Global MHD simulations: Magnetosphere – Ionosphere Coupling Dependence on Conductance Model

Eighty-five geomagnetic storms were simulated with the SWMF Geospace model using two different ionospheric conductance models. One set used the legacy conductances within the Ridley ionosphere model, while the other set used the newly-developed CMEE conductance model. As input and other model setup parameters were identical, we use this unique simulation suite to assess the impacts of ionospheric conductance on the ionospheric and magnetotail state during magnetic storms. The results show that higher conductance somewhat improves predictions of ground magnetic disturbances, as measured by the AL index. The cross-polar cap potential was lower for higher ionospheric conductance. In the magnetotail, higher ionospheric conductivity led to slightly lower ring current intensity and weakened Earthward flows, while the tail current magnitude was relatively insensitive to the conductance model. These results are an important step in understanding how the ionosphere impacts the magnetospheric state and the magnetosphere – ionosphere coupling.