During SHEBA, special output was obtained from the ECMWF forecast model over the SHEBA ice camp, including short range (12-36 hour) predictions of cloud and precipitation properties, surface temperature and radiation, and boundary layer structure. Since the ECMWF model has a sophisticated suite of physical parameterizations that have not been extensively tested against Arctic data, and since SHEBA soundings were assimilated into the model to ensure that the basic thermodynamic structure of the atmosphere was correctly maintained, the data taken during SHEBA represent a rigorous test of the model's ability to correctly reproduce cloud, precipitation and boundary layer structure.
We present comprehensive comparison of the model with selected data taken mainly during November 1997. This includes surface temperature, heat and radiation flux, cloud phase (from lidar), and cloud presence and reflectivity (from mm-wavelength radar). In general the model performs remarkably well, but we show deficiencies in the surface temperature prediction (due to an overly simple ice model) and cloud prediction (due to the model's microphysical assumptions) and discuss how these are being used to improve ECMWF's forecast model for Arctic conditions.