A new method for global magnetosphere simulations: an implicit scheme with limited numerical diffusion

We are introducing a new scheme to model the global magnetosphere with less numerical diffusion. The new scheme combines the stability of an implicit solver with a limited diffusive numerical flux. The new scheme is an alternative to the standard "Boris correction" that solves the semi-relativistic MHD equations with an artificially reduced speed of light. While the Boris correction is an efficient and well established method, it changes the time dependent behavior of the equations, since it artificially reduces the propagation speeds. The new scheme on the other hand does not modify the physics, only the numerical algorithm. We are comparing the limited numerical diffusion scheme with the Boris correction for idealized problems as well as for magnetic storm simulations.