Impact of Typhoon Bolaven on the Ecological Characteristics of the East China Sea and the Yangtze River Estuary

Typhoons are strong air–sea interactions that significantly affect the physical and biogeochemical processes of the upper ocean. Based on the Regional Ocean Modeling System-Carbon–Silicate–Nitrate Ecosystem coupled model, the influence of Typhoon Bolaven (2012) on physical and ecological variables in the East China Sea and the underlying mechanisms were investigated. The results showed that the typhoon induced intense vertical mixing in the upper ocean, leading to sea surface cooling, increased salinity, nutrient concentrations, and phytoplankton blooms. Conversely, warming, reduced salinity, and decreased nutrient concentrations occurred in the subsurface layer. In the Yangtze River Estuary, the passage of typhoons effectively affected wind and current directions, shaping the dipole distribution patterns of the environmental elements. Diagnostic analysis indicated that tropical cyclone-induced horizontal advection is key in driving changes in both the physical and ecological variables within the estuary region. This study provides novel insights into the physical-ecological coupling processes and driving mechanisms governing oceanic environmental changes during typhoon events, particularly in the waters adjacent to the Yangtze River Estuary.