HR: 17:00h
AN: SM14A-05    [Abstracts]
TI: Three-Dimensional MHD Simulation of Current Sheet Evolution During the Growth Phase of Magnetospheric Substorms
AU: * Hall, F
EM: fh@why.gi.alaska.edu
AF: Geophysical Institute University of Alaska, Fairbanks, 903 Koyukuk Drive P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Otto, A
EM: ao@how.gi.alaska.edu
AF: Geophysical Institute University of Alaska, Fairbanks, 903 Koyukuk Drive P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AB: Current sheet thinning in the near-Earth magnetotail is an important element of growth phase dynamics since it determines the conditions for substorm onset. The growth phase is initiated by the erosion of closed dayside magnetic flux. This flux is replenished by convection of closed magnetic flux from the near-Earth tail region to the dayside. However, this process of magnetic flux replenishment is subject to the entropy and mass conservation constraints imposed on the slow quasi-static convection of magnetic flux tubes from the mid- and far-tail regions, first identified by {\it Erickson and Wolf\/} (1980). We examine whether the depletion of flux from a finite reservoir in the near-Earth tail region leads to the observed current sheet thinning. This hypothesis is tested using a self-consistent three-dimensional MHD code which is coupled to a semi-empirical magnetic field model. The resulting system was relaxed to an equilibrium state using a modification of a `ballistic relaxation' method. We discuss the structure of the equilibrium near-Earth magnetotail. A plasma outflow is prescribed in the near-Earth magnetotail to model the depletion of the `flux reservoir' described above. The resulting evolution of the current sheet is discussed.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2753 Numerical modeling
DE: 2760 Plasma convection
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting