Nearshore Bathymetry Based on Shore-Based Microwave Radar

An ocean water bathymetry method for analyzing sea clutter time series from shore-based microwave radar is proposed. Based on the relationship between wave phase velocity and water depth, a quantitative model is established for the breaking wave Doppler velocity, peak period, and depth. This method combines a short-time Fourier transform technique for retrieving breaking wave velocity by evaluating the high-speed echoes and the maximal overlap discrete wavelet transform for retrieving the corresponding wave peak period. Compared with conventional radar image-based methods, the main advantages of this approach are given as follows: 1) the time–frequency analysis-based and wavelet-based approaches are localized, naturally fitting the typical inhomogeneous conditions observed in nearshore areas; 2) the method is dynamic and the time-evolving model satisfies the instability condition of the sea surface state; 3) it does not rely on the wavenumber-frequency spectrum to fit the dispersion curve, thus avoiding the influence of surface current; and 4) it utilizes a single azimuth time series without the need for continuous radar images. The validity of the method is confirmed through experimentation with actual radar sea clutter. The bathymetry results of the proposed approach demonstrate consistency and robustness under different conditions of sea clutter.