Numerical rough surface scattering simulations using the FVTD method

A method for numerically calculating the scattering from randomly rough surfaces has been developed and implemented in a finite-volume time-domain (FVTD) computational engine. A formulation that computes the total-field for planar multi-layered media was implemented and used as the source in a scattered-field implementation of the FVTD method. Computational geometries with rough surfaces exhibiting Gaussian statistics were created. Monte Carlo simulations for the scattering from the rough surfaces were performed using a scattered-field formulation of the FVTD method, which represents the rough surface as contrast sources. These contrast sources generate the scattered-fields and are more easily absorbed by the absorbing boundary conditions (ABCs), improving efficiency and accuracy. A far-field transformation is made and the normalized radar cross-section is computed. The validity of the technique is demonstrated by showing favorable comparisons with the small perturbation model (SPM). We demonstrate the applicability with a practical example for sea ice remote sensing.