A Quasi-linear Inversion Algorithm for Retrieving Sea Surface Elevation from GF-3 SAR Images
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摘要: 通过对海面起伏场进行分析,不仅可获取常用的海浪统计参数,还能细致描述单个波浪的特性、检测异常巨浪、研究波群与波组的演变过程,从而更精准地描述大面积非均匀海况。该文基于准线性模型,提出一套适用于高分三号合成孔径雷达(SAR)图像的海面起伏场反演方案。该方案不依赖外部辅助数据,可在10 s内完成单景SAR数据的海面起伏场快速反演,并有效提取沿距离向传播的波浪信息。通过3种典型海况下的反演实例,体现出该方法在提取最大波高、识别波群与波组结构等方面的优势。进一步将2405景高分三号波模式SAR图像的反演结果与ERA5再分析海浪谱及高度计实测数据进行对比。结果显示,反演有效波高与ERA5数据的均方根误差为0.48 m。在有效波高低于3 m的中低海况下,反演有效波高与ERA5及高度计数据均保持良好一致性。本研究为基于高分3号SAR的海况信息快速监测与分析提供了有效工具。Abstract: Sea surface elevation is crucial for characterizing individual waves, wave groups, and freak waves, offering an accurate representation of inhomogeneous sea states. This study presents a quasi-linear inversion strategy for retrieving sea surface elevation from GF-3 Synthetic Aperture Radar (SAR) images. The algorithm enables rapid inversion within 10 s per scene without the need for external data and effectively resolves range-traveling waves. Case studies conducted under three distinct sea states demonstrate its ability to extract maximum wave heights and identify wave groups. Additionally, inversion results from 2405 GF-3 wave mode SAR images following quality control are compared with ERA5 reanalysis spectra and altimeter data. The comparisons reveal that the retrieved Significant Wave Height (SWH) has a root mean square error of 0.48 m compared with ERA5 data. In low-to-moderate sea states, with significant wave heights below 3 m, the retrieved SWH shows strong consistency with ERA5 spectra and altimeter measurements. This algorithm serves as an effective tool for rapid monitoring and analysis of sea states using GF-3 SAR.
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Key words:
- Synthetic Aperture Radar (SAR) /
- GF-3 /
- Sea surface elevation /
- Quasi-linear model /
- Rapid inversion
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表 1 :不同ERA5有效波高区间下的海浪积分参数对比
Table 1. The comparison of wave integrating parameters under different intervals of ERA5 significant wave heights
海况类别 样本
数量有效波高 $ {H}_{\mathrm{s}} $ 平均波周期 $ {T}_{\text{mw}} $ RMSE (m) Bias (m) Corr RMSE (s) Corr $ {H}_{\mathrm{s}} $ < 1.5 m 392 0.156 0.052 0.721 1.158 0.623 1.5 m < $ {H}_{\mathrm{s}} $ < 3 m 1,759 0.463 0.186 0.537 1.174 0.649 $ {H}_{\mathrm{s}} $ > 3 m 254 0.829 0.427 0.526 1.176 0.681 -
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