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

智力上的优点：打破内潮被认为是深海昼夜混合的主要驱动力。然而，输入到它们中的大部分能量都是在最初的几个模式中输入的，这些模式在破裂之前可以传播1000‘S公里。因此，尽管众所周知，全球环流模型对混合的地理位置很敏感，但人们对它们在哪里以及如何破裂知之甚少。因此，这项研究将通过将最先进的技术应用于卫星测高、系泊和数值模式的组合来构建全球低模内部潮汐能量通量和耗散图。该方法既捕捉到了粗糙地形附近的非均匀正压向斜压潮汐转换，也捕捉到了由于低模内部潮汐的非均匀消散而产生的斑块状。卫星高度计的全球覆盖使其成为可用于这一任务的唯一实用观测工具。然而，任何一颗卫星的空间分辨率都很低，测高无法探测到时间上的非相干信号，这阻碍了对过去对低模内潮汐能量和能量通量的测高估计的解释。这项研究解决了这些缺点，以便制作所需的全球地图：(1)为了解决低分辨率问题，该小组将通过结合来自T/P-Jason、T/P-Jason Tandem、GFO和ERS的多个卫星测高数据，扩展他们以前的工作(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得到了演示，并表明空间分辨率得到了提高，达到了测高估计与高分辨率数值模式相一致的程度。(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，PIS将分析一种新的高分辨率全球模拟，其中包括真实的内部潮汐场以及真实的中、大尺度海洋环流。非均匀运动海洋如何使内潮不连贯的模型估计将通过对全球各地收集的几个长时间系泊时间序列的分析来验证。有了这些改进，这些技术现在应该能够胜任绘制全球低模内潮的能量通量和耗散的任务。通过这样做，这个项目将导致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的影响将是对耗散的大小和地理的更好的理解和参数化，这对大气环流模式具有已知的重要性。此外，该小组将通过网站和/或与PI的直接联系，向所有研究人员和公众提供高度观测到的内部潮汐数量的地图。除了在规划实验中非常有用外，这些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推广项目，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，作为华盛顿太空拨款计划的一部分，该计划是华盛顿州和美国国家航空航天局的联合计划，旨在鼓励华盛顿大学的学生追求科学事业。

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.