INVERSION OF MONTE-CARLO MODEL FOR ESTIMATING VEGETATION CANOPY PARAMETERS

The Monte Carlo technique for estimating model parameters is presented. The bidirectional reflectance factor is calculated by the Monte Carlo method of solving the integral equation of radiation transfer in plant canopies. A general inversion technique for the estimation of canopy parameters is considered. The method of calculating derivatives of the bidirectional reflectance factor with respect to unknown parameters using the same photon trajectories as in the solution of the direct problem is developed. The leaf dimensions are taken into account using a new extinction coefficient. Finally, numerical results for estimating three optical canopy parameters (coefficients of leaf reflectance, transmittance, and soil albedo) and four geometrical canopy parameters (leaf area index, two parameters of leaf angle distribution functions, and leaf size parameter) are briefly discussed.