NSFGEO-NERC: Collaborative Research: Subpolar North Atlantic Processes - Dynamics and pRedictability of vAriability in Gyre and OverturNing (SNAP-DRAGON)

NSFGEO-NERC：合作研究：北大西洋次极过程 - 环流和翻转变化的动力学和可预测性 (SNAP-DRAGON)

• 批准号: 2038495
• 负责人: Stephen Yeager
• 金额: $ 1.43万
• 依托单位: University Corporation For Atmospheric Res
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2038495&HistoricalAwards=false
• 关键词: NSFGEO; NERC; Collaborative; Research; Subpolar

This is a project that is jointly funded by the National Science Foundation's Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with their own country. The subpolar North Atlantic Ocean, stretching between the UK, Greenland, and Canada, plays a crucial role in local and global climate. This is the critical region where much of the warm water flowing northward in the upper North Atlantic releases its heat to the atmosphere and is converted to cold, dense water, before flowing southward again at depth in what is known as the Atlantic overturning circulation. The large amount of heat this circulation carries northward and releases to the atmosphere impacts the track of storms and determines the weather over western Europe. The overturning circulation also has profound implications for African rainfall and hurricane development via its effect on sea surface temperature at lower latitudes. In addition, the sinking of water in the subpolar region ventilates the deep ocean, transferring heat and carbon away from the surface and moderating the impact of anthropogenic greenhouse gases on surface temperature. Any warm water which does not sink in the subpolar region recirculates or carries its heat further north towards the Arctic, influencing sea-ice conditions and polar marine ecosystems before it too sinks and flows south. This study aims to produce a step change in our understanding of the processes that link atmospheric changes to subpolar ocean variability, their implications for ocean and climate predictability in this region, and the degree to which we can trust their representation in climate models. Recently, the first ever observations of the overturning circulation in the subpolar North Atlantic have been made by the Overturning in the Subpolar North Atlantic Program (OSNAP, www.o-snap.org). These have revealed large amplitude variations in the overturning and raised questions about the locations and processes that give rise to this variability and its likely impact on surface ocean conditions and climate. Representing this region properly in climate models is essential for making useful climate predictions on seasonal, interannual, decadal and longer timescales. However, the current generation of models struggle to represent the processes known to be important here and disagree with the observations on the locations in which warm water is transformed into dense water. The disagreements limit our confidence in model predictions. The scientific community cannot assess model performance properly because there is limited understanding of all the links between atmospheric conditions and ocean circulation variability. This project will combine OSNAP and other observations with numerical models that can represent small-scale processes to reveal the cause of the variations in subpolar ocean circulation. Once it is clear which processes are most important and how they work, the team will be able to establish what climate models are getting wrong and suggest improvements. This will improve predictions of ocean and climate variability in the subpolar North Atlantic and beyond. The team will investigate how cold, dense waters find their way into the boundary currents that export them to the south. It will establish the role that winds play, which is likely more complicated than we have assumed in the past and it will determine the impact on overturning variability of changes in freshwater export from the Arctic and Greenland. To characterize and quantify these key processes, in addition to using ocean observations, the investigators will perform "What if?" experiments in ocean models, asking questions such as: what happens to the subpolar ocean circulation if the atmospheric jet stream over the Atlantic shifts or strengthens? They will use statistical methods more common in weather forecasting to figure out how subpolar ocean properties and overturning connect to potentially predictable larger-scale atmospheric circulation patterns. Innovative ways of combining models with observations will be used to determine a best estimate of the evolution of the subpolar North Atlantic over the OSNAP observation period.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.

这是一个由国家科学基金会地球科学理事会（NSF/GEO）和联合王国国家环境研究理事会（NERC）通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了一项奖励，每个机构将为与本国有关的预算和调查员提供资金。亚极地北大西洋，延伸在英国，格陵兰岛和加拿大之间，在当地和全球气候中起着至关重要的作用。这是一个关键的区域，在北大西洋上部向北流动的大部分温暖的水将其热量释放到大气中，并转化为寒冷，密集的水，然后在被称为大西洋翻转环流的深处再次向南流动。该环流向北携带大量热量并释放到大气中，影响风暴的轨迹并决定西欧的天气。翻转环流还通过其对低纬度海面温度的影响，对非洲降雨和飓风的发展产生深远影响。此外，副极地区域的水下沉使深海通风，将热量和碳从地表转移出去，减缓了人为温室气体对地表温度的影响。任何没有在亚极地地区下沉的温水都会再循环或将其热量带到更北的北极地区，影响海冰状况和极地海洋生态系统，然后再下沉并流向南方。这项研究旨在使我们对大气变化与副极地海洋变化之间的联系过程、它们对该地区海洋和气候可预测性的影响以及我们可以在多大程度上信任它们在气候模型中的代表性的理解发生一步变化。最近，北大西洋副极地翻转计划（OSNAP，www.o-snap.org）首次对北大西洋副极地翻转环流进行了观测。这些发现揭示了翻转的大幅度变化，并提出了关于引起这种变化的位置和过程及其对表面海洋条件和气候的可能影响的问题。在气候模式中正确地代表这一区域对于在季节、年际、十年和更长时间尺度上进行有用的气候预测至关重要。然而，目前这一代的模型很难代表这里已知的重要过程，并且不同意对温水转化为稠密水的位置的观察。这些分歧限制了我们对模型预测的信心。科学界无法正确评估模型性能，因为对大气条件与海洋环流变异性之间的所有联系的了解有限。该项目将把联合收割机OSNAP和其他观测与能够代表小尺度过程的数值模型结合起来，以揭示副极地海洋环流变化的原因。一旦明确了哪些过程最重要以及它们是如何工作的，该团队将能够确定哪些气候模型出错并提出改进建议。这将改善对北大西洋亚极地及更远地区海洋和气候变化的预测。该小组将调查寒冷，密集的沃茨如何进入边界流，将它们出口到南方。它将确定风所起的作用，这可能比我们过去假设的更复杂，它将确定对北极和格陵兰淡水出口变化的影响。为了描述和量化这些关键过程，除了使用海洋观测外，调查人员还将进行“如果？“海洋模型的实验，提出的问题，如：如果大西洋上空的大气急流转移或加强，副极地海洋环流会发生什么？他们将使用天气预报中更常见的统计方法来弄清楚副极地海洋特性和翻转如何与潜在的可预测的大规模大气环流模式联系起来。将模型与观测相结合的创新方法将用于确定OSNAP观测期间北大西洋副极地演变的最佳估计。该奖项反映了NSF的法定使命，并被认为值得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来支持。