Collaborative Research: Overturning in the Subpolar North Atlantic - Labrador Basin and Floats

北大西洋热量、淡水和物质输送的变化与一些社会相关因素有关，包括海平面变化、海冰和冰川融化以及深海中人为碳储存。然而，目前对这种变化的驱动因素的理解是有限的，使得对副极地地区倾覆的调查成为关键的海洋研究优先事项。该实地方案明确解决了这一差距。此外，通过让更大的国际社会参与研究北大西洋，亚极地北大西洋计划（OSNAP）在促进国际合作，综合和资源共享以及培训后代方面发挥着催化科学进步的关键作用。后者的关键是一个早期职业科学家网络，他们的专业成长将继续通过在OSNAP初始阶段经过测试和改进的有针对性的活动得到促进。将对研究生和博士后进行海上作业以及处理和分析观测数据方面的培训，这一实地项目的总体目标，连同北大西洋的其他测量，是确定中层和深层水的形成与翻转环流之间的联系-这种联系存在于气候模型中，但尚未观察到。该项目还将首次全面了解次极地盆地深水沃茨的扩展路径。从2014年开始，美国主导的国际项目，在次极地北大西洋计划（OSNAP）的颠覆，提供了一个完整的水柱，跨流域的热量，质量和淡水通量的连续记录在次极地北大西洋，与英国，荷兰，加拿大，德国和中国合作。从第一个21个月的完整的OSNAP观测系统的数据已被用来产生一个初始的时间序列的纬向翻转，热量和淡水通量的次极地盆地。这些初步结果揭示了一个高度可变的翻转在盆地，内部通道的溢出沃茨，令人惊讶的精力充沛的边界电流系统的时间尺度从几天到几个月，和强大的溢出羽在冰岛盆地。另外两年的OSNAP观测将涵盖足够的时间框架，以便与其他翻转时间序列进行比较，并优化OSNAP测量系统-在请求进行长期测量之前的所有必要任务。OSNAP（OSNAP West）的这一组成部分是与德国和加拿大协调，用于格陵兰岛和加拿大之间拉布拉多海的西部阵列。OSNAP的次级目标是量化西格陵兰边界流系统的结构和迁移，并确定其可变性和陆架-陆坡交换的性质。此外，通过分析2014年以来收集的地下浮标数据和高分辨率海洋环流模型的输出，将研究整个副极地地区的溢流水路径及其变化机制。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Variability in the transport of heat, freshwater and mass in the North Atlantic has been linked to a number of societally relevant factors including sea level change, the melting of sea and glacial ice, and anthropogenic carbon storage in the deep ocean. However, the current understanding of the drivers of such changes is limited, making an investigation of overturning in the Sub-polar region a key ocean research priority. This field program explicitly addresses this gap. Furthermore, by engaging the larger international community studying the North Atlantic, Overturning in the Sub-polar North Atlantic Program (OSNAP) is playing a key role in catalyzing scientific progress by promoting international collaborations, synthesis, and the sharing of resources and by training future generations. Key to the latter is a network of early career scientists whose professional growth will continue to be facilitated through targeted activities that have been tested and improved during OSNAP's initial phase. Graduate students and post-docs will be trained in seagoing operations and in the processing and analysis of observational data.The overall goal of this field project, in conjunction with other measurements in the North Atlantic, is to establish determination of the linkage between intermediate and deep water formation and the overturning circulation--a connection that is present in climate models, but has yet to be observed. This project will also provide the first comprehensive view of spreading pathways for the deep waters in the Sub-polar basin. Starting in 2014, the US-led international project, Overturning in the Sub-polar North Atlantic Program (OSNAP), provides a continuous record of the full-water column, trans-basin fluxes of heat, mass and freshwater in the Sub-polar North Atlantic, in partnership with the UK, Netherlands, Canada, Germany and China. Data from the first 21 months of the full OSNAP observing system has been used to produce an initial time series of the meridional overturning, heat and freshwater fluxes for the Sub-polar basin. These preliminary results reveal a highly variable overturning in the basin, interior pathways for overflow waters, surprisingly energetic boundary current systems on timescales from days to months, and a strong overflow plume in the Iceland Basin. The additional two years of OSNAP observations will cover a time frame sufficient to make comparisons with other overturning time series and optimize the OSNAP measurement system--all necessary tasks prior to a request for longer term measurements. This component of OSNAP (OSNAP West) is for the western array across the Labrador Sea between Greenland and Canada in coordination with Germany and Canada. The sub-goal for OSNAP is to quantify the structure and transport of the West Greenland boundary current system and determine the nature of its variability and shelf-slope exchange. In addition, the overflow water pathways throughout the subpolar region and the mechanisms responsible for their variability will be studied by analyzing the subsurface float data collected since 2014 and the output of high-resolution ocean circulation models.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.