A New Parameterization Scheme for Shortwave Radiative Properties of Water Clouds

Abstract

A new parameterization scheme for the shortwave radiative properties of water clouds is presented, using versatile cloud drop size distributions ( DSDs). As for single-scattering properties, a new parameterization for cloud optical thickness is proposed by using the separation of the dependence of r on the total number of theDSDs, the cloud thickness, and the liquid water content, combined with equivalent radius. The cloud bulk radiative properties are obtained from the delta-Eddington approximation for our cloud models. It is shown that the flux reflectivity, transmissivity, and absorptivity are uniquely fitted by a dimensionless parameter X or the cloud optical thickness 7. The parameterization is compared with other schemes. The features and potential use of the scheme are discussed.