Synthetic Aperture Radar Imaging of Abrupt Underwater Topography

Traditional Synthetic Aperture Radar (SAR) imaging theory of underwater topography is explained by flow field model, wave model and radar backscatter model. However, the models are simplified and there are still many uncertain problems to be studied. In order to study the imaging theory of large scale abrupt underwater topography SAR, a nonlinear flow field model is introduced. This model is helpful to obtain nonlinear details of the sea surface modulated by topographic waves. The hybridizable discontinuous Galerkin (HDG) is used to solve compressible Navier-Stokes (NS) equation to obtain the nonlinear interaction between topography and flow field. The calculation results are taken into the equation of action spectrum balance, then the radar backscattering coefficient is calculated based on Bragg scattering. Finally, the nonlinear sea surface is imaged by BP imaging algorithm. The results show that the SAR image fringe with nonlinear flow field corresponds to the topography, and the SAR imaging based on linear flow field is not obvious.