Two-dimensional topography inversion of underwater bottom by using SAR imagery

Interaction between the current and the underwater bottom topography modulates the roughness of the sea surface, which in turn yields a variation of the radar scattering echo. By using the continuity equation and weak hydrodynamic interaction theory in the relaxation time approximation, the spatial variation of the radar scattering cross-section has been proved as being proportional to the gradient of the current velocity. In this paper, the current direction is first determined by using two-dimensional (2-D) correlation of spatial variation of backscattering measured by the SAR imagery. We derived an inverse algorithm to successively derive the 2-D underwater bottom topography from the SAR imagery. As an application, the SAR SIR-C images over the area of Hong Kong, China are studied.