A modified Lie transform for rough sea surface modeling with breaking waves

Sea surface modeling is a powerful tool for radar signal simulation and sea clutter analyses. Especially in some challenging scenarios, e.g., under high sea states, collection of radar sea clutter data is probably unavailable, while realistically modeling of sea surface and electromagnetic echo simulation thereafter enable comprehensive measurements and analyses. Under high sea states, the wind-induced breaking wave phenomenon becomes serious and occupies a large portion of radar backscattering power. However, the standard Lie transform, employed for the nonlinear sea surface generation process, does not take into account the influence of wind speed and direction and therefore cannot describe breaking wave under high sea states. In this paper, a modified Lie transform is proposed for breaking wave modeling under high sea states. The proposed method utilizes a second-order approximation of the Lie transform and incorporates the wind speed and direction factors for nonlinear superposition, allowing for precise descriptions of sea surface varying with sea states. Experiment results validate that the proposed method is consistent with the Cox-Munk testing model and outperforms the standard Lie transform.