Collaborative Research: Internal Waves across the Pacific

[04:24 . 717]智力优势：风和潮汐将绝大部分能量输入到内波场，内波场的破裂是海洋湍流混合的主要驱动力。最近已经很清楚，大部分输入能量是以低模内波的形式出现的，这种能量可以传播很远（1000公里）。因此，原则上，湍流混合的全球大小和分布主要取决于传播的低模态内波的来源和随后的演化。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，由于与其他内波、地形和中尺度背景的相互作用，远程波的传播受到强烈调制，有时甚至完全中断。该项目旨在更好地理解控制远距离内波传播的过程，其最终的长期目标是确定内波驱动混合的全球分布、强度和时间依赖性。该项目将包括三项主要活动：o远距离传播的观测研究。6个系泊剖面仪从夏威夷向北延伸，横跨26N-37N，将在50天内测量100-2600米至2米范围内的速度和密度。船载传感器将沿着这条轨迹测量上层海洋切变和密度，获得两个宽快照和三个纬度的3个5天大潮时间序列。能量、能量通量和耗散率（来自倾覆尺度）将在所有测量位置计算。这一实验将使我们能够获得超过1200公里的潮汐远距离传播的连贯图像。将进行一系列假设驱动的受控数值实验，以优化设计观测结果，并研究可以从传播的内部潮汐中消耗能量的动态过程。o将对船载仪器的系泊记录和上层海洋切变的历史数据进行分析，以表征内波切变、射线斜率、能量和通量的空间依赖性，并为上述模拟提供大尺度观测背景。更广泛的影响：这项工作对更广泛的社区有四个重要的影响。首先，为了准确地理解和模拟过去、现在和未来气候的大尺度环流，需要对混合的地理结果进行动力学理解。观测和面向过程的建模相结合将有助于构建与大尺度环流动态耦合的物理驱动混合参数化所需的知识。其次，卫星测高已日益被视为监测全球内波场的重要社区资源。仔细比较测高结果和地下观测将有助于解释测高数据。第三，50天1200公里的阵列是一个原型观测系统，不仅可以长期监测内部潮汐和相关湍流，还可以监测许多其他中尺度现象。第四，建议的工作将有助于教育，为两名博士后提供支持和指导，并为几名研究生提供海上经验。结果将在国家和国际研讨会和会议上分享。

0424717Intellectual 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.