Effects of 3-D clouds on atmospheric transmission of solar radiation: Cloud type dependencies inferred from A-train satellite data

Three-dimensional (3-D) effects on broadband shortwave top of atmosphere (TOA) nadir radiance, atmospheric absorption, and surface irradiance are examined using 3-D cloud fields obtained from one hour's worth of A-train satellite observations and one-dimensional (1-D) independent column approximation (ICA) and full 3-D radiative transfer simulations. The 3-D minus ICA differences in TOA nadir radiance multiplied by , atmospheric absorption, and surface downwelling irradiance, denoted as I, A, and T, respectively, are analyzed by cloud type. At the 1 km pixel scale, I, A, and T exhibit poor spatial correlation. Once averaged with a moving window, however, better linear relationships among I, A, and T emerge, especially for moving windows larger than 5km and large (0). While cloud properties and solar geometry are shown to influence the relationships amongst I, A, and T, once they are separated by cloud type, their linear relationships become much stronger. This suggests that ICA biases in surface irradiance and atmospheric absorption can be approximated based on ICA biases in nadir radiance as a function of cloud type. Key Points The 3-D minus ICA irradiance is obtained at TOA, atmosphere, and surface level For larger scale, linear relationships emerge among the three difference terms Cloud type determines the relationships among the three difference terms