Retrieval of Green Tide Concentration and Interannual Variation Analysis in Yellow Sea Based on Multi-Source Remote Sensing Monitoring

The economic losses and ecological damage caused by green tide in Yellow Sea have been very serious over the years, but the research on the risk of green tide is still in its infancy. The regional concentration is considered as a key factor in assessing the risk of green tides, because the harmful effects of the green tide come from the excessive accumulation and anoxia release of the decaying algae. Satellite remote sensing is recognized as the most effective means of monitoring the green tide. But different pixel resolution leads to inconsistence in multi-source satellite information fusion. In this paper, a general concentration retrieval model of green tide based on multi-source remote sensing monitoring is established for the disaster risk assessment and data fusion requirements in operational emergency. The model computes the green tide's concentration based on the minimum decision grid, which inputs the operational multisource satellite data, and outputs the green tide's concentration of any designated area such as coastal areas and some key areas of concern. Based on the proposed model, the paper computes the overall concentration of the green tide in Yellow Sea for 11 years since the occurrence year based on the operational multi-source satellite data. The results indicates that the interannual distribution of the green tide in Yellow Sea from 2008 to 2018 is generally on the rise, and the areas with higher concentration are distributed in the south coasts of Shandong Peninsula, China. Affected areas generally extend southward, and the center of the risk zone located parallel to the Yancheng and Lianyungang coasts of Jiangsu Province, pointing to the direction of Shandong Qingdao, China, and the risk becomes bigger from south to north.