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合成孔径雷达（SAR，Synthetic Aperture Radar）是一种重要的海浪观测手段，研究其SAR图像海浪谱反演结果的精度，是其广泛应用于海浪观测的前提。欧洲航天局（欧空局，European Space Agency，ESA）的哨兵1号卫星和我国自主研发的高分3号卫星是目前在轨运行的两颗SAR卫星，利用两颗卫星的SAR数据反演海浪和风场参数是目前国内外研究团队最为关注的问题之一。本文重点研究并对比了哨兵1号卫星SAR IW模式（Interferometric Wide swath）和高分3号卫星SAR条带模式数据海浪谱反演的精度。选取印度洋海上丝绸之路海域和太平洋、大西洋近岸海域不同海况下的两卫星SAR数据进行海浪参数反演，将反演结果分别与欧洲天气预报中心（ECMWF，European Center for Medium-range Weather Forecasts）的ERA-5数据和浮标海浪数据进行了对比，结果显示，与ERA-5数据对比， 哨兵1号卫星反演有效波高和平均波周期的均方根误差（RMSE，Root Mean Squared Error）分别为0.30m、0.63s，高分3号卫星反演有效波高和平均波周期的均方根误差分别为0.37m、0.99s；与浮标数据对比，哨兵1号卫星反演有效波高和平均波周期的均方根误差分别为0.40m、0.91s，高分3号卫星反演有效波高和平均波周期的均方根误差分别为0.42m、0.94s。结果表明，基于海浪谱反演的高分3号卫星与哨兵1号卫星SAR海浪参数反演精度满足海洋遥感的要求，二者海浪谱反演结果精度相当。
Objective: Ocean wave is one of the important Marine dynamic phenomena affecting human activities. At present, the main observation means include buoy observation, marine numerical prediction model and microwave remote sensing observation. However, we cannot carry out large-scale observation by buoy and marine numerical prediction model’s result is not measured data. Spectrometers and altimeters in microwave remote sensing instruments can also measure spectral parameters, but SAR which has higher resolution can provide two-dimensional sea surface information. Sentinel-1 satellite of ESA and Gaofen-3 satellite independently developed by China are now in orbit causing that many teams are committed to retrieving wave parameters from SAR data of these two satellites. In this paper, we carried out a comparison of the wave parameter inversion accuracy of Sentinel-1 SAR Interferometric Wide Swath model and Gaofen-3 SAR strip model based on wave spectrum, which provides a reference for the wide application of Gaofen-3 SAR data. Methods: Generally, sea states according to ERA-5 data of ECMWF are divided into three categories: low, moderate and high sea states. And the sea areas of Hormuz Strait and Malacca Strait of the maritime Silk Road in the Indian Ocean and the coastal waters of the Pacific and Atlantic Ocean are selected as the study areas. Besides, the SAR data of Sentinel-1 and Gaofen-3 satellites under different sea states are selected as the data source. Taking the E spectrum as the initial guess, the wave spectrum and wave parameters are retrieved by MPI method. Subsequently, the SAR data inversion results of the two satellites under different sea states are compared with ERA-5 data and buoy wave data. By calculating the values of root mean square error (RMSE) and scatter index (SI), the inversion accuracy of wave parameters can be verified and the inversion accuracy of wave parameters of the two satellites under different sea conditions can also be compared. Results: Compared with ERA-5 data, the RMSE of significant wave height(Hs) retrieved by Gaofen-3 SAR under low, moderate and high sea conditions are 0.30m, 0.34m and 0.48m, and the RMSE of mean wave period(Tm) are 1.02s, 0.99s and 0.95s respectively. In addition, the RMSE of Hs retrieved by Sentinel-1 SAR under low, moderate and high sea conditions are 0.30m, 0.29m and 0.33m respectively, and the RMSE of Tm are 0.94s, 0.51s and 0.64s respectively. Compared with ERA-5 data, the RMSE of Hs and Tm under different sea conditions retrieved by Gaofen-3 SAR are 0.38m and 0.99s, and the RMSE of Hs and Tm retrieved by Sentinel-1 SAR are 0.31m and 0.70s, respectively. Compared with the buoy data, the RMSE of the retrieved Hs and Tm of Gaofen-3 satellite are 0.42m and 0.94s, and the RMSE of the retrieved Hs and Tm of Sentinel-1 are 0.40m and 0.91s respectively. Conclusion: In general, the SAR wave parameter inversion of Sentinel-1 and Gaofen-3 SAR based on wave spectrum shows that the inversion results of the two satellites meet the index requirements in this field, and the accuracy of the inversion results of wave spectrum is the same. As the first self-developed SAR satellite in China, the strip mode SAR data of Gaofen-3 satellite has broad prospects in marine research fields.