This grant will promote the diagnosis and understanding of the behavior of global climate models in polar regions. The diagnostic tasks will complement upcoming Arctic field programs (SHEBA, ARM), driven by the need to narrow the uncertainties in model simulations of climate change. Research will draw upon daily output of a set of global climate models to (1) assess the Arctic cloud-radiation-temperature associations in the model simulations, permitting direct comparisons with results of the field measurements, (2) determine the frequency and spatial distribution of extreme events in the atmospheric model simulations, and (3) determine the contribution of surface winds to apparent biases in simulated evapotranspiration over polar surfaces. In addition, the PI will compose a review paper synthesizing many recent sea ice sensitivity experiments with global climate models to identify priorities for improving the treatment of sea ice in climate models. The research is important because it will increase understanding of climate processes in polar regions, as well as improve our ability to simulate these processes with mathematical/physical models.