ICS-13 Abstract View


The Substorm Current Wedge
Kepko, L., larry.kepko@nasa.gov
Over 40 years ago the concept of the substorm current wedge (SCW) was developed to explain the pattern of magnetic signatures observed on the ground and in geosynchronous orbit during the substorm expansion phase. The ensuing decades saw advancements in our understanding of this system from new observations, including radar and low-altitude spacecraft, theoretical considerations, and MHD simulations, and the SCW remains a guiding paradigm on the large scale to this day. Although the line current model of the SCW broadly explains the general characteristics and patterns of magnetic perturbations observed on the ground, recent work has necessitated a need to modify this picture, and there still remain major open questions. A principal alteration is the inclusion of a Region-2 sense current earthward of the traditional SCW, which has support in MHD simulations and some observational support. And while the substorm current wedge (SCW) is able to represent the large scale characteristics of this couple system, it represents an integration of many small scale current systems. The relationship between small-scale, filamented currents observed in the magnetosphere and the larger current system is not well understood. In this paper I review the current state of understanding of this important piece of MI coupling, including new results from MMS.
(1) NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA