Radar sensitivity to tree geometry and woody volume: a model analysis

A model, based on radiative transfer theory and the matrix doubling algorithm, is described and used to compute the backscatter coefficients σ°s of forests. The objective is to investigate the radar sensitivity to woody biomass and some geometrical tree properties like branch dimensions and orientation. Model computations show that the backscatter coefficient is sensitive to the woody volume, particularly at HV polarization, P and L band; however, the radar response is appreciably influenced also by branch dimensions and orientation. Comparisons with experimental results available in the literature are shown. The correspondence between predicted and measured σ°s is generally good, although a slight overestimation is noted at L band, while uncertainties about data calibration and soil properties make the comparisons more difficult, in some cases, at P band