Abstract

Characteristics of field-aligned currents (FACs) obtained from the observations of SWARM satellites during two strong magnetic storms in March 16–19, 2015 and September 6–9, 2017 are presented. The storms were accompanied by high-intensity substorms. Satellites crossed the dusk, noon, pre- and after midnight MLT sectors. It was shown that variations in FAC density and the latitudinal position of the equatorial FAC boundaries are controlled by both the development of the storm and, to a considerable degree, substorm activity. The average densities of downward and upward FACs reach 3–4 μA/m² at a substorm’s peak, while the undisturbed level is about 0.2 μA/m². The minimum latitude of equatorial FAC boundaries is limited to 50° MLat. Large-scale FACs consist of small-scale filamentary structures with high current density, which are always present in SWARM observations. Small-scale peak currents with a density of 50–100 µA/m² appear during periods of a general increase in density during activation of substorms. Local increases in concentration and temperature of electrons show that the current structure can be associated with a mesoscale discrete auroral arc.

中文翻译：

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第24个太阳周期的电磁风暴中的极场对准电流：2015年3月和2017年9月

摘要

呈现了从2015年3月16日至19日和2017年9月6日至9日的两次强磁暴中对SWARM卫星的观测获得的场对准电流（FAC）的特征。暴风雨伴随着高强度的亚暴雨。卫星在MLT扇区的午夜之前和之后越过黄昏，中午。结果表明，FAC密度和赤道FAC边界的纬度位置的变化既受风暴的发展，也受相当程度的亚风暴活动控制。向下和向上的FAC的平均密度在亚暴峰时达到3-4μA/ m ²，而不受干扰的水平约为0.2μA/ m ^2。。赤道FAC边界的最小纬度限制为50°MLat。大型FAC由具有高电流密度的小规模丝状结构组成，这些结构通常出现在SWARM观测中。在子风暴激活期间密度普遍增加的期间，出现了密度为50–100 µA / m ^2的小规模峰值电流。电子的浓度和温度的局部增加表明，当前结构可能与中尺度离散的极光弧有关。