INCLUSION OF A SIMPLE MULTIPLE-SCATTERING MODEL INTO A MICROWAVE CANOPY BACKSCATTER MODEL

A simple multiple scattering model has been incorporated into a microw ave canopy backscatter model for forest stands with continuous or disc ontinuous tree canopies. The multiple scattering model was empirically derived using available calculated multiple scattering values and Mon te Carlo simulation. All orders of scattering within canopies beyond s ingle scattering were assumed to be isotropic. Multiple scattering was divided evenly among HH, HV, VH, VV polarizations. The corresponding single scattering term was polarization-sensitive. The effect of the m ultiple scattering term on modeled canopy backscatter was less at long wavelengths than at short wavelengths. At a given wavelength, the mul tiple scattering term affected copolarized scattering less than cross- polarized scattering. These predictions were consistent with calibrate d SAR observations and with our understanding of microwave scattering in forested environment. Including multiple scattering effects improve d the agreement between modeled and measured canopy backscatter partic ularly for cross-polarized backscatter at short wavelengths. (C) Elsev ier-Science Inc., 1998.