用广义随底坐标海洋模式研究南海2000年夏季环流  

A study of the circulation in the South China Sea during the summer of 2000 using a generalized terrain-following ocean model

作　　者：王惠群[1] 袁耀初[1] 管卫兵[1] 楼如云[1] 王康墡[1] 

机构地区：[1]国家海洋局第二海洋研究所

出　　处：《海洋学报》2003年第6期20-30,共11页

基　　金：国家重点基础研究发展规划项目 (G19990 4 380 5 ) ;预研项目 (2 0 0 1ccb0 0 5 0 0 ) ;国家海洋局青年基金资助项目(2 0 0 0 2 0 9)

摘　　要：基于 2 0 0 0年 8月在南海调查航次得到的水文资料 ,首次采用广义随底坐标形式的改进POM模式对南海夏季环流进行了数值研究 .用正交曲线性水平网格覆盖观测区域 ,在垂向上对近表海面层次采用近似z坐标 ,而近底层则为随底坐标 .在计算海区实际地形及假设的水平均匀而垂直层化的密度分布下 ,实施的两个数值计算试验表明 ,本模式采用的垂直坐标方案比传统的σ坐标方案优越 ,随底坐标模式因压力梯度项在起伏地形下产生的系统计算误差将变得十分的微小 .在南海 2 0 0 0年夏季环流的实际计算中 ,首先对观测资料进行了 6 0d的诊断计算 ,然后在诊断已得到的动力场结果基础上 ,又进行了 1 0d左右的预报运行得到半诊断结果 .从计算结果来看 ,它依赖于参数Cvis与Cdif的选择 ,特别是参数Cvis,文中取值为Cvis=Cdif=0 0 8.比较诊断与半诊断两个计算过程的结果 ,它们在定性上较为一致 ,在定量上有些差别 .这是因为半诊断计算的方法对密度场作适当的动力调整 ,使其与地形、风场等更加匹配 .在大尺度环流结构不受影响的情况下 ,尽可能地消除了小尺度噪声 ,可使计算得到的流场更为清晰 .2 0 0 0年 8月南海计算区域环流的最大特点是多涡结构 ,其中有些反气旋暖涡和气旋式冷涡相间分布 .在越南东南海域自表层至 1 0 0 0m水?Based on the hydrographic data obtained by the cruise in August 2000 in the South China Sea (SCS), the revised Princeton Ocean Model (POM) with a generalized terrain-following coordinate system, i.e., the G-T-F ocean model (GTFOM) was firstly adopted to study the circulation in the SCS during summer. The observational area is covered well by an orthogonal curvilinear grid in the horizontal, while in the vertical a generalized terrain-following grid is set up which is similar to a z-level grid in most part of z direction, but departs from the z-level constraint near the bottom boundary, such that the lowest layer follows the bottom topography. With the actual topography and horizontally uniform, vertically varying buoyancy field, the comparison between the two numerical experiments shows that the adopted vertical grid scheme of GTFOM is better than the traditional sigma coordinate scheme, and the systematic error produced by the horizontal pressure gradient calculation near steep topography becomes much smaller when the scheme GTFOM is used. For the calculation of circulation in the SCS during the summer of 2000, there are two computed methods, i.e., the diagnostic and semi-diagnostic calculations. The horizontal mixing coefficients for viscosity and diffusivity are calculated by two Smagorinsky-type formulations. It is found by several numerical experiments that the computational results are sensitive to the taken values of their parameters. Comparisons between the diagnostic and semi-diagnostic results indicate that they agree qualitatively, but there are some differences between them in quantity. In the semi-diagnostic calculation, the flow field is hydrodynamically adjusted with the density field, wind stress and bottom topography, moreover, the small scale noises are removed. The main feature of circulation over the computational domain of SCS during August 2000 is as follows: There exists many warm and cold eddies, and among them the most notable eddy is the anti-cyclonic warm eddy southeast off Vietnam, and

关 键 词：广义随底坐标 POM模式 夏季环流 三维数值模拟 

分 类 号：P722.7[天文地球—海洋科学] P731.21