Shallow sea topography detection using fully polarimetric Gaofen-3 SAR data based on swell patterns

Compared to single-polarization synthetic aperture radar (SAR) data, fully polarimetric SAR data can provide more detailed information of the sea surface, which is important for applications such as shallow sea topography detection. The Gaofen-3 satellite provides abundant polarimetric SAR data for ocean research. In this paper, a shallow sea topography detection method was proposed based on fully polarimetric Gaofen-3 SAR data. This method considers swell patterns and only requires SAR data and little prior knowledge of the water depth to detect shallow sea topography. Wave tracking was performed based on preprocessed fully polarimetric SAR data, and the water depth was then calculated considering the wave parameters and the linear dispersion relationships. In this paper, four study areas were selected for experiments, and the experimental results indicated that the polarimetric scattering parameter α had higher detection accuracy than quad-polarization images. The mean relative errors were 14.52%, 10.30%, 12.56%, and 12.90%, respectively, in the four study areas. In addition, this paper also analyzed the detection ability of this model for different topographies, and the experiments revealed that the topography could be well recognized when the topography gradient is small, the topography gradient direction is close to the wave propagation direction, and the isobath line is regular.