Abstract

A fast and numerically accurate model for monochromatic radiative transfer in scattering atmospheres has been developed to extend the capabilities of the existing LBLRTM line-by-line model [Clough et al., 1992] to the treatment of clouds and aerosols. The algorithm is based on the adding-doubling method and is specifically designed to perform radiance calculations in both the thermal and solar regimes using any specified number of computational streams. The efficient implementation of the adding-doubling scheme makes it possible to use the multiple-scattering algorithm in retrieval applications, an essential requirement for the intended use of the algorithm in atmospheric validation studies. The algorithm is applied to daytime observations of water clouds from the ground-based high spectral resolution Atmospheric Emitted Radiance Interferometer (AERI) [Smith et al., 1995]. Cloud particle size and density, and cloud fraction are retrieved from the spectral measurements in the 520-1500 cm^-1 and 1800-3020 cm^-1 bands. An initial assessment is made of the spectral information content of the AERI measurements for water cloud properties, and of the quality of the spectral fits obtainable with those three free parameters in the two bands.

© 1997 Optical Society of America