A cloud workshop was held from 6-8 July 2005 at Fort Collins, Colorado. In this workshop, all the key outstanding problems of prognostic cloud-parameterization and cloud-radiation interactions were discussed. Dr. Yogesh Sud (Code 613.2) presented some recent upgrades to McRAS, a cloud scheme in use in the Climate and Radiation Branch, as well as some new methodologies currently being evaluated to extract number density and dropsize distribution of cloud particles from first principles of physics of nucleating condensation under the influence of vertical motion.

Dr. Sud also discussed the feasibility of use of Kohler's equation for activating aerosols as a cloud condensation nuclei within the Nenes scheme of parameterizing aerosols in GCMs; specifically, aerosol population splitting hypothesis for varying the droplet growth. Some single-column model test results were shown at the meeting that suggest a realistic solution to number density of cloud particulates as compared to the empirical aerosol activation methods used by the modeling community at large.

(submitted by Yogesh Sud)