Initial results from the coupled magnetosphere-ionosphere-thermosphere model: thermosphere-ionosphere responses

The thermosphere-ionosphere nested grid (TING) model has been successfully coupled with the Lyon-Fedder-Mobarry (LFM) global magnetosphere MHD code. The coupling between these models is two-way: the LFM provides the TING model with global electric fields and precipitating electron energy fluxes, and the TING model feeds ionospheric conductances back to the LFM. This code coupling enables studies of the global energy budget of the magnetosphere-ionosphere-thermosphere system. In this paper, we present simulation results from the coupled magnetosphere-ionosphere-thermosphere (CMIT) model under solar minimum, northern hemisphere summer conditions. The IMF input to the CMIT model changed its direction every 4 h. Comparisons are made between the simulated results of the CMIT model and those of the stand-alone TING model. It is found that the CMIT model predicted higher cross polar cap potential drops than the empirical model used by the stand-alone TING model. The energy input to the upper atmosphere by precipitating electrons, however, was much lower in the CMIT model during the southward IMF interval. The simulated responses of the thermosphere and ionosphere were also significantly different, As a result of the greater Joule heating calculated in the CMIT model, neutral temperatures and winds were significantly enhanced in the CMIT model in comparison with the stand-alone TING model. (C) 2004 Elsevier Ltd. All rights reserved.