Remote sensing of cirrus cloud parameters using AVHRR data

Abstract

We have developed a retrieval scheme for the inference of the emissivity and temperature of cirrus clouds using the data obtained from the advanced very high resolution radiometer (AVHRR) 3.7 and 10.9 micrometers channels. The scheme, which is applicable to the entire day, is based on the numerical solution of a set of nonlinear algebraic equations that are derived from the theory and parameterizations of infrared radiative transfer. The solution involves an effective extinction ratio for the two wavelengths, which is dependent on ice crystal size distribution. Based on radiative transfer calculations and cloud physics observations, the cloud optical depth and the ice crystal size distribution in terms of mean effective size can be determined from cloud emissivity and cloud temperature, respectively.