Extended MHD and Coupled Fluid-Kinetic Simulations of Planetary Magnetospheres: Applications to Mercury and Ganymede

Global simulations have become an invaluable tool in planetary magnetosphere studies, aiding in interpreting satellite observations, uncovering new physics and processes, and generally deepening our understanding of the basic behavior of the magnetosphere. Because of their relatively large system sizes, planetary magnetospheres are normally simulated with ideal magnetohydrodynamics (MHD) models, treating plasma ions and electrons as a combined fluid. Nevertheless, proper treatment of key processes occurring in planetary magnetospheres, like magnetic reconnection, calls for global models that go beyond the ideal MHD approach. Towards this end, the Space Weather Modeling Framework (SWMF) modeling group at the University of Michigan have recently developed a variety of extended MHD models and coupled fluid-kinetic models that allow us to capture kinetic effects in global magnetosphere simulations. In this presentation, we will focus on the application of these sophisticated models to Mercury and Ganymede. We will use these examples to demonstrate our novel modeling capabilities and discuss the new physical insights gained through the simulations into reconnection-driven dynamics and its consequences on the global coupling between the ambient plasma and the magnetosphere.