Revised Estimates of Ocean Surface Drag in Strong Winds

Air-sea drag governs the momentum transfer between the atmosphere and the ocean, and remains largely unknown in hurricane-force winds. We revisit the momentum budget and eddy-covariance methods to estimate the surface drag coefficient in the laboratory. Our drag estimates agree with field measurements in low-to-moderate wind speeds, and previous laboratory measurements in hurricane-force winds. The drag coefficient saturates at $2.6 \times 10^{-3}$ and $U_{10} \approx 25\ m\ s^{-1}$, in agreement with previous laboratory results. During the analysis of the data, we discovered an error in the scaling to 10-m winds in the original source code used by Donelan et al. (2004). We present the corrected data and describe the correction procedure. Although the correction to the data does not change the key finding that the drag saturates in strong winds, the magnitude and the wind speed threshold of drag saturation are significantly changed. We recommend that the correction be applied to any surface flux parameterization schemes in weather and ocean prediction models that relied on the original laboratory data.