Development and Evaluation of a Shortwave Full-Spectrum Correlated K- Distribution Radiative Transfer Algorithm for Numerical Weather Prediction

摘要

The Full Spectrum Correlated k-distribution (FSCK) method, originally developed for applications in combustion systems, is adapted for use in shortwave atmospheric radiative transfer. By weighting k-distributions by the solar source function, the FSCK method eliminates the requirement that the Planck function be constant over a spectral interval. Consequently, integration may be carried out across the full spectrum as long as the assumption of correlation from one atmospheric level to the next remains valid. Errors resulting from the lack of correlation across the full spectrum are removed by partitioning the spectrum at a wavelength of 0.68 m into two bands. The resulting two-band approach in the FSCK formalism requires only 15 quadrature points per atmospheric layer. This represents a 40 90% reduction in computation time relative to existing correlated k-distribution models.