A comparison of four-stream approximations for the radiative flux calculations

The four-stream discrete ordinates method and the four-stream successive orders of scattering method are compared for the radiative flux calculations in this paper. With the Rayleigh scattering phase function and the Henyey-Greenstein phase function, the effects of the two four-stream method are investigated. The delta-M method is used to deal with the strong forward-peaked scattering and the 3 2-stream DISORT is used as the benchmark for assessments of the relative accuracy of the two methods. With the comparisons for the accuracy of flux, the two four-stream methods are roughly comparable in accuracy and the absorbing media lead to larger errors of flux compared with that of the non-absorbing case.