Challenges in Modeling the Coupled Magnetosphere-Ionosphere-Thermosphere-Mesosphere System

The success of the Center for Integrated Space Weather Modeling (CISM) depends on the production of an ever-improving series of comprehensive scientific models describing the Solar Terrestrial environment from the solar surface to the upper atmosphere of earth. This requires us to combine existing codes developed to model separate regions and processes to into cohesive models. We require technical solutions capable of the efficient transmission of information among codes, interpolation of quantities between different grids, translation of physical variables between codes with differing physical models, and control mechanisms to synchronize the interaction of codes. We also need to handle the scientific aspects of the interaction of codes with very different physics models, for example, the very different thermodynamic models used in coronal and solar wind codes. We illustrate these challenges we face and our approach toward meeting them from the perspective of our Geospace coupling efforts involving the combination of the Lyon-Fedder-Mobarry (LFM) code, the Rice Convection Model (RCM) code, and the Thermosphere-Ionosphere Nested Grid model (TING). [This work is supported by NSF grant ATM-0120950 and NASA grant NAG5-12652].