A static-state field-line reconnection model for the Earth's magnetosphere

Abstract

A magnetostatic boundary value problem has been solved within the magnetospheric cavity and in the interplanetary space in order to incorporate the interplanetary magnetic field in a quantitative magnetospheric vacuum- B-field model. The boundary condition for the closed model, B ⊥ = 0 at the magnetopause, is replaced by the condition that the normal component of the total field penetrates the boundary continuously. Penetration of the B-field depends on a ‘merging-constant’ C 0, which is assumed to be independent of position on the magnetopause. C 0 = 0 indicates the closed model and C 0 = 1 describes, the complete interconnection between the magnetospheric and the interplanetary field. The model is valid for the field-line topology on the dayside including the polar cusp region. The position of the polar cusp's equatorial edge depends on the actual value of the merging constant C 0 and the orientation of the interplanetary magnetic field. Plasma-physical effects enter the model implicitly by the fact that a magnetopause shields the solar wind from the magnetospheric cavity. The static model neglects the hydrodynamic behaviour of the field-line merging process.