Collaborative Research: Vortex dynamics and interannual variability in the Labrador Sea

合作研究：拉布拉多海的涡动力学和年际变化

• 批准号: 0751775
• 负责人: Annalisa Bracco
• 金额: $ 20.28万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-15 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0751775&HistoricalAwards=false
• 关键词: Collaborative; Research; Vortex; dynamics; interannual

Accumulating evidence suggests that deep convective ventilation in the Labrador Sea is partly controlled by mechanisms other than local surface forcing and local density gradients. It now appears that there exists an active eddy-driven restratification which is modulated by variations in boundary current dynamics. Large inter-annual variations in both eddy shedding and buoyancy transport from the boundary current have been observed but not explained. This project will investigate the processes controlling eddy generation and associated buoyancy transport by combining realistic and idealized numerical modeling, data analysis, and theory. Ensembles of numerical experiments with a high-resolution regional model will explore the sensitivity of eddy generation and property transport to variations in local and external forcing parameters. Extended analysis of eddy and boundary current properties in data, centrally the now fifteen-year TOPEX/Poseidon and Jason altimeter records, will allow comparison of modeled and actual vortex characteristics over a wide range of oceanic conditions. Theory, supported by idealized experiments, will provide criteria to test candidate hypotheses as to the nature of the instability, and will suggest possibilities for its parameterization. The net result will be an understanding of the links between local and non-local forcing variability, and the eddy-driven buoyancy fluxes which limit deep convection. This process-oriented study should form an important step toward the larger goal of understanding and accurately modeling variability of the Atlantic Meridional Overturning Circulation in general.Intellectual Merit: This work has a direct benefit to the representation of the Labrador Sea branch of the Atlantic Meridional Overturning Circulation (AMOC) in large-scale climate models, in which details of the narrow boundary current instability are not possible to resolve. In the face of dramatically increasing freshwater discharge from the Arctic, it is critical to understand the transport of buoyancy from boundary current to the convection region, and in particular, to identify the factors underlying its variability. Furthermore, this collaborative project will contribute to the broader effort of realistically representing the effects of mesoscale features on the large-scale circulation in coarse-resolution numerical models.Broader Impacts: The primary societal benefit of this work is its relevance to understanding and possibly predicting variations of the AMOC. Results will be presented in graduate classes by two of the investigators, A. Bracco at Georgia Tech and J. Pedlosky at WHOI-MIT. The two graduate students supported by the project will benefit from exposure to modeling, analytical investigation and data analysis techniques. Analysis algorithms developed in this work will be freely distributed to the greater scientific community, by inclusion in JLAB, J. M. Lilly?s open-source software package for Matlab. The proposed research will also be incorporated into teaching material for high school teachers in the Atlanta area, with the support of the Center for Education Integrating Science, Mathematics and Consulting (CEISMC).

越来越多的证据表明，拉布拉多海的深部对流通风部分受局部表面强迫和局部密度梯度以外的机制控制。现在看来，存在一种受边界流动态变化调制的活跃的涡动驱动的再层化。已经观测到边界流的涡脱和浮力输送的年际变化很大，但无法解释。本项目将结合现实和理想化的数值模拟、数据分析和理论，研究控制涡旋产生和相关浮力输送的过程。用高分辨率区域模式进行的数值试验将探索涡旋的产生和性质输送对局地和外部强迫参数变化的敏感性。对数据中涡流和边界流特性的扩展分析，主要是现在15年的TOPEX/Poseidon和Jason高度计记录，将允许在广泛的海洋条件下比较模拟的和实际的涡流特征。理想化实验支持的理论将为检验关于不稳定性质的候选假设提供标准，并将为其参数化提供可能性。最终的结果将是了解本地和非本地强迫变率之间的联系，以及限制深层对流的涡流驱动的浮力通量。这项面向过程的研究应该是朝着更大的目标迈出的重要一步，即理解和准确模拟总体上的大西洋子午线翻转环流的可变性。智力上的价值：这项工作直接有利于在大型气候模式中表示大西洋子午线翻转环流(AMOC)的拉布拉多海分支，在大型气候模式中，窄边界洋流不稳定的细节无法解决。在北极淡水排放量急剧增加的情况下，必须了解浮力从边界流到对流区域的传输，特别是确定其变化的因素。此外，这项合作项目将有助于在粗分辨率数值模式中真实地展示中尺度特征对大尺度环流的影响的更广泛的努力。广泛的影响：这项工作的主要社会效益是它与理解和可能预测AMOC的变化有关。结果将由两名研究人员在研究生课堂上公布，他们是佐治亚理工学院的A·布拉科和世界卫生组织麻省理工学院的J·佩德洛斯基。该项目支持的两名研究生将受益于学习建模、分析调查和数据分析技术。在这项工作中开发的分析算法将被免费分发给更大的科学界，通过包含在JLAB，J.M.Lilly？S的MatLab开源软件包中。在科学、数学和咨询综合教育中心(CEISMC)的支持下，拟议的研究还将被纳入亚特兰大地区高中教师的教材。