Method for ocean surface currents measurement by SAR

A new method for mapping shallow water topography surface currents from SAR image is introduced based on the shallow water topography SAR imaging mechanism. M4S (presented by Romeiser R.) was used to forward simulate radar signatures of the oceanic features over the ocean surface. The first guessed surface currents can be estimated from the normalized radar cross section (NRCS) of the shallow water topography profile in the SAR image according to the Apers-Hennings linear theory, the NRCS induced by the varying shallow water topography surface currents could be simulated by the forward simulating model. The wind speed and shallow water topography surface currents gradients are modified using the iterative method until the simulated radar signals close to the NRCS calculated from SAR image. By this method, the wind speed and the surface currents can be retrieved finally. This method is tested on an ERS-2 SAR image in the Taiwan Shoal. Results show that the simulated shallow water topography radar signal is consistent with the NRCS extracted from SAR image, and their correlation coefficient is up to 90%, which means that this method is convergent and applicable.