一个斜压海洋环流数值模式及其数值试验

A NUMERICAL BAROCLINIC OCEAN CIRCULATION MODEL AND NUMERICAL TEST

为研究大尺度海洋环流和一些大尺度海洋物理过程,我们建立了一个无海底地形的三层斜压海洋环流数值模式。模式方程采用了静力近似和Boussinesq近似,在上边界采用了钢盖近似。同时,还做了两个数值试验:第一个模拟试验,海洋从静止状态开始,以4个季节的气候平均风应力和海表大气季节平均温度为强迫条件,积分区城选择45℃以北的太平洋,数值积分了5个模式年,这时海洋的上层环流和温度的年变化趋于平稳。计算结果再现了太平洋气候平均状态的海温分布和主要海流的大尺度特征以及它们的年变化特征。如西部强化流、赤道潜流等。第二个数值试验,在第一个数值模拟的基础上给定赤道西太平洋一个风应力异常区,数值积分了几个月。从计算结果中可看到类似E1 Ni■o的现象,并且初步地分析了赤道波动在E1 Ni■o形成过程中的作用。

A three-level baroclinic ocean model has been developed for studying large-scale oceanic circulation. The formulation of the model is based on primitive equations with hydrostatic and Bousinesq approximation. The rigid-lid condition is adopted in the model. Two test integrations have been performed.In the first one, the model integration starts from a rest state with seasonal mean wind stress and air temperature near the ocean surface as forcing. The domain of the model is the Pacific Ocean from 45°S to 55°N. A seasonal equilibrium in the upper layers is reached after five years of integration. The simulated results reproduce the major large-scale features of temperature field and main currents in the Pacific Ocean and their seasonal variation, such as the relatively strong current at western boundaries, the Equatorial Undercurrent, the Equatorial Countercurrent, etc. The second experiment incorporates wind stress anomalies over western equatorial Pacific. The results show that oceanic response to wind stress anomalies is similar to the El Nino phenomenon. The effect of equatorial waves on the El Nino is preliminary analysed.