Intercomparison of directional wave spectra from an NDBO discus-hulled buoy and a wavestaff array

The 12 m discus-hulled buoy, XERB, has played a key role in development by NOAA of techniques for measurement of directional wave spectra. A verification study was performed which compared directional wave data from XERB with equivalent data acquired from a three-element wavestaff array near which the buoy was deployed for a seventeen-month period. The study, including techniques used for verification, is described and comparison data are presented. It is concluded that the XERB system accurately measured one-dimensional wave spectra and mean wave direction as a function of frequency. The treatment of a wavestaff array as a height/slope gage is also examined.