Relative contributions of large-scale and wedgelet currents in the substorm current wedge
説明
<jats:title>Abstract</jats:title><jats:p>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 <jats:italic>R</jats:italic><jats:sub>E</jats:sub> 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.</jats:p>
収録刊行物
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- Earth, Planets and Space
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Earth, Planets and Space 72 (1), 2020-07-20
Springer Science and Business Media LLC