Vector electromagnetic scattering from layered rough surfaces with buried discrete random media for subsurface and root-zone soil moisture sensing

In this work, a 3D scattering model from layered arbitrarily random rough surfaces with embedded discrete random scatterers is constructed based on the scattering matrix approach. Scattering matrix of a single rough surface is found using the stabilized extended boundary condition method (SEBCM). Meanwhile, by finding the T matrices of discrete scatterers using analytical or numerical methods, the random medium scattering solution is found based on the recursive T-matrix approach and near-to-far field transformed numerical plane wave expansion of the vector spherical harmonics. Solutions provided in this work include multiple scattering effects among the medium scatterers and between subsurfaces and sublayers. The high computational efficiency and accuracy of this method enable it to serve as a powerful tool for studying the role of vegetation roots and other sublayer inhomogeneities in retrieval of subsurface and root zone soil moisture from radar measurements.