New Cloud-radiation and Hydrologic Cycle Parameterizations

The availability of new observational data from field programs has yielded new insights into the relationships between cloud microphysics and cloud radiative effects. Tests in single-column mode, carried out in the maritime tropics, in polar regions, and in mid-latitudes, have shown that parameterizations based on these new results can significantly reduce typical model biases in cloud-modulated fields such as surface insolation. One fruitful strategy for evaluating advances in GCM parameterizations is to use short-range numerical weather prediction (NWP) as a testbed within which to implement and improve parameterizations for modeling and predicting climate variability. The work reported here consists of three distinct elements. One element involves the development of new parameterizations for improved treatment of cloud-radiation interactions. A second element concentrates on using a single-column model, which is a process-oriented or phenomenological model, for direct evaluation of the parameterizations against measurements. The third element involves testing the parameterizations in operational NWP models and in a range of GCMs.