Influence of the gaseous atmosphere on solar fluxes of inhomogeneous clouds

The influence of spatially inhomogeneous water vapour distributions on the solar radiative fluxes of inhomogeneous clouds has been estimated by means of Monte Carlo radiative transfer calculations and line by line calculation s for transmission at water vapour and oxygen. 96 cloud realizations obtain ed by the atmospheric model GESIMA have been considered for the following c ases: 1) Clouds embedded in a 3d inhomogeneous gas atmosphere and 2) clouds embedded in a stratified gas atmosphere. The resulting differences in sola r broadband radiative fluxes appear to be neglectable. Thus, a stratified g aseous atmosphere seems sufficiently adequate for solar radiative transfer calculations. The reasons for these small differences are basically due to the strong correlation between cloud optical thickness and water vapour den sity as produced by the cloud model used in this study. (C) 2000 Elsevier S cience Ltd. All rights reserved.