Simulated and observed backscatter at P-, L-, and C-bands from ponderosa pine stands

We compared the output of the Santa Barbara microwave canopy backscatter model to polarimetric synthetic aperture radar ( S A R ) data for three ponderosa pine stands (ST2, ST-11, and SP-2) with discontinuous tree canopies near Mt. Shasta, California, at P-band (0.68-m wavelength), L-band (0.235m wavelength), and C-band (0.056-m wavelength). Given the SAR data calibration uncertainty, the model made good predictions of the P-HH, P-VV, L-HH, C-HH, and C-HV backscatter for the three stands, and the P-HV and L-HV backscatter for ST-2 and SP-2. The model underestimated C-VV for the three stands, and P-HV , L-HV, and L-VV backscatter for ST-11. The observed and modeled VV-HH phase differences were 2: 0" for the three stands at C-band and L-band, and for SP-2 at P-band. At P-band, the observed and modeled VV-HH phase differences were at least -80" for ST-2 and ST-11, which indicates that double-bounce scattering contributes to the total backscatter for the two stands.