沿岸海区冬季垂直环流及其温盐结构的数值研究 Ⅰ.环流的基本特征

为了揭示沿岸海区冬季垂直环流及其温盐结构的分布特征和变化规律，利用三维斜压流体动力学模型，对具有岸界坡度变化、河流入海、海湾、岛屿和海槽的理想海区冬季的垂直环流及其温盐结构进行了数值模拟。其环流的数值结果表明，冬季沿岸海区的垂直环流普遍呈逆时针流动。在近表层为向岸流，沿岸为下降流，近表层以下为离岸流；近表层以下的离岸流在外海有明显的上升趋势；沿岸下降流自表层至底层逐渐由强变弱；就整个海区而言，随着自南往北海区水深的逐渐变浅和岸界地形坡度的由大变小，其沿岸下降流则由强变弱。

NUMERICAL STUDY ON VERTICAL CIRCULATION AND T-S STRUCTURE IN COASTAL SEA AREA DURING WINTERTIME I.BASIC CHARACTERISTICS OF THE CIRCULATION

In order to identify pattems of distribution and spatial variahons of the vertical circulation, and temperature and salinity smictures in the coasta sea area during the wintertime, numerical simulations were catried out for an ideal sea area using a variety of data sets for the seabed topography, and river discharges into the sea. The simulahons were based upon a three-dimensional baroclinic ocean model.The computational results show the formation of an anhclockwise vertical circulation during wintenime, shoreward currents in the nearsurface layer, downwelling in the nearshore area, arid off shore currents below the nearsurface layer, with a rising tendency in the outside sea- The downwelling gradually weakens from the surface layer to the bottom layer. over the whole coasta area, the intensity of the downwelling decreases with the decreasing of water depth and seabed slope. The coastal downwelling mechanism can be attributed mainly to a coupling effect between wind stress and seashore, and the inhomogeneous distribuhons of temperature and salinity.