Numerical Simulation Of The Circulation And The Mesoscale Eddies In The East China Seas In Winter

A three-dimension baroclinic prognostic model on the o-coordinate isestablished based on POM to simulate the wintertime circulation and the eddies in the East China Seas,considering the topography,inflow and outflow on the open boundary,Yangtse runoff,heat flux and wind stress on the sea surface. Besides,some numerical experiments were done by changing the following factors------theTaiwan Strait inflow,sea surface wind stress,Kuroshio inflow respectively,to find out the effects of these factors on the wintertime circulation and the eddies in the East China Seas .The results show that,the Kuroshio flows along the continental slope of the East China Seas,its trajectory varies along with the slope topography,and some eddies appear on the both sides of it.On surface layer,the Taiwan warm current is mainly derived from the inflow of the Kuroshio,little portion from the inflow of the Taiwan Strait;between 10m and 50m,the portion from the Taiwan strait is as much as the portion from Kuroshio northeast of the Taiwan Island;Under 50m,Kuroshio is the main resource of the Taiwan warm current.Tsushima current is formed by the confluence of the following currents:(1)a current separated from the Kuroshio and entering the continental shelf northwest of Amami Oshima. (2) the current starting from the outflow through the Taiwan Strait,i.e.,the Taiwan current. (3)the Korea coast current.Both the Taiwan warm current branch and Tsushima current branch are the main resources of the Yellow Sea warm current. From south to north,the Yellow Sea warm current separates the circulation of Yellow Sea into two parts. TheYellow Sea warm current flows northwestwardly into the north of Bohai. The feature of the circulation in Bohai is:northward inflow and southward outflow.Three branches separating from Kuroshio flow toward the interior of the Yellow Sea,and formate three eddies respectively. The mid-eddy centers on12437'E,37N,and the south eddy centers on 124E,3530'N. The descriptionof the two eddies above is according with the situation of the distribution of temperature and salinity.A large cyclonic eddy exists at the southwest of the Cheju Island,whichcenters on 125.1E,30.5 N. It's a closed structure conformed by theeast-northward the Taiwan warm current,west-northward Yellow Sea warm current and southward coastal current.Kuroshio intrusion engenders an eddy at the west of Kyushu Island of Japan. The branch of Kuroshio is the direct dynamic factor of the formation of this eddy. Moreover,both the topographic influence and the northward wind prevailing in winter affect the eddy's formation positively.On the continental shelf,left of Kuroshio (125.3E,28.5N),there exists alarge cyclonic eddy. Next to the Kuroshio tongue-shaped intrusion onto the continental shelf,northeast of Taiwan,there is a puny cyclonic refluence section.