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

知识专长：内潮破裂是深海底辟混合的主要驱动力。然而，大部分能量输入到他们是在前几个模式，可以传播1000公里之前打破。因此，尽管已知全球环流模型对混合地理的敏感性，但人们对它们在何处以及如何破裂知之甚少。因此，本研究将构建一个全球地图的低模式内潮能通量和耗散的应用国家的最先进的技术相结合的卫星测高，系泊，和一个数值模型。这种方法既能捕捉到粗糙地形附近的非均匀正压-斜压潮汐转换，也能捕捉到由于低模态内潮的非均匀耗散而产生的斑块现象，卫星高度计的全球覆盖使其成为唯一可用于这项任务的实用观测工具。然而，任何一个单一的卫星的空间分辨率差，无法测高检测时间上不相干的信号，阻碍了过去的高度估计的解释低模式的内部潮汐能量和能量通量。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，该团队将通过组合多个卫星来扩展他们之前的工作（其中他们使用了T/P-Jason串联使命）来自T/P-Jason、T/P-Jason串联、GFO和ERS的测高数据。最近在北太平洋演示了多卫星技术，并表明空间分辨率已提高到测高估计与高分辨率数值模型相一致的程度。(2)为了了解在不断变化的海洋中传播的内部潮汐的相干性损失，PI将分析一个新的高分辨率全球模拟，其中包括一个现实的内部潮汐场以及现实的中尺度和大尺度海洋环流。通过对地球仪周围的几个长时间序列的分析，将验证非均匀运动海洋如何使内潮不相干的模型估计。随着这些改进，该技术现在应该能够完成绘制地球仪上的低模内潮能量通量和耗散的任务。在这样做的过程中，这个项目将导致更好地了解的过程，影响内潮的传播和消散在全球范围内。更广泛的影响：这项工作的主要更广泛的影响将是一个更好的理解和参数化的大小和地理的耗散，已知的重要性，大气环流模式。此外，该小组将通过网站和/或与PI的直接沟通，向所有研究人员和公众提供测高观测的内部潮汐量地图。除了在规划实验中有很大用处外，这种地图还与各种物理和地球化学研究有关。这些地图和模型模拟将用于社区外展计划，如APL的K-12志愿者名单和西雅图的太平洋科学中心。这项研究还将教育三名本科生，作为华盛顿太空赠款计划的一部分，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事业。

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.