Application of the spectrally integrated Voigt function to line-by-line radiative transfer modelling

We show that a new approach based on the spectrally integrated Voigt function (SIVF) enables the computation of line-by-line (LBL) radiative transfer at reduced spectral resolution without loss of accuracy. The algorithm provides rapid and accurate computation of area under the Voigt function in a way that preserves spectral radiance and, consequently, radiant intensity. The error analysis we provide shows the high-accuracy of the proposed SIVF approximations. A comparison of the performance of the method with that of the traditional LBL approach is presented. Motivations for the use and advantage of the SIVF as a replacement for conventional line function computations in radiative transfer are discussed. -- Highlights: •The spectrally integrated Voigt function is applied to radiative transfer. •An algorithm for the rapid and accurate computation of the integrated is described. •The traditional line function is replaced improving efficiency and accuracy. •The efficient computation of radiance is enabled at reduced spectral resolution. •Computational testing and an error analysis illustrate algorithmic performance