Initial results from the coupled magnetosphere ionosphere thermosphere model: magnetospheric and ionospheric responses

The Center for Integrated Space Weather Modeling (CISM) is developing a simulation package of the coupled Sun-Earth system by connecting existing models within each region. The Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model combines the Lyon-Fedder-Mobarry global magnetohydrodynamic (MHD) magnetospheric (LFM) model with the Thermosphere Ionosphere Nested Grid (TING) model. The LFM uses the ideal MHD equations to model the interaction between the magnetospheric plasma and the solar wind. It includes the magnetosphere-ionosphere interaction by requiring the conservation of current flowing between the magnetosphere and a two dimensional ionosphere. TING is a three dimensional code designed to simulate the thermosphere-ionosphere system by solving the mass, momentum, and thermodynamic energy equations for the global thermosphere and ionosphere. Normally, TING uses parameterized models to describe the magnetospheric input into the ionosphere. We begin this paper with a description of how the TING model is used to replace the simple two dimensional ionosphere within the LFM to produce the CISM CMIT Model. The results from the coupled model for a series of steady IMF conditions are compared with the results from the LFM to show that these models have been successfully combined. The problem of high cross polar cap potentials remains, but the structure of the magnetosphere is not dramatically altered by the coupling and the ionospheric conductances show a more realistic distribution driven by EUV radiation as well as a more clearly defined auroral oval. (C) 2004 Elsevier Ltd. All rights reserved.