Measurement method of the wind stress at high wind speeds in laboratory experiments

At the high wind speeds, wave breaking and splash droplets strongly affect the wind stress measurements. In this study, we considered the measurement method of the wind stress at high wind speeds using: the two-type wind profile method based on the log-law wind profile and the log-wake-law wind profile, and the momentum budget method in a wind wave tank. The wind speed at 10 m height, U_10 ranges from 13.0 m/s to 45.9 m/s. In the two-type wind profile method, we calculated the friction velocity of air from the vertical distributions of the wind speed using the L and western types pitot tube at low and high wind speeds, respectively. In the momentum budget method, the friction velocity of air was calculated from the pressure, the average water surface level, and the displacement of the water surface at two points. In the log-law wind profile method, the friction velocity of air increased with the wind speeds. Moreover, we also considered the log wake law wind profile method and momentum budget method.