黄海冷水团对长江冲淡水扩展的影响

THE IMPACT OF THE YELLOW SEA COLD WATER MASS ON THE EXPANSION OF THE CHANGJIANG DILUTED WATER

利用作者已建立的σ坐标系下三维非线性斜压陆架模式，研究黄海冷水团（YSCWM）对长江冲淡水（CDW）扩展的影响。数值试验结果表明，黄海冷水团产生的余流，与黄海冷水团的强度和海底地形有关。在长江口海区由于底形的影响，黄海冷水团产生了向北流动的海流，阻碍着长江冲淡水沿岸向南扩展。在远离长江口海区，黄海冷水团产生的气旋式黄海环流诱导冲淡水向东南运动。总的黄海冷水团的作用是使长江冲淡水低盐水舌伸向东北，黄海冷水团越强，这种作用就越明显。黄海冷水团在夏季长江冲淡水伸向东北过程中起着重要的作用。

A three-dimension nonlinear baroclinic and continental shelf model with primitive equations in o coordinate system was used to study the impact of the Yellow Sea Cold Water Mass(YSCWM) on the expansion of the Changjiang Diluted Water (CDW). The calculation domain is the whole East China Sea. The horizontal resolution of the model is 7.5' × 7.5' ， and the vertical resolution is 11 layers. The ocean control equations were discreted in a completely staggered grid system and the Altemating Direction Implicit (ADI) scheme was adopted for the numerical resolution.The semi-momentum scheme which is quadratic conservation was adopted for the nonlinear terms in the momentum equations. The implicit scheme was used for the the vertical eddy diffusion terms in the tempetature and salt equation.The numerical experiments showed that the YSCWM induced the residual current's northward flows along the Zhejang coast in the sea area near the Changjiang mouth due to the effect of the topography that blocked the CDW's southward expansion along the coast.The YSCWM induced cyclonic Yellow Sea cireulation guides the CDW's southastward expansion in the sea area far from the Changjiang mouth. Taking into consideration the factors of the Kuroshio,Taiwan Warm Current,coastal current,wind stress and topography, thes numerical experiment showed the nouthast expanding freshwtter tongue and the cireulationature in the East China Sea in summr. The YSCWM has significant influence on the northeastward turning direction of the CDW.The stronger the YSCWM is, the greater the effect of the YSCWM induced residual currents and the more obvious the northeastward turning of the CDW.