Plane - Parallel canopy radiation transfer modeling: Recent advances and future directions

Abstract

Canopy radiative transfer (RT) modeling provides the basis for vegetation bidirectional reflectance distribution function (BRDF) modeling studies. RT models based on plane-parallel geometry have been increasingly used in vegetation remote sensing due to their reasonable balance between accuracy of representing the reality and computational simplicity. In this paper, the evolution of canopy RT modeling is examined with the emphasis on reviewing the recent advances in model development, inversion and application. The most significant advances in vegetation RT modeling in recent years are concisely summarized, which include considerations of the finite-dimension of canopy elements, canopy hotspot effect, nonleaf canopy elements and nonrandom dispersion of foliage elements, and coupled atmosphere-canopy formulations. Various applications of canopy RT models are also reviewed in terms of model inversion, RT model aided design of optimal vegetation index, elimination of the angular effects on remotely sensed data with RT models, and calculation of vegetated land surface albedo. The issues on both modeling and application and priorities in the future are finally discussed and some recommendations are also made.