Collaborative Research: Tasmanian Tidal Dissipation Experiment (T-TIDE)

合作研究：塔斯马尼亚潮汐消散实验（T-TIDE）

• 批准号: 1129782
• 负责人: Jonathan Nash
• 金额: $ 67.94万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129782&HistoricalAwards=false
• 关键词: Collaborative; Research; Tasmanian; Tidal; Dissipation

Intellectual MeritTidal mixing of the deep ocean does not necessarily occur where energy is lost from the barotropic tide, but rather where the low-mode baroclinic tide dissipates, perhaps thousands of kilometers away. Ocean general circulation models are sensitive to the magnitude and geography of deep mixing, but very few observations of this process exist. Understanding the location and mechanisms of tidal dissipation is necessary for their continued improvement. The Tasmanian Tidal Dissipation Experiment?s (T-TIDE) hypothesis is that significant tidal dissipation takes place where propagating low-mode internal tides impinge on steep continental slopes. Slope geometry affects wave reflection, transmission, scattering, and breaking, which in turn determine the spatial distribution of mixing. Important breaking mechanisms may include lee effects at small-scale bathymetry and nonlinear bore formation near critical slopes. We propose a coordinated observational/modeling effort to understand the physics geometry, and magnitude of dissipation and mixing. The goals are to 1) identify where mixing occurs on the continental slope, 2) determine the dominant dissipative processes, 3) assess the amount of energy transmitted onto the shelf and reflected back into the deep sea to be dissipated elsewhere, and 4) generalize these results as a parameterization of topographic scattering and dissipation in numerical models, which ideally depends on the topography, stratification, and the barotropic and/or low-mode baroclinic tides. The three main components to the experimental plan are 1) intensive 2D and 3D modeling before and after the fieldwork to plan and contextualize the measurements; 2) a glider based Scout Experiment to identify dynamic processes, evaluate models, and finalize mooring sites; and 3) a comprehensive Process Experiment using ships, gliders, and moorings with the time and space resolution to address T-TIDEs hypothesis and achieve its goals. An array of profiling and fixed-sensor moorings will be combined with gliders acting as virtual moorings. Tidally-resolving or higher-frequency observations will measure internal wave motions, energy fluxes, and dissipation and mixing either directly or via finescale parameterizations. An altimetric analysis of internal-tide sea surface height will assess mesoscale refraction of the incident internal tide along with Australian gliders, which will monitor hydrography and internal tidal displacements in the Tasman Sea. Broader ImpactsThe proposed work will provide global insights on the dissipation of tidal energy. Specifically, inclusion of tidal dissipation on continental slopes may be an important component of the next generation of mixing parameterizations in climate models. Graduate students will be trained as part of the experiment. In addition to its scientific import, T-TIDE will sponsor and participate in two training seminars with high school science teachers who are charged with delivering the earth science program in San Diego Unified School District. This effort will be performed in conjunction with the Birch Aquarium at Scripps. Finally, an essential element of the project is the development of strong collaboration and resource sharing with Australian and Canadian scientists.

深海的潮汐混合并不一定发生在正压潮汐能量损失的地方，而是发生在低模态斜压潮汐消散的地方，也许在数千公里之外。 海洋环流模式对深度混合的规模和地理位置很敏感，但对这一过程的观测却很少。 了解潮汐消散的位置和机制对于持续改进潮汐消散是必要的。 塔斯马尼亚潮汐消散实验？s（T-TIDE）假设是，当传播的低模式内潮冲击陡峭的大陆坡时，发生显著的潮汐耗散。 斜坡的几何形状影响波的反射、透射、散射和破碎，这反过来又决定了混合的空间分布。 重要的破碎机制可能包括在小尺度测深和非线性孔形成临界斜率附近的背风效应。 我们提出了一个协调的观测/建模工作，以了解物理几何，耗散和混合的幅度。 目标是：1）确定大陆坡上发生混合的位置，2）确定主要的耗散过程，3）评估传递到大陆架上并反射回深海以耗散在其他地方的能量，4）将这些结果归纳为数值模型中地形散射和耗散的参数化，理想情况下，这取决于地形、分层、以及正压和/或低模态斜压潮汐。 实验计划的三个主要组成部分是：1）在实地工作之前和之后进行密集的2D和3D建模，以规划和安排测量; 2）基于滑翔机的侦察实验，以确定动态过程，评估模型，并最终确定系泊地点;以及3）使用船舶，滑翔机，和系泊的时间和空间分辨率，以解决T-TIDES假说和实现其目标。 一系列的剖面和固定传感器系泊装置将与充当虚拟系泊装置的滑翔机相结合。 潮汐分辨率或更高频率的观测将直接或通过精细尺度参数化来测量内部波动、能量通量、耗散和混合。 内潮海面高度的测高分析将评估事件内潮沿着与澳大利亚滑翔机的中尺度折射，这将监测水文和内潮位移在塔斯曼海。 更广泛的影响拟议的工作将提供全球的见解潮汐能的耗散。具体而言，在大陆坡纳入潮汐消散可能是下一代气候模型混合参数化的一个重要组成部分。 研究生将作为实验的一部分接受培训。 除了其科学进口，T-TIDE将赞助和参加两个培训研讨会与高中科学教师谁是负责提供地球科学计划在圣地亚哥联合学区。 这项工作将与斯克里普斯的桦树水族馆一起进行。最后，该项目的一个基本要素是与澳大利亚和加拿大科学家开展强有力的合作和资源共享。