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

合作研究：受热的风和波浪驱动的海洋表面边界层：观测和模拟的协同分析

• 批准号: 2219816
• 负责人: Seth Zippel
• 金额: $ 30.74万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219816&HistoricalAwards=false
• 关键词: Collaborative; Research; Heated; Wind; Wave

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.

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，从而控制气候、天气和地球系统动力学。 OSBL 中的湍流会分布可漂浮（浮力）的生物地球化学和生态相关示踪剂，例如浮游生物、气泡、营养物、石油和微塑料。风和波浪以几种关键方式驱动 OSBL 湍流：风产生的洋流；波流相互作用导致与风对齐的涡流，称为朗缪尔湍流（LT）；破碎波向地下注入湍流动能。当前波驱动 OSBL 动力学的概念和理论框架很大程度上基于表面热通量被假设为中性或有利于翻转地表水柱的条件。然而，白天的加热或降雨事件会阻止倾覆，并且在世界海洋上无处不在。该项目将利用数值模拟和现有数据集分析来探索表面加热条件下表面波对分层 OSBL 的影响。本研究的目的是：（1）确定传统表面边界假设由于波浪效应的局限性； (2) 基于动量、浮力和湍流动能的系统分析，揭示波浪对加热 OSBL 影响的动力学； (3) 整合数据和模拟，建立湍流状态图，揭示朗缪尔湍流 (LT) 和碎波效应影响 OSBL 动力学的条件； (4) 对湍流统计进行分析，以评估并提出改进的海洋混合参数化。这些新的参数化将用于证明日间 OSBL 加热过程中波浪效应对浮力示踪剂传输的重要性。这项工作将与许多海洋学和大气子学科相关；支持早期职业研究人员；培养研究生；并开展外展活动。 拟议的研究将测试具体假设：（1）波对热 OSBL 动力学的影响是显着的，并且可以通过观察和模拟进行量化； (2) LT 对于 OSBL 混合至关重要，但足够强的加热会为喷射引起的剪切驱动湍流产生有利条件； (3)破碎波防止强加热条件下的流动层化； (4) 加热 OSBL 中的波驱动混合可以在改进的湍流混合参数化中准确表示，以捕获加速射流传输和浮力示踪剂的深度浸没。该团队可以获得多个广泛的观测数据集，从中他们将能够确定表面加热过程中 LT 的存在，并评估 LT 对 OSBL 动力学的影响。数值实验将使用大涡模拟 (LES) 进行，该模拟通过涡流强迫产生 LT，并包括破碎波的影响。根据综合数据的结果，将开发、评估加热 OSBL 的 LES 建模分析、物理驱动和实用混合参数化，并将其应用于浮力示踪剂（例如微塑料、浮游生物或石油）的运输。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。