The airborne stepped frequency microwave radiometer (SFMR) provides the measurements of 10-m ocean surface wind speed in high and extreme wind conditions. These winds are calibrated using the surface-adjusted wind estimates from the so-called dropsondes. The surface-adjusted winds are obtained from layer-averaged winds scaled to 10-m altitude to eliminate the local surface variability not associated with the storm strength. The SFMR measurements and, consequently, the surface-adjusted dropsonde winds represent a possible reference for satellite instrument and model calibration/validation at high and extreme wind conditions. To this end, representativeness errors that those measurements may introduce need to be taken into account to ensure that the storm variability is correctly resolved in satellite retrievals and modeling. In this work, we compare the SFMR winds with the dropsonde surface-adjusted winds derived from the so-called WL150 algorithm, which uses the lowest 150-m layer between 10 and 350 m. We use nine years of data from 2009 to 2017. We focus on the effects of the layer altitude and thickness. Our analysis shows that the layer altitude has a significant impact on dropsonde/SFMR wind comparisons. Moreover, the averaged winds obtained from layers thinner than the nominal 150 m and closer to the surface are more representative of the SFMR surface wind speed than the WL150 speeds. We also find that the surface-adjusted winds are more representative of 10-km horizontally averaged SFMR winds. We conclude that for calibration/validation purposes, the WL150 algorithm can introduce noise, and the use of actual 10-m dropsonde measurements should be further investigated.

中文翻译：

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降落式探空仪表面调整风及其在步进频率微波辐射计风速校准中的应用

机载步进频率微波辐射计 (SFMR) 可在强风和极端风条件下测量 10 米海面风速。这些风是使用所谓的投降式探空仪的表面调整风估计来校准的。表面调整的风是从按比例缩放到 10 米高度的层平均风获得的，以消除与风暴强度无关的局部表面变化。SFMR 测量结果以及因此表面调整的投降式探空仪风代表了在高风和极端风条件下卫星仪器和模型校准/验证的可能参考。为此，需要考虑这些测量可能引入的代表性误差，以确保在卫星反演和建模中正确解决风暴变异性。在这项工作中，我们将 SFMR 风与源自所谓的 WL150 算法的下落式探空地面调整风进行比较，该算法使用 10 到 350 m 之间的最低 150 米层。我们使用从 2009 年到 2017 年的九年数据。我们关注层高和厚度的影响。我们的分析表明，层高对 dropsonde/SFMR 风比较有显着影响。此外，从比标称 150 m 更薄且更靠近地表的层获得的平均风速比 WL150 风速更能代表 SFMR 地表风速。我们还发现，经过表面调整的风更能代表 10 公里水平平均 SFMR 风。我们得出结论，出于校准/验证目的，WL150 算法会引入噪声，应进一步研究实际 10 米投降式探空仪测量的使用。