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: 0751835
• 负责人: Joseph Pedlosky
• 金额: $ 17.72万
• 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: 2008
• 资助国家: 美国
• 起止时间: 2008-03-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0751835&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，拉布拉多海的深层对流通风部分受局部地表强迫和局部密度梯度以外的机制控制。现在看来，存在一种由边界电流动力学变化调制的主动涡流驱动的再气化。观测到涡旋脱落和边界流浮力输送的年际大变化，但没有解释。本项目将结合实际和理想的数值模拟、数据分析和理论，研究控制涡流产生和相关浮力传输的过程。高分辨率区域模式的数值实验集将探索涡旋产生和性质传输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型和实际涡旋特性。理论，在理想实验的支持下，将为检验关于不稳定性本质的候选假设提供标准，并将为其参数化提供可能性。最终结果将是了解局部和非局部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。这项以过程为导向的研究应该是理解和准确模拟大西洋经向翻转环流变异性这一更大目标的重要一步。知识价值：这项工作对在大尺度气候模式中表现大西洋经向翻转环流（AMOC）的拉布拉多海分支有直接的好处，在这种模式中，窄边界流不稳定的细节是不可能解决的。面对北极急剧增加的淡水流量，了解从边界流到对流区的浮力输送，特别是确定其变化的因素是至关重要的。此外，该合作项目将有助于更广泛地在粗分辨率数值模式中真实地表现中尺度特征对大尺度环流的影响。更广泛的影响：这项工作的主要社会效益是它与理解和可能预测AMOC变化的相关性。研究结果将由两名研究人员——乔治亚理工学院的A. Bracco和WHOI-MIT的J. Pedlosky在研究生课上发表。该项目支持的两名研究生将受益于建模、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免费分发给更大的科学界，包括JLAB， J. M. Lilly？s的Matlab开源软件包。在科学、数学和咨询综合教育中心（CEISMC）的支持下，拟议的研究也将被纳入亚特兰大地区高中教师的教材。