Collaborative Research: Tracing the Missing Physics of Submesoscale Entrainment and Subduction

合作研究：追踪亚尺度夹带和俯冲缺失的物理现象

• 批准号: 2149041
• 负责人: Baylor Fox-Kemper
• 金额: $ 47.39万
• 依托单位: Brown University
• 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: 2022-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149041&HistoricalAwards=false
• 关键词: Collaborative; Research; Tracing; Missing; Physics

This project will investigate the exchange between the well-mixed surface layer of the ocean and the stratified interior at the so-called submesoscales; horizontal length scales of hundreds to thousands of meters, where the rotation of the Earth is still felt but is not the dominant factor like it is at larger scales. This exchange is widely recognized as one of the primary mechanisms through which submesoscale processes affect upper ocean variability and biogeochemistry. However, despite extensive work demonstrating the impacts of submesoscale entrainment and subduction on diverse topics across the field of oceanography— including for example the global mixed-layer heat budget, primary productivity, and the export of carbon to the interior—the essential physical mechanisms remain incompletely described. In particular, next steps need to include the impact of the submesoscale interactions between the surface boundary layer and the interior on large-scale models, as parameterizations of submesoscale processes explicitly avoid entrainment fluxes. This avoidance severely underestimates submesoscale impacts on biogeochemistry and climate (e.g., long-term carbon and heat uptake). Recent work, some from this group, further indicates that cross-scale interactions between submesoscale flows, surface gravity waves, and turbulence may also significantly alter the exchange at the base of the surface mixed layer. However, the balance of several possible mechanisms for this exchange has not been established. This project will quantify the effect of these multiscale interactions using new theoretical and computational tools, resulting in more complete models of submesoscale exchange between the ocean interior and surface boundary layer. Advances for both climate-scale and high-resolution Large Eddy Simulation models will be shared with the science community. New techniques in tracer diagnostics and theory will be developed, and used to clarify the role of multiscale interactions in affecting exchange between the boundary layer and interior, providing guidance towards new approaches in multiscale numerical modeling, parameterization, and ocean observing. The majority of the funds for this project will go towards supporting early career scientists: a graduate student, a postdoctoral researcher, an early career research scientist, and an early career faculty member.Reynolds-averaged numerical simulations (RANS) will quantify the impact of incorporating entrainment fluxes into a widely utilized parameterization of submesoscale mixedlayer instability, including the impact of the improved parameterization on realistic simulations incorporating ocean biogeochemistry in the Southern Ocean. Large-eddy simulations (LES) will determine the processes and parameter dependence through which submesoscale instabilities, surface gravity wave-driven effects such as Langmuir turbulence, and small-scale three-dimensional turbulence interact to modify entrainment and subduction of tracers. New insights into these multiscale interactions will be enabled by recent developments in boundary layer energetics, potential vorticity dynamics, and techniques for eddy-flux diagnostics developed as part of this project. These advances will be applied to a set of state-of-the-art large-domain LES that resolve scales of order 1 m to 10km, providing new benchmarks in exascale ocean modeling. Together these activities will simulate and quantify the essential mechanisms of entrainment and subduction at the submesoscale, their cross-scale interactions, and their accurate interpretation in observations and representation in numerical models. Community ocean and climate model improvements will be furthered through inclusion of improved and vetted representation of entrainment fluxes in two parameterizations, including the most widely used parameterization of submesoscale mixed-layer instability and a newer process parameterization. The LES that will be performed will be made available for immediate community use, providing a valuable new resource supporting other investigations into submesoscale-Langmuir-turbulence, and physical-biogeochemical interactions.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.

该项目将调查海洋混合良好的表层和所谓的亚中尺度的分层内部之间的交换;水平长度尺度为数百至数千米，在那里仍然可以感觉到地球的旋转，但不像在更大的尺度上那样是主导因素。这种交换被广泛认为是次中尺度过程影响上层海洋变率和海洋地球化学的主要机制之一。然而，尽管大量的工作证明了亚中尺度卷吸和俯冲对海洋学领域各种主题的影响-包括例如全球混合层热收支，初级生产力和碳出口到走廊-基本的物理机制仍然没有完全描述。特别是，接下来的步骤需要包括表面边界层和大尺度模型内部之间的亚中尺度相互作用的影响，因为亚中尺度过程的参数化明确避免了夹带通量。这种回避严重低估了对地球化学和气候的次中尺度影响（例如，长期的碳和热吸收）。最近的工作，其中一些来自这一组，进一步表明，跨尺度的次中尺度流，表面重力波和湍流之间的相互作用，也可能显着改变交换的基础上的表面混合层。然而，这种交流的几种可能机制的平衡尚未建立。该项目将使用新的理论和计算工具量化这些多尺度相互作用的影响，从而建立更完整的海洋内部和表面边界层之间的亚中尺度交换模型。气候尺度和高分辨率大涡模拟模型的进展将与科学界分享。将开发示踪剂诊断和理论方面的新技术，并用于澄清多尺度相互作用在影响边界层和内部之间交换方面的作用，为多尺度数值模拟、参数化和海洋观测方面的新方法提供指导。该项目的大部分资金将用于支持早期职业科学家：一名研究生，一名博士后研究员，一名早期职业研究科学家和一名早期职业教员。哈罗德平均数值模拟（RANS）将量化将卷吸通量纳入广泛使用的亚中尺度混合层不稳定性参数化的影响，包括改进的参数化对现实模拟的影响，包括南大洋的海洋地球化学。大涡模拟（LES）将确定过程和参数依赖性，通过这些过程和参数依赖性，亚中尺度不稳定性、表面重力波驱动效应（如朗缪尔湍流）和小尺度三维湍流相互作用，以修改示踪剂的夹带和俯冲。这些多尺度相互作用的新见解，将使最近的发展，边界层能量，位涡动力学和技术的涡流通量诊断开发作为本项目的一部分。这些进展将应用于一套最先进的大域LES，解决1米到10公里的规模，提供新的基准exascale海洋建模。这些活动将共同模拟和量化次中尺度卷吸和俯冲的基本机制、它们的跨尺度相互作用以及它们在观测中的准确解释和在数值模式中的表示。将通过在两个参数化中纳入经过改进和审查的卷吸通量表示法，包括最广泛使用的亚中尺度混合层不稳定参数化和更新的过程参数化，进一步改进社区海洋和气候模式。LES将被立即提供给社区使用，提供了一个有价值的新资源，支持其他调查亚中尺度朗缪尔湍流，物理-地球化学相互作用。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。