The delta-Eddington approximation for radiative flux transfer

摘要: Abstract This paper presents a rapid yet accurate method, the “delta-Eddington” approximation, for calculating monochromatic radiative fluxes in an absorbing-scattering atmosphere. By combining Dirac delta function and two-term it overcomes poor accuracy of Eddington approximation highly asymmetric phase functions. The fraction scattering into truncated forward peak is taken proportional to square asymmetry factor, which distinguishes delta-Eddington from others similar nature. Comparisons albedos, transnmissivities absorptivities with more exact calculations reveal typical differences 0–0.022 maximum 0.15 over wide ranges optical depth, sun angle, surface albedo, single-scattering albedo asymmetry. Delta-Eddington are error, on average, by no than 0.5%0, at 2% incident flux. computationally fa...