PNNL

Abstract

Both individual and combined effects of the horizontal and vertical variability of cumulus clouds on solar radiative transfer were investigated using a two-dimensional (x- and z-directions) cloud radar dataset. This high-resolution dataset of typical fair-weather marine cumulus was derived from ground-based 94-GHz cloud radar observations. The domain-averaged (along x-direction) radiative properties were computed by a Monte Carlo method. It is shown that (i) different cloud-scale resolutions can be used for accurate calculations of the mean absorption, upward and downward fluxes; (ii) the resolution effects can depend strongly on the solar zenith angle; and (iii) a few cloud statistics can be successfully applied for calculating the averaged radiative properties.