Collaborative Research: Turbulent fluxes and boundary layer structure due to near-shore internal tides

内潮是近岸水流的一种普遍特征，对近岸的生态、生物地球化学和沉积环境起着基础性的作用。例如，在珊瑚礁上，由于层化的影响，湍流混合可以决定水柱和珊瑚礁之间的耦合强度。同样，内波对海藻林等环境也很重要，在这些环境中，内波可能是幼虫生物跨岸运输的关键手段。因此，了解浅水中内波的行为及其产生的混合是沿海海洋学中的一个基本问题。更广泛地说，物理测量的高空间和时间分辨率将产生一个独特的数据集，能够将大陆坡和大陆架上的大小规模物理过程联系起来。这些数据将有助于开发更精确的边界层湍流和混合的参数。特别是，它将能够确定简单的经验关系，就像那些在实验室实验和计算中发现的，但在现场尺度上有效的，可以在广泛的环流模型中使用的。该项目将测量在浅海内潮和表面波存在的情况下近岸底部边界层中的雷诺应力、湍流浮力通量和湍流耗散率。利用夏威夷大学运营的基洛纳鲁天文台的能力，这些测量将在瓦胡岛南岸20米深的水域进行。像许多内陆架区域一样，拟议的野外选址提供了一个内潮和表面波共同存在的环境。所有的湍流仪器都将通过电缆连接到岸上，这样就可以不受功率或内存的限制，以高速率采集数据。利用对表面波和内潮的持续观测，湍流测量将得到使用ADCP、热敏电阻和盐度传感器链以及波浪/潮汐测量仪进行的平均流量测量的补充。现场测量将产生一个高质量的湍流数据集，在这样的设置下，我们将对平均流动有一个相当完整的总体描述。该实地考察项目将涉及夏威夷大学和斯坦福大学的研究生和本科生。这些将参与工作的所有阶段，特别是安装和找回成套仪器所需的科学潜水作业。这一群体将包括两所大学的几名女博士生和博士后。

Internal tides are a generic feature of near shore flows, playing a fundamental role in the ecology, biogeochemistry, and sedimentary environment of the near shore. For example, on coral reefs, turbulent mixing, as modified by stratification, can determine the strength of coupling between the water column and the reef. In a like fashion, internal waves can also be important to such environments as kelp forests where they may be a critical means of cross-shore transport of larval organisms. Thus, understanding the behavior of internal waves and the mixing they produce in shallow water is a fundamental problem in coastal oceanography. More generally, the high spatial and temporal resolution of physical measurements will result in a unique data set capable of linking large and small-scale physical processes on the continental slope and shelf. This data will be useful in developing more accurate parameterizations of boundary layer turbulence and mixing. In particular, it will be able to determine simple empirical relations like those found in lab experiments and computations but valid at field scales, that can be used in a wide range of circulation models. This project will measure Reynolds stresses, turbulent buoyancy fluxes, and turbulence dissipation rates in the near shore bottom boundary layer in the presence of shoaling internal tides and surface waves. Taking advantage of the capabilities of the Kilo Nalu Observatory operated by the University of Hawaii, these measurements will be made in 20 meters of water on the south shore of Oahu. Like many inner shelf regions, the proposed field site provides an environment in which both internal tides and surface waves are common. All the turbulence instruments will be cabled to shore, allowing acquisition of the data at high rates not limited by power or memory. Leveraging ongoing observations of surface waves and internal tides, the turbulence measurements will be supplemented by mean flow measurements made with ADCPs, thermistor and salinity sensor chains, and wave/tide gauges. The field measurements will yield a high quality turbulence data set, made in a setting for which we will have a fairly complete overall description of the mean flow. The field program will involve graduate and undergraduate students from University of Hawaii and Stanford University. These will be involved in all phases of the work, in particular, the scientific diving operations needed to install and recover the instrument suite. This group will include several women Ph. D. students and postdocs at both institutions.