Variation of the fresh water in the western Nordic Seas

该项目的目标是捕捉和分析北欧西部海域的淡水波动，确定其来源并了解其基本机制。北欧海的形状是由强烈的盐度对比所产生的盐水大西洋水沿着其东部边缘向北流动和非常新鲜的极地水沿着其西部边缘在东格陵兰海流（EGC）中向南流动。从大陆径流和太平洋向北冰洋输入的大量淡水，以及通过海冰形成而积累在地表的淡水被排到北大西洋。其中一部分以海冰和液体形式携带在EGC中。在北欧海，来自格陵兰的径流量增加，使EGC增加淡水。一小部分淡水从EGC通过分支和中尺度特征流入北欧海中部。这种淡水的数量和垂直分布影响北欧海的密度分层，从而影响对流深度和深层沃茨的形成。在过去的几十年里，北欧海的淡水产量和分布以及对流活动发生了重大变化。最近的研究，也是FOR1740第一阶段的研究，表明大部分海冰是北欧内海的淡水来源。在这个项目中，我们将调查从EGC的淡水泄漏到北欧西部内海的长期（几个月到几个季节）的滑翔机任务的结构，并分析基本的过程及其变化。我们将在Argo浮标产生的内流域淡水变化的背景下分析这种渗漏，并使用TP 2.1的输入来评估净降水与EGC渗漏相比的贡献。

The goal of this project is to capture and analyse the freshwater fluctuations in the western Nordic Seas, to identify their sources and to understand the underlying mechanisms. The Nordic Seas are shaped by the strong salinity contrast arising from the northward flow of saline Atlantic Water along their eastern rim and the southward flow of very fresh Polar Water along their western rim in the East Greenland Current (EGC). The huge import of freshwater to the Arctic Ocean from continental runoff and from the Pacific Ocean, and the freshwater accumulated at the surface through sea ice formation is drained to the North Atlantic. Part of it is carried in the EGC as sea ice and in liquid form. In the Nordic Seas freshwater is added to the EGC by an increasing rate of runoff from Greenland. A fraction of this freshwater drains from the EGC via branching and through mesoscale features into the central Nordic Seas. The amount and the vertical distribution of this freshwater influence the density stratification in the Nordic Seas and thus the convection depth and the formation of deep waters. The last decades showed significant changes of the freshwater yield and distribution in the Nordic Seas and of the convective activity. Recent studies, also those of the first phase of FOR1740, indicate that mostly sea ice is the source of freshwater for the inner Nordic Seas. In this project we will investigate the structure of the freshwater leakage from the EGC to the inner western Nordic Seas by long-term (months to seasons) glider missions, and analyse the underlying processes and their variability. We will analyse this leakage in the context of freshwater changes in the inner basins derived from Argo floats and use input from TP2.1 for assessing the contribution of net precipitation as compared to the leakage from the EGC.