Causes and impacts of Greenland atmospheric Blocking changes

格陵兰岛大气阻塞变化的原因和影响

• 批准号: NE/W005875/1
• 负责人: Edward Hanna
• 金额: $ 82.06万
• 依托单位: University of Lincoln
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW005875%2F1
• 关键词: Causes; impacts; Greenland; atmospheric; Blocking

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.

该项目旨在为了解格陵兰上空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/英国地区的气候变化和极端天气条件的后果提供重大进展。以及它们对格陵兰冰盖质量损失和全球海平面上升的影响。北半球中高纬度地区的高压阻塞是大气环流的一个重要特征，它与人口稠密的中纬度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及其如何响应和影响更大范围的气候变化知之甚少，特别是在连接天气（每日）和气候（年对年或更长时间）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式无法很好地模拟这一点。这种缺乏可能与最近北极海冰的迅速消失有关，而气候模式也没有很好地捕捉到这一点。然而，最新一代气候模式与早期版本相比有所改善，尽管在模拟和观测到的格陵兰阻塞表现之间仍有一些差异。我们的建议通过使用新方法、更新的观测和最新的最先进的气候模式模拟的综合比较来解决这种模式-观测不匹配的问题。我们试图通过从日到年的广泛时间尺度上的观测数据来了解格陵兰阻塞变化的原因，分析极端格陵兰阻塞事件的变化如何与气候变化和趋势联系起来，并考虑极端格陵兰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，最近格陵兰阻塞在夏季的显著趋势是一年中大西洋范围的海面温度变化（称为大西洋多年代际变率）与格陵兰冰盖的融化和径流变化最密切相关的时候。因此，我们将比较具有不同海洋和海冰表示的模式的气候模式输出，以确定海洋和/或北极海冰损失可能对格陵兰冰盖变化产生的影响。在未来几十年里，夏季格陵兰冰盖的持续增加将产生深远的影响：例如，格陵兰冰盖的融化和质量损失加剧。最近的研究结果表明，冰盖表面融化和径流对温度上升的非线性加速响应，其中后者与最近夏季阻塞的增加部分相关。至关重要的是，了解格陵兰冰盖如何应对未来的气候变化，以及由此对全球海平面上升的影响，取决于能够更好地模拟格陵兰地区的大气环流变化。因此，我们将利用我们从该项目早期工作中获得的见解和新的气候模式实验来评估未来格陵兰阻塞变化对北大西洋和欧洲天气和气候、格陵兰冰盖物质平衡以及全球海平面上升的可能影响。我们期望我们在北大西洋这一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提供重要的一步，并有助于指导下一代全球气候模式的发展。

项目成果

Short- and long-term variability of the Antarctic and Greenland ice sheets

• DOI: 10.1038/s43017-023-00509-7
• 发表时间: 2024-02
• 期刊: Nature Reviews Earth & Environment
• 作者: Edward Hanna;Dániel Topál;J. Box;S. Buzzard;Frazer D. W. Christie;Christine Hvidberg;M. Morlighem