【作者】 苏健；

【导师】 孙文心； 魏皓；

【作者基本信息】 中国海洋大学 ， 物理海洋， 2005， 博士

【摘要】 本文对浅海陆架锋的跨锋面水交换进行了数值研究,分别对南海北部陆架锋和南黄海的潮汐锋进行了数值模拟,利用模拟的结果揭示了跨锋面垂向环流的主要特征和跨锋面水交换的物理机制。 本文采用POM模式对冬季南海北部陆架锋区进行了三维斜压的数值模拟,本文是首次对南海北部陆架锋进行了三维数值模拟,并对跨锋面水交换进行了量化。结合走航观测资料,卫星资料,地波雷达资料等对该海域的海洋锋进行了系统全面的整理和研究,这些数据也作为检验数值模拟是否成功的依据。 在验证模拟和实测符合良好的基础上,本文以模拟的结果为主,结合观测资料,对南海北部陆架锋的特征,垂向环流结构,跨锋面水交换量等着重进行分析和探讨,同时设计了数值试验,把各个物理因子参数化,通过试验探讨跨锋面水交换的物理机制,得到一系列有意义的结论: 1) 从模拟的结果来看,陆架锋的位置沿30m-40m等深线分布,锋面强度大约为1℃/n m,跨锋面垂向是双圈环流结构。从观测的结果来看,跨锋面的断面也是典型的双圈环流结构,控制锋面两侧水平环流的流系是广东沿岸流和南海暖流,这两支流动对锋面的位置和强度起很重要的作用。 2) 通过观测估算的跨锋面水交换量为1.5Sv,上层厚大约为25-30m,水流方向向岸,底层厚大约为5-10m,流速方向向外海。通过模拟的结果而估计的跨锋面水交换量大约为1.89Sv,平均速度向岸大约7-8cm/s。 3) 通过对跨锋面机制的探讨,作者认为南海北部陆架锋跨锋面水交换有两个分量:其中非锋生的机制是风的影响,风海流本身就有跨锋面的分量,而风的变化造成了锋面两侧流系的变化也对跨锋面水交换有影响;另一个跨锋面的流动分量是锋面本身造成,最主要的控制机制是锋面的斜压不稳定。 本文也是首次对不同锋面的垂向环流结构进行了比较。采用三维陆架海模型更多还原

【Abstract】 In this thesis, the cross-front water exchange is studied by numerical simulation. The simulation includes two areas: shelf front in the Northern South China Sea (NSCS) and tidal front in the Yellow Sea (YS). The results show the cross-front circulation and the dominant mechanisms of cross-front water exchange.It is the first time to use 3D numerical model to study shelf front in NSCS, and it is the first time to calculate the cross-front water exchange, too. In NSCS, we have in situ observations, high resolution CTD, ADCP data, satellite pictures and CODAR data. These data are used to validate the results of the model.After the validation the good agreement between simulated results and observed ones, the characteristics of the shelf front in NSCS are studied. Some sensitive experiments are done to study the dominant mechanism of cross-front water exchange. We draw a series of meaningful conclusions as follows, the main of these are:1) The front is along isobath the 30-40m, and the gradient of the front is l℃/n m. The cross-front circulation is double cells. The two important currents are Guangdong Coastal Current and South China Sea Warm Current. The position and the gradient of the front is controlled by these two currents.2) The calculated water exchange with the observation is 1.5 Sv onshore, and which in the simulation is 1.89 Sv. In the observation, the up-layer is about 25-30m onshore and the bottom layer is 5-10m offshore.3) There are two component in the cross-front water exchange, one is non-front mechanism which is wind force in this study, the other is front mechanism which is baroclinic instability.In thesis, we also use a numerical model (HAMSOM) to study the tidal front in the Yellow Sea. It is the first time to do some comparison of two different fronts. Themain conclusions we draw are:1) The tidal front in YS is in strong tidal area, and the shelf front in NSCS is in weak tidal area. The dominant mechanism of cross-front water exchange in NSCS is wind and baroclinic instability, and the one in YS is tidal mixing.2) The jet along the tidal front is very clear in YS, while the velocity shear in NSCS can not be seen. The vertical circulation of tidal front is multi-cell, and which of the shelf front is double cells.3) The cross-front water exchanges in both fronts are in the upper layer. The water exchange in both fronts can not be neglected for its importance in sendiment transportation.更多还原