Toward a Global Magnetospheric Equilibrium Model
Abstract
A ``quasi-static" equilibrium between magnetic (Lorentz) forces and plasma pressure gradient forces exists at most times in the magnetosphere, except for periods of explosive activity such as substorms. The magnetospheric evolution is thus slow enough so that it can be portrayed as a time sequence of such equilibria. In order to model quasi-static equilibria, we have started the development of a comprehensive three-dimensional self-consistent model of the magnetosphere, by coupling a 3-D equilibrium code in flux coordinates [Cheng, 1995, Zaharia et al., 2004] covering the inner/middle magnetosphere with an asymptotic ``tail equilibrium" model [Birn, 1987]. The coupling project is facilitated by the similar magnetic field representation, in terms of Euler potentials, in both models. We will present initial results from this effort, focusing on global configurations (including both closed- and open-field regions) obtained by coupling the two models for particular cases, such as north-south symmetry and 2-D geometry. We will discuss the results obtained by using different coupling procedures, boundary conditions and input pressure functions. Presenting computed sequences of quasi-static equilibria, we will also discuss how the magnetosphere evolves under changing external (solar wind) conditions, modeled by changes in magnetic flux boundaries and pressure profiles. In particular, we will discuss the possibility for appearance of thin cross-tail current sheets under boundary deformations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFMSM43A1139Z
- Keywords:
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- 2740 Magnetospheric configuration and dynamics;
- 2744 Magnetotail;
- 2753 Numerical modeling;
- 2764 Plasma sheet;
- 2799 General or miscellaneous