珠江河口拉格朗日拟序结构及其在浊度锋识别中的应用

发布时间：2018-04-22 12:07

本文选题：浊度锋 + 拉格朗日拟序结构(LCSs)　；参考：《海洋工程》2017年02期

【摘要】：基于珠江河口水文实测资料和三维水动力数值模型,利用有限时间李雅普诺夫指数提取分析了流场中的拉格朗日拟序结构(LCSs),并结合卫星遥感图像探讨珠江河口LCSs时空分布与其浊度锋的关系。结果显示,河口浊度锋与LCSs在时空上存在很好的契合,LCSs所形成的输运通道与壁垒对河口浊度锋的位置、形态及变化过程有显著影响。落潮时,泥沙随蕉门、洪奇门和横门的落潮射流注入伶仃洋,与虎门下泄的冲淡水对峙形成了一条明显的FTLE脊线,制约着浊度锋的形成和分布形态。涨潮时,来自西北三口门的淡水径流受口门外涨潮流的顶托作用,强烈的水平速度与密度梯度在此处形成LCS,阻碍径流挟带悬浮泥沙的输运而产生浊度锋。由于LCSs很好地勾画了不同动力性质的水体边界,因此可以用来对河口浊度锋进行识别、追踪和动力解释。
[Abstract]:Based on the hydrological data of the Pearl River Estuary and the three dimensional hydrodynamic numerical model, The Lagrangian pseudo-sequence structure in the flow field is extracted and analyzed by using the finite time Lyapunov exponent, and the relationship between the spatial and temporal distribution of LCSs in the Pearl River estuary and its turbidity front is discussed with satellite remote sensing images. The results show that there is a good agreement between estuarine turbidity front and LCSs in time and space. The transport channels and barriers formed by LCSs have a significant influence on the location, morphology and variation process of estuarine turbidity front. During the ebb tide, sediment was injected into Lingdingyang with the falling tide jet of Jiaomen, Hongqimen and Hengmen, which formed an obvious FTLE ridge line with the fresh water discharged from Humen, which restricted the formation and distribution of turbidity front. At high tide, the fresh water runoff from the third entrance of the northwest is supported by the rising tide outside the entrance. The strong horizontal velocity and density gradient form LCSs here, which hinders the transport of suspended sediment by runoff and produces turbidity front. LCSs can be used to identify, trace and explain the turbidity front in estuaries because of its good delineation of the boundary of water body with different dynamic properties.
【作者单位】：热带海洋环境国家重点实验室;中国科学院大学;
【基金】：广州市科技计划项目(201607020042) 热带海洋环境国家重点实验室自主研究项目(LTOZZ1503)
【分类号】：P731.2

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