Identifying 3D Radiative Cloud Effects Via Derived Distributions of Liquid Water Path That Conserve MODIS Visible Reflectance Measurements

Abstract:

Cloud feedback processes are one of the dominant causes for variability among general circulation models. The poor simulation of in-cloud microphysical properties causes much of this variability due to treating these properties as homogenous. Studies have shown that shortwave albedo of clouds is sensitive to variability of in-cloud liquid water. A method developed by Foster et al., 2011 derives distributions of cloud liquid water path over partially cloudy scenes while conserving the total-scene reflectance. Potential uses of this include generating model validation datasets and facilitating satellite record inter-comparison studies. This study explores another use: identifying and quantifying cloud 3D effects. This methodology has been applied to MODIS AQUA and TERRA satellites for the duration of their records over a selection of ocean regions. Initial findings include, seasonal and geographical patterns in the efficiency of the methods in the North Pacific, South Pacific, and South Atlantic. This study investigates whether areas where the method works best correspond with significant 3D cloud effects. Sensitivity to spatial and temporal variables such as geography, seasonality, cloudiness, viewing geometry, and distributions of cloud microphysical properties is also studied. Initial results from 3D radiative transfer simulations from the I3RC will be presented.