Fast radiative transfer codes for infrared imaging radiometry: applications to cirrus clouds

Fast radiative transfer codes have been developed for simulating outgoing radiances to be measured by the Infrared Imaging Radiometer (IIR) of the space mission CALIPSO. Their performance is presented in terms of accuracy. One main objective of the IIR mission concerns cloud characterization and radiative codes have been developed to account for scattering and absorbing effects. Comparisons with a reference code have shown that the accuracy of the codes is about 0.2 K on brightness temperatures. This accuracy is adequate for IIR data analysis. Codes have been applied for the retrieval of cirrus cloud properties.