Collaborative Research: A study of the energy dissipation of the internal tide as it reaches the continental slope of Tasmania

合作研究：研究内潮汐到达塔斯马尼亚大陆坡时的能量耗散

• 批准号: 1434722
• 负责人: Amy Waterhouse
• 金额: $ 56.1万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434722&HistoricalAwards=false
• 关键词: Collaborative; Research; study; energy; dissipation

Surface tides supply about one terawatt of power to internal tides as they propagate up and over large topographic features. Most of the energy of these internal tides propagates away from the generation regions in the form of low-mode internal tides. The ultimate fate of this energy is unknown and has a large impact on the global distribution of ocean properties. Previous studies of low-mode internal tide propagation have observed regions where the internal tide was diffuse and exhibited complex interference patterns, making it difficult to close the energy budget. The Tasman Sea differs from previous sites because it is believed to contain one of the most energetic and focused internal-tide beams in the world. The beam is generated south of New Zealand, propagates 1,500 km across the Tasman Sea, and strikes the Tasman continental margin. This project called T-Beam will document the rate of decay of a focused internal tide beam, compare the measured flux convergence with novel in situ measurements of turbulent mixing, and investigate the dynamical processes responsible for the observed decay. The results from T-Beam should lead to significant improvement in parameterizations of internal-wave induced mixing in global climate models. A major goal of the analysis is to compare in situ internal tide fluxes with those inferred from satellite altimetry; the latter are known to be biased low in the presence of strong mesoscale currents but the extent of the bias is not well documented. T-Beam investigators have established collaborations with Australian scientists who will complement the T-Beam measurements with a suite of synergistic geological and biological analyses. During the field campaign, T-Beam investigators will prepare press releases and publish a daily blog. Undergraduate and graduate students in the United States and Australia will be offered the opportunity for at-sea experience, modeling and analysis.In T-Beam, the investigators will obtain high-resolution estimates of internal-tide energy flux and dissipation rates in the Tasman Sea. The study site is favorable because it has a single strong generation region, contains a long energetic and confined internal-tide "beam", and is sheltered from remotely generated internal tides. The proposed experiment will be highly coordinated with the NSF-funded Tasmanian Tidal Dissipation Experiment (T-TIDE), which will examine the dissipation of the internal tide as it shoals on the Tasmanian continental slope. T-Beam will enhance T-TIDE by providing synoptic measurements of incident internal-tide energy flux that will reduce uncertainties in estimates of the fraction of energy flux that is dissipated over the continental slope. T-TIDE will enhance T-Beam by providing additional observations (adaptive glider sampling and shipboard surveying) to help identify mechanisms and better constrain the open-ocean decay rates observed during T-Beam. A decade ago, the Hawaiian Ocean Mixing Experiment (HOME) provided a comprehensive look at the internal tide generation process. Together, T-Beam and T-TIDE will complete that life cycle by providing the first comprehensive observations of an internal-tide beam as it propagates through the open ocean and dissipates on a continental slope. The Schmidt Ocean Institute is providing 28 days of ship time coincident with T-TIDE. This project will deploy a two-month mooring situated in the center of the observable internal-tide beam, conduct intensive ship-based surveys of density, velocity and turbulence to resolve the along- and across-beam spatial structure, and numerically model the formation, variability, and dissipation of internal-tide beams in the presence of arbitrary topography and mesoscale variability.

表面潮汐供应大约一台电源，因为它们在大型地形特征上传播并传播到内部潮汐。这些内部潮汐的大部分能量以低模式内部潮汐的形式远离产生区域。这种能量的最终命运是未知的，对海洋物业的全球分布有很大影响。先前对低模式内部潮汐传播的研究观察到了内部潮汐分散并表现出复杂的干扰模式的区域，因此很难结束能量预算。塔斯曼海与以前的地点有所不同，因为据信它包含世界上最有活力，最集中的内部潮流之一。该梁是在新西兰南部产生的，在整个塔斯曼海繁殖了1,500公里，并击中了塔斯曼大陆边缘。这个称为T梁的项目将记录聚焦的内部潮汐梁的衰减速率，将测得的通量收敛与新颖的湍流混合的原位测量结果进行比较，并研究导致观察到的衰减的动力学过程。 T梁的结果应导致全球气候模型中内波诱导混合的参数化显着改善。该分析的主要目的是将原位内部潮汐通量与卫星高度学推断的助焊剂进行比较。已知后者在存在强度中尺度电流的情况下被偏低，但偏见的程度尚未得到充分记录。 T梁研究人员已经与澳大利亚科学家建立了合作，他们将通过一系列协同的地质和生物学分析来补充T梁测量值。在现场活动期间，T梁调查人员将准备新闻稿并发布每日博客。在美国和澳大利亚的本科生和研究生将有机会进行海上经验，建模和分析的机会。在T梁中，研究人员将获得塔斯曼海内部潮汐能量和耗散率的高分辨率估计。研究地点之所以有利，是因为它具有一个强大的生成区域，其中包含一个长长的能量和狭窄的内部潮汐“束”，并避免了远程产生的内部潮汐。提出的实验将与NSF资助的塔斯马尼亚潮汐耗散实验（T-Tide）高度协调，该实验将检查内部潮汐的耗散，因为它在塔斯马尼亚大陆斜坡上铺上。 T梁将通过提供入射内部潮气通量的概要测量来增强T-TIDE，这将减少估计在大陆斜率上消失的能量通量的不确定性。 T-TIDE将通过提供其他观察结果（自适应滑翔机采样和船舶测量）来增强T梁，以帮助识别机制并更好地限制T梁期间观察到的开放式衰减率。 十年前，夏威夷海洋混合实验（Home）对内部潮汐生成过程进行了全面了解。一起，T梁和T-TIDE将通过在开放海洋传播并在大陆坡上消散时，通过提供内部潮汐束的第一个全面观察来完成这一生命周期。施密特海洋研究所（Schmidt Ocean Institute）提供28天的船时间与T-Tide一致。该项目将在可观察到的内部潮汐束的中心部署一个两个月的系泊设备，进行密集的基于船舶的密度，速度和湍流的调查，以解决沿着沿着光束的空间结构，并在数值上建模形成，变异性，可变性，以及在有其自我层表型和Messcalesscale and Messcale and Messcale and Messcale and Messcale and Messcale and Messcale and Messcales and Messcape and Messcape和Messcales的散发状态。