Integration of Vegetation and Topography Models for GNSS-R

Various electromagnetic scattering models have been developed for reflections of signals of opportunity (SoOp), such as global navigation satellite system (GNSS) signals, from land surfaces with vegetation cover. These include models that treat vegetation solely as an attenuating layer [1, 2] and those that include provisions of both specular and diffuse scattering using the distorted Born approximation and radiative transfer theory [3–5]. More recently, fast hybrid methods are being developed to compute the transmissivity of vegetation layers using a combination of full-wave numerical solvers and the Foldy-Lax equations for multiple scattering [6].