The significant wave height distribution retrieved from marine X-band radar images

The determination of significant wave height (SWH) from marine X-band radar image sequences is based on an empirical relationship with the signal-to-noise ratio (SNR). To reduce the dependence of in-situ calibrations, the variations of SNR with the range from the radar station and the relative azimuth between the antenna looking angle and the wave propagation direction are analyzed. Then a method was developed to correlate the SNR with the fluctuations of the sea surface elevations, by taking out the variations of SNR with range and azimuth. Moreover, the method is validated using marine X-band radar image sequences from a field experiment, comparisons of the corrected SNR with a buoy show that the method gives a more accurate estimation of SWH than the uncorrected SNR does. Besides, the method can remove the influence of the noise caused by light rain as well.