Peak Wave Direction Measurement Using Shipboard Coherent Microwave Radar

The peak wave direction is a crucial parameter to quantify the physical characteristics of the ocean waves. For shipboard coherent microwave radar, the radar-illuminated space changes with the movement of the ship, and this fact leads to an unsolved problem for wave direction estimation. To address the issue, an approach is proposed to estimate peak wave direction using shipboard coherent microwave radar. After estimating water particles’ radial velocity and obtaining the peak wave energy from the radar echoes received with antennas, the 180° ambiguity is removed by comparing the variance of the left and right boundaries of sea echoes in the range-Doppler spectrum. The approach is validated using the datasets collected with a shipboard coherent S-band wave radar and a wave buoy in the South China Sea in 2019. The comparison with the wave buoy data shows that the root-mean-square error (RMSE) of peak wave direction is 10.6°. This result indicates that the method can work effectively.