The Solar Wind Control of the Magnetopause Shape:A Comparison of A Model Magnetopause and Empirical Models

Abstract

The solar wind control of the magnetopause shape is studied with a model magnetopause that results form three sources of magnetic field. One source is the geomagnetic field produced by the Earth¡¦s dipole. Another results form an image dipole placed in front of the magnetopause to produce the effect of the magnetopause current which limits the spatial extent of the geomagnetic field. The third is a southward interplanetary magnetic field (IMF) in the Earth¡¦s vicinity. With an image dipole strength and the location to account for the effect of the solar wind dynamic pressure (Dp), the shape of the model magnetopause can be regarded as controlled by Dp and the southward IMF. As an image dipole strength is about fourteen times the Earth¡¦s dipole and the location is at thirty times the Earth¡¦s radius, the shape of the model magnetopause is consistent with observational results for a southward IMF. A comparison of the shape of the model magnetopause and an empirical model by Shue et al. (1997) shows that the image dipole strength at a fixed location correlates linearly with Dp for a southward IMF. In addition, they agree qualitatively for high Dp and a southward IMF. 

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