The Application Of MITgcm On The Study Of The Circulation In The China Adjacent Seas

A variable-grid global ocean circulation model is established based on MITgcm to study the ocean circulation of the China adjacent seas and its seasonal variation. The horizontal resolution of the model is fine (1/6°) in the South China(SCS),East China Seas, and Japan/East Sea, and coarse(2°) in the rest part of the world ocean.The model-produced monthly mean transport stream functions and the anomalies of the sea surface heights .Comparison to the TOPEX/Poseidon data shows that the model-produced monthly sea surface height anomalies are in good agreement with altimeter measurement. This shows the correctness of the result of the model.Based on the model result, the monthly and annual mean freshwater, heat and salt transports through the open boundaries of the Bohai Sea, Yellow Sea, East and South China Seas are calculated. The model results are in fairly good agreement with the existing estimates based on measurements. The computation shows that the volume, heat and salt transports of the Kuroshio in the East China are 23.35Sv, 1.96PW and 805.49Gg/s. Only about 2.6% of those transports pass through the passage between Iriomote and Okinawa. The result indicates that the South China Sea is an important pathway of the Pacific to Indian Ocean throughflow. The calculation of heat balance indicates that the atmosphere gains net heat flux from the Baohai, Yellow and East China Seas with a rate 0.02PW while the South China Sea absorbs net heat flux from the sun and atmosphere with a rate of 0.03PW.Based on the model results, the circulation of Bohai, Yellow and East China Seas and their seasonal variation are studied. Kuroshio is reproduced reasonable well. Kuroshio mainly intrudes the East China Sea through the Taiwan-Iriomote passage and flows out through the Tokara Strait. The transports are strongest in summer and weakest in autumn. Tanwan-Tsushima Warm Current System is well reproduced. The water of Taiwan Warm Current is mainly from the Taiwan Strait and Kuroshio with significant seasonal variability, the water from Taiwan Warm Current is more important. The water of Tsushima Warm Current has three sources, their contribution is seasonal variable. The part of Taiwan Strait is weak in winter and autumn and the strongest in summer. There are some deviations between the model and the observation, it show that the model doesn't work very well in the Yellow Sea and there are something we should improve.Based on the model results, the circulation of South China Seas and their seasonal variation are studied.It shows that the Kuroshio can enter the South China Sea all the year, which is wearker in summer. The anticyclone eddies in the south of South China Sea in summer, the Vietnamese Offshore Current and the cyclone eddies in winter are reproduced very well. The circulation in the upper layer is different from the circulation in the middle layer and the bottom layer.