A Global Distributed Observing Program for Shear, Energy Flux, and Mixing by Internal Waves

全球分布式剪切、能量通量和内波混合观测计划

• 批准号: 2232796
• 负责人: James Girton
• 金额: $ 422.46万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2232796&HistoricalAwards=false
• 关键词: Global; Distributed; Observing; Program; Shear

Mixing rates in the ocean of the future will be determined to a large extent by the distribution of internal waves. Changes in the forcing of these waves by winds and tides, and modifications of the currents and density stratification that modulate internal wave propagation, evolution, and eventual dissipation into turbulence, are likely to be simulated with some skill by numerical coupled climate models. But the waves themselves and their impacts on the climate system through diffusive transport of heat, chemicals, and other tracers are a more difficult challenge. This project starts a global sampling program for internal waves using profiling floats- measuring temperature, salinity, velocity, and turbulence—that will yield new insights into internal wave regimes and parameterizations, and that will provide direct and derived data products tailored for use by modeling groups for comparison and validation. Velocity profiling floats paired with microstructure sensors are an ideal, proven platform for globally- distributed measurements of internal waves and their mixing impacts. Much of the energy in the internal wave field enters at large vertical scales (particularly true for internal tides), yet energy dissipation happens through shear and strain at small scales. Velocity profiles resolve this full range of vertical scales, and bursts of profiles provide the direction and magnitude of energy flux in dominant frequency bands. Deployment of profiling floats in all dynamical regimes around the globe will provide data sets resolving both the waves and their impact on mixing. This project will also create data practices for sharing direct and derived products (metrics) with numerical modelers. The improved insight into internal wave forcing, propagation, and dissipation will lead to improved forecasts of processes that are influenced by internal wave mixing and transport. These include centennial-scale forecasts of heat and carbon penetration into the deep ocean, seasonal forecasts of coastal ecosystem nutrient supply through upwelling and shelf-slope exchange, and decadal and longer evolution of upper-ocean stratification and the meridional overturning circulation. Once developed, the sampling methodologies and data tools can be applied to future velocity and turbulence profiling float data sets. In addition, this work will permit maintenance of instrument development and seagoing field work expertise and will support ongoing education and outreach efforts.Principal activities Include (1) deployment of 50 velocity and microstructure profiling floats from 6 cruises of opportunity, over 3 years, in diverse locations around the globe spanning the range of the dominant parameters that determine the internal wave environment. (2) derivation of internal wave products for use in (a) estimating internal wave impacts on mixing and the kinetic energy budget of the ocean, (b) projecting surface signatures of internal waves seen by satellite sensors into subsurface vertical structure and frequency bands, (c) validation of internal wave resolving models, and (d) internal wave resolving data assimilation. (3) Development of operational data pathways from velocity and microstructure profile collection to operational modeling and archiving centers. (4) Using the merged and augmented profiling float measurement database to assess the relative roles of wind, tides, topography, and mesoscale variability in generating and dissipating the energy seen in the oceanic internal wave field.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

未来海洋的混合率将在很大程度上由内波的分布决定。风和潮汐对这些波浪的强迫作用的变化，以及调节内波传播、演变和最终消散为湍流的海流和密度分层的改变，可能通过数值耦合气候模式有一定技巧地模拟出来。但是海浪本身以及它们通过热量、化学物质和其他示踪剂的扩散传输对气候系统的影响是一个更困难的挑战。该项目启动了一项利用剖面浮标测量温度、盐度、速度和湍流的全球内波采样计划，这将产生对内波状态和参数化的新见解，并将为建模小组提供量身定制的直接和衍生数据产品，用于比较和验证。速度剖面浮标与微结构传感器配对，是一种理想的、经过验证的全球分布内波测量及其混合影响的平台。内波场中的大部分能量在大的垂直尺度上进入（对于内部潮汐尤其如此），然而能量耗散是在小尺度上通过剪切和应变发生的。速度剖面解决了整个垂直范围的问题，而爆发剖面则提供了主要频段能量通量的方向和大小。在全球所有动力系统中部署剖面浮标将提供解决波浪及其对混合影响的数据集。该项目还将创建与数值建模者共享直接和派生产品（指标）的数据实践。对内波强迫、传播和耗散的深入了解将有助于改进对受内波混合和输运影响的过程的预报。这些预测包括对深海热量和碳渗透的百年尺度预测，通过上升流和大陆架斜坡交换的沿海生态系统养分供应的季节预测，以及上层海洋分层和经向翻转环流的年代际和更长时间的演变。一旦开发成功，采样方法和数据工具可以应用于未来的速度和湍流剖面浮子数据集。此外，这项工作将使仪器开发和海上实地工作的专门知识得以维持，并将支助正在进行的教育和外联工作。主要活动包括(1)在3年多的时间里，在全球不同的地点进行6次航行，部署50个速度和微观结构剖面浮标，跨越决定内波环境的主要参数范围。(2)推导内波产品，用于(a)估计内波对海洋混合和动能平衡的影响，(b)将卫星传感器看到的内波表面特征投射到地下垂直结构和频带中，(c)验证内波解析模型，以及(d)内波解析数据同化。(3)从速度和微观结构剖面收集到操作建模和存档中心的操作数据路径的发展。(4)利用合并和增强的剖面浮子测量数据库，评估风、潮汐、地形和中尺度变率在海洋内波场能量产生和耗散中的相对作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。