In this letter, we first propose two empirical models to retrieve significant wave height (SWH) using two global navigation satellite system reflectometry (GNSS-R) observables derived from the delay-Doppler map (DDM), namely, DDM average (DDMA) and leading edge slope (LES). Then, we utilize minimum variance to establish a combined model to enhance the SWH estimation performance. Collocated ERA5 SWH data are utilized as the ground truth for the development and evaluation of the SWH models. The results show that the SWH estimates by the three models are highly consistent with ERA5 SWH data, with a root-mean-square error (RMSE) less than 0.502 m and a correlation coefficient (CC) higher than 0.88. In particular, the combined model has a significantly smaller RMSE of 0.428 m and larger CC of 0.91, and compared with the combined model based on the weighted average (WA) method and LES observable model based on integral delay waveform, the RMSE is improved by 20.15% and 14.74%, respectively. The performance of spaceborne GNSS-R SWH retrieval can be greatly enhanced by the construction of integrated model, as demonstrated by this letter.

中文翻译：

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CYGNSS DDMA和LES测量的有效波高估计新方法


在这封信中，我们首先提出了两个经验模型，使用从延迟多普勒图（DDM）导出的两个全球导航卫星系统反射计（GNSS-R）观测值来反演有效波高（SWH），即DDM平均值（DDMA）和前缘斜率（LES）。然后，我们利用最小方差建立组合模型来提高 SWH 估计性能。并置的 ERA5 SWH 数据被用作开发和评估 SWH 模型的基本事实。结果表明，三种模型的SWH估计与ERA5 SWH数据高度一致，均方根误差（RMSE）小于0.502 m，相关系数（CC）高于0.88。特别是，组合模型的RMSE明显较小，为0.428 m，CC较大，为0.91，与基于加权平均（WA）方法的组合模型和基于积分延迟波形的LES可观模型相比，RMSE改善了分别为20.15%和14.74%。正如这封信所证明的那样，通过构建集成模型可以大大提高星载GNSS-R SWH反演的性能。