Nishimura Y, Lyons L R, Gabrielse C, Weygand J M, Donovan E F, Angelopoulos V
Department of Electrical and Computer Engineering and Center for Space Physics, Boston University, Boston, MA USA.
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA USA.
Earth Planets Space. 2020;72(1):106. doi: 10.1186/s40623-020-01234-x. Epub 2020 Jul 20.
We examined how much large-scale and localized upward and downward currents contribute to the substorm current wedge (SCW), and how they evolve over time, using the THEMIS all-sky imagers (ASIs) and ground magnetometers. One type of events is dominated by a single large-scale wedge, with upward currents over the surge and broad downward currents poleward-eastward of the surge. The other type of events is a composite of large-scale wedge and wedgelets associated with streamers, with each wedgelet having comparable intensity to the large-scale wedge currents. Among 17 auroral substorms with wide ASI coverage, the composite current type is more frequent than the single large-scale wedge type. The dawn-dusk size of each wedgelet is ~ 600 km in the ionosphere (~ 3.2 in the magnetotail, comparable to the flow channel size). We suggest that substorms have more than one type of SCW, and the composite current type is more frequent.
我们利用THEMIS全天空成像仪（ASI）和地面磁力计，研究了大规模和局部向上及向下电流对亚暴电流楔（SCW）的贡献程度，以及它们如何随时间演变。一类事件由单个大规模电流楔主导，在浪涌区有向上电流，在浪涌区极向 - 东向有广泛的向下电流。另一类事件是与流束相关的大规模电流楔和小电流楔的组合，每个小电流楔的强度与大规模电流楔相当。在17次有广泛ASI覆盖的极光亚暴中，复合电流类型比单一大规模电流楔类型更频繁。每个小电流楔在电离层中的晨昏方向尺寸约为600公里（在磁尾中约为3.2 ，与流动通道尺寸相当）。我们认为亚暴有不止一种类型的SCW，且复合电流类型更频繁。
