A new magnetosphere-ionosphere coupling scheme for temporal and global magnetospheric MHD simulations

We describe a new process of the magnetosphere-ionosphere (MI) coupling for global MHD simulations. In the MI coupling process, field-aligned currents and electric potentials interact with each other in the region between the ionosphere and the inner boundary of the magnetosphere. In order to examine these field-aligned currents and electric potentials selfconsistently, we consider the boundary condition as a problem of wave reflection, assuming that the changing of field-aligned currents as a result of MI-coupling process is associated with the reflection of shear Alfven waves. Separating the perturbed components from the correct solutions, the equation of current continuity of these components is considered. Then we determine the perturbed components generated by the MI coupling. Since the perturbed components of the electric potentials are associated with the reflected shear Alfven wave, we can describe a spatiotemporal development of ionospheric potential as summation of reflection processes of shear Alfven wave at the inner boundary, and then the new process is applicable to the general problems of the MI coupling