Parameterizations of condensational growth of droplets for use in general circulation models

The first scheme developed here is based on theory and numerical calculations of droplet condensational growth, while the second is based on Twomey's analytical approach. Both methods are evaluated against detailed model calculations, and a method for implementing either scheme in general circulation models and remote sensing applications is described. The new parameterization produces accurate (within a few percent) estimates of the effective droplet radius as a function of height, while the cloud optical thickness compares favorably (often to within <10%) with the model calculations. Twomey's scheme gives reasonable estimates of optical thickenss, but tends to underestimate the droplet concentration and overestimate the effective radius for typical maritime and continental CCN spectra. -from Authors