A new parameterization of canopy radiative transfer for land surface radiation models

Abstract

A new parameterization of canopy asymmetry factor on phase function, which is dependent on the leaf normal distribution and leaf reflection/transmission, is derived. This new parameterization is much more accurate than the existing scheme. In addition, the new solutions for both the diffuse and direct radiation can be obtained using the Eddington approximation. It is found that the direct radiation can be described as a function of the diffuse radiation. This new approach offers a substantial improvement in accuracy, as compared with the hemispheric constant method, for both isotropic and anisotropic cases. Given the analytical nature of the solution and its high accuracy, we recommend the new parameterization for application in land surface radiation modeling.