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标题：Relative contributions of large-scale and wedgelet currents in the substorm current wedge
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作者：Y. Nishimura ; L. R. Lyons ; C. Gabrielse 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2020
卷号：72
期号：1
页码：106-115
DOI：10.1186/s40623-020-01234-x
出版社：Springer Verlag
摘要：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 R E 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.© The Author(s) 2020.
关键词：Bursty bulk flow (BBF);Field-aligned current (FAC);Plasma sheet;Substorm current wedge (SCW);Westward traveling surge (WTS)