Ocean Dynamics Impacting Shelf Sea Level in Eastern Atlantic (ODISSEA)

由于陆冰融化和海洋热膨胀的综合影响，全球平均海平面正以每年约3.5毫米的速度上升。然而，就区域而言，海平面也受到大尺度洋流强度和路径变化的强烈影响，而长期趋势往往被几年来的大幅度变化所掩盖。对沿海社区来说，量化和预测区域模式至关重要，因为极端海平面事件的规模和频率与社会直接相关。在美国东海岸，海平面上升和变化模式与大西洋经向翻转环流(AMOC)密切相关。然而，在西北部的欧洲大陆架上，人们对AMOC对海平面变化、变化和极端情况的影响知之甚少。实现这一点的一个关键障碍是了解大陆坡上的海洋动力学--深海和浅层大陆架之间的界面。从深海流向大陆架的洋流可能不会持续到大陆架上，而是可能进入环绕欧洲西北部大陆架的沿斜坡的快速边界流。了解每个过程的相对重要性，以及它们是如何随着时间的推移而变化的，对于了解海平面将如何在海岸发生变化是关键。预计大范围的洋流将随着气候变暖而变化，AMOC预计将在未来30年内急剧减弱。然而，提供这些预测的气候模式缺乏所需的细尺度分辨率来捕捉这些变化对区域尺度陆架海平面的影响，特别是窄边界流在调制沿海深海环流影响方面的作用。因此，如果要有效地预测洋流变化对沿海海平面的影响，充分了解边界流动力学是至关重要的。在这个项目中，我们将直接测量从开阔海洋流向欧洲西北部大陆架的流量，以及测量边界流强度和大陆架海平面。这将使我们能够确定边界动力学在调节陆架海平面海洋环流影响方面所发挥的作用。我们还将使用该地区的实验模拟来量化正在发挥作用的物理过程，并了解这些过程如何在更长的时间尺度上发生变化。最后，我们将进行未来高分辨率的大西洋模拟，以研究这些过程将如何在未来30年内随着AMOC的减弱而演变，并评估其对沿海海平面变化、可变性和极端事件的影响。

Global mean sea level is rising at around 3.5 mm per year due to the combined effects of melting land ice and ocean thermal expansion. Regionally however, sea level is also strongly influenced by changes in the strength and the pathways of large-scale ocean currents, and the long-term trend is often masked by large-amplitude changes over several years. Quantifying and predicting regional patterns is crucial for coastal communities where the magnitude and frequency of extreme sea level events are of immediate societal relevance. At the U.S. East Coast, sea level rise and variability patterns have been strongly linked to the Atlantic meridional overturning circulation (AMOC). However, on the NW European shelf, comparatively little is known about the impact of AMOC on sea level change, variability, and extremes.A key barrier to achieving this is understanding the ocean dynamics over the continental slope - the interface between the deep ocean and the shallow continental shelf. Currents directed from the deep ocean towards the slope might not continue onto the shelf and might instead feed into the rapid along-slope boundary current which encircles the NW European shelf. Understanding the relative importance of each of these processes, and how they change over time, is key to understanding how sea level will change at the coast.Large scale ocean currents are predicted to change with the warming climate, with the AMOC projected to weaken dramatically in the next 30 years. However, the climate models which yield these predictions lack the fine-scale resolution required to capture the effect of these changes on shelf sea level at a regional scale, in particular the role of narrow boundary currents in modulating the influence of the deep ocean circulation at the coast.It is therefore critical that boundary current dynamics are fully understood if the effect of changing ocean currents on coastal sea level is to be effectively predicted. In this project, we will directly measure the flow directed from the open ocean towards the NW European shelf, as well as measuring the boundary current strength and shelf sea level. This will allow us to establish the role that boundary dynamics play in modulating the effect of ocean circulation of shelf sea level. We will also use experimental simulations of the region to quantify the physical processes at play and understand how these change over longer time scales. Finally, we will run a high-resolution future Atlantic Ocean simulation to study how these processes will evolve as the AMOC weakens during the next three decades, and evaluate the impacts on coastal sea level change, variability, and extremes.