Fast and Accurate Infrared Radiative Transfer Calculation Method in Gaseous Atmospheres

This paper presents the ℓ-distributions method for calculating the gaseous absorption in inhomogeneous atmospheres. The tropical, midlatitude summer, midlatitude winter and US standard atmosphere profiles providing the volume mixing ratio of 28 gaseous molecules are studied. Using the standard line-by-line calculation results as benchmark, the accuracy of the method is evaluated and compared to the correlated k- distributions method. For various observation angles, results indicate that the maximum absolute errors are less than 2.5% in spectral transmissivity. These errors can reach 20% and 10% with the correlated k-distributions method at 16 and 32 Gaussian quadrature points, respectively. Using an Intel Xeon W1250P 4.10Ghz computer, the computational time of the method is about 6 seconds per model studied.