AN ITERATIVE INVERSION ALGORITHM WITH APPLICATION TO THE POLARIMETRICRADAR RESPONSE OF VEGETATION CANOPIES

The retrieval of scene parameters from polarimetric radar data using a n iterative inversion approach is considered in this paper. The theore tical development of a general, model-based iterative algorithm for in version of polarimetric radar data is presented. Factors relevant to i ts implementation, such as sensor configuration, algorithm optimizatio n and computational structure are discussed. The algorithm is applied to the specific problem of inverting the vector radiative transfer mod el for a simplified, representative vegetation canopy consisting of ve rtical trunks, leaves, and a rough ground surface. The results of this inversion are in excellent agreement with simulated data generated us ing the radiative transfer model. The convergence properties of the al gorithm are evaluated, and it is found that successful convergence is achieved in about 90% to 95% of the cases tested for the implementatio n used in this work. An error analysis is presented which considers th e effect of both systematic and measurement derived errors. Typical er ror bounds for the current application are approximately +/-3%, allowi ng for +/-0.5 dB accuracy in the measured radar data.