Parameterization of Ice Growth for Numerical Calculations of Cloud Dynamics

Abstract

Parametric equations describing the growth of ice particles in the range 10?11?1 g are presented. Three subranges (10?11?5 ? 10?8, 5 ? 10?8?10?4, and 10?4?1 g) are used. The parametric equations were developed with the aid of a complex method of calculating ice-particle growth. Two approaches to using the parametric equations in a simulation resembling a natural cloud situation are described. One method breaks the ice-particle spectrum into three components, the sizes of each being monitored. The other assumes a size distribution that can be characterized by a ?growth-median? size, so that only one size need be monitored to describe the rate of growth. The parametric method is compared with more complicated methods in a simulated cloud environment, and the results are regarded as satisfactory.