HF radar measurements of ocean wave parameters during NURWEC

The Netherlands/U.K. Radar, Wavebuoy Experimental Comparison (NURWEC) was a collaborative experiment between the University of Birmingham, the Dutch Rijkswaterstaat (RWS), and the Institute of Oceanographic Sciences (IOS), and was designed to assess the availability and accuracy of ocean wave data using the University of Birmingham (BU) ground-wave radar. The experiment lasted for two months during which time over 110 h of radar data were collected and transferred to Birmingham for wave-parameter extraction. Estimates of significant wave height are found to have a standard deviation of 15 percent (by comparison with the Datawell WAVEC buoy) if they were less than 2 m, and of 20 percent if greater, although in this case there is a positive bias of 41 percent. A mean difference in first-moment wave period of 0.6 s over the range 3-10 s is found. The long-wave directional spectrum is found to be in good agreement in the limited number of cases for which comparison is appropriate, with differences of 21 percent in height, 6 percent in period, and in direction. The limitations to these measurements are identified, and suggestions are made for improvements in radar operations and for further research.