Paper#: 2
Poster #:
Session Name: Plenary
Room: West Ballroom
Day: Tuesday
Time: 9:20-9:45 a.m.
Abstract Title: Instability Theory for Substorm Expansion Onset
PresentSurname: Lui, A.
All Authors: A. Lui
Abstract : The idea of a current-driven instability as the basic cause of substorm expansion has been suggested early on in substorm research. Kinetic effects are now recognized to be important for the substorm onset process, as indicated by the dynamic activity of the near-Earth current sheet which is thinned to a thickness comparable to the ion gyroradius prior to substorm expansion onsets. In this paper, we discuss observations and simulation results which provide important insights into the nature of the current-driven instability responsible for substorm expansion and how such an instability can account for the finding that northward turning of interplanetary magnetic field is one of the triggers for substorm expansion. We also provide reasons why substorms may not occur during steady magnetospheric convection intervals even though the magnetosphere is strongly-driven by the solar wind during such times.