Analysis of wind measurements from a moored buoy

Abstract

Summary form only given. The wind data from remotely located heave-pitch-roll buoy stations operated by the National Data Buoy Center (NDBC) have both climatological and operational uses. In this study, the author investigated the wind measurements and its relation to buoy motions during severe seas. Wind data were collected from a NDBC 3-m heave-pitch-roll discus buoy during high seas caused by the Hurricane Gordon. The data were from a on-board time series data recorder that recorded measurements of wind speed, wind direction, and buoy motions. The wind speed and direction measurements were shown to be closely related to the buoy motions at frequencies higher than 0.03 Hz, which, as a result, significantly affects the 8-second gust wind speed. But the 8-minute average wind speed and direction were not affected. Depending on the wind direction and the wave direction, the wind speed measured at the peak of the wave crest could be higher or lower than that in the wave trough. This study indicated that any attempt to measure high-frequency wind turbulence near the ocean surface boundary from a moored heave-pitch-roll buoy is subject to possible distortions caused by buoy motions. The magnitude and characteristics of such effects could depend on buoy hull-mooring design, wave direction, and wind direction.