东中国海环流及其相关动力过程的模拟与分析

【作者】 鲍献文；

【导师】 冯士筰； 孙文心；

【作者基本信息】 中国海洋大学 ， 海洋科学， 2003， 博士

【摘要】 黑潮及其台湾海峡、对马海峡的水体输送；通过海面热和水气交换以及潮流混合作用下的海水温、盐分布与结构的四季演替过程；潮流潮汐过程；环流的季节性变化等。这些重要物理过程决定了东中国海海洋环境状况，关系着东中国海的能量与物质的输运。 东海各海峡水道的流速分布与流量季节变化对东海黑潮及陆架环流有重要影响。论文首先利用OCCAM全球模式结果，分析了中国近海重要海峡水道的流速分布及流量的月季变化。结果表明：台湾以东水道年平均流量为25.8Sv，夏季流量大，春、秋季次之，冬季最小。吐噶喇海峡水交换量年平均27.9Sv，夏季最大，春季、冬季次之，秋季最小。台湾海峡终年有水量从南海流入东海，7月流量最大，为3.1Sv，11月最小，仅有0.9Sv，年平均流量为2.0Sv；对马海峡平均流量为2.3Sv，月变化较小，仅0.4Sv。 温度水平分布和垂直结构的变化是影响东中国海环流分布的重要因素，是环流研究的基础。通过获取、分析和校正1990-1999年间逐周的卫星遥感海表温度资料，并通过最优插值技术获得东中国海18x 18km周平均和月平均海面温度场，论文还系统分析了东中国海月平均海表温度场的分布特征。 潮汐潮流是东中国海，尤其是渤、黄海重要的动力要素之一，是影响东中国海的温、盐分布和环流特征的基本物理过程。论文构建了一个基于垂直σ坐标系统下的半隐式三维正压模式，并模拟东中国海四大分潮的潮汐和潮流。该模式可大大提高时间步长，与目前广泛使用的POM模式相比，效率可提高数十倍。论文系统分析了东中国海四大分潮的潮汐和潮流特征，潮流模拟结果表明，东海陆架边缘到黄海，潮流基本呈顺时针方向旋转。而在黄海，其潮流基本呈往复流特征。半日潮流在黄海中部、渤海海峡和辽东湾存在三个往复流区。 针对以往温、盐资料分析和模式诊断方法为主的东中国海环流研究的局限性，通过改造POM模式，克服因陡峭地形和大密度梯度给模拟带来的困难，建立了东中国海环流准预报模式，运用本文第三章获得的SST资料和全球大区模式的结果作为模式的边界条件，模拟了东中国海温度分布与环流结构。分析结果表明，中段黑潮流幅山南至北增宽，流速变大，流核所达深度变浅。东海东北部陆架海域冬季黑潮以其分支形式向北入侵，夏季则主要以大陆边缘流的形式向北进入陆架。台湾暖流终年表现出东、北两分支结构，但两分支表现出明显的季节性变化特征。与夏季相比，冬季北分支流速较小，流辐较窄，而东分支的流辐比夏季宽。黄海暖流仅在冬季出现，支持“黄海暖流是一强北风作用下的补偿性海流”观点。论文还对东海各暖流的水源及其季节变化也进行了系统的分析。 黄海环流的季节变化显著依赖温度分布及垂直结构。通过建立黄海斜压模式并考虑潮汐、风和湍流混合，成功模拟了黄海温度结构的年循环过程。分析结果表明，渤海和黄海浅水域的热结构分冬季均一型和夏季层化型，层化与对流的交替作用决定黄海中部温度垂直结构，黄海冷水团、黄海暖流、陆架锋支配着黄海局域温度结构。黄海暖流敏感依赖于冬季的偏北风，冬季黄海暖流在南黄海呈现两分支，其中西分支是黄海暖流的核心。黄海中部夏季环流非常弱，沿其冷水团的边缘呈现逆时针的水平环流。 近海环流及其环境问题的研究迫切需要岸界适应的数值方法，通过将微分水平坐标变换和。垂直变换巧妙结合，创建了能完全适应岸边界和底地形网格的曲线坐标三维正压数值模式，并将模式成功运用渤海的潮流模拟。该模式与现有其它潮模式相比，使用岸界拟合网格数值模式，使数值模式所提边界条件更精确，数值计算更简化，同时还能减少岸界因网格“锯齿”带来的伪效应，使模拟结果更加可靠。更多还原

