The objective of the proposed study in Phase II is to develop a novel, logical and coherent algorithm which will provide the specialized cloud information required for an accurate assessment of radiance degradation under typical cirrus cloud conditions, using data gathered from satellites. The proposed program includes (1) synthetic analyses for the retrieval of temperature, emissivity and fractional cover of cirrus clouds from NOAA AVHRR channels based on the theory of radiative transfer, (2) removal of 3.7 micrometer solar radiances during daytime based on 0.63 micrometer channel radiances and radiative transfer parameterizations, (3) application and verification of the cirrus retrieval algorithm to selected AVHRR data, and (4) preparation of computer software for the cirrus retrieval algorithm and ice crystal extinction program. Once the cirrus cloud temperature is retrieved, mean ice crystal size distribution can be computed from the light-scattering programs developed for hexagonal particles. It is anticipated that the end-product of Phase II will be a module in equation forms and in appropriate computer codes for spectral cirrus cloud extinction, using the cirrusparameters inferred from an effective satellite retrieval algorithm.
