Wave Impacts in Upper Ocean Mixing

上层海洋混合中的波浪影响

• 批准号: 0850551
• 负责人: Eric D'Asaro
• 金额: $ 150万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0850551&HistoricalAwards=false
• 关键词: Wave; Impacts; Upper; Ocean; Mixing

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Intellectual Merit. Surface waves are believed to play a key role in the upper ocean boundary layer, yet do not appear explicitly in any of the major boundary layer parameterizations used in ocean circulation or climate models. This project will assess whether this neglect is important by testing the following hypothesis:(1) Mixed layer turbulence intensity and entrainment efficiency, scaled by wind stress, will increase with surface wave age, in the presence of swell, and with decreasing boundary layer depth as predicted by recent and proposed Large Eddy Simulations (LES).(2) A boundary layer model that includes these sea state dependencies, in addition to the usual dependencies on surface stress, buoyancy flux, and subsurface shear, will be significantly more accurate than one which does not.Multi-year data from the NOAA/PMEL long-term mooring at OWS Papa, will be used to test the second hypothesis. In collaboration with the OWS-P team at NOAA/PMEL, a dedicated surface wave measuring buoy will be deployed at the OWS-P site. Combined with existing measurements of air-sea fluxes, ocean stratification and shear, these data will provide complete, high quality data for the forcing and testing of 1-D ocean boundary layer models with waves. Existing boundary layer parameterizations, including KPP and a second moment turbulence closure, will be modified for the effect of variations in sea state on mixed layer entrainment, via critical bulk Richardson numbers criteria or through Turbulence Kinetic Energy (TKE) production rates or equilibrium levels. This ensemble of models will be compared against 3 years of enhanced OWS-P data to test the second hypothesis.Data from water-following Lagrangian floats operated in the upper ocean boundary layer will be used to test the first hypothesis. These instruments, deployed over the last 17 years, have produced measurements from which profiles of vertical kinetic energy and flux profiles of heat, salt and buoyancy can be estimated. These data span almost the entire range of oceanic wind speeds [0-57 m/s] and a wide range of mixed layer depths [0-250m], but do not span a wide range of wave conditions at each wind speed. The quality of wind speed, surface wave and ocean shear measurements also vary greatly among these data. The data set will be enhanced with an additional float deployment in mature, big seas near OWS-P, and on very young, small seas in the lee of a floating bridge over Lake Washington. Remote sensing and operational wind/wave products will be used to supplement both the new and existing float data. This enhanced data, coupled with both idealized and observationally-based LES case studies for model-data comparison, will be analyzed uniformly to test the first hypothesis.Broader Impacts. Turbulent mixing in the oceanic boundary layer is a key component in the climate system, playing a crucial role in setting the surface values and thus fluxes of temperature and CO2 as well as the transition layer nutrient fluxes supporting upper ocean productivity. Operational models now routinely make global predictions of surface wave fields. Incorporation of this information into models could have significant impacts on physical and biogeochemical models on a wide range of scales.The OWS-P data used in this work will be available publicly in near-real time thus providing a long-term, high quality data set for future studies. The project will support continuing outreach and education efforts to K-12 students and their teachers. The project will support training and research experience for one undergraduate engineering major, and a unique forecasting experience for an undergraduate meteorology student.

该奖项是根据2009年美国复苏和再投资法案（公法111 - 5）资助的。表面波被认为在海洋上层边界层中起着关键作用，但在海洋环流或气候模式中使用的任何主要边界层参数化中都没有明确出现。本项目将通过检验以下假设来评估这种忽略是否重要：（1）混合层湍流强度和卷吸效率（按风应力换算）将随着表面波年龄、涌浪的存在以及边界层深度的减小而增加，正如最近和拟议的大涡模拟（LES）所预测的那样。(2)一个边界层模型，包括这些海况的依赖性，除了通常的依赖表面应力，浮力通量，和地下剪切，将显着更准确的比一个没有。多年的数据从NOAA/PMEL长期停泊在OWS Papa，将被用来检验第二个假设。与NOAA/PMEL的OWS-P团队合作，将在OWS-P现场部署一个专用的表面波测量浮标。结合现有的海气通量、海洋层结和切变的测量，这些数据将为一维海洋边界层波浪模型的强迫和测试提供完整、高质量的数据。现有的边界层参数化，包括KPP和二阶矩湍流封闭，将修改的影响，在混合层夹带的海洋状态的变化，通过临界散装理查森数标准或通过湍流动能（TKE）生产率或平衡水平。这套模式将与3年的增强OWS-P数据进行比较，以检验第二个假设。在海洋上层边界层中运行的水跟随拉格朗日浮子的数据将用于检验第一个假设。这些仪器在过去17年中部署，已经产生了测量结果，根据这些测量结果可以估计垂直动能分布和热、盐和浮力的通量分布。这些数据几乎涵盖了整个海洋风速范围[0 - 57 m/s]和广泛的混合层深度范围[0 - 250 m]，但没有涵盖每个风速下的广泛波浪条件。风速、表面波和海洋切变测量的质量在这些数据中也有很大差异。数据集将通过在OWS-P附近的成熟大海和华盛顿湖上浮桥背风处的非常年轻的小海中部署额外的浮子来增强。遥感和业务风/波产品将用于补充新的和现有的浮动数据。这个增强的数据，再加上理想化的和基于观测的LES案例研究模型数据比较，将统一分析，以测试第一个假设。海洋边界层中的湍流混合是气候系统的一个关键组成部分，在确定表面值以及温度和CO2通量以及支持海洋上层生产力的过渡层营养通量方面发挥着至关重要的作用。业务模型现在通常对表面波场进行全球预测。将这些信息纳入模型可能会对物理和地球化学模型产生重大影响，在广泛的scales.The OWS-P数据在这项工作中使用的将是近实时公开，从而为未来的研究提供了一个长期的，高质量的数据集。该项目将支持继续对K-12学生及其教师进行宣传和教育。该项目将支持一个本科工程专业的培训和研究经验，并为本科气象学学生提供独特的预报经验。