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: 1503298
• 负责人: Michael Steele
• 金额: $ 16.26万
• 依托单位: University of Washington
• 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 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1503298&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.

非技术层面北冰洋海水的盐度决定了其浮力的很大程度，从而决定了不同水层的稳定性。这一点很重要，因为海洋层结的稳定性决定了其环流、热量传输和深水的形成，进而影响当地和区域气候系统，以及较低纬度的海洋/大气/气候相互作用。因此，了解低盐度水(称为淡水)的循环、积聚和释放的基本过程，对于了解北冰洋的未来状况至关重要。该项目将研究格陵兰岛以北海洋区域淡水成分和总淡水库存的动态和变异性，那里的水和海冰最终走两条路径中的一条向南。这项研究的主要目标是了解浮力在北冰洋内是如何重新分配的，以及淡水是如何积累和释放的。该项目特别感兴趣的是不同的淡水成分在这一过程中所起的作用。为此目的，将把作为北极观测网一部分收集的数据与模型模拟进行比较，反之亦然，以检验关于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。各个淡水组成部分和其他综合产出的循环模式，以及协助教育工作者所需的信息和文件，将通过一个网站向公众公布，预计该网站将吸引学术界和中学教育工作者的大量流量。这个项目将为研究生提供博士论文的核心。技术了解淡水的循环、积聚和释放的基本过程对于研究未来淡水透镜覆盖北冰洋的可能情景、淡水在北冰洋内部环流中的作用以及淡水在北欧海和北大西洋对流区域深水形成中的作用至关重要。该项目将在整个北冰洋淡水组成来源和途径分析的背景下，研究开关站(SY)地区淡水组成和总淡水库存的动态和可变性。这项研究的主要目标是了解浮力在北冰洋内是如何重新分配的，以及淡水是如何积累和释放的。将特别强调不同的淡水成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)。在Alert和北极之间的SY观测表明，随着总淡水含量的逐渐变化，个别淡水成分在总库存中所占比例迅速变化。通过根据海冰漂移模式在时间上追溯地表环流，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地区域和路径的变化，时间尺度上的变化最短为一年，也就是观测频率。该项目将把SY淡水成分数据与以前(破冰船)探险的数据结合起来，以确定其分布的主要特征。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。他们将追踪观测到的淡水成分回到它们的源头地区，并向前推进到它们从北极的出口点，并将确定影响淡水成分循环的机制，特别是在SY地区，因为那里有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模式模拟获得的淡水成分清单和路径相结合，推断控制淡水成分分布的动力学及其作为源项和大气强迫的函数的调节。