MAPPING TRANSFORMATIONS FOR BROAD-BAND ATMOSPHERIC RADIATION CALCULATIONS

We describe two methods of mapping the line-by-line absorption coefficient (k) spectrum onto a new variable to produce a set of k coefficients which can be used for accurate and efficient broadband radiative transfer calculations in vertically inhomogenous, non-gray scattering atmospheres. These methods are intended for applications for which the less accurate correlated-k method is inadequate. We tested these methods for model atmospheres containing CO2 and H2O, with pressure in the range 0.05-0.9 bar. We obtained results that differed by no more than 1 or 2% from the line-by-line results if the number of k coefficients was about 100 times less than the number required for the line-by-line calculation. These algorithms can be used for gas mixtures and for a variety of pressure-temperature profiles. © 1990.