SM058-01
Relative contributions of large-scale and wedgelet currents in the substorm current wedge

Wednesday, 16 December 2020: 11:30
Virtual
Toshi Nishimura, Boston University, Boston, MA, United States, Larry R Lyons, University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, United States, Christine Gabrielse, The Aerospace Corporation, El Segundo, CA, United States, James M Weygand, IGPP/UCLA---ESS, Los Angeles, CA, United States, Eric Donovan, University of Calgary, Calgary, AB, Canada and Vassilis Angelopoulos, University of California Los Angeles, Department of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, Los Angeles, CA, United States
Recorded Presentation
Abstract:
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 types of SCW, and the composite current type is more frequent.
Previous Abstract | Next Abstract >>