夏季苏北沿岸流对长江冲淡水扩展影响的数值模拟

建立一个σ坐标系下三维非线性斜压浅海与陆架模式，并首次应用于长江冲放展机制的研究。考虑实际海岸形状和海底地形，在空间完全交错的网格系统丈犀离散化控制方程组，采用ＡＤＩ计算方法数值求解。数值试验结果首次表明，在夏季长江口水位向外倾斜，冲淡水穿越等水位线运动，远离长江口水位倾向东北，冲淡水沿水位坡面运动，同时再现了伸向东北的冲淡水舌和东海陆架上的环流结构。夏季苏北沿岸流作为长江口北部海区的一股势力，阻

Numerical Simulation of the Impact of the Subei Coastal Current on the Expansion of the Changjiang River Diluted Water in Summer

A three-dimension nonlinear baroclinic shallow water and continental shelf model ina coordinate system was developed and applied for the first time in the study of the expansion ofthe Changjiang River diluted water. The real shape of the coast and topography were considered. The ocean control equations were discreted in a completely staggered grid system and theAlternating Direction Implicit (ADI) scheme was adopted for the numerical resolution. The numerical experiment indicated for the first time that the water level sloped outward, the dilutedwater ran across the isoclinal lines of water level near the mouth of the Changjiang River. Farfrom the mouth, it sloped toward northeast, and the diluted water flowed along the sloping surface of water level in summer. Meantime, the freshwater tongue which expand to northeast andthe circulation structure on the continental shelf of the Doughai sea were reappeared. In summer the Subei Coastal Current was as a strand of force in the sea area north of the mouth of theChangjiang River, blocked the diluter water flowing northward along the coast and makde itturning to east. The more stronger the Subei Coastal Current was, the more difficult the dilutedwater flowed northward, conversely, it was deepened to flow northward. It was an indispensableexternal factor in determining the general distributed patten of the Changjiang River freshwaterin summer.