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

未来海洋中的混合率在很大程度上将由内波的分布决定。风和潮汐对这些波的强迫的变化，以及将内部波的传播、演化和最终耗散调制为湍流的洋流和密度分层的改变，可能会用数值耦合气候模式来模拟。但海浪本身及其通过热量、化学品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。该项目启动了使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，这将对内波的状况和参数产生新的见解，并将提供直接和派生的数据产品，供建模小组用于比较和验证。速度剖面浮标与微结构传感器配合使用，是对内波及其混合影响进行全球分布测量的理想平台。内波场中的大部分能量以大的垂直尺度进入(特别是内潮)，而能量耗散是在小尺度上通过剪切和应变发生的。速度剖面解析了整个垂直尺度范围，而剖面的爆发提供了主导频带中能量流的方向和大小。在全球所有动力系统中部署剖面浮标将提供分析海浪及其对混合的影响的数据集。该项目还将创建与数值建模人员共享直接和派生产品(指标)的数据实践。对内波强迫、传播和耗散的更深入的洞察将导致对受内波混合和传输影响的过程的更好的预报。其中包括对进入深海的热量和碳渗透的百年尺度预测，通过上升流和陆架-斜坡交换对沿海生态系统养分供应的季节性预测，以及上层海洋层结和经向翻转环流的年代际和更长时间的演变。一旦开发完成，采样方法和数据工具就可以应用于未来的速度和湍流剖面浮子数据集。此外，这项工作将允许维持仪器开发和海上实地工作的专门知识，并将支持正在进行的教育和外联工作。主要活动包括(1)在全球不同地点部署50个速度和微结构剖面浮标，这些浮标来自3年多的6次机会巡航，涉及决定内部波环境的主要参数范围。(2)内波产品的推导，用于：(A)估计内波对混合和海洋动能收支的影响，(B)将卫星传感器看到的内波的表面特征投影到次表层垂直结构和频带，(C)内波分辨模型的验证，以及(D)内波分辨数据同化。(3)从速度和微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)使用合并和扩充的剖面浮标测量数据库，评估风、潮汐、地形和中尺度变化在海洋内波场中产生和消散能量的相对作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.