Collaborative Research: Dynamics and Variability of Freshwater Components in the Arctic Ocean

合作研究：北冰洋淡水成分的动态和变化

• 批准号: 1504404
• 负责人: Robert Newton
• 金额: $ 43.75万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1504404&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamics; Variability; Freshwater

Non-technicalThe salinity of water in the Arctic Ocean determines much of its buoyancy and thus how stable the various layers of water are. This is important because stability of the stratification of the ocean determines its circulation, heat transport and formation of deep water, which in turn affect the local and regional climate system, as well as ocean/atmosphere/climate interaction in lower latitudes. Thus understanding the basic processes of the circulation, buildup, and release of lower salinity water (called 'freshwater') is of fundamental importance for understanding future states of the Arctic Ocean. This project will study the dynamics and variability of the freshwater components and the overall freshwater inventories, in the region of the ocean north of Greenland, where water and sea ice ultimately take one of two pathways south. The main goal of the study is to understand how buoyancy is redistributed within the Arctic Ocean and how freshwater accumulates and is released. The project is especially interested in the role distinct freshwater components play in this process. For this purpose data collected as part of the Arctic Observing Network will be compared to model simulations and vice versa to test hypotheses concerning the circulation, accumulation and release of freshwater and its components in the Arctic Ocean and to test the performance of an Arctic Ocean model. This project will create data products for researchers and educators interested in the Arctic and its response to climate change. Circulation patterns of the individual freshwater components and other synthesized outputs, along with information and documentation needed to assist educators, will be made publicly available through an online site that is expected to have significant traffic from educators in academia and secondary school levels. This project will provide the core of a PhD dissertation for a graduate student. TechnicalUnderstanding the basic processes of the circulation, buildup, and release of freshwater is of fundamental importance for examining possible future scenarios of the freshwater lens covering the Arctic Ocean, the role of freshwater in internal circulation within the Arctic, and the role of freshwater in deep water formation in the convective regions of the Nordic seas and the North Atlantic. This project will study the dynamics and variability of the freshwater components and the overall freshwater inventories, in the Switchyard (SY) region in the context of an Arctic Ocean-wide analysis of freshwater component sources and pathways. The main goal of the study is to understand how buoyancy is redistributed within the Arctic Ocean and how freshwater accumulates and is released. There will be special emphasis on the role distinct freshwater components play in this process. Recent long-term observations conducted in the Switchyard (SY) region as part of the Arctic Observing Network (AON) program, have revealed detailed information on both the total freshwater balance, and the components contributing to it: Pacific Water (PW), Meteoric Water (MW: River Runoff and P-E), and Sea Ice Meltwater (SIMW). The SY observations along a section between Alert and the North Pole show rapid changes in the contributions of individual freshwater components to the total inventory along with gradual changes in the total freshwater content. From backtracking the surface circulation in time based on sea ice drift patterns, the group infers that the rapid changes in the freshwater components are probably due to shifts in the sea ice and surface water source regions and pathways on time scales as short as one year, the frequency of their observations. This project will combine the SY freshwater component data with those from previous (icebreaker) expeditions to characterize the main features of their distributions. In a second step, the team will extend the sea ice tracking method developed by Maslanik and Fowler to include Ekman transport in the surface ocean and will download GCM runs that simulate individual FW components. They will track the observed freshwater components back to their source regions, and forward to their exit points from the Arctic, and will identify mechanisms impacting the freshwater component circulation, especially in the SY region where they have an 8-year time series. The principal intellectual contributions will come from integrating observed freshwater component inventories and pathways with those obtained from model simulations, inferring the dynamics governing the freshwater component distributions and their adjustment as functions of source terms and atmospheric forcing.

北冰洋海水的盐度决定了它的浮力，从而决定了不同水层的稳定性。这一点很重要，因为海洋分层的稳定性决定了海洋的环流、热量输送和深水的形成，而这些又影响到当地和区域气候系统以及低纬度地区海洋/大气/气候的相互作用。因此，了解低盐度水（称为“淡水”）的循环，积累和释放的基本过程对于了解北冰洋的未来状态至关重要。该项目将研究格陵兰北部海洋区域淡水组成部分的动态和可变性以及总体淡水存量，在该区域，水和海冰最终将沿两条路径之一向南流动。该研究的主要目标是了解浮力如何在北冰洋内重新分配，以及淡水如何积聚和释放。该项目特别关注不同的淡水组成部分在这一过程中发挥的作用。为此目的，将把作为北极观测网络一部分收集的数据与模型模拟进行比较，反之亦然，以检验有关北冰洋淡水及其组成部分的循环、积累和释放的假设，并检验北冰洋模型的性能。该项目将为对北极及其对气候变化的反应感兴趣的研究人员和教育工作者创建数据产品。各个淡水组成部分的流通模式和其他综合产出，连同沿着协助教育工作者所需的资料和文件，将通过一个在线网站向公众提供，预计学术界和中学一级的教育工作者将对该网站进行大量访问。这个项目将为一名研究生的博士论文提供核心内容。了解淡水的循环、积累和释放的基本过程，对于研究覆盖北冰洋的淡水透镜的未来可能情景、淡水在北极内部循环中的作用以及淡水在北欧海洋和北大西洋对流区深水形成中的作用具有根本重要性。该项目将在北冰洋范围内分析淡水成分来源和途径的背景下，研究开关站（SY）区域淡水成分的动态和变化以及总体淡水库存。该研究的主要目标是了解浮力如何在北冰洋内重新分配，以及淡水如何积聚和释放。将特别强调不同的淡水组成部分在这一进程中发挥的作用。作为北极观测网络（AON）计划的一部分，最近在开关站（SY）地区进行的长期观测揭示了有关总淡水平衡及其组成部分的详细信息：太平洋水（PW），大气水（MW：河流径流和P-E）和海冰融水（SIMW）。SY观测结果沿着阿勒特和北极之间的一段显示，随着淡水总含量的逐渐变化，各个淡水成分对总库存的贡献沿着迅速变化。通过基于海冰漂移模式回溯地表环流的时间，该小组推断，淡水成分的快速变化可能是由于海冰和地表水源区域以及时间尺度短至一年的路径的变化，这是他们观察的频率。该项目将联合收割机SY淡水成分数据与以前（破冰船）考察的数据相结合，以描述其分布的主要特征。在第二步中，该团队将扩展Maslanik和Fowler开发的海冰跟踪方法，以包括表层海洋中的Ekman传输，并将下载模拟单个FW组件的GCM运行。他们将追踪观察到的淡水成分回到其来源地区，并将其从北极的出口点，并将确定影响淡水成分循环的机制，特别是在SY地区，他们有一个8年的时间序列。主要的智力贡献将来自于将观测到的淡水成分清单和路径与从模型模拟中获得的结果相结合，推断出淡水成分分布的动态及其作为源项和大气强迫函数的调整。