Hall MHD in the Magnetopause with OpenGGCM

Abstract:

Dayside magnetic reconnection plays a major role in the global dynamics of the magnetosphere as it interacts with the solar wind. Global MHD simulations typically use finite resistivity to mediate reconnection; however, in realistic parameters, resistive scales are significantly smaller than ion scales. Previously, 2-D studies have shown that including ion scale physics through the Hall term in the generalized Ohm's law can dramatically alter dynamics and reconnection rates when compared with resistive MHD models. In this study, we use OpenGGCM to investigate magnetopause reconnection at high Lundquist numbers with synthetic solar wind conditions. OpenGGCM has recently been extended to include a van-Leer constrained-transport numerical scheme (Stone 2008) similar to that used in the Athena code. We compare global simulations with asymmetric 2-D cases where, unlike in the magnetopause, flux tubes are not free to advect around the diffusion region. We also show how the Hall term affects the structure of flux transfer events.