A Dictionary-Based Integrated Simulation Approach to Model Large- and Small-Scale Coherent Surface Scattering Phenomena in Radar Sounder Data

With the increasing number of radar sounder (RS) instruments being used in planetary exploration, there is an increasing need for advanced and efficient RS data simulators. In this context, it is important to combine the advantages of the different simulators to produce end-to-end simulations at multiple scales in a reasonable time. This article addresses this problem by presenting a novel dictionary-based integrated simulation approach to model both large- and small-scale surface scattering phenomena at relatively low computational costs. The method combines the advantages of a ray-tracing approach for simulating large surface areas at low resolution and a numerical technique for simulating the small-scale wave-target interaction at higher resolution. The proposed approach generates an instrument dictionary (i.e., a finite set of high-resolution rough responses at the small-scale) that can be used for surface target simulations. The method is validated by comparing its response with that obtained by a numerical simulator (known to have high accuracy). Then, it is demonstrated for the forward modeling of small-scale roughness on a synthetic target and for the inversion of small-scale roughness from existing RS data. The results demonstrate the capability of the method to achieve high accuracy and computational efficiency in addressing the problem of small-scale surface scattering on a large-scale scenario.