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

基本信息

批准号：
NE/T001399/1
负责人：
Michel Tsamados
金额：
$ 34.07万
依托单位：
University College London
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%2FT001399%2F1
关键词：
PRE MELT Preconditioning trigger rapid

项目摘要

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“最后的冰区”——被认为对气候变暖影响最大的地区——最古老、最厚的海冰在过去一年里意外破裂了两次。我们目前的理论认为，随着未来几十年全球变暖的加速，夏末冰雪覆盖的地区将稳步退回到北极中部盆地。然而，2018 年发生的动态分手事件挑战了这一普遍观点。在这里，我们假设，北极中部冰层较弱、移动性越来越强，现在很容易发生动态碎裂，这可以为冰在夏季快速融化做好准备。这种动态季节性预处理机制在全球气候模型中没有得到考虑，因此我们目前最好的预测忽略了北极最后一个冰区快速解体的可能性。我们的团队已经证明，季节性预处理已经对邻近的波弗特海变成冰负有责任。 -过去五年免费两次。十年前，该地区还存在厚厚的常年海冰，与北冰洋中部形成镜像，但现在已转变为北冰洋边缘海。导致波弗特海冰盖下降的过程是否会开始在北极中部显现出来？目前，夏季北极浮冰卫星观测的不足使我们无法检验我们的假设。我们迫切需要对冰融化速率进行泛北极观测，但到目前为止，只能在冬季进行海冰厚度的卫星观测。因此，我们的项目将通过双卫星：ESA 的 Cryosat-2 和 NASA 的 ICESat-2，在夏季首次测量北极海冰厚度。我们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，无论表面融化状态如何，为填补现有夏季观测“空白”提供了突破。利用最近启动的多个极地侦察SAR任务，我们的项目将整合有关冰包消融、运动和变形的信息，以生成高北极地区独特的全年海冰量预算。该记录将为高分辨率冰动力学模拟提供信息，该模拟使用一套最先进的海冰模型进行，从独立（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，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，我们将分析力学在格陵兰岛北部这一关键地区的作用，以仔细研究冬季破裂事件（例如 2018 年目睹的事件）与夏季融化速率的耦合和预处理。使用耦合模型，我们将量化由于海洋和大气反馈而导致北极最后一个冰区比预期更早破裂的可能性，以及这将如何影响冰和淡水冲入北大西洋。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Record winter winds in 2020/21 drove exceptional Arctic sea ice transport

2020/21年创纪录的冬季风推动了北极海冰的异常运输

DOI：
10.1038/s43247-021-00221-8
发表时间：
2021-08-03
期刊：
Communications Earth & Environment
影响因子：
7.9
作者：
R. Mallett;J. Stroeve;S. Cornish;A. Crawford;J. Lukovich;M. Serreze;A. Barrett;W. Meier;H. Heorton;M. Tsamados
通讯作者：
M. Tsamados

Mapping Arctic Sea Ice Thickness: A New Method for Improved Ice Freeboard Retrieval from Satellite Altimetry

绘制北极海冰厚度图：改进卫星测高冰干舷反演的新方法