Scattering from cultural grass canopies: measured and modeled data

Abstract

The validity of a coherent grassland scattering model is determined by comparing the model predictions with direct measurements of a representative grass canopy. A wheat field was selected as this test target, and polarimetric, multi-frequency backscattering data was 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 relation to the row direction of the wheat. The C-band measurements likewise resulted in interesting backscattering data, with /spl sigma//sub vv//sup 0/ actually increasing with incidence angle for many cases. The coherent scattering model provides backscattering data which match and predict these measured data, and most of the other measured data quite well. The model shows that at L-band, the incoherent scattering power alone is insufficient for predicting the measured results, as the coherent terms can dominate the total scattered energy. Additionally, the model, which accounts for this non-uniform illumination of the wheat elements, likewise demonstrates the peculiar data observed for C-band.