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: 2219825
• 负责人: Tobias Kukulka
• 金额: $ 39.99万
• 依托单位: University of Delaware
• 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 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219825&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来控制气候，天气和地球系统动力学。OSBL中的湍流分布可漂浮（浮力）的生物地球化学和生态相关示踪剂，如浮游生物，气泡，营养物质，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;波流相互作用导致风对齐的漩涡，称为朗缪尔湍流（LT）;破碎的波浪将湍流动能注入地下。目前的概念和理论框架的波驱动OSBL动力学在很大程度上是基于表面热通量被假定为中性或有利于推翻地表水柱的条件。然而，昼夜加热或降雨事件防止倾覆，并且在世界海洋上无处不在。本项目将利用数值模拟和现有数据集的分析，探讨在地面加热条件下表面波对分层OSBL的影响。本研究的目的是：（1）识别由于波浪效应引起的传统表面边界假设的局限性：（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的影响动力学;（3）综合数据和模拟，建立湍流状态图，揭示朗缪尔湍流（LT）和破碎波影响OSBL动力学;（4）进行湍流统计分析，以评估和提出改进的海洋混合参数化。这些新的参数化将被应用于证明在昼夜OSBL加热的浮力示踪剂的运输波的影响的重要性。这项工作将涉及许多海洋学和大气子学科;支持早期职业研究人员;培训研究生;并参与外联活动。 本研究将验证以下假设：（1）波浪对加热OSBL动力学的影响是显著的，并且可以通过观测和模拟进行量化;（2）LT对于OSBL混合是必不可少的，但是足够强的加热会产生由于射流而产生的剪切驱动湍流的有利条件;（3）在强加热条件下，破碎波浪会阻止流动层流化;（4）改进的湍流混合参数化方法可以准确地描述加热OSBL中的波浪驱动混合，以捕捉加速的射流输送和浮力示踪剂的深潜。该团队可以访问几个广泛的观测数据集，从中他们将能够确定在表面加热期间LT的存在，并评估LT对OSBL动态的影响。将使用大涡模拟（LES）进行数值实验，通过涡强迫产生LT，并包括破碎波的影响。基于综合数据的结果，LES建模分析，加热OSBL的物理动机和实际混合参数化将被开发，评估，并应用于漂浮示踪剂的运输，如微塑料，浮游生物或油。该奖项反映了NSF的法定使命，并被认为值得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来支持。