【Abstract】 The main physical processes in the East China Sea include the Kuroshio and water flux of the Taiwan strait and Tsushima strait, the thermohaline structure and its seasonal variation by exchange of heat and water on sea surface and mixing of tide, as well as the tide and tidal current, and circulation and its seasonal variation. These processes control the distributions of oceanography factors and the transports of mass and energy in the East China Sea (ECS).Knowledge of the fluxes, velocity distributions and their variations in each of straits in the ECS were very important for study of the circulation and coastal environment in ESC. The OCCAM global ocean model results were applied to calculate monthly water transport through 4 main straits around ECS. Analysis results showed that annual mean flux in Eastern Taiwan was about 25.8Sv and the flux in summer was larger than that in spring and autumn, as well as smallest in winter. Annual mean flux in Togara Strait was about 27.9Sv and the flux in summer was larger than that in spring and winter, as well as smallest in autumn. Water always flowed from the South China Sea to the ECS in each season in the Taiwan Strait. The maximum flux was about 3.1Sv that appeared in July, and minimum was only 0.9Sv in November. The annual mean flux was about 2.0Sv. In the Tsushima Strait, the annual mean flux was 2.3Sv and its monthly variation just was only 0.4Sv.The thermocKne structure and its variation affected the circulation system in the ECS. The weekly and monthly mean sea surface temperatures (SST) in the ECS were obtained by analysis and calibration of SST data from satellites during 1990-1999. The character of monthly mean SST distribution in the ECS were descript in detail.The tide and tidal current were important processes in the ECS. A three -dimensional model, imbedded a closure turbulence sub-model, was built andapplied to simulate the barotropic tides and tidal currents in the ECS. Model results showed that tidal currents over the shelf from the continental edge to the entrance of the Yellow Sea rotated in a clockwise direction, while the currents in the Yellow Sea were rectilinear following and their direction of propagation along the coast. The semi-diurnal tidal ellipse showed three rectilinear regions that located in the middle of the Yellow Sea, the Bohai Strait and the Liaodong Bay.The studies of circulation in ECS were most based on the analysis of temperature and salinity data and diagnostic mode. Aim at breaking this limitation, we had established a quasi-predictive model in the ECS by reconstructing the POM model to overcome the difficulties brought to the simulations by steep terrain and great density gradient In the new model, the monthly mean SST data in the ECS and the result of global ocean model were used as the boundary conditions to simulate the distribution of the temperature and the circulation structure in the ECS. The analytical result showed that, the width of Kuroshio in the middle part became wider from south to north, and the velocity increased, and the depth of the core became shallow. In the northeast continental shelf in ECS, the Kuroshio intruded towards north in several branches in winter, while in summer, the Kuroshio intruded the northern shelf through continental marginal flow. The Taiwan warm current showed that an east and a north branches existing through the whole year, but the two branches showed obvious seasonal variations. In winter, the north branch had a lower speed and a narrower width, compared with that in summer, but the width of East branch was wider than that in summer. Huanghai warm current exist only in winter, which support the conclusion that it was a compensatory current under a strong north wind. The thesis has also done a systematical analysis on the sources and the seasonal variations of the warm currents in the ECS.The pattern an it seasonal variety of circulation in the Yellow Sea, significantly depended on distribution and vertical structure of temperature. In this paper, yearly cyclic更多还原