Collaborative Research: Mechanisms of Freshwater Exchange Across the East Greenland Shelf

合作研究：东格陵兰陆架淡水交换机制

• 批准号: 1433448
• 负责人: Thomas Haine
• 金额: $ 37.22万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1433448&HistoricalAwards=false
• 关键词: Collaborative; Research; Mechanisms; Freshwater; Exchange

Freshwater flowing out of the Arctic and from Greenland ice melt has the potential to modulate or even shut down deep convection in the sub-polar North Atlantic. The processes that control this exchange, and how they depend on external factors such as wind and outflow from the Arctic, are not well known and are not well resolved in basin-scale and climate models. Better understanding of the freshwater budget on the shelf, and how these waters get into the deep ocean interior, is essential to improve climate models and understand how the ocean will respond to a changing climate. The dynamically-based diagnostics planned in this project using a hierarchy of numerical ocean circulation models will also inform on mechanisms, locations, and times of exchange in other sensitive areas, such as the east coast of Labrador. Findings from the project will be used in undergraduate and graduate classes. Undergraduate students supported by the Woods Hole Oceanographic Institution Summer Student Fellowship program and assisted by graduate students will gain research experience. Material from the project will also be used in a textbook on ocean circulation. A graduate student will be trained in physical oceanography, geophysical fluid dynamics, and ocean modeling at Johns Hopkins University. The exchange of freshwater between the east Greenland shelf and the interior of the sub-polar North Atlantic and Nordic Seas is a key element in the maintenance and variability of the Atlantic Meridional Overturning Circulation (AMOC) and its sensitivity to changes in atmospheric forcing and freshwater outflow from the Arctic Ocean. A realistic, very high resolution, regional model of the east Greenland shelf and adjacent deep ocean will be combined with idealized, process oriented models and in-situ observations to identify the strength, mechanisms, and sensitivity of this exchange. Processes likely important for this cross-shelf exchange include: surface and bottom Ekman layers; nonlinear eddy fluxes; local and remote wind-forcing; and wind-driven sea ice. The exchange will be diagnosed in a series of realistic model runs. Experiments will be designed with the idealized model to isolate the relevant processes for further study and understanding, and comparisons will be made with in-situ mooring and hydrographic observations and remotely sensed sea ice data. The main goal of the project is to reach a basic understanding of what controls the flux of freshwater from the shelf to the basin interior and how it depends on external forcing (wind, outflow from the Arctic, Greenland runoff) and environmental conditions such as bottom bathymetry and the ambient stratification.

从北极和格陵兰冰融化流出的淡水有可能调节甚至关闭北大西洋副极地的深层对流。控制这种交换的过程，以及它们如何依赖风和北极流出等外部因素，尚不清楚，也没有在盆地规模和气候模型中得到很好的解决。更好地了解大陆架上的淡水预算以及这些水域如何进入深海内部，对于改进气候模型和了解海洋如何应对气候变化至关重要。该项目计划使用数字海洋环流模型层次结构进行基于动态的诊断，还将了解其他敏感区域（例如拉布拉多东海岸）的交换机制、位置和时间。该项目的研究结果将用于本科生和研究生课程。由伍兹霍尔海洋研究所暑期学生奖学金计划支持并由研究生协助的本科生将获得研究经验。该项目的材料还将用于海洋环流教科书。一名研究生将在约翰·霍普金斯大学接受物理海洋学、地球物理流体动力学和海洋建模方面的培训。东格陵兰陆架与副极地北大西洋和北欧海内部之间的淡水交换是大西洋经向翻转环流（AMOC）维持和变化及其对大气强迫和淡水变化的敏感性的关键因素从北冰洋流出。东格陵兰陆架和邻近深海的现实的、非常高分辨率的区域模型将与理想化的、面向过程的模型和现场观测相结合，以确定这种交换的强度、机制和敏感性。对于这种跨货架交换可能重要的过程包括：表面和底部 Ekman 层；非线性涡流；本地和远程风力；和风驱动的海冰。该交易所将通过一系列现实模型运行进行诊断。将利用理想化模型设计实验，分离出相关过程以供进一步研究和理解，并与现场系泊和水文观测以及遥感海冰数据进行比较。该项目的主要目标是基本了解是什么控制着淡水从大陆架到盆地内部的流量，以及它如何依赖于外部强迫（风、北极流出物、格陵兰岛径流）和底部等环境条件。测深和环境分层。