Abstract The widely used δ ‐Eddington approximation improves the accuracy of radiative transfer calculations by representing the fraction of scattering into the forward peak as the square of the asymmetry factor. However, in systems composed of multiple optical components, such as gases, aerosols, and clouds, the appropriate formulation for this forward‐scattering fraction has not yet been fully clarified. Current climate models typically adopt an additive treatment of component‐wise forward‐scattering contributions. This study proposes a physically consistent aggregated‐scaling method that determines the forward‐scattering fraction based on the collective optical properties of the entire medium. Applied to realistic atmospheric profiles incorporating gas absorption, Rayleigh scattering, aerosols, and clouds, the new method reduces the root‐mean‐square error in shortwave boundary flux up to 10.1%. This improvement enhances the accuracy of radiation calculation for Earth's energy budget.
Li et al. (Fri,) studied this question.