Reflected fluxes for broken clouds over a lambertian surface

Abstract

The present study demonstrates that not only radiances but also radiative fluxes over high albedo surfaces may be decreased by the presence of broken cloudiness. Most cloud retrieval schemes are built around the assumption that cloud radiances (brightnesses) are always greater than the background, it is incorrect for clouds over high albedo surfaces such as found in polar regions. However, nonabsorbing finite clouds over a highly reflecting surface will decrease the system albedo. As a result, surface absorption is increased, the result of multiple scattering between surface and cloud layer, controlled by cloud morphology and cloud optical thickness. A simple parameterization of the effects of cloud contamination upon retrieved albedo is given in terms of solar zenith angle, cloud optical depth, surface albedo, cloud cover, and plane-parallel cloud albedo. -from Authors