Electromagnetic scattering from grassland Part II: Measurement and modeling results

The validity of a coherent, grassland scattering model is determined by com paring the model predictions with direct measurements of a representative g rass canopy, A wheat held was selected as the test target, and polarimetric , multifrequency backscattering data were collected over an entire growing season, along with a complete set of ground-truth data. The L-band measured data demonstrated a strong dependence on azimuthal look direction in relat ion to the row direction of the wheat. The C-band measurements likewise sho wed an interesting backscattering response, wherein sigma(vv)(0) actually i ncreased with incidence angle for many cases, The coherent scattering model provides backscattering data that match and p redict these measured data and most of the other measured data well. The mo del shows that at L-band, the incoherent scattering power alone is insuffic ient for predicting the measured results, as the coherent terms can dominat e the total scattered energy, Additionally, the model, which accounts for t his nonuniform illumination of the wheat elements, demonstrates the peculia r data observed for C-band, Likewise, it is demonstrated that the fidelity used to model grass constituents (e.g., curvature) is required to match the scattering measurements accurately.