A combined method to model microwave scattering from a forest medium

• Published in: IEEE transactions on geoscience and remote sensing 2006-04, Vol.44 (4), p.815-824
• Main Authors: Jinyang Du, Jiancheng Shi, Tjuatja, S., Kun Shan Chen
• Format: Article
• Language: English
• Subjects: Algorithms; Animal, plant and microbial ecology; Applied geophysics; Backscatter; Backscattering; Biological and medical sciences; Combined model; Dielectrics; Earth sciences; Earth, ocean, space; Exact sciences and technology; forest; Forests; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Half spaces; Integral equations; Internal geophysics; Mathematical analysis; Mathematical models; matrix doubling; Microwave theory and techniques; Predictive models; Radar scattering; Reflectivity; Rough surfaces; Scattering; Studies; Surface roughness; Teledetection and vegetation maps; Vegetation; X-band
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2006.872289

A novel method, which employs both a matrix doubling algorithm and the first-order solution of a radiative transfer (RT) equation for modeling microwave backscattering from forest, is presented in the paper. The method is based on the assumption that a forest canopy can be divided into a number of distinct horizontal vegetation layers over a dielectric half-space rough surface. The scattering phase matrix of each layer is calculated by either matrix doubling to account for the multiple-scattering effect or first-order solution of an RT equation, depending on the scattering characteristics of the layer. The first-order solution of the RT equation is used for the trunk layer while the matrix doubling technique is applied to both the crown layer and understory. The advanced integral equation model and reflectivity matrix are used to calculate the noncoherent and coherent surface boundary conditions. Comparisons between model predictions and field measurements on radar backscattering coefficients for a walnut orchard showed a good agreement at both L-band and X-band and for all three polarizations. Comparative analyses of model predictions for backscattering from a forest medium calculated using the combined model, first-order RT model, and the standard matrix doubling model were also presented. Understory effects, that can significantly change the weight of each scattering mechanism, were also evaluated by using the combined method.