Langmuir Circulation - Internal Wave Interactions: Data and Modeling

摘要：基于动力学的简单混合层模型低估了长期观测记录中所见的加深。一种增强混合的机制显然缺失了。一种可能的机制是混合层的涡旋运动穿透温跃层。另一种是由于内波（其本身可能在局部或其他地方产生）而增强的剪切和/或翻转。在这两种情况下，在风驱动混合的模型中包括温跃层的顺应性似乎都很重要;即，为了回答这些问题，该项目将分析作为夏威夷海洋混合实验（HOME）一部分收集的高分辨率数据。该仪器包括一个多波束表面侧扫多普勒声纳系统，其设计用于确定混合层运动的长度和时间尺度（例如朗缪尔环流）、定向表面波和与高频内波相关的表面应变场，一个快速剖面CTD，其提供的密度剖面在时间和深度上的分辨率足以通过翻转（索普尺度）估计混合。一个8波束编码脉冲多普勒声纳系统，对水柱（从400米上下）上的水流和切变进行采样。风速和风向仪。这个项目的中心问题是“内波是否影响混合层运动，从而改变最上层密度跃层的夹带和混合？“为了验证他们这样做的假设，研究人员将研究高频内波对表面速度结构的形式和动力学的影响，就像数据中看到的那样。该提案的一个组成部分是采用从朗缪尔环流建模社区绘制的博士后，将内部波物理学的复杂性逐渐增加，并重新采样输出以模拟数据。重点是深入的数据/模型比较，而不是模型开发本身：该战略涉及重新采样和统计比较。预期成果包括改进对海洋表层混合的理解和模型。智力上的优点。该项目侧重于空气/海洋系统中至关重要但尚未完全了解的一个环节：海洋表层的净混合。混合层和最上层的密度跃层形成了大气和深海之间的重要屏障，控制着热量、动量、营养物质和温室气体的净通量。这一最上层对海洋生物也至关重要，它是光线和营养物质相遇的场所，也是污染物和污染物扩散的场所。这些结果将有助于改进海气交换的估计，从而改进气候影响，从而有助于改进决策所依据的信息。将广泛传播数据集、解释和结果，以加强科学理解，并促进进一步的重新审查和解释。将向公众和政策制定者提供摘要。拟议的活动将为博士后提供培训和教学机会。将积极发展跨学科和跨机构的伙伴关系和协作。

ABSTRACTOCE-0525256Straightforward dynamics-based mixed layer models underestimate the deepening seen in long-term observational records. A mechanism that augments mixing is apparently missing. One possible mechanism involves penetration of the thermocline by eddy motions from the mixed layer. Another is enhanced shear and/or overturns due to internal waves (which may themselves be generated either locally or elsewhere). In either case, it appears important to include the compliance of the thermocline in models of wind-driven mixing; i.e., to study the interaction of the actively forced Langmuir circulations with high-frequency internal waves.In order to answer these questions, this project will analyze high resolution data collected as part of the Hawaiian Ocean Mixing Experiment (HOME). The instrumentation includes a multi-beam surface-sidescan Doppler sonar system that is designed to define the length and time scales of the mixed layer motion (e.g. Langmuir circulation), directional surface waves, and surface strain fields associated with high-frequency internal waves, a rapid-profiling CTDs that provides density profiles with resolution in both time and depth sufficient to estimate mixing via overturns (Thorpe scales). an 8-beam coded pulse Doppler sonar system that samples flows and shears over the water column (upward and downward from 400m). and wind speed and direction instruments. The central question addressed by this project is "Do internal waves affect the mixed layer motions, and hence alter entrainment and mixing in the uppermost pycnocline?" To test the hypothesis that they do, the investigators will look at effects of high-frequency internal waves on the form and dynamics of the surface velocity structures like those seen in the data. An integral component of this proposal is employing a post-doc drawn from the Langmuir circulation modeling community, incorporating internal wave physics of incrementally increasing complexity, and re-sampling the output to mimic the data. The focus is on in-depth data/model comparisons, rather than on model development per se: the strategy involves re-sampling and statistical comparisons. The anticipated results include improved understanding and models of oceanic surface layer mixing. Intellectual merit. The project focuses on a link in the air/ocean system that is vitally important yet incompletely understood: net mixing through the surface layer of the sea. The mixed layer and uppermost pycnocline forms a crucial barrier between the atmosphere and deep ocean, controlling the net fluxes of heat, momentum, nutrients and greenhouse gases. This uppermost layer is also vital to marine life, setting the scene where light and nutrients meet, and where pollutants and contaminants are dispersed.Broader impacts. The results will help improve air-sea exchange estimates, and hence climate effects, thereby helping improve the information by which policy decisions are made. The data sets, interpretations, and results will be disseminated broadly to enhance scientific understanding and facilitate further re-examination and interpretation. Summaries accessible to the public and policy makers will be made available. The proposed activity will provide training and teaching opportunities for a post-doc. Partnerships and collaborations across disciplines and institutions will be actively developed.