Collaborative Research: Overturning in the Subpolar North Atlantic-the Irminger and Iceland Basins

北大西洋热量、淡水和物质输送的变率与若干社会相关因素有关，包括海平面变化、海洋和冰川融化以及深海人为碳储存。然而，目前对这种变化的驱动因素的了解是有限的，这使得对亚极地地区倾覆的调查成为海洋研究的关键优先事项。这个实地项目明确地解决了这一差距。此外，通过吸引更大的国际社会研究北大西洋，“北大西洋次极翻转计划”（OSNAP）通过促进国际合作、综合和资源共享以及培训后代，在促进科学进步方面发挥了关键作用。后者的关键是一个由早期职业科学家组成的网络，他们的专业成长将继续通过有针对性的活动得到促进，这些活动在OSNAP的初始阶段已经经过了测试和改进。研究生和博士后将接受航海操作和观测数据处理和分析方面的培训。该野外项目的总体目标是，结合北大西洋的其他测量，确定中深水形成与翻转环流之间的联系——这种联系存在于气候模型中，但尚未被观察到。该项目还将首次全面了解亚极地盆地深水的扩散途径。从2014年开始，由美国主导的国际项目“北大西洋亚极区翻转计划”（Overturning in the亚极区北大西洋项目）与英国、荷兰、加拿大、德国和中国合作，提供了北大西洋亚极区全水柱、跨盆地热通量、质量通量和淡水通量的连续记录。利用整个OSNAP观测系统头21个月的数据编制了次极盆地经向翻转、热量和淡水通量的初始时间序列。这些初步结果揭示了盆地中高度可变的倾覆，溢出水的内部路径，从几天到几个月的时间尺度上令人惊讶的高能边界流系统，以及冰岛盆地中强烈的溢出羽流。额外的两年OSNAP观测将覆盖足够的时间框架，与其他倾覆时间序列进行比较，并优化OSNAP测量系统——所有这些都是在要求进行长期测量之前的必要任务。OSNAP （OSNAP East）的这个组成部分是针对格陵兰和苏格兰之间的东部阵列，与英国和荷兰协调。美国的贡献包括东格陵兰岛近海和海上阵列，冰岛盆地阵列，以及所有OSNAP测量的整合。OSNAP东部项目的次级目标是量化格陵兰东海岸和冰岛盆地内边界流的结构和输送，并确定其变率和强迫机制。该奖项反映了美国国家科学基金会的法定使命，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 East) is for the eastern array between Greenland and Scotland in coordination with the UK and the Netherlands. The US contribution includes the East Greenland inshore and offshore arrays, the Iceland Basin array, and the integration of all OSNAP measurements. The sub-goal for OSNAP East is to quantify the structure and transport of the boundary currents off the east coast of Greenland and within the Iceland Basin, as well as determine their variability and forcing mechanisms.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.