Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5429573 | Journal of Quantitative Spectroscopy and Radiative Transfer | 2011 | 8 Pages |
Global climate models require accurate and rapid computation of the radiative transfer through the atmosphere. Correlated-k methods are often used. One of the approximations used in correlated-k models is the weak-line approximation. We introduce an approximation Tγ which reduces to the weak-line limit when optical depths are small, and captures the deviation from the weak-line limit as the extinction deviates from the weak-line limit. This approximation is constructed to match the first two moments of the gamma distribution to the k-distribution of the transmission. We compare the errors of the weak-line approximation with Tγ in the context of a water vapor spectrum. The extension Tγ is more accurate and converges more rapidly than the weak-line approximation.
Research highlights⺠An alternative to the weak-line limit is provided. âºThis alternative reduces to the weak-line limit when the path length is small. âºThis alternative provides a better estimate of transmission for a larger range of path lengths than the weak-line limit.