Collaborative Research: Internal Waves Across the Pacific

0425283智力优点：风和潮汐将绝大多数能量输入内波场，内波场的破碎是海洋湍流混合的主要驱动力。最近已经清楚的是，大部分输入能量采取低模内波的形式，它可以传播很远（1000公里）。因此，原则上，湍流混合的全球幅度和分布主要取决于传播的低模内波的源和随后的演变。对历史系泊的新解释、夏威夷海洋混合实验的新观测和新的数值模拟结果表明，长程波传播受到强烈调制，有时甚至完全中断，这是由与其他内波、地形和中尺度背景的相互作用造成的。该项目旨在更好地了解控制长程内波传播的过程，最终的长期目标是确定内波驱动混合的全球分布，幅度和时间依赖性。该项目将包括三项主要活动：从夏威夷向北延伸的一条由六个系泊剖面仪组成的线路，跨越北纬26 - 37度，将测量100-2600米至2米尺度的速度和密度，为期50天。船载传感器将测量上层海洋切变和密度沿着这一轨道，获得两个广泛的快照和三个春潮5天的时间序列在三个纬度。将在所有测量位置计算能量、能流和耗散率（来自倾覆尺度）。这项实验将使潮汐的长距离传播超过约1200公里的连贯图片。o数值模拟。将进行一系列假设驱动的受控数值实验，以优化观测设计，并研究可能从传播的内潮中消耗能量的动力学过程。o将对系泊记录和船载仪器的上层海洋切变进行历史数据分析，以确定内波切变、射线斜率、能量和通量的空间依赖性，并为上述模拟提供大规模的观测背景。更广泛的影响：这项工作对更广泛的社区有四个重要影响。首先，需要对混合地理的动态理解，以便准确理解和模拟过去、现在和未来气候中的大尺度环流。观测和面向过程的建模相结合，将有助于构建物理动机的混合参数化，动态耦合到大尺度环流所需的知识。第二，卫星测高日益被视为监测全球内波场的一个重要社区资源。仔细比较测高结果和地下观测结果将有助于解释测高数据。第三，50天、1 200公里的阵列是一个原型观测系统，不仅可长期监测内潮和相关湍流，而且可长期监测许多其他中尺度现象。第四，拟议的工作将通过为两名博士后提供支持和指导以及为几名研究生提供海上经验来促进教育。将在国家和国际讲习班和会议上分享成果。

0425283Intellectual Merit:The wind and the tides input the overwhelming majority of the energy into the internal-wave field, whose breaking is the primary driver of turbulent mixing in the ocean. It has recently become clear that much of the input energy takes the form of low-mode internal waves, which can propagate far ( 1000 km). It follows that, in principle, the global magnitude and distribution of turbulent mixing depends primarily on the sources and subsequent evolution of the propagating, low-mode internal waves. New interpretation of historical moorings, new observations from the Hawaii Ocean Mixing Experiment, and new numerical modeling results suggest that long-range wave propagation is strongly modulated and, at times, completely disrupted, by interactions with other internal waves, topography, and the mesoscale background. This project seeks to better understand the processes that govern long-range internal-wave propagation, with an ultimate long-range goal of determining the global distribution, magnitude and time-dependence of internal-wave driven mixing. The project will integrate three principal activities:o Observational Study of Long-range Propagation. A line of six Moored Profilers extending northward from Hawaii, spanning 26N-37N, will measure velocity and density from 100-2600 m down to 2-m scales, for 50 days. Ship-based sensors will measure upper-ocean shear and density along this track, obtaining 2 broad snapshots and three spring-tide 5-day time series at three latitudes. Energy, energy flux, and dissipation rate (from overturning scales) will be computed at all measurement locations. This experiment will enable a coherent picture of the long-range propagation of the tide over about 1200 km. o Numerical simulations. A series of hypothesis-driven, controlled numerical experiments will be conducted to optimally design the observations, and to investigate dynamical processes that can drain energy from a propagating internal tide.o Historical Data Analysis of moored records and upper-ocean shear from ship-based instruments will be done to characterize the spatial dependence of internal-wave shear, ray slopes, energy and flux, and to provide large-scale observational context for the above simulations. Broader Impacts:This work has four vital implications for the broader community. First, a dynamical understanding of the resultant geography of mixing is required for accurate understanding and modeling of the large-scale circulation in past, present and future climates. The combination of observations and process-oriented modeling will contribute to the knowledge required to construct physically motivated mixing parameterizations that are dynamically coupled to the large-scale circulation. Second, satellite altimetry has been increasingly seen as an important community resource for monitoring global internal-wave fields. Careful comparison of altimetric results and subsurface observations will help interpretation of altimetric data. Third, the 50-day, 1200-km array is a prototype observing system for long-term monitoring not only of the internal tide and associated turbulence, but of many other mesoscale phenomena. Fourth, the proposed work will contribute to education by providing support and mentoring for two post-docs, and at-sea experience for several graduate students. Results will be shared at national and international workshops and conferences.