Propagation of sudden impulses in the magnetosphere: Linear and nonlinear waves

Dynamics of MHD wave propagation is studied in the magnetosphere when strong initial impulses are assumed at the magnetopause. In a linear wave approximation, we will present simulations results, which show the strong effects of refraction in the magnetosphere. In a nonlinear approximation, we adopt the approach of simple waves which is often used in ordinary fluids. We obtain an exact MHD solution for the velocity profile in space and time when arbitrary initial perturbations are assumed in a simplified model.