Abstract Accurate representation of wind stress is important for modelling and predictions of marine environmental conditions. The effect of sea state on wind stress is usually parameterized by relating the equivalent sea surface roughness to the wave age or wave steepness. In this study, a new parameterization is presented for the dependences of sea surface roughness on the wind speed and sea state based on observations. Analyses of observations demonstrate that the sea surface roughness is correlated with the wave age stronger than the wave steepness. As a result, the wave-dependent sea surface roughness is parameterized in terms of the wave age in the new parameterization. The new parameterization features that the sea surface roughness has different dependences on the wave age under wind-sea-dominated, mixed and swell-dominated sea states. Younger waves have larger values of the drag coefficient under wind-sea-dominated and mixed sea states but older waves have larger values under swell-dominated sea states. The drag coefficient predicted by the new parameterization is enhanced at low winds and levels off at high winds. The applicability of the new parameterization is investigated using a nested-grid wave model for the northwest Atlantic based on WAVEWATCH III. The wave model results during a winter storm in March 2014 are compared with the available measurements from buoys and satellite altimeters over the study region. Our results demonstrate that the new parameterization reduces deficiencies of three existing parameterizations of underestimating significant wave heights (SWHs) at low winds (or old waves) and overestimating SWHs at moderate and high winds (or young waves). Overall, the new parameterization performs the best in predicting SWHs during the winter storm in comparison with the existing schemes.

中文翻译：

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重新审视海面阻力系数对风速和海况的依赖性

摘要 风应力的准确表示对于海洋环境条件的建模和预测非常重要。海况对风应力的影响通常通过将等效海面粗糙度与波龄或波陡度相关联来参数化。在这项研究中，基于观测，提出了一种新的参数化方法，用于说明海面粗糙度对风速和海况的依赖性。观测分析表明，海面粗糙度与波龄的相关性强于波陡。因此，在新参数化中，根据波龄对与波浪相关的海面粗糙度进行了参数化。新的参数化特征在于，在风-海主导、混合和涌浪主导的海况下，海面粗糙度对波龄具有不同的依赖性。在风-海主导和混合海况下，年轻的波浪具有较大的阻力系数值，而在膨胀主导的海况下，较老的波浪具有更大的值。新参数化预测的阻力系数在低风时增强，在大风时变平。使用基于 WAVEWATCH III 的西北大西洋嵌套网格波模型研究了新参数化的适用性。将 2014 年 3 月冬季风暴期间的波浪模型结果与研究区域浮标和卫星高度计的可用测量结果进行了比较。我们的结果表明，新的参数化减少了三个现有参数化的不足，即在低风（或旧浪）时低估显着波高（SWH）和在中风和强风（或新浪）时高估了 SWH。