Photon transport in vegetation canopies with anisotropic scattering Part II. Discrete-ordinates/exact-kernel technique for one-angle photon transport in slab geometry

Abstract

In this paper, we discuss a computational technique for photon transport in vegetation canopies involving anisotropic scattering. The exact kernel technique eliminates the need for finite Legendre polynomial expansions and thus the inherent expansion errors. The scattering phase function (see Part I) now takes the form of a transfer matrix, whose elements are the actual phase function evaluated at discrete quadrature angles. To use the non-expanded scattering cross-sections in transport calculations, a modified discrete-ordinates method is formulated. The proposed method is tested for energy conservation and its results are compared with tabulated (reflection and transmission) functions of some standard solutions in atmospheric photon transport studies. Finally, the method was used to study the one-angle problem of photon transport in vegetation canopies.