Microwave Inversion of Leaf Area and Inclination Angle Distributions from Backscattered Data

Abstract

The backscattering coefficient from a slab of thin randomly oriented dielectric discs over a flat lossy ground is used to reconstruct the inclination angle and area distributions of the discs. The discs are employed to model a leafy agricultural crop, such as soybeans, in the L-band microwave region of the spectrum. The distorted Born approximation, along with a thin disc approximation, is used to obtain a relationship between the horizontal-like polarized backscattering coefficient and the joint probability density of disc inclination angle and disc radius. Assuming large skin depth reduces the relationship to a linear Fredholm integral equation of the first kind. Due to the ill-posed nature of this equation, a Phillips-Twomey regularization method with a second difference smoothing condition is used to find the inversion. Results are obtained in the presence of 1 and 10 percent noise for both leaf inclination angle and leaf radius densities.