PRE-MELT: Preconditioning the trigger for rapid Arctic ice melt

融化前：预处理北极冰层快速融化的触发器

• 批准号: NE/T000546/1
• 负责人: Jack Landy
• 金额: $ 26.54万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT000546%2F1
• 关键词: PRE; MELT; Preconditioning; trigger; rapid

The oldest, thickest sea ice in the 'last ice area' of the Arctic - a region thought to be most resilient to climate warming - unexpectedly broke up twice in the past year. Our current theories assume that the end-of-summer ice-covered area will steadily retreat into the Central Arctic Basin as global warming accelerates over coming decades. However, the dynamic break-up events witnessed in 2018 challenge this prevailing view. Here we hypothesise that a weaker, increasingly mobile Central Arctic ice pack is now susceptible to dynamic episodes of fragmentation which can precondition the ice for rapid summer melt. This mechanism of dynamic seasonal preconditioning is unaccounted for in global climate models, so our best current projections are overlooking the possibility for rapid disintegration of the Arctic's last ice area.Our team has demonstrated that seasonal preconditioning is already responsible for the neighbouring Beaufort Sea becoming ice-free twice in the past five years. Even ten years ago this region contained thick perennial sea ice, mirroring the Central Arctic Ocean, but it has now transitioned to a marginal Arctic sea. Could the processes responsible for the decline of the Beaufort Sea ice pack start to manifest themselves in the Central Arctic? Currently, a shortfall in satellite observations of the Arctic pack ice in summer prevents us from testing our hypothesis. We desperately require pan-Arctic observations of ice melting rates, but so far satellite observations of sea ice thickness are only available during winter months. Our project will therefore deliver the first measurements of Arctic sea ice thickness during summer months, from twin satellites: ESA's Cryosat-2 & NASA's ICESat-2. We have designed a new classification algorithm for separating ice and ocean radar altimeter echoes, regardless of surface melting state, providing the breakthrough required to fill the existing summer observation 'gap'. Exploiting the recent launch of multiple SAR missions for polar reconnaissance, our project will integrate information on ice-pack ablation, motion and deformation to generate a unique year-round sea ice volume budget in the High Arctic. This record will inform high-resolution ice dynamics simulations, performed with a suite of state-of-the-art sea ice models from stand alone (CICE), ocean-sea ice (NEMO/CICE), to fully coupled regional high resolution (RASM), and global coarser resolution (HadGEM) models, all now equipped with the anisotropic (EAP) sea ice rheology developed by our team. Using the regional and stand-alone models we will analyse the role of mechanics in this keystone region north of Greenland to scrutinise the coupling and preconditioning of winter breakup events - such as those witnessed in 2018 - to summer melting rates. Using the coupled models, we will quantify the likelihood of the Arctic's last ice area breaking up much sooner than expected due to oceanic and atmospheric feedbacks and how this will affect the flushing of ice and freshwater into the North Atlantic.

北极“最后一片冰区”最古老、最厚的海冰--被认为是最能适应气候变暖的地区--在过去的一年里意外地破裂了两次。我们目前的理论假设，随着未来几十年全球变暖的加速，夏末的冰层覆盖区域将稳步退缩到北极盆地中部。然而，2018年见证的动态分手事件挑战了这一流行观点。在这里，我们假设，一个较弱的，越来越移动的北极中部冰盖现在容易受到动态片段，可以预处理的冰快速夏季融化。这种动态季节性预调节机制在全球气候模型中没有得到解释，因此我们目前最好的预测忽略了北极最后一个冰区迅速解体的可能性。我们的团队已经证明，季节性预调节已经导致邻近的博福特海在过去五年中两次无冰。即使在十年前，这一地区也有厚厚的常年海冰，反映了北冰洋中部，但现在它已经过渡到边缘的北冰洋。导致博福特海冰减少的过程会在北极中部开始显现吗？目前，卫星观测北极夏季浮冰的不足使我们无法验证我们的假设。我们迫切需要对冰融化速度的泛北极观测，但到目前为止，对海冰厚度的卫星观测只能在冬季进行。因此，我们的项目将在夏季提供北极海冰厚度的第一次测量，来自双卫星：欧空局的Cryosat-2和NASA的ICESat-2。我们已经设计了一种新的分类算法，用于分离冰和海洋雷达高度计回波，无论表面融化状态，提供了填补现有夏季观测“空白”所需的突破。利用最近启动的多个SAR任务进行极地侦察，我们的项目将整合有关冰盖消融，运动和变形的信息，以生成一个独特的全年海冰体积预算在高北极。这些记录将为高分辨率冰动力学模拟提供信息，这些模拟使用一套最先进的海冰模型进行，从独立的（CICE），海洋海冰（NEMO/CICE），到完全耦合的区域高分辨率（RASM）和全球粗分辨率（HadGEM）模型，所有这些模型现在都配备了我们团队开发的各向异性（EAP）海冰流变学。使用区域和独立模型，我们将分析格陵兰岛北部这个关键地区的力学作用，以仔细研究冬季解体事件（如2018年目睹的事件）与夏季融化率的耦合和预处理。使用耦合模型，我们将量化北极最后一个冰区由于海洋和大气反馈而比预期更快破裂的可能性，以及这将如何影响冰和淡水流入北大西洋。

项目成果

Network connectivity between the winter Arctic Oscillation and summer sea ice in CMIP6 models and observations

• DOI: 10.5194/tc-2021-387
• 发表时间: 2022-01
• 期刊: The Cryosphere
• 作者: W. Gregory;J. Stroeve;M. Tsamados

A Bayesian approach towards daily pan-Arctic sea ice freeboard estimates from combined CryoSat-2 and Sentinel-3 satellite observations

根据 CryoSat-2 和 Sentinel-3 卫星观测数据，采用贝叶斯方法对每日泛北极海冰干舷进行估计

• DOI: 10.5194/egusphere-egu21-11462
• 发表时间: 2021
• 作者: Gregory W

ESD Ideas: Arctic Amplification's Contribution to Breaches of the Paris Agreement

ESD 理念：北极放大对违反《巴黎协定》的贡献

• DOI: 10.5194/egusphere-2023-810
• 发表时间: 2023
• 作者: Duffey A

Increasing Multiyear Sea Ice Loss in the Beaufort Sea: A New Export Pathway for the Diminishing Multiyear Ice Cover of the Arctic Ocean

波弗特海多年海冰流失加剧：北冰洋多年冰盖减少的新出口途径

• DOI: 10.1002/essoar.10509833.1
• 发表时间: 2021
• 作者: Babb D

A 10-year record of Arctic summer sea ice freeboard from CryoSat-2

• DOI: 10.1016/j.rse.2021.112744
• 发表时间: 2022-01
• 期刊: Remote Sensing of Environment
• 影响因子: 13.5
• 作者: G. Dawson;J. Landy;M. Tsamados;A. Komarov;S. Howell;H. Heorton;T. Krumpen