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

As a strong air-sea interaction phenomenon, typhoons significantly impact the physical and biogeochemical processes of the upper ocean. Based on the Regional Ocean Modeling System - Carbon, Silicate, Nitrate Ecosystem model (ROMS-CoSINE) coupled model, the influence of Typhoon Bolaven (2012) on physical and ecological variables in the East China Sea and the underlying mechanisms are investigated. The results show that the typhoon has induced intense vertical mixing in the upper ocean, leading to sea surface cooling, increased salinity and nutrient concentrations, as well as a phytoplankton bloom. Conversely, warming, reduced salinity, and decreased nutrient concentrations occurred in the subsurface layer. In the Yangtze River Estuary, the typhoon's passage effectively affected the wind and current directions, thereby shaping the dipole distribution patterns of environmental elements. Diagnostic analysis indicates that TC-induced horizontal advection played a dominant role in driving the changes in both 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.