Collaborative Research: Next-generation Global Altimetric Maps of Internal Tide Energy Flux and Dissipation

合作研究：下一代全球内潮汐能量通量和耗散高度图

• 批准号: 1129129
• 负责人: Zhongxiang Zhao
• 金额: $ 58.62万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129129&HistoricalAwards=false
• 关键词: Collaborative; Research; Next; generation; Global

Intellectual Merit:Breaking internal tides are known to be a major driver of deep-ocean diapycnal mixing. However, much of the energy input into them is in the first few modes, which can propagate 1000's of kilometers before breaking. As a result, little is known about where and how they break, in spite of the known sensitivity of global circulation models to the geography of mixing. Therefore, this study will construct a global map of low-mode internal tide energy flux and dissipation by application of state-of-the-art techniques to a combination of satellite altimetry, moorings, and a numerical model. The approach captures both the non-uniform barotropic-to-baroclinic tide conversion near rough topography as well as patchiness due to the non-uniform dissipation of low-mode internal tides.The global coverage of satellite altimeters makes them the only practical observational tool available for the task. However the poor spatial resolution of any single satellite, and the inability of altimetry to detect temporally incoherent signals, have hampered the interpretation of past altimetric estimates of low-mode internal tide energy and energy flux. This study addresses these shortcomings in order to produce the needed global maps:(1) To address the low-resolution problem, the team will expand on their previous work (in which they used the T/P-Jason tandem mission) by combining multiple satellite altimetric data from T/P- Jason, T/P-Jason tandem, GFO, and ERS. The multi-satellite technique was recently demonstrated in the North Pacific, and showed that spatial resolution is improved to the point where the altimetric estimates agree with high-resolution numerical models.(2) To understand the loss of coherence of internal tide propagating in an ever-changing ocean, the PIs will analyze a new high-resolution global simulation that includes a realistic internal tide field as well as realistic meso- and large-scale ocean circulations. The model estimate of how the non- uniform moving ocean makes internal tide incoherent will be validated by the analysis of several long moored time series collected around the globe.With these improvements, the techniques should now be up to the task of mapping the low-mode internal tide's energy flux and dissipation on the globe. In doing so, this project will lead to a better understanding of the processes that affect the propagation and dissipation of internal tide on a global scale.Broader Impacts:The primary broader impact of this work will be an improved understanding and a parameterization of the magnitude and geography of dissipation, of known importance to general circulation models. In addition, the team will provide maps of altimetrically-observed internal tide quantities to all researchers as well as the public via a website and/or direct communication with the PI's. In addition to being of great use in planning experiments, such maps will be of relevance for a variety of physical and biogeochemical studies. The maps and the model simulations will be used in community outreach programs such as APL's K-12 volunteer list and Seattle's Pacific Science Center. The study will also educate three undergraduate students as part of the Washington Space Grant program, a joint program between Washington State and NASA seeking to encourage students at the University of Washington to pursue science careers.

智力优势：众所周知，内潮汐的破裂是深海二重混合的主要驱动力。然而，输入到它们中的大部分能量都是前几种模式，在破裂之前可以传播数千公里。因此，尽管全球环流模型对混合地理的敏感性众所周知，但人们对它们在何处以及如何破裂知之甚少。因此，本研究将通过应用最先进的技术结合卫星测高、系泊和数值模型来构建低模内潮汐能量通量和耗散的全球地图。该方法捕获了崎岖地形附近不均匀的正压到斜压潮汐转换，以及由于低模内潮汐的不均匀消散而产生的斑块。卫星高度计的全球覆盖范围使其成为执行该任务的唯一实用观测工具。然而，任何单个卫星的空间分辨率都很差，并且测高仪无法检测时间上不相干的信号，阻碍了对过去低模内潮汐能量和能量通量的测高估计的解释。本研究解决了这些缺点，以便生成所需的全球地图：（1）为了解决低分辨率问题，该团队将通过结合来自 T/P-Jason、T/P-Jason tandem、GFO 和 ERS ​​的多个卫星高度数据来扩展他们之前的工作（其中他们使用了 T/P-Jason tandem 任务）。多卫星技术最近在北太平洋进行了演示，表明空间分辨率已提高到高度估计与高分辨率数值模型一致的程度。（2）为了了解不断变化的海洋中传播的内潮的相干性丧失，PI将分析新的高分辨率全球模拟，其中包括真实的内潮场以及真实的中观和大尺度海洋 流通量。非均匀移动海洋如何使内潮不一致的模型估计将通过对全球收集的几个长停泊时间序列的分析来验证。通过这些改进，这些技术现在应该能够胜任绘制全球低模式内潮能量通量和耗散的任务。在此过程中，该项目将有助于更好地了解影响全球范围内潮汐传播和消散的过程。 更广泛的影响：这项工作的主要更广泛影响将是更好地理解和参数化消散的幅度和地理，这对于一般环流模型具有已知的重要性。此外，该团队将通过网站和/或与 PI 直接沟通，向所有研究人员和公众提供高度测量观测到的内潮汐量地图。除了在规划实验中具有很大的用途外，此类地图还将与各种物理和生物地球化学研究相关。这些地图和模型模拟将用于社区外展计划，例如 APL 的 K-12 志愿者名单和西雅图太平洋科学中心。该研究还将教育三名本科生，作为华盛顿太空资助计划的一部分，该计划是华盛顿州和美国宇航局之间的联合计划，旨在鼓励华盛顿大学的学生从事科学职业。