Causes and impacts of Greenland atmospheric Blocking changes

这个项目旨在提供一个重大的进步，在理解大气环流变化的原因（特别是阻塞或持续高气压的变化），它们与北大西洋大气和海洋环流系统变化的关系，它们对格陵兰和更广泛的北大西洋/西北欧/联合王国地区气候变化和极端天气状况的后果，北方中高纬度地区的高压阻塞是大气环流的一个重要特征，与中纬度人口稠密地区的急流和极端天气事件密切相关。人们对阻塞的物理原因以及它如何响应和影响更大规模的气候变化知之甚少，特别是在连接天气（每日）和气候（逐年或更长时间）的时间尺度方面。最近的研究表明，自1990年左右以来，格陵兰地区的阻塞显著增加，主要是在夏季。目前可用的全球气候模型无法很好地模拟这一情况。这一不足可能与最近北极海冰的迅速丧失有关，气候模型也没有很好地捕捉到这一点。然而，最新一代的气候模式显示出一些改进，与早期版本相比，虽然仍然有一些差异模拟和观测的格陵兰Blocking.Our建议解决这种模式观测不匹配的综合比较，使用新的方法，更新的观测和最新的国家的最先进的气候模式模拟。我们试图通过从每日到十年的广泛时间尺度上的基于观测的数据来了解格陵兰岛阻塞变化的原因，分析极端格陵兰岛阻塞事件的变化如何与气候变化和趋势相关联，并考虑极端格陵兰岛阻塞事件的基本物理原因（加热和/或大气环流变化）。自然变率是阻塞的一个重要方面，最近格陵兰岛夏季阻塞的显著趋势是一年中南极洲范围内海面温度变化（称为大西洋年代际变率）与格陵兰冰盖融化和径流变化最密切相关的时间。因此，我们将比较气候模式输出的模式与不同的海洋和海冰的代表性，以确定可能的海洋和/或北极海冰损失对格陵兰阻塞的影响changes.There将在未来几十年的夏季格陵兰阻塞的持续增加的深远影响：例如，加强格陵兰冰盖的融化和质量损失。最近的结果表明，冰盖的表面融化和径流的非线性，加速响应温度上升，后者部分与最近的阻塞增加在夏季。至关重要的是，了解格陵兰冰盖如何应对未来气候变化，以及对全球海平面上升的影响，取决于能否更好地模拟格陵兰地区的大气环流变化。因此，我们将利用我们从项目早期工作中获得的见解和新的气候模型实验来评估未来格陵兰岛阻塞变化对北大西洋和欧洲天气和气候的可能影响，以及对格陵兰冰盖质量平衡和全球海平面上升的影响。我们希望我们在北大西洋气候关键部分的研究结果将为理解格陵兰岛阻塞的原因和影响迈出重要一步，并有助于指导下一代全球气候模型的开发。

This project aims to provide a major advance in the understanding of the causes of atmospheric circulation changes (specifically changes in blocking or persistent high air pressure) over Greenland, their relation to variations in the North Atlantic atmospheric and oceanic circulation systems, their consequences for climate change and extreme weather conditions over Greenland and the wider North Atlantic/Northwest Europe/UK region, and their impacts on Greenland Ice Sheet mass loss and global sea-level rise.High-pressure blocking in Northern Hemisphere mid-high latitudes is an important feature of the general circulation of the atmosphere that is closely linked to the jet stream and extreme weather events over densely populated mid-latitude regions. The physical causes of blocking and consequently how it responds to and influences broader-scale climate change are poorly understood, especially in terms of connecting weather (daily) and climate (year-to-year or longer) timescales. Recent research shows a significant increase in blocking over the Greenland region, mainly in summer, since around 1990. This is not well simulated by currently available global climate models. This deficiency may be linked to recent rapid Arctic sea-ice loss which is also not well captured by the climate models. However, the latest generation of climate models show some improvement compared with earlier versions, although still have some differences between modelled and observed representations of Greenland Blocking.Our proposal addresses this model-observation mismatch by means of a comprehensive comparison using new methods, the updated observations and the latest state-of-the-art climate model simulations. We seek to understand the causes of changes in Greenland Blocking through observation-based data on a wide range of timescales from daily to decadal, analysing how changes in extreme Greenland Blocking events are linked to climatological variations and trends, and considering fundamental physical causes (heating and/or atmospheric circulation changes) of extreme Greenland Blocking events. Natural variability is an important aspect of blocking, and the recent significant trend in Greenland Blocking in summer is the time of year when changes in Atlantic-wide sea-surface temperatures - called Atlantic Multidecadal Variability - are most closely associated with melt and runoff changes from the Greenland Ice Sheet. We will therefore compare climate-model output from models with varying representations of the ocean and sea ice in order to identify possible oceanic and/or Arctic sea-ice loss influences on Greenland Blocking changes.There would be profound implications of a continued increase in Greenland Blocking in summer over the coming decades: for example, enhancing melting and mass loss of the Greenland Ice Sheet. Recent results indicate a non-linear, accelerating response of the ice sheet's surface melt and runoff to rising temperatures where the latter are partly linked with the recent blocking increase in summer. Crucially, understanding how the Greenland Ice Sheet responds to future climate change, and the resulting effects on global sea-level rise, depends upon being able to better model atmospheric circulation changes over the Greenland region. Therefore, we will use our insights gained from earlier work in the project and novel climate model experiments to evaluate the likely impacts of future Greenland Blocking changes on North Atlantic and European weather and climate, and on the Greenland Ice Sheet mass balance and hence global sea-level rise. We expect that our results from this climatically crucial part of the North Atlantic will provide a major step forward for understanding the causes and impacts of Greenland Blocking and help guide development of the next generation of global climate models.