HY-1C/D卫星CZI数据海面太阳耀光反射校正

Correction of seawater surface sunglint reflection from HY-1C/D CZI images

  • 摘要: 耀光反射是海洋光学遥感数据中难以忽略的现象,其差异有助于海洋环境问题的监测,同时也给水色信息的反演带来影响,准确计算或评估耀光反射信号是海洋遥感的一个研究热点。适用于粗空间分辨率数据的耀光统计模型,因尺度效应等影响,难以适用于高空间分辨率数据。发展基于近红外-短波红外水体吸收特征的谱间关系法,是实现高空间分辨率海洋光学数据太阳耀光反射校正的有效途径。本文以空间分辨率为50米的海洋一号C/D卫星(Haiyang-1C/D,HY-1C/D)海岸带成像仪(Coastal Zone Imager,CZI)数据为研究对象,基于耀光反射的光学过程和海洋目标的图像特征,详细分析了高空间分辨率海洋光学数据中耀光反射的图像特征与遥感尺度效应,发展了CZI数据可见光波段耀光反射校正的方法。研究结果表明耀光校正后,CZI数据中涡旋、水团等水色信息得以凸显; CZI数据Rrc反射率在460 nm,560 nm以及650 nm不确定性分别降低了65%,80%,89%。该方法不依赖于大气参数,有助于利用CZI数据快速开展近海水色的动态监测和反演。

     

    Abstract: Sunglint reflection is a phenomenon that is hard to ignore in marine optical remote sensing. Its difference helps the monitoring of marine environmental problems but brings influence to the inversion of ocean color information. Accurate calculation or evaluation of sunglint reflection signal is a research hotspot in marine remote sensing. The sunglint statistical model suitable for coarse spatial resolution data is difficult to be applied to high spatial resolution data due to the influence of the remote sensing scale effect. In this case, an effective remedy lies in developing a method with the spectral relationship based on the water absorption characteristics of near-infrared or short-wave infrared band. In this study, taking the Coastal Zone Imager (CZI) data of Haiyang-1 C/D (HY-1C/D) satellite with a spatial resolution of 50 m as the research object, based on the optical process of sunglint reflection and the image features of ocean targets, the image features and remote sensing scale effect of sunglint reflection in high spatial resolution images were analyzed in detail. As a result, the sunglint reflection correction method of CZI images in visible band was developed. It is suggested that ocean color information such as eddy and water mass are prominent in CZI images after sunglint correction; and the uncertainty of the Rrc reflectance at 460 nm, 560 nm, and 650 nm is reduced by 65%, 80%, and 89%, respectively. Furthermore, the method does not depend on the atmospheric parameters, which is helpful to realize the dynamic monitoring and inversion of offshore ocean color quickly.

     

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