Improvement of SSA Approach for Numerical Simulation of Sea Surface Scattering at High Microwave Bands

Small slope approximation (SSA) is a widely accepted approach in sea surface electromagnetic (EM) scattering studies. Nevertheless, the spatial sample interval used for sea surface should be around or even smaller than one-eighth of the incident wavelength to ensure EM scattering calculation accuracy, which requires a huge amount of computation, creating an obstacle to scattering numerical simulation, especially for high microwave band incident waves and large sea surface scenes. In this paper, a novel realization approach for SSA is proposed to significantly decrease the computation demands and computer memory requirements in sea surface scattering simulation. First, the sea surface is decomposed into two scales, and each scale has its own spatial sample interval. Then, the inclination state of the large-scale sea surface is determined under a specific wind speed. After that, scattering calculations of a typical surface cell with a finely sampled structure are completed and saved in all possible situations. Finally, scattering results for all the cells of a concrete sea surface are extracted from the saved cell scattering data base. From the different kinds of scattering result comparisons, it is demonstrated that this novel SSA realization approach can attain almost similar scattering results to exact SSA. This approach can be broadly applied in composite scattering studies, and remote sense imaging simulation of large sea surfaces with multiple targets