Modified correlated k-distribution methods for remote sensing applications

In this paper we discuss the application of correlated k-distribution metho ds for the computation of radiative transfer through the atmosphere in the visible, near IR, and IR spectral regions. Whereas the correlated k-distrib ution is a good approximation overall to line-by-line calculations, it is i naccurate in regions of strong absorber overlap. Several approaches (band s plitting, strength-based splitting, double and triple correlated k) are pro posed to modify the conventional correlated k-distribution and improve its predictions in these regions of absorber line overlap. A comparison with li ne-by-line computations in the infrared spectral region demonstrates that a combination of these methods produces brightness temperatures within less than 0.25 K of those obtained from line-by-line computations at significant ly less computation costs. In the visible and near IR, when atmospheric sca ttering is included, the new treatment of overlapping mixed gases also prod uces excellent agreement with the line-by-line model. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.