The goal of the present study is to observationally test the idea that the substorm current wedge (SCW) is an ensemble of wedgelets, mesoscale current systems that correspond to plasma sheet flow channels. According to this hypothesis, the SML index, SuperMAG equivalent to the AL index, represents a single particular wedgelet at a given time, whereas midlatitude positive bays are a sum of the remote effects of all wedgelets but with more weighting on ones closer in longitude. However, both event‐based and statistical studies of isolated substorms show that (1) midlatitude N (northward) and E (eastward) ground magnetic variations are highly correlated with SML even far from midnight; (2) the correlation between midlatitude magnetic variations and SML are organized by the magnetic local time (MLT) of the peak westward electrojet intensity (as identified by SML), and their longitudinal structures are consistent with the conventional SCW model; and (3) eastward and westward midlatitude E variations observed at dusk and dawn, respectively, are well correlated. If the SCW is an ensemble of wedgelets, these results would imply that wedgelets with similar intensities are formed side by side throughout the SCW and evolve in parallel with each other, which is highly questionable from both physical and morphological points of view. Instead, it is suggested that the SCW is basically a globally coherent system. Although the SCW may evolve from a wedgelet formed at the onset of substorms, wedgelets are probably not a primary constituent of the SCW for most of the subsequent expansion phase.

中文翻译：

---

亚风暴当前的楔形物是楔形物的集合吗？：重新进入中纬度正海湾

本研究的目的是观察性地测试亚暴电流楔形体（SCW）是楔形体，中尺度电流系统的集合，这些系统对应于等离子体薄板流动通道。根据该假设，SML索引（相当于AL索引的SuperMAG）在给定时间代表单个特定的楔形波，而中纬度正向湾是所有楔形波的远程影响的总和，但对经度更近的楔形波的权重更大。但是，基于事件的事件和对孤立的亚暴的统计研究都表明（1）中纬度N（向北）和E（向东）的地面磁变化与SML高度相关甚至离午夜；（2）中纬度磁变化与SML之间的相关性是由西电喷峰强度的局部磁场时间（MLT）来组织的（如SML所确定），其纵向结构与传统的SCW模型一致; 和（3）东纬西纬E分别在黄昏和黎明观察到的变化具有良好的相关性。如果SCW是楔形的集合体，那么这些结果将暗示具有相似强度的楔形在SCW上并排形成并且彼此平行地演化，这在物理和形态学角度都令人质疑。相反，建议SCW基本上是一个全局一致的系统。尽管SCW可能会从亚暴天气开始时形成的楔形演化而来，但对于随后的大多数扩展阶段，楔形可能都不是SCW的主要组成部分。