Comparison of Wave Height Measurement Algorithms for Ship-Borne X-Band Nautical Radar

In this article, a comparison of signal-to-noise ratio (SNR) and shadowing-based algorithms for ocean wave height estimation from ship-borne X-band nautical radar sea surface images is presented. Modifications, including selecting a subarea along the upwind direction and smoothing the edge pixel intensity histogram, are made to the original shadowing algorithm to achieve more accurate wave height measurements. Tests of the algorithms are conducted using radar and buoy data acquired in a sea trial in the North Atlantic Ocean off the east coast of Canada. Compared with the original shadowing algorithm, the modified algorithm improves the wave height estimation with a decrease of about 1.70 m in the root mean square (RMS) difference with respect to in situ measurements. In addition, the result of the comparison shows that the modified shadowing algorithm produces more accurate wave heights than the SNR method with improvements of about 0.05 in the correlation coefficient and about 0.04 m in the RMS difference.