Waves much shorter than those measured by operational systems make significant contribution to the ocean surface roughness. This article describes a method to obtain the L-band tilting ocean surface roughness using wind speed and windsea dominant wave period coupled with a wind–wave spectrum model. Examples are presented with wind and dominant wave data from ocean buoys and hurricane hunters. Several related issues are discussed: high-frequency wave spectrum, integration limit, swell contribution, and measurements in extreme winds: 1) it is well known since the 1970s that with stationary sensors, extending the frequency range in measuring elevation spectrum does not yield useful short-wave information because of the low signal level and large Doppler frequency shift involved in measuring short waves. 2) Low-pass mean square slopes (LPMSSs) integrated to 5 and 11 rad/m are computed to quantify their difference as a function of wind speed and inverse wave age (IWA). The normalized difference decreases with increasing wind speed and decreasing IWA. 3) Swell contribution to the L-band LPMSS is almost negligible for wind speed greater than 5 m/s (less than 5% in 99% of observations). In low-wind conditions (wind speed less than 5 m/s), the swell contribution is difficult to assess because of inaccuracy in identifying the weak windsea system. 4) The coarse resolution in National Data Buoy Center (NDBC) wave spectra causes large data scatter in the computed LPMSS in very high winds (greater than 20 m/s). A mitigating solution is offered.

中文翻译：

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从操作系统的测量中推导出 L 波段倾斜海洋表面粗糙度

比业务系统测量的波浪短得多的波浪对海洋表面粗糙度有重大影响。本文描述了一种利用风速和风海主导波周期结合风浪谱模型获得 L 波段倾斜海洋表面粗糙度的方法。示例提供了来自海洋浮标和飓风猎人的风和主导波浪数据。讨论了几个相关问题：高频波谱、积分极限、涌浪贡献和极端风中的测量：1) 众所周知，自 1970 年代以来，使用固定传感器，扩展测量海拔谱的频率范围不会产生有用的由于测量短波时信号电平低且多普勒频移大，因此无法获得短波信息。2) 计算集成到 5 和 11 rad/m 的低通均方斜率 (LPMSS) 以量化它们作为风速和逆波年龄 (IWA) 函数的差异。归一化差异随着风速的增加和 IWA 的减小而减小。3) 对于大于 5 m/s 的风速，膨胀对 L 波段 LPMSS 的贡献几乎可以忽略不计（在 99% 的观测中小于 5%）。在低风况下（风速小于 5 m/s），由于识别弱风海系统不准确，很难评估涌浪的贡献。4) 国家数据浮标中心 (NDBC) 波谱的粗分辨率导致计算出的 LPMSS 在非常大的风（大于 20 m/s）中出现大量数据散射。提供了一种缓解解决方案。