Red Tide Monitoring in the Bohai Sea Based on Domestic High-Resolution Data

In recent years, red tide disasters occur frequently in China's sea areas. In 2022,17 red tide events occurred in the Bohai Sea area, which had a significant impact on the local environment. This paper focuses on the red tide event that occurred in the Qinhuangdao sea area from May 13th to May 15th, 2022. The event were extracted the red tides by using SDGSAT-1 and GF1-WFV data, and analyzed the accuracy by using the GF1-RI Red Tide Detection Index algorithm, the Dual Band Ratio method, and the Maximum Likelihood Classification method. Additionally, the temporal characteristics of this red tide event were analyzed using HJ2A/B data. The results indicate that the area of red tide detected by SDGSAT-1 data using the GF1-RI Red Tide Detection Index algorithm was 17.46 km2, while the area extracted by the GF1-WFV data using the Dual Band Ratio method was 18.51 km2. These two methods produced results that were close to the actual area, while the maximum likelihood classification method led to larger error. Hence, for small-scale red tide monitoring, priority should be given to the GF1-RI red tide detection algorithm and the two-band ratio method.