Exploration of Anisotropy and Inhomogeneity of Ocean Boundary Layer Turbulence

海洋边界层湍流的各向异性和不均匀性探索

• 批准号: 2344156
• 负责人: Andrey Shcherbina
• 金额: $ 119.59万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-15 至 2027-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2344156&HistoricalAwards=false
• 关键词: Exploration; Anisotropy; Inhomogeneity; Ocean; Boundary

Ocean Surface Boundary Layer is a turbulent region that governs the interaction between air-sea fluxes and the ocean's deeper layers. Since the regional and global numerical models cannot fully resolve OSBL processes, simplified parameterization schemes are used to approximate them. Recent evidence suggests that discrepancies between different parameterizations and other errors may result from the limited and idealized representation of physics, such as the assumption that small-scale turbulence is uniform by direction (isotropy) and location (homogeneity). OSBL turbulence is anticipated to deviate from this idealized model due to the influences of shear, stratification, and waves. This project will provide the first direct observational study of anisotropy and inhomogeneity of OSBL turbulence with measurements from acoustic instruments that drift with the water flow. These custom instruments will have acoustic beams pointing horizontally, vertically, and diagonally to carry out direct and simultaneous observations of turbulence statistics in multiple directions, encompassing scales from centimeters to tens of meters, thereby resolving their anisotropy and inhomogeneity. The observations from this project will produce both an empirical insight and a comprehensive dataset that could be used for development, refinement, and benchmarking of simulations and turbulence closures. Thus, this project will contribute to the evolution of our capacity to forecast the dynamics of the Earth's system across scales ranging from local phenomena to the broader spectrum of global climate dynamics. Understanding the inhomogeneity and anisotropy of ocean turbulence will clarify the errors, biases, and limitations associated with various techniques used to characterize turbulence and lead to the development of corrections for existing observations and better future observational practices. This project will support a number of complementary Applied Physics Laboratory outreach efforts aimed at general broadening of public awareness and participation in science. It will provide dedicated line-item support for APL STEM Development Program Coordinator to develop ongoing and future outreach projects at APL, facilitate connections to local schools as well as undergraduate students attending UW, surrounding community colleges, and technical schools.This project will deploy two Lagrangian floats, each equipped with a pair of customized Acoustic Doppler Current Profilers (ADCPs) providing a total of 10 acoustic Doppler beams on each float pointing horizontally, vertically, and diagonally. These beams, used in combinations, will gather multiple directional second- and third-order statistics of velocity fluctuations, thereby estimating how turbulence energy and energy flux is partitioned across scales and directions. The observations will be conducted in a turbulent tidal channel and at the Ocean Climate Station P site (North Pacific) providing a variety of forcing conditions. The primary impact of the project will be an enhanced understanding of the extent to which ocean boundary layer turbulence deviates from the idealized model of homogeneity and isotropy. A more comprehensive description of ocean turbulence will lead to a deeper understanding of the complex processes that drive and govern turbulence in the ocean. It will help clarify the mechanisms responsible for turbulence generation, dissipation, and energy transfer, leading to a more comprehensive understanding of the dynamics of oceanic flows. The project will specifically address a number of outstanding scientific questions, such as: What is the extent of the isotropic inertial subrange in OSBL turbulence? What is the magnitude and distribution of anisotropy? Can anisotropy be predicted and parameterized? How does anisotropy affect the measurements and parameterization of ocean turbulence?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.

海面边界层是一个湍流区域，它控制着空气通量与海洋更深层之间的相互作用。由于区域和全局数值模型无法完全解析OSBL进程，因此使用简化的参数化方案来近似它们。最近的证据表明，不同的参数化和其他误差之间的差异可能是由于物理学的有限​​和理想化的表示，例如假设小规模的湍流按方向（同型）和位置（同质性）均匀。由于剪切，分层和波浪的影响，预计OSBL湍流将偏离这种理想化的模型。该项目将提供对OSBL湍流各向异性和不均匀性的首次直接观察性研究，并通过水流漂移的声学仪器进行测量。这些自定义仪器将具有水平，垂直和对角线指向的声学束，以在多个方向上直接和同时观察湍流统计，包括从厘米到数十米的尺度，从而解决了它们的各向异性和不显性。该项目的观察结果将产生经验洞察力和全面数据集，可用于开发，改进和基准模拟和湍流封闭。因此，该项目将有助于我们在从当地现象到更广泛的全球气候动态范围的范围内预测地球系统动力学的能力的演变。了解海洋湍流的不均匀性和各向异性将阐明与用于表征湍流的各种技术相关的错误，偏见和局限性，并导致对现有观察结果的校正和更好的未来观察实践的开发。该项目将支持许多辅助物理实验室外展工作，旨在普遍扩大公众意识和参与科学。 It will provide dedicated line-item support for APL STEM Development Program Coordinator to develop ongoing and future outreach projects at APL, facilitate connections to local schools as well as undergraduate students attending UW, surrounding community colleges, and technical schools.This project will deploy two Lagrangian floats, each equipped with a pair of customized Acoustic Doppler Current Profilers (ADCPs) providing a total of 10 acoustic Doppler每个浮子上的梁水平，垂直和对角线指向。这些梁用于组合，将收集速度波动的多个方向二阶和三阶统计，从而估计湍流能量和能量通量如何在尺度和方向上分配。该观察结果将在湍流的潮汐通道和海洋气候站P地点（北太平洋）中进行，以提供各种强迫条件。该项目的主要影响将增强对海洋边界层湍流偏离理想化的均匀性和各向同性模型的程度。对海洋湍流的更全面描述将使人们对驱动和控制海洋湍流的复杂过程有更深入的了解。它将有助于阐明负责产生湍流，耗散和能量转移的机制，从而更全面地了解海洋流动的动力学。该项目将专门解决许多杰出的科学问题，例如：OSBL湍流中各向同性惯性次数的程度是多少？各向异性的幅度和分布是什么？可以预测和参数化各向异性吗？各向异性如何影响海洋湍流的测量和参数化？该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响评估标准，被认为值得通过评估来获得支持。