The goal of this study was to investigate the performance of a spectral-transformation wave retrieval algorithm and confirm the accuracy of wave retrieval from C-band Chinese Gaofen-3 (GF-3) Synthetic Aperture Radar (SAR) images. More than 200 GF-3 SAR images of the coastal China Sea and the Japan Sea for dates from January to July 2020 were acquired in the Quad-Polarization Strip (QPS) mode. The images had a swath of 30 km and a spatial resolution of 8 m pixel size. They were processed to retrieve Significant Wave Height (SWH), which is simulated from a numerical wave model called Simulating WAves Nearshore (SWAN). The first-guess spectrum is essential to the accuracy of Synthetic Aperture Radar (SAR) wave spectrum retrieval. Therefore, we proposed a wave retrieval scheme combining the theocratic-based Max Planck Institute Algorithm (MPI), a Semi-Parametric Retrieval Algorithm (SPRA), and the Parameterized First-guess Spectrum Method (PFSM), in which a full wave-number spectrum and a non-empirical ocean spectrum proposed by Elfouhaily are applied. The PFSM can be driven using the wind speed without calculating the dominant wave phase speed. Wind speeds were retrieved using a Vertical-Vertical (VV) polarized geophysical model function C-SARMOD2. The proposed algorithm was implemented for all collected SAR images. A comparison of SAR-derived wind speeds with European Center for Medium-Range Weather Forecasts (ECMWF) ERA-5 data showed a 1.95 m/s Root-Mean-Squared Error (RMSE). The comparison of retrieved SWH with SWAN-simulated results demonstrated a 0.47 m RMSE, which is less than the 0.68 m RMSE of SWH when using the PFSM algorithm.

Weizeng Shao;Xingwei Jiang;Zhanfeng Sun;Yuyi Hu;Armando Marino;Youguang Zhang

College of Marine Sciences,Shanghai Ocean University,Shanghai,China;National Satellite Ocean Application Service,Ministry of Natural Resources,Beijing,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou,China;Natural Sciences,University of Stirling,Stirling,UK

地球空间信息科学学报（英文版）

[1]Weizeng Shao;Xingwei Jiang;Zhanfeng Sun;Yuyi Hu;Armando Marino;Youguang Zhang-.Evaluation of wave retrieval for Chinese Gaofen-3 synthetic aperture radar)[J].地球空间信息科学学报（英文版）,2022(02):229-243

WAves,theocratic,SPRA,PFSM,Elfouhaily,SARMOD2

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