| 摘要: |
| 根据海水温度和盐度平流扩散方程给出一种数值计算方案并采用混合长度理论给出垂直涡动粘性系数的计算方法。对于温度和盐度方程，其平流过程采用了Lax-Wendroff格式，水平扩散采用显格式，垂直扩散采用隐格式。时间步长主要受平流过程的Courant-Friedrichs-Lewy条件限制。垂直涡动粘性系数计算依据Prandtl混合长度理论，并考虑了海水层化的抑制作用，因而其数值与流场及密度场结构有关。温度、盐度及垂直涡动粘性系数的计算与动力方程中内模态的计算同步进行。应用本模式模拟渤、黄、东海由潮流、密度流和风海流迭加而成的综合海流，得出了良好的结果。 |
| 关键词: 温度和盐度方程 Lax－Wendroff格式 垂直涡动粘性系数 混合长度理论 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，49136142,49576280号;国家科委资助项目，85-903-08-02号 |
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| A THREE-DIMENSIONAL NUMERICAL MODEL FOR BAROCLINIC OCEAN DYNAIVIICSII. COMPUTATIONS OF TEMPERATURE, SALINITY AND VERTICAL EDDY VISCOSITY |
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YU Ke-jun,FANG Guo-hong
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Institute of Oceanology, The Chinese Academy of Sciences, Qingdao, 266071
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| Abstract: |
| A numerical scheme for solving water temperature and salinity equations and a method for computing vertical eddy viscosity are presented. The advection processes of temperature and salinity are calculated prognostically with the Lax-Wendroff scheme and the vertical and lateral diffusions are calculated with implicit and explicit schemes respectively. The time step is mainly restricted by the Courant-Friedrichs-Lewy condition for advection processes. The coefficient of the vertical eddy viscosity is calculated based on Prandtl’s mixing length theory with suppressive effect from seawater stratification considered, and thus varies with variation of the structures of flow and density fields. The temperature, salinity and vertical eddy viscosity are calculated at the same steps as the calculations of the internal modes of velocities.
As a preliminary application, a numerical model of the Bohai, Yellow, and East China Seas was established. The model grid resolution is 15' × 15' with 15 levels in vertical. The monthly resultant currents driven by tide, wind, and density are computed diagnostically. The water levels along the open boundaries are specified a priori. Their oscillating part is predicted from the tidal harmonic constants. The mean water level part is adjusted so as to produce appropriate mean inflow/out?ow volume transports. The monthly water density fields are created by objectively analyzing the recorded temperature and salinity data. The optimal interpolation technique is used in the objective analysis. The Hellerman-Rosenstein’s (1983) monthly wind stress fields are imposed on the sea surface. The present paper shows a part of the computed current ?elds. It can be observed that the currents on the shelf are governed by tides and those in the southeastern East China Sea are controlled by the Kuroshio. Counter currents appear to the southeast of the Kuroshio. |
| Key words: Temperature and salinity equations, Lax-Wendroff scheme, Vertical eddy viscosity, Mixing length theory |
