Inversion of underwater bottom topography by using the SAR imagery

Interaction between current and underwater bottom topography modulates roughness of the sea surface, which in turn yields 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 proportional to the gradient of 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. The authors derived an inverse algorithm to successively derive 2-D underwater bottom topography from the SAR imagery. As an application, the SAR SIR-C images over the area of Hong Kong, China is studied