Access of Atlantic Water to East Greenland glaciers

格陵兰冰盖正在加速失去质量，使其成为当今全球海平面上升的最大贡献者之一。来自大西洋的变暖的海底（中）海水与格陵兰周围峡湾内的海洋终止冰川相互作用被认为是冰盖退缩的重要驱动因素。在我们OGreen79项目的SPP“区域海平面机会与社会”的第一阶段，我们能够基于对格陵兰东北部大陆架的成功现场观测表明，79-North冰川（79NG）的浮冰舌全年都暴露在温暖的大西洋中间水（AIW）的快速流入中。令人惊讶的是，流入冰架空腔的水是由冰川崩解前沿的地形梯控制的，这是我们在一次探险中发现的。我们还证明，在年代际尺度上，79NG冰舌急剧变薄90米是由AIW变暖驱动的。在A2Green这一后续提案中，我们将对第一阶段的重要发现采取后续行动。我们现在扩大了视野，在区域而不是局部范围内研究海洋与冰川的相互作用。我们建议将我们的研究扩展到丹麦海峡以北的整个东格陵兰大陆架，在那里，地下AIW的存在-与许多海洋终止冰川相互作用-代表了一个无处不在的特征。该地区的独特之处在于，在大陆架上发现的AIW主要由单一来源提供，即大西洋水在弗拉姆海峡的再循环。总的来说，将追求与了解海洋-冰盖相互作用有关的三个目标。我们将研究1 .东格陵兰大陆架上存在的AIW的多年大尺度海洋联系；大陆架和大陆架边缘过程对大陆架AIW变率的作用；近岸地形对两个不同海洋-冰川系统的时变AIW流入的控制。79NG位于相对靠近海峡再环流的位置，将继续是一个重要的焦点。此外，Scoresby Sound（远离Fram海峡，靠近我们工作区域的南部边界）将成为一个新的重点。东格陵兰最大的冰川之一，多加德·詹森冰川，终止于斯考斯比峡湾系统。调查将通过分析Fram海峡和东格陵兰大陆架的历史和活动系泊时间序列以及水文数据集来实现。将采用基于海洋-海冰环流模式的高分辨率模拟，将结果置于更大的时空背景下。

The Greenland Ice Sheet is losing mass at an accelerating rate, making it today one of the largest contributors to global sea level rise. Warming subsurface (intermediate) ocean waters of Atlantic origin interacting with marine terminating glaciers within fjords around Greenland are regarded an import driver of the retreating ice sheet. During the first phase of SPP ”Regional Sea Level Chance and Society” within our project OGreen79 we able to show based on successful in situ observations on the shelf of Northeast Greenland, that the floating ice tongue of the 79-North Glacier (79NG) is exposed all-year-round to a swift inflow of warm Atlantic Intermediate Water (AIW). Surprisingly, the inflow into the ice shelf cavity is hydraulically controlled by a topographic sill right at the glacier calving front, which was discovered during one of our expeditions. We also demonstrated that the dramatic, ongoing thinning of the ice tongue of the 79NG by 90 m on decadal time scales has been driven by AIW warming. In this follow-up proposal, A2Green, we follow up on the important findings made during the first phase. We now widen the view to investigate ocean-glacier interaction on a regional rather than a local scale. We propose to extend our investigations to the entire East Greenland shelf north of Denmark Strait where the presence of subsurface AIW - interacting with numerous marine terminating glaciers - represents a ubiquitous feature. What makes the area unique, is that the AIW found on the shelf is mainly supplied be a single source, namely the recirculation of Atlantic Water in Fram Strait. Overall, three objectives will be pursued, relevant for the understanding of ocean-ice sheet interaction. We will investigate i. the multiannual large-scale ocean connections of the AIW present on the East Greenland continental shelf, ii. the role of shelf and shelf edge processes for AIW variability on the continental shelf, and iii. near-coastal, topographic control on time variable AIW inflows toward two different ocean-glacier systems. The 79NG - being located relatively close to the recirculation in Fram Strait - will remain an important focus. In addition, Scoresby Sound -located away from Fram Strait near the southern boundary of our work domain - will represent a new focus. One of the largest East Greenland glaciers, the Daugaard Jensen Glacier, terminates into the Scoresby Sound fjord system. The investigations will be achieved by analyzing both historical and active mooring time series in Fram Strait and on the shelf of East Greenland together with hydrographic data sets. High resolution simulation relying on an ocean-sea ice general circulation model will be applied to put the results into a larger spatial and temporal context.