Phenomenon Analysis And Modeling Study On The Key Physical Processes Impacts On The Plankton In The Yellow Sea & Bohai Sea

To examine the physical processes impacts on the biological processes,we follow the idea of GLOBEC focusing on three steps:field survey,process analysis and modeling study. By analyzing the abundance distribution of the Calanus sinicus at the fronts in the two surveys,we try to find the direct dominant physical processes. And on the basis of that,provide a simple coupled physical and biological model and apply it in the Bohai Sea.The position of the tidal fronts and vertical circulation structure near the fronts are examined using the Blumberg & Mellor 3D nonlinear numerical coastal circulation model incorporating with Mellor & Yamada level 2.5 turbulent closure model. Vertical distribution of phytoplankton biomass and numerical abundance of Calanus sinicus were investigated across the tidal fronts in the Yellow sea,in October 2000 and May 2001. The abundance of Calanus sinicus was higher at the frontal region than at the adjacent stratified and mixed areas while the Chlorophyll-a concentration was highest in the stratified area or mixed area adjacent frontal region. By combining with the simulation result of the vertical circulation structure,we propose that the factors induced the distribution difference of Calanus sinicus and Chlorophyll-a concentration not only include the grazing activities,vertical circulation structure at the fronts also plays an important role.The circulation of Bohai Sea in spring is examined to provide a reliable physical environment for biological model. The model results indicate that the tidalresidual current,density residual current has contribution to the springtime How in the Bohai Sea while the wind stress is an dominant process in driving the flow. And also the model results suggest the importance of the wind variation to the whole circulation,especially for numerical study.A 3D coupled physical and biological model was used to examine the marine ecosystem of the Bohai Sea. The biological model described a simple,nitrate and phosphate based,lower trophic food web system. The model results indicated that the eddies induced by the baroclinic effect had the contribution to the patch distribution of the phytoplankton. A phytoplankton bloom may occur at the mouth of the river due to the high nutrient concentration because of the fresh water discharge. The wind variation has significant impact on the phytoplankton distribution at Laizhou Bay. Vertically,tidal mixing had a direct impact on the distributions of nutrients and phytoplankton. Nutrients and phytoplankton were well mixed vertically by tidal mixing.The vertical circulation structure at the center of the Yellow Sea Cold Water Mass is still not so clear. Since Calanus sinicus always stays in the Yellow Sea Cold Water Mass in summer,it's urgent to find out the relationship between them.More work is needed to apply the coupled model in the Yellow Sea and study the transportation of the nutrient at the front zone and upwelling zone. And also the biological parameters and the climatologic data,such as the wind variation,irradiance,net heat flux,need to be improved to get a more realistic result.