P2.32 An intercomparison of MODIS-derived and WRF-simulated cloud data for an intense extratropical cyclone

Wednesday, 27 June 2007
Summit C (The Yarrow Resort Hotel and Conference Center)
Jason A. Otkin, CIMSS/Univ. of Wisconsin, Madison, WI; and T. Greenwald

Sophisticated numerical weather prediction models, such as the Weather Research and Forecasting (WRF) model, are routinely used today to perform very high-resolution model simulations. Cloud microphysical and planetary boundary layer parameterization schemes currently available in the WRF model contain varying levels of complexity, which can directly impact the accuracy of the model-simulated cloud and thermodynamic fields. Validation of high-resolution model output is notoriously difficult, however, due to a lack of high-quality in-situ observations with the appropriate spatial and temporal resolution. Cloud data derived from satellite radiances can partially fill this void by providing reasonable estimates of bulk cloud properties, such as cloud top pressure and cloud optical thickness.

For this study, eight WRF model simulations of an intense extratropical cyclone over the North Atlantic Ocean were performed using different combinations of cloud microphysical and planetary boundary layer schemes. Cloud data from each simulation was subsequently compared to cloud products from three Moderate-resolution Infrared Sounder (MODIS) overpasses in order to assess the ability of each parameterization scheme to realistically simulate the observed cloud features. Preliminary results indicate that the various simulations captured the observed cloud water path frequency distribution reasonably well with larger differences evident in the cloud optical thickness distributions. Overall, the more sophisticated schemes generally outperformed the less sophisticated schemes.

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