Nishimura, Y.Lyons, L. RGabrielse, C.Weygand, J. MDonovan, E. FAngelopoulos, V.2020-07-262020-07-262020-07-20Earth, Planets and Space. 2020 Jul 20;72(1):106http://hdl.handle.net/1880/11233610.11575/PRISM/44169Abstract 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 RE 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.Journal Article2020-07-26enThe Author(s)https://doi.org/10.1186/s40623-020-01234-x