关键词: 垂直非均一云, SBDART, 短波辐射强迫, 浅积云

Abstract: Large eddy simulations were used to get profiles of liquid water content and droplet effective radius in shallow cumulus clouds. Results show that both liquid water content and droplet effective radius increase with height (vertically inhomogeneous). Then the atmospheric radiative transfer model SBDART were used to study the effects of vertical distributions of microphysical properties on radiative transfer. The shortwave radiative forcings from a vertically inhomogeneous cloud and a vertically homogeneous cloud with the same liquid water path were compared. Results indicate that vertical distributions of microphysical properties have significant effects on radiative transfer. When droplet effective radius of the vertically homogeneous cloud is equal to 76% -90% of the cloud-top droplet effective radius in a vertically inhomogeneous cloud, the two clouds have similar radiatve forcing. This means that in global climate models, the assumption of vertical homogeneity of a cloud must be used carefully and the associated droplet effective radius must be about 76% -90% of the observed value at cloud top for shallow cumulus clouds. Results in this study are consistent with previous studies for stratified clouds.

Key words: vertically inhomogeneous clouds, SBDART, shortwave radiative forcing , shallow cumulus clouds