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

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 R_rc 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.