【作者】 山峰；

【导师】 乔方利；

【作者基本信息】 中国海洋大学 ， 物理海洋学， 2009， 博士

【摘要】 本文运用POM模式，对黄海和东中国海的以下几个水文现象进行数值研究。观测资料表明，东海黑潮在约129°E，30°N转向，在数值模拟中注意到，当模式水平分辨率低时，模拟出的黑潮转向点往往偏北，当分辨率提高时，黑潮转向点随之向南移动。在本文第二章数值实验显示，斜压项对黑潮转向点的位置无明显影响。进一步数值实验表明，可以用一种新的思路解释黑潮转向点的位置变动的问题：黑潮在转向点附近流径可近似为一圆弧，黑潮转向点偏北，黑潮转向半径R偏小，若黑潮转向点向南移动，则可视为转向半径R变大。不同水平分辨率下算出的黑潮流速不同，当分辨率低时，算出的黑潮往往流幅宽，流速小，分辨率高时则算出的黑潮流幅窄，流速大。黑潮流速越大，对应的转向半径就越大，于是黑潮转向点向南移动。本文进一步解释了为什么实际海洋中黑潮转向点的位置会发生季节变动，夏季偏南，冬季偏北。第三章运用数值模拟的方法探讨长江冲淡水的夏季扩展机制，重点放在夏季长江口外海区温度锋面的影响。观测显示：夏季长江冲淡水流出长江口以后，先向东北方向扩展，在到达约123°E后，转向东南。本章发现长江冲淡水的夏季扩展形态是受温度锋与环流的共同作用而形成的。在长江口的东南海域，一冷水带沿浙江沿岸分布，其温度锋从海底抬升至海面，形成屏障，冲淡水在该方向的扩展被该温度锋阻止。在长江口的东部海域，底冷水团的温度锋未抬升到海面，而是离海面有5m的距离，这5m的距离成为冲淡水的“通道”，冲淡水通过该“通道”向东扩展至122．5°E，台湾暖流分支出一股北向海流，而长江口外122．5°E恰巧是该海流的流径。冲淡水被此海流携带，向偏北方向扩展。在长江口的东北海域，在约122．5°E，34°N有一冷水带，其温度锋抬升至海面形成屏障，迫使上述的北向海流流向由东北转为东南，冲淡水也改向东南扩展。第四章研究冬季黄海双暖舌现象。卫星遥感资料显示：冬季黄海中部的表层温度场分布呈现双暖舌结构：西暖舌和东暖舌。本章通过数值实验来研究双暖舌结构的形成机制及其与黄海暖流的关系。数值实验结果表明：西暖舌是由黄海暖流形成的，而黄海暖流由于冬季季风海流的补偿作用而得到加强。东暖舌是在黄海海槽的一逆时针方向的环流的作用下形成，该环流是由夏季和秋季黄海冷水团的温度锋所诱发形成的。在该环流东部，暖水被向北携带，在黄海海槽东侧形成暖舌，该暖舌会维持到冬季一月。第五章研究夏季东中国海一温度垂向均匀水柱的形成机制。在约124°E，32°N，东中国海北部海区，夏季八月观测到一温度为垂向均匀的水柱，该水柱被周围垂向层化的海水包围。本文采用数值模拟方法去探讨其形成机制。结果表明，来自海面的浪致混合与来自海底的潮致混合在约124°E，32°N联结在了一起。浪致混合与潮致混合共同作用使得整个水柱温度垂向均匀。它们对该水柱的形成都是不可缺少的。更多还原

【Abstract】 Several hydrographic phenomena in the Yellow Sea (YS) and the East China Sea(ECS) are studied using POM model as tool, with results as below:Observations show that in the ECS, the Kuroshio veers at about 129°E,30°N. In numerical simulations it is noticed that when the horizontal resolution is low, the simulated veering point of Kuroshio is often farther north than that observed, with the horizontal resolution increased, the veering point is shifted southward. In Chapter 2, this phenomenon is studied with POM model. The first run of numerical simulation shows that baroclinic effect has little effect on the veering position of the Kuroshio. The second run of numerical simulation shows the veering mechanism of the Kuroshio can be explained by the maximum velocity of Kuroshio. In the veering area, the Kuroshio flows in the formation of an arc, when the veering latitude is farther north, it can be considered that the veering radius is small, while it is large when the veering point is shifted southward. With different horizontal resolution, numerical models produce different velocities of the Kuroshio. If the horizontal resolution is low, the simulated Kuroshio often has lower velocity and corresponding smaller veering radius, if the horizontal resolution gets higher, the simulated velocity of Kuroshio will be intensified, the veering radius will get bigger, and the veering point will be shifted southward. The velocity of Kuroshio is the key factor in determining the veering latitude. In the real ocean, the Kuroshio also has seasonal migration on veering latitude, this can be explained by the same mechanism.In Chapter 3, the expansion mechanism of the Yangtze River Diluted Water (YRDW) during summer season, particularly in August is studied by numerical simulations based on POM model. The control experiment reproduces the main pattern of YRDW’s expansion: After flowing eastward off the Yangtze River estuary, YRDW veers northeastward, it veers once again southeastward at reaching 123°E. This expansion pattern is mainly influenced by the combination of the thermal front and current. In the region southeast to the estuary, a band-shaped thermal front is uplifted from the bottom to the surface, prevents YRDW from expanding in this direction. In the region east to the estuary, the thermal front is uplifted to 5m below the surface, leaving this 5m-depth as the "passage" for YRDW. YRDW expands eastward through this "passage" to about 122.5°E, where happens to be the pathway of a northward Taiwan warm current. YRDW is carried by this current northeastward. Northeast to the estuary ,at about (122.5°E,34°N) there is another thermal front which is uplifted to the sea surface and acts as a barrier to the current, this current is forced to change its direction from northeastward to southeastward, then YRDW is carried southeastward.In Chapter 4, satellite remote sensing observations show that sea surface temperature (SST) presents the double warm tongue structure in the Yellow Sea Trough during winter: the western and the eastern warm tongues respectively. Numerical experiments based on POM are carried out to study the forming mechanism of this thermal structure and its relation to the Yellow Sea Warm Current (YSWC). The control experiment reproduces this phenomenon quite well, numerical experiments investigate the effects of wind and tide. It is found that the western warm tongue is mainly caused by YSWC, which can be strengthened by wintertime southward wind. The eastern warm tongue develops under the influence of an anti-clockwise circulation which is induced by the temperature front of the Yellow Sea Cold Water Mass (YSCWM) in summer and autumn. In the eastern portion of this circulation, the northward current carries warm water to north, forming the eastern warm tongue, which remains till winter.In Chapter 5, At about (124°E,32°N), in the northern East China Sea, the forming mechanism of a vertically well-mixed water column observed in August is studied. This column is surrounded by ambient stratified water. Numerical simulations based on POM model are carried out to investigate its forming mechanism. The results show that the wave-induced mixing from the surface is connected to the tide-induced mixing from the bottom at about 124°E,32°N. The combination of wave-induced mixing and tide-induced mixing makes the temperature of whole water column uniform. Both of them are indispensable for the yield of this water column.更多还原