HY-1E COCTS2 Near-Real-Time Skin Sea Surface Temperature Retrieval

The new-generation Chinese ocean color observation satellite Haiyang (HY)-3A (also referred to as HY-1E) was successfully launched on 16 November 2023. The Chinese Ocean Color and Temperature Scanner 2 (COCTS2) onboard HY-3A contains three thermal infrared channels centered at 3.74 μm, 10.8 μm, and 12 μm. The nadir resolution is 500 m, which is higher than that of Chinese Ocean Color and Temperature Scanner (COCTS) onboard Haiyang-1C (HY-1C) and Haiyang-1D (HY-1D), and the capability for observing Sea Surface Temperature (SST) is improved. A near-real-time skin SST retrieval algorithm is developed using radiative transfer modeling. Cloud and quality are determined by flags assigned to each pixel. The SST products are evaluated against in situ measurements and Sea and Land Surface Temperature Radiometer (SLSTR) observations. Using a 9 km spatial window and 1-hour temporal window, the bias and robust standard deviation of COCTS2 SST relative to in situ SST are –0.17°C and 0.48°C for the split-window algorithm (daytime and nighttime), and 0.16°C and 0.41°C for the nighttime triple window algorithm. The bias and robust standard deviation of COCTS2 SST relative to SLSTR SST are 0.04°C and 0.45°C for the split-window algorithm (daytime and nighttime) and 0.38°C and 0.40°C for the nighttime triple-window algorithm. These results indicate that the COCTS2 near-real-time SST product has high accuracy.