Inversion of Bohai Sea Ice Thickness Based on HY-1D Data

The sea ice in the Bohai Sea of China significantly impacts the maritime traffic and economic activities. Sea ice monitoring is crucial to disaster prediction and warning in China, and sea ice thickness is one of the key parameters. The Haiyang-1D satellite (HY-1D), as one of China Haiyang-1 (HY-1) optical satellites for ocean observation, has the potential for sea ice thickness detection. However, the research on this topic is limited. Therefore, in this study, a sea ice thickness retrieval method is proposed based on the observations of COCTS (Chinese Ocean Color and Temperature Scanner) on HY-1D in the Bohai Sea. The raw COCTS data undergo preprocessing, including geometric correction, radiometric calibration, and sea ice masking. The correlation between the solar shortwave broadband albedo extracted from MODIS and the reflectance of COCTS bands is analyzed. Then, a linear regression model is established between the MODIS albedo and the COCTS reflectance to obtain the albedo from COCTS data. Using the empirical model of sea ice thickness and the albedo, the sea ice thickness is retrieved from COCTS data. This method has been applied to monitor sea ice thickness in the Bohai Sea in the winter from 2021 to 2023. Our work is useful for the operational monitoring of the sea ice in the Bohai Sea, and also easily expands to new satellites, such as HY-1E, for sea ice detection.