Parameterization of microphysics in cumulus convective clouds

I will show results of a new cumulus microphysical parameterization which is an expansion of the Khairoutdinov and Kogan (KK) parameterization previously developed for low layer stratocumulus clouds. The cumulus convective clouds are dynamically more vigorous and exhibit a much broader range of cloud parameters relative to boundary layer stratocumulus. Because of their prevalence over much of the subtropical and tropical oceans, they play an important role in the energy balance of the climate system. The development and testing of the cumulus convection parameterization was based on the CIMMS LES model (SAMEX) using observations of a trade wind cumulus convective cloud system during RICO field campaign and a drizzling stratocumulus cloud boundary layer during ASTEX project. The new formulation of autoconversion and accretion rates, and accounting for selfcollection process resulted in a significantly enhanced rain production compared to the KK formulation. I will present results of the tests of the new parameterization, and describe a PDF based approach to apply parameterization in large scale models. The results of testing various PDF formulations will also be presented.