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

北冰洋水的盐度在很大程度上决定了它的浮力，从而决定了各水层的稳定程度。这是很重要的，因为海洋分层的稳定性决定了它的环流、热输送和深水的形成，这反过来又影响了局部和区域气候系统，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，对于了解北冰洋未来的状态至关重要。这个项目将研究格陵兰岛以北海洋区域淡水组成部分的动态和可变性以及总的淡水库存，那里的水和海冰最终会从两条途径中的一条向南移动。这项研究的主要目标是了解浮力是如何在北冰洋内重新分配的，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式模拟进行比较，反之亦然，以检验关于北冰洋淡水及其成分的环流、积累和释放的假设，并检验北冰洋模式的性能。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。个别淡水组成部分和其他综合产出的流通模式以及协助教育工作者所需的资料和文件将通过一个联机网站公开提供，该网站预计将有来自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。了解淡水的环流、积累和释放的基本过程对于研究覆盖北冰洋的淡水透镜体的可能未来情景、淡水在北极内部环流中的作用以及淡水在北欧海和北大西洋对流区深水形成中的作用具有根本的重要性。该项目将在整个北冰洋范围内对淡水成分来源和途径进行分析的背景下，研究开关站（SY）地区淡水成分的动态和可变性以及总体淡水库存。这项研究的主要目标是了解浮力是如何在北冰洋内重新分配的，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过程中所起的作用。作为北极观测网（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淡水总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）。沿阿勒特和北极之间一段的SY观测显示，单个淡水成分对总储量的贡献迅速变化，淡水总量逐渐变化。根据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的变化以及在短至一年的时间尺度上的路径，即他们观测的频率。该项目将把SY淡水成分数据与以前（破冰船）考察的数据结合起来，以确定其分布的主要特征。第二步，该团队将扩展Maslanik和Fowler开发的海冰跟踪方法，将表层海洋中的Ekman运输包括在内，并下载模拟FW各个组件的GCM运行。他们将跟踪观测到的淡水成分回到它们的来源地区，并转发到它们从北极的出口点，并将确定影响淡水成分环流的机制，特别是在SY地区，他们有8年的时间序列。主要的智力贡献将来自将观测到的淡水成分清单和路径与模式模拟所得的清单和路径结合起来，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整。

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.