子隙区，1区FAC与近赤道磁尾的对流涡度有关。而在膨胀阶段，在前一个阶段（生长阶段），分裂迅速发生，增强的向西电流和生长阶段的离子核心部分转变为爆炸部分。区域1感测FAC与该电流中断相关联，并且反向区域I感测FAC（和/或多个电流短路）也与中断区域的极向和相邻相关联。离子核部分向远赤道方向移动，与区域2-有义FAC结合，并在那里合并区域2和区域1 FAC。

Electric current flowing in the near-equatorial magnetosphere(L--4-9 R_E)consists of two basic elements : azimuthal current and radial current. Azimuthal current flows westward around the earth. Radial current flows toward the earth in the late-evening to premidnight sector and away from the earth in the midnight to early-morning sector.Presence of magnetospheric radial current is consistent with the counter current of ionosphere Pedersen current at auroral latitudes that is projected in the magnetospheric equatorial plane.Inhomogenuity in azimuthal and radial current associates field-aligned current(FAC)and forms a three-dimensional current loop, respectively. Region 1 FAC and Region 2 FAC that are determined at low altitudes, manifest the superimposed, resultant effect of these current loops.During the substorm growth phase, ion plasma sheet that was inferred from the precipitating particles, consists of core part and cleft-like part. In the ion core part domain, enhanced westward azimuthal current loop associates Region 2-sense FAC and furthermore radial current loop causes Region 2 plus Region 1-sense FAC in pair. In the domain of ion cleft-like part, Region 1-sense FAC is associated with the convective flow vorticity in the near equatorial magnetotail. Whereas, in the expansion phase, disruption occurs rapidly in the preceding(growth phase), enhanced westward current and the growth phase-ion core part trns into the explosive part. Region 1-sense FAC is associated with this current disruption and reversed-Region I sense FAC(and/or multiple current shetts)is also associated, pole-ward of and adjacent-to the disruption region. The ion core part shifts far equator-ward and associates Region 2-sense FAC, and c upled Region 2 plus Region 1 FAC there.