A new method for retrieving equivalent cloud base height and equivalent emissivity by using ground-based high-resolution infrared radiance

Abstract

Based on the ground-based high-resolution infrared radiances observed by the Atmospheric Emitted Radiance Interferometer (AERI), a new method is proposed to identify the clear sky. Meanwhile, we also develop the new algorithms for retrieving the zenith equivalent cloud base height (CBHe) and the equivalent emissivity (εe), respectively. The retrieval results in Shouxian indicate that the differences between the CBHe and observational cloud base height (CBH) are much smaller for thick low cloud, and increase with the increasing CBH. The average εe for the low, middle, and high cloud is 0.967, 0.781, and 0.616 for the 50 cases, respectively. It decreases with the increasing CBH. The new methods will be useful for studying the role of cloud in the radiation budget in the window region and cloud parameterizations in the climate model.