Langmuir环流在上层海洋混合中的作用

项目名称： Langmuir环流在上层海洋混合中的作用

项目编号： No.40876012

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 能源与动力工程

项目作者： 宋金宝

作者单位： 中国科学院海洋研究所

项目金额： 44万元

中文摘要： 海洋上混合层（OML）不仅直接影响海洋与大气间的动量、热量和水汽等交换，而且对海洋和大气许多过程有重要作用。海浪破碎及Langmuir 环流（LC）等小尺度过程，对OML内湍流生成和混合的影响至关重要，进而影响OML。本项目利用大涡模拟等方法，研究了不同海况条件下LC的结构、生成、演化和消衰过程及其在海洋上层混合中的作用，导出了LC引起的表层条纹间距与风速及混合层深度的关系；研究了LC与其它动力和热力过程的相互作用机制及不同物理过程与LC 的相关性，特别是波浪破碎和LC共同作用所引起的强混合问题。利用改进的三维大涡模式模拟了CBLAST观测，模拟结果与观测数据符合良好；研究了LC的物理特征参数与风速等的关系，并通过修改湍封闭模块，将LC引起的混合作用参数化到海洋模式ROMS中，模拟了波浪破碎和LC对南海上层混合的影响；对波浪修正Ekman漂流模型，在涡粘性随深度缓变假定下，得到了一组定常流速近似解析解；研究了波浪破碎对雷达后向散射模型的影响及水中岩石坠落激发表面波的生成机制；计算了不同对流项离散方式和湍流模型对柱体绕流计算的影响及使用一维模型和气象数据对上层海洋温度时空结构的重构等。

中文关键词： Langmuir环流（LCs）;混合;湍流;波浪

英文摘要： The ocean surface mixed layer (OML) not only has a direct influence on the air-sea exchange of momentum, heat and gases, but also shows the important role in ocean and atmosphere dynamic processes. Small-scale processes, such as wave breaking or Langmuir Circulation (LC), are thought to contribute to turbulence generation and vertical mixing. Thus, they have vital impact on the dynamic structure and thermodynamic structure of the OML. Using the large eddy simulation (LES) and other methods, this project studied the structure, the production, the growth and the decay of LC, and its effects on the upper ocean mixing under the different sea condition, proposed the relationships between the spacing of LC and wind speed or the depth of mixed layer; studied the interaction between LC and the other dynamic or thermodynamic process as well as the relativity between LC and other physical processes. An improved LES model is used to conduct hindcast simulations of the CBLAST observations and great agreements are obtained; studied the physical feature parameters of LC and its relations with wind speed, wave parameters and others. Incorporatted the mixing effects of LC into the large-scale ocean circulation model ROMS by modifing the Mellor Yamada turbulence closure mixing scheme and studied the effects of LC and wave breaking on the upper ocean mixing in South China Sea; an approximate steady solution of the wave-modified Ekman current is presented for gradually varying eddy viscosity；studied the effects of wave breaking on microwave backscattering and the mechanism of wave generation by the falling rock in the two-dimensional wave tank; different advection schemes and two-equation turbulence closure models are used to compute the drag coefficient around a circular cylinder or square cylinder at high Reynolds number; a 1D numerical code based on Mellor-Yamada turbulence closure model is used to reconstruct the upper ocean thermal structure, utilizing the atmospheric forcing data from ship-borne weather station.

英文关键词： Langmuir Circulation (LC); Mixing; Turbulence; Waves