Comparisons between Model Forecast and Observed Boundary Layer Profiles and Related Comments on Cloud Prediction

In this study comparisons are made between Met Office mesoscale model boundary layer profiles, and radiosonde data collected in the central United Kingdom during three intensive boundary layer cloud experiments. Significant differences between forecast and observed profiles were found. An assessment of whether these differences are dominated by sonde random error or model error is performed. Results suggest that sonde random errors are insignificant for stratocumulus fields, but not for cumulus ones. Results show that model fields do not represent the fine vertical structure seen in the observations. The impact of this result for cloud prediction is discussed, and an estimate for the vertical resolution required to adequately parameterize the cloud field is provided.