Abstract. During magnetically active periods the storm-time disturbance signal on the ground commonly develops an azimuthal asymmetry. Negative deflections of the magnetic horizontal ( H ) component are enhanced in the 18:00 local time sector and smallest in the morning sector. This is commonly attributed to the asymmetric ring current effect. In this study we investigate the average characteristics of anti-sunward net currents that are not closing in the ionosphere. Their intensity is growing proportionally with the amount of solar wind input to the magnetosphere. There is almost twice as much current flowing across the polar region in the winter hemisphere as on the summer side. This seasonal dependence is more pronounced in the dusk sector than in the dawn sector. Event studies reveal that anti-sunward currents are closely related to the main phase of a magnetic storm. Since the asymmetry of storm-time disturbances also builds up during the main phase, we suggest a relation between these two phenomena. From a statistical study of ground-based disturbance levels during magnetically active periods, we obtain support for our suggestion. We propose a new 3D current system responsible for the zonally asymmetric storm-time disturbance signal that does not involve the ring current. The high-latitude anti-sunward currents are connected at their noon and midnight ends to field-aligned currents that lead the currents to the outer magnetosphere. The auroral net current branch on the morning side is closed along the dawn flank near the magnetopause, and the evening side currents flow along the dusk flank magnetosphere. Regardless through which loop the current is flowing, near-Earth storm-time disturbance levels will in both cases be reduced in the morning sector and enhanced in the evening.

中文翻译：

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从 CHAMP 观测推导出的非对称环流效应与反太阳极光电流之间的关系

摘要。在磁活动期间，地面上的风暴时间扰动信号通常会产生方位角不对称。磁水平 (H) 分量的负偏转在当地时间 18:00 部分增强，而在早上部分最小。这通常归因于不对称环电流效应。在这项研究中，我们调查了在电离层中未关闭的反向日净电流的平均特性。它们的强度与输入到磁层的太阳风量成正比增长。流经冬季半球极地地区的电流几乎是夏季一侧的两倍。这种季节性依赖性在黄昏扇区比黎明扇区更为明显。事件研究表明，逆阳流与磁暴的主要阶段密切相关。由于风暴时间扰动的不对称性也在主要阶段建立，我们建议这两种现象之间存在关系。通过对磁活动期间地面扰动水平的统计研究，我们的建议得到了支持。我们提出了一种新的 3D 电流系统，负责不涉及环流的区域不对称风暴时间扰动信号。高纬度反太阳电流在中午和午夜连接到磁场对齐的电流，将电流引导到外磁层。晨侧的极光净流支路沿磁层顶附近的黎明侧翼闭合，傍晚侧流沿黄昏侧翼磁层流动。