Limitations of global MHD models of the Earth's magnetosphere

Global MHD models are an important asset in the collection of models that forecast and specify space weather effects in the near-Earth space environment. To further improve space weather forecasting accuracy, it is necessary to not only improve skill scores in a variety of model-data comparisons but also improve the models' performance by comparing model results with expectations derived from fundamental physics principles. For example, ideal MHD models are expected to have the same electric potential on conjugate foot points of closed magnetic field lines. We test the degree of non-idealness in 4 global MHD models (SWMF, OpenGGCM, LFM and GUMICS) at the Community Coordinated Modeling Center using magnetosphere-ionosphere mapping tools. Field-line resonances seen at ULF wave frequencies are another challenge where model responses can be measured. The analysis of the causes of disagreements between models and between models and observations can be used to improve the way models are run in the community (through the CCMC and elsewhere).