Wave Height and Wave Period Measurements Using Small-Aperture HF Radar

Abstract

A small-aperture receiving array occupying a small area provides convenience for the layout of HF radars. However, this kind of antennas has a wide beam, which adversely affects wave measurements. To solve this problem, a method for extracting wave parameters from wide-beam radar echoes, that models current variations across the beam, is proposed in this article. The nondirectional wave spectrum is extracted from the echoes of a small-aperture HF radar and wave parameters such as the significant wave height, the peak and mean wave period are then calculated from it. Simulation is carried out to assess the performance of the method for different current velocities, radar frequencies and wind conditions. The proposed method is then applied to a 9-day data set collected by an MHF-C radar for further validation via comparisons between the radar-estimated and the buoy-measured wave parameters. Some factors that may affect the performance of wave height measurements are analyzed, such as the signal-to-noise ratio and radial current velocity. The correlation coefficient (CC) between the radar-estimated and the buoy-measured significant wave height is 0.90, and the root mean square difference (RMSD) is 0.51 m. For the mean wave period, the CC is 0.61 and the RMSD is 0.67 s. The results demonstrate that the significant wave height and the mean wave period extracted by the proposed method are consistent with the buoy-measured values and the proposed method can overcome the broadening influence of the Doppler spectrum caused by ocean currents.