A physical model for microwave radiometry of vegetation

A physical microwave radiometry model based on an iterative solution of the radiative transfer equations is developed for a vegetation canopy. The model generalizes the restrictions imposed by earlier models with regard to the canopy type, the canopy physical temperature profile, and the sky radiation, and it is successfully reduced to those reported in the literature. Other novel features of the model are that it (1) satisfies energy conservation; (2) gives a brightness temperature formulation independent on the scattering albedo; and (3) provides explicit expressions for different scattering and emission processes contributing to the canopy brightness temperature. Numerical simulations showed a good agreement between the model predictions and published data acquired over corn and soybean canopies. They also gave a quantitative understanding for the influence of soil moisture, scattered radiations within the canopy, and the canopy physical temperature profile on the canopy brightness temperature.