Collaborative Research: Systematic Direct Mixing Measurements within the Global Repeat Hydrography Program (SYSDMM)

合作研究：全球重复水文学计划 (SYSDMM) 内的系统直接混合测量

• 批准号: 1335282
• 负责人: Jonathan Nash
• 金额: $ 57.63万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335282&HistoricalAwards=false
• 关键词: Collaborative; Research; Systematic; Direct; Mixing

To date, less than a thousand profiles of turbulence have been acquired in the deep ocean and these are concentrated in only a few geographic regions. As a result of this paucity of direct measurements, the distribution of mixing is inferred largely through proxies and parameterizations that have known limitations. Mixing budgets remain poorly constrained. The purpose of this pilot project is to demonstrate that systematic, repeated sequences of turbulent mixing over full-ocean depths can be obtained in a broad distribution throughout the global ocean. To accomplish this goal, the investigators in this project will deploy chi-pods - "turbulent mixing meters" on standard shipboard CTD/LADCPs package operated by the Global Repeat Hydrography Program. A few thousand turbulence profiles will be collected and analyzed over a three-year period. The chi-pods are self-contained instruments that have been quantifying mixing on equatorial moorings since 2005. They use fast response thermistors and precision accelerometers to measure microscale temperature gradients, from which the dissipation rate of temperature variance, ÷ and the eddy diffusivity of heat and other tracers. Unlike traditional velocity microstructure measurements based on shear probes, temperature microstructure measurements are not sensitive to platform vibration - a necessity for deployment on moorings with a surface expression or from a CTD rosette. The CTD-chi-pod has modifications that allow it to be easily clamped to a standard rosette with minimal impact during repeat hydrography operations, and has been proven successful in several recent pilot experiments in shallower waters.Intellectual Merit: Diapycnal mixing in the ocean interior has a strong influence on upper ocean heat and nutrient budgets, abyssal circulation, and water mass distributions. An initial attempt to develop and implement parameterizations of diapycnal mixing for large-scale models is underway as part of an NSF-funded Climate Process Team. The largest impediment to that effort is the incredible scarcity of direct turbulence observations, particularly those that cover the full water column depth. This project will demonstrate the feasibility and value of collecting a global dataset of microstructure observations that will be made publicly available as soon as possible after acquisition, following repeat hydrography protocols. The data will allow the PIs, as well as the broader scientific community, to calculate better global and regional averages of diapycnal mixing rates, explore underlying dynamics that control the geographic distribution of ocean turbulence, evaluate gradual changes in basin-averaged mixing rates, assess uncertainty and systematic bias in finescale shear and strain parameterizations of mixing that are becoming widely used, and validate turbulence parameterizations that will be going into the next generation of regional and climate models.Broader Impacts: The proposed measurements will be the first comprehensive set of direct mixing observations easily available to the broader community. These measurements can be used by a wide range of scientists to constrain everything from regional tracer budgets to biological nutrient fluxes to global energetics. The results will be particularly useful for testing and improving parameterizations of turbulent mixing being developed for global climate models (http://www-pord.ucsd.edu/~jen/cpt/), as diapycnal mixing rates remain one of the most influential tuning parameters in such models. This project will train one graduate student and give other students exposure to open-ocean observational techniques.

迄今为止，在深海中获得了不到一千个湍流，这些湍流仅集中在几个地理区域。由于缺乏直接测量，混合的分布主要是通过已知局限性的代理和参数来推断的。混合预算仍然受到限制。该试点项目的目的是证明，可以在整个全球海洋的广泛分布中获得系统的系统，重复的湍流混合序列。为了实现这一目标，该项目中的调查人员将在全球重复水文计划操作的标准船上CTD/LADCPS软件包上部署CHI -POD-“湍流混合仪”。将在三年的时间内收集和分析几千个湍流概况。 Chi-Pods是自2005年以来一直在量化系泊设备时量化混合的独立仪器。它们使用快速响应的热水瓶和精度加速度计来测量显微镜温度梯度，温度方差的耗散速率÷÷g和热量的涡流难度和热量和其他示踪剂的涡流难度。与基于剪切问题的传统速度微观结构测量不同，温度微结构测量值对平台振动不敏感 - 对于具有表面表达或CTD玫瑰花结的系泊的部署所必需的。 CTD-CHI-POD具有修改，使其可以轻松地夹在重复水文操作期间具有最小影响的标准玫瑰花结构，并且已在较浅的水域中的几个试点实验中被证明是成功的。智能优点：在海洋内部的二比混合对海洋内部的混合对上海热和营养预算的强大影响，并分配了质量，并分配了质量，并且质量分配了质量，并且质量为水。作为NSF资助的气候过程团队的一部分，正在为大规模模型开发和实施大型模型混合参数的初步尝试。这项工作的最大障碍是直接湍流观察的令人难以置信的稀缺性，尤其是那些覆盖完整水柱深度的人。该项目将证明收集微观结构观测值的全局数据集的可行性和价值，该数据集将在收购后尽快公开可用，并按照重复的水文协议进行。数据将使PI和更广泛的科学界能够计算出更好的全球和区域平均二彩混合速率的平均值，探索控制海洋湍流地理分布的基本动力，评估盆地水平混合率的等级变化，评估不确定性和系统性偏见的范围和系统性偏见，这些偏向于危险范围的范围，以及范围内的范围，并将其范围呈现为广泛的范围，并在范围内广泛地参数，以至于范围内广泛的范围，以至于范围内的范围范围内的范围范围的范围范围的范围范围的范围范下一代区域和气候模型的影响：拟议的测量将是一组综合的直接混合观测值，该观察值易于使用。这些测量值可以由广泛的科学家使用，以限制从区域示踪剂预算到生物营养通量再到全球能源的一切。由于Diapycnal的混合速率仍然是此类模型中最有影响力的调音参数，因此该结果对于为全球气候模型开发的湍流混合参数（http://www-pord.ucsd.edu/~jen/cpt/）特别有用。该项目将培训一名研究生，并使其他学生接触开放式观察技术。