Effects of successive two typhoons on the water environment and primary productivity in the northern East China Sea

Typhoon is one of the several most serious catastrophic weather events that affect East China Sea (ECS). We study the effects of successive two typhoons (Maemi and Choi-Wan) passing over the northern South China Sea in 2003 in 8-day interval based on field observation, remote sensing, and numerical modeling on water environment and primary productivity. Results show that the second typhoon made the water column even more vertical-mixed, and the decrease of SST and the increase of primary productivity following the second typhoon were somewhat relieved owing to the early influence of the first typhoon. In addition, the two typhoons altered the advection structure in the upper ocean, and the distributions of temperature, salinity, and chlorophyll were significantly reshaped. The chlorophyll content in the subsurface layers changed more greatly than in the surface layer under the two-typhoon effect. At some stations, the subsurface chlorophyll maximum (SCM) layers were destroyed after typhoon, and several days later, they resumed and reached much greater chlorophyll concentrations than previous ones.