Relative contributions of large-scale and wedgelet currents in the substorm current wedge
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.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSM058..01N
- Keywords:
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- 2427 Ionosphere/atmosphere interactions;
- IONOSPHERE;
- 2736 Magnetosphere/ionosphere interactions;
- MAGNETOSPHERIC PHYSICS;
- 2740 Magnetospheric configuration and dynamics;
- MAGNETOSPHERIC PHYSICS;
- 2788 Magnetic storms and substorms;
- MAGNETOSPHERIC PHYSICS