Roles of breaking waves and Langmuir circulation in the surface boundary layer of a coastal ocean
Roles of breaking waves and Langmuir circulation in the surface boundary layer of a coastal ocean
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DOI：
10.1002/jgrc.20387
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发表时间：
2013-10
影响因子：
--
通讯作者：
Shuang Li;Ming Li;G. Gerbi;J. Song
中科院分区：
文献类型：
--
作者：
Shuang Li;Ming Li;G. Gerbi;J. Song
破碎波和朗缪尔环流是风驱动上层海洋中两个重要的湍流过程。为了研究它们在沿海海洋表面边界层湍流产生中的作用，采用大涡模拟模式对玛莎葡萄园岛海岸天文台海气相互作用塔在2003年耦合边界层和海气转移（CBLAST）实验中收集的湍流测量数据进行了模拟。该模型对垂直速度变化、湍流动能、能量耗散率和热流密度的垂直分布有较好的预测效果。在海面附近，破碎波主导着湍流的产生，而在水柱深处，则是Langmuir环流所特有的湍流大涡流。模型中TKE收支的诊断分析表明，地表附近湍流输运和耗散之间的平衡占主导地位，而较深处剪切产生和耗散之间的平衡占主导地位。尽管Stokes产量在地表附近的TKE预算平衡中是一个重要的指标，但它比剪切产量要小。湍流输运在近地表区域较大，在受Langmuir环流影响的区域仍然显著。这些结果与最近对CBLAST站点近地表湍流测量的分析得出的结论一致。
Breaking waves and Langmuir circulation are two important turbulent processes in the wind-driven upper ocean. To investigate their roles in generating turbulence in the surface boundary layer of a coastal ocean, a large eddy simulation model is used to simulate the turbulence measurements collected at the Martha's Vineyard Coastal Observatory's Air-Sea Interaction Tower, during the Coupled Boundary Layers and Air-Sea Transfer (CBLAST) experiment in 2003. The model provides reasonable predictions for the vertical profiles of vertical velocity variance, turbulent kinetic energy (TKE), energy dissipation rates, and heat flux. It shows breaking waves dominating turbulence generation near the ocean surface and turbulent large eddies characteristic of Langmuir circulation deeper in the water column. Diagnostic analysis of TKE budget in the model shows a dominant balance between turbulent transport and dissipation near the surface and a dominant balance between shear production and dissipation at deeper depths. Although the Stokes production is a significant term in the TKE budget balance near the surface, it is smaller than shear production. The turbulent transport is large in the near-surface zone and is still significant in the region affected by Langmuir circulation. These results are in agreement with a conclusion inferred from a recent analysis of the near-surface turbulence measurements at the CBLAST site.