Collaborative Research: The Heated Wind- and Wave-Driven Ocean Surface Boundary Layer: Synergistic Analyses of Observations and Simulations

与大气接触的海洋表层(或表面边界层--OSBL)通过海-气通量耦合海洋和大气，控制气候、天气和地球系统的动态。OSBL中的湍流分布了可漂浮(漂浮)的生物地球化学和生态相关示踪剂，如浮游生物、气泡、营养物、石油和微塑料。风和海浪以几种关键方式驱动OSBL湍流：风产生的洋流；波与流的相互作用导致风向涡旋，称为朗缪尔湍流(LT)；以及破碎的海浪向次表面注入湍流动能。目前波浪驱动的OSBL动力学的概念和理论框架在很大程度上是基于假设地表热通量为中性或有利于倾覆地表水柱的条件。然而，白天的加热或降雨事件防止了倾覆，在世界大洋上无处不在。该项目将利用数值模拟和对现有数据集的分析来探索表面加热条件下表面波对层状OSBL的影响。本研究的目标是：(1)确定由于波浪效应导致的传统表面边界假设的局限性；(2)基于对动量、浮力和湍动能的系统分析，揭示波浪效应对加热的OSBL的动力学作用；(3)将数据和模拟相结合，建立湍流制度图，揭示朗缪尔湍流(LT)和破碎波效应影响OSBL动力学的条件；(4)进行湍流统计分析，以评估并提出改进的海洋混合参数。这些新的参数将被用来证明在OSBL日间加热期间，波浪效应对浮力示踪物传输的重要性。这项工作将涉及许多海洋学和大气分学科；支持早期职业研究人员；培训研究生；并参与外联活动。这项拟议的研究将检验具体的假设：(1)波对加热的OSBL动力学的影响是显著的，并且可以通过观测和模拟来量化；(2)LT对于OSBL混合是必要的，但足够强的加热为急流的切变驱动湍流创造了有利的条件；(3)在强加热条件下，破碎波防止了流动分层；(4)加热OSBL中的波驱动混合可以准确地用改进的湍流混合参数来表示，以捕捉加速的射流传输和浮力示踪物的深淹没。该小组获得了几个广泛的观测数据集，从中他们将能够确定地表加热期间LT的存在，并评估LT对OSBL动力学的影响。数值试验将使用大涡模拟(LES)进行，它通过涡旋强迫产生LT，并包括来自破碎波的影响。基于综合数据、大涡模拟分析、物理激励和实用的加热OSBL混合参数的结果，将开发、评估并应用于浮力示踪剂的运输，例如微塑料、浮游生物或石油。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。

The ocean's surface layer in contact with the atmosphere (or surface boundary layer -- OSBL) controls climate, weather, and Earth system dynamics by coupling the ocean and atmosphere through air-sea fluxes. Turbulence in the OSBL distributes biogeochemical and ecologically relevant tracers that are floatable (buoyant), such as plankton, bubbles, nutrients, oil, and microplastics. Wind and waves drive OSBL turbulence in several critical ways: Wind-generated ocean currents; wave-current interactions result in wind-aligned vortices, called Langmuir turbulence (LT); and breaking waves inject turbulent kinetic energy to the subsurface . The present conceptual and theoretical framework of wave-driven OSBL dynamics is largely based on conditions for which surface heat fluxes are assumed to be either neutral or conducive to overturn the surface water column. However, diurnal heating or rain events prevent overturning and are omnipresent over the world oceans. This project would use numerical simulations and analysis of existing data sets to explore the effects of surface waves on the stratified OSBL in surface heating conditions. The objectives of this study are to: (1) identify limitations of traditional surface boundary assumptions due to wave effects; (2) reveal the dynamics of wave effects on the heated OSBL, based on a systematic analysis of momentum, buoyancy, and turbulent kinetic energy; (3) integrate data and simulations to establish a turbulence regime diagram that reveals the conditions in which Langmuir turbulence (LT) and breaking wave effects affect OSBL dynamics; (4) perform an analysis of turbulence statistics to assess and proposes improved ocean mixing parameterizations. These new parameterizations will be applied to demonstrate the importance of wave effects on the transport of buoyant tracers during diurnal OSBL heating. The work will be relevant across many oceanographic and atmospheric sub-disciplines; support an early career researcher; train graduate students; and engage in outreach. The proposed research will test specific hypotheses: (1) wave effects on heated OSBL dynamics are significant and quantifiable through observations and simulations; (2) LT is essential for OSBL mixing but sufficiently strong heating generates favorable conditions for shear-driven turbulence due to jets; (3) breaking waves prevent flow laminarization in strong heating conditions; and (4) wave-driven mixing in heated OSBLs can be accurately represented in improved turbulent mixing parameterizations to capture accelerated jet transport and the deep submergence of buoyant tracers. The team has access to several extensive observational data-sets, from which they will be able to determine the presence of LT during surface heating and assess the impact of LT on OSBL dynamics. Numerical experiments will be conducted using Large Eddy Simulations (LES) which produce LT through vortex forcing and include effects from breaking waves. Based on results from a combined data, LES modeling analysis, physics-motivated and practical mixing parameterizations for the heated OSBL will be developed, assessed, and applied to transport of buoyant tracers, such as microplastics, plankton or oil.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.