Principal Component Analysis of Simulated and Measured Upwelling Cloudy-sky Radiances over Antarctica

Accurate climate modeling relies on an understanding of the interactions of clouds with radiation. Other studies have used principal component and empirical orthogonal function analysis of simulated and measured radiances to determine the sensitivity of top of atmosphere radiance to cloud properties. A similar analysis is presented here for both ice and liquid clouds for atmospheric and surface-emissivity conditions typical of the Antarctic. Simulations were performed for a variety of cloud effective radii, liquid and ice water paths, cloud temperatures and optical depths. The principal components of the simulated data are compared to those of measurements made by the Interferometric Monitor for Greenhouse Gases (IMG) over Antarctica from 1996 to 1997 to infer the origin of cloud variability for this dataset.