Collaborative Research: Export Pathways from the Subpolar North Atlantic: Phase Two

合作研究：北大西洋副极地的出口途径：第二阶段

• 批准号: 0824652
• 负责人: Amy Bower
• 金额: --
• 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: 2008-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0824652&HistoricalAwards=false
• 关键词: Collaborative; Research; Export; Pathways; Subpolar

Intellectual Merit: Profiling float observations in the western subpolar North Atlantic made in the 1990s appeared to contradict the current understanding of the Deep Western Boundary Current (DWBC) as the dominant export pathway for Labrador Sea Water (LSW) from subpolar to subtropical latitudes. All of the profiling floats that exited the Labrador Sea in the DWBC left the boundary well north of the Tail of the Grand Banks, turning eastward into the ocean interior along the path of the North Atlantic Current (NAC) at about 50°N. This unexpected observation motivated a long-term observational effort to obtain a better understanding of LSW pathways and their variability with new float observations and historical hydrographic data analyses.The field component of this project, which began in 2003, is nearly complete. For three years, groups of six acoustically tracked RAFOS floats were released nominally every three months in the DWBC near 50ºN at Upper LSW and Classical LSW levels. When the last floats surface in November 2008, two-year high-resolution trajectories from about 62 RAFOS floats will be available for analysis. Two important results have emerged to date from a study of RAFOS floats that have already surfaced and "e-floats" generated from an ocean eddy-resolving general circulation model. First, there is little evidence for a "fast-track" from the subpolar to the subtropical basin along the DWBC. Second, a significant number of RAFOS and e-floats trace an interior pathway for LSW southward from the Newfoundland Basin to the eastern subtropical gyre, a pathway that was not observed at all by the profiling floats. These results raise critical questions about the importance of the DWBC as an export pathway for newly-ventilated waters, and hence its role in the Atlantic Meridional Overturning Circulation (AMOC) which is a near-term priority of the Ocean Research Priorities Plan (ORPP).With the conclusion of the RAFOS field work in sight, and the capability to generate e-float trajectories in hand, the investigators are now poised to make significant advances in the understanding of the export pathways of LSW and their impact on the AMOC. The specific objectives of this analysis are to:1. Complete the statistical analysis of the full RAFOS float data set and compare to a similar study using e-floats generated from an ocean general circulation model.2. Reconcile the apparent contradiction between the rapid loss of floats from the DWBC in the Newfoundland Basin and the concept of the DWBC as a direct LSW export pathway from the subpolar to subtropical region.3. Elucidate the impact of mesoscale, interannual and decadal variability on LSW pathways.4. Assess the importance of the interior pathway of LSW, relative to the DWBC, to the volume and property transport of the AMOC.Broader Impacts: By providing an improved understanding of subpolar-to-subtropical ocean pathways, this proposed research will contribute to an unraveling of the ocean's role in global climate. The Lagrangian perspective will provide valuable information on the continuity of the lower limb of the AMOC and as such will aid in the design of monitoring programs. This project will also have a broader impact in that it will contribute to the training and education of a graduate student at Duke University and a postdoctoral investigator at Woods Hole Oceanographic Institution.

智力优点：在1990年代制作的西部亚北大西洋中的浮点观测似乎与当前对深西边界电流（DWBC）的理解是从亚光到亚热带纬度到亚光纬度的主要出口途径。 DWBC中退出拉布拉多海的所有谱图都离开了大银行尾巴以北的边界，向东转向沿北大西洋电流（NAC）（NAC）的海洋内部（约50°N）。这种意外的观察促使人们进行了长期的观察努力，以更好地了解LSW途径及其在新的FLOAT观测值和历史水文数据分析中的可变性。该项目的现场成分始于2003年，几乎是完整的。三年来，由六个精确跟踪的Rafos Floats组成的小组名义上每三个月在上LSW和古典LSW水平的50ºN附近每三个月释放每三个月的DWBC。当2008年11月的最后一个浮子表面时，将提供来自约62个Rafos浮子的两年高分辨率轨迹。迄今为止，从已经浮出水面和“ E-Floats”的Rafos Floats的研究中出现了两个重要的结果，从海洋涡流总循环模型产生。首先，几乎没有证据表明沿着DWBC的亚热带到亚热带盆地的“快速轨道”。其次，大量的Rafos和E-Floats追踪了LSW从纽芬兰盆地向南到东部亚热带Gyre的内部途径，这是通过分析浮子完全没有观察到的途径。 These results raise critical questions about the importance of the DWBC as an export pathway for newly-ventilated waters, and hence its role in the Atlantic Meridional Overturning Circulation (AMOC) which is a near-term priority of the Ocean Research Priorities Plan (ORPP).With the conclusion of the RAFOS field work in sight, and the capabilities to generate e-float trajectories in hand, the investigators are now poisoned to make significant了解LSW的出口途径及其对AMOC的影响方面的进步。该分析的具体目标是：1。完成对完整RAFOS浮点数据集的统计分析，并使用来自海洋一般循环模型产生的E-Floats进行比较。2。调和纽芬兰盆地DWBC迅速丧失的浮子与DWBC的概念是从子极到亚热带区域的直接LSW出口途径之间的明显矛盾。3。阐明了中尺度，年际和际变异性对LSW途径的影响4。评估LSW相对于DWBC的内部途径对AMOC的数量和财产运输的重要性。BOADER的影响：通过对亚波面到掩盖的海洋途径的了解，这项拟议的研究将有助于对海洋在全球气候中的作用的揭示。拉格朗日的观点将提供有关AMOC下肢连续性的有价值信息，因此将有助于设计监视程序。项目还将产生更广泛的影响，因为它将有助于杜克大学的研究生培训和教育，以及伍兹霍尔海洋学机构的博士后研究员。