Thwaites Interdisciplinary Margin Evolution (TIME)

思韦茨跨学科利润演变（TIME）

• 批准号: NE/S006788/1
• 负责人: Tun Jan Young
• 金额: $ 73.6万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS006788%2F1
• 关键词: Thwaites; Interdisciplinary; Margin; Evolution; TIME

The global scientific community considers the West Antarctic Ice Sheet to be the most significant risk for coastal environments and cities, given its potentially large contribution to future sea-level rise. The risk posed by the WAIS is exacerbated because it is in direct contact with the warming ocean and because its reverse bed slope makes the ice vulnerable to a prolonged unstable retreat. Although scientists have been aware of the precarious setting of the WAIS since the early 1970s, it is only now becoming apparent that the flow of ice in several large drainage basins is undergoing dynamic change, which is consistent with - although not certain to be - the beginning of a sustained and potentially unstoppable disintegration. Two of the fundamental global challenges facing the scientific community today include understanding the controls on the stability of the WAIS, and enabling a more accurate prediction of sea-level rise through improved computer simulations of ice flow. In the TIME project, we directly address both challenges by:a) using frontier technologies to observe rapidly deforming shear margins hypothesized to exert strong control on the future evolution of ice flow in the Thwaites Glacier drainage basin, andb) using observational records to develop parameterisations for important processes which are yet to be implemented in the ice sheet models used to predict the Antarctic contribution to sea level rise.TIME will test the key hypothesis that the future evolution of ice flow through the Thwaites Glacier drainage basin is governed by the dynamics of the shear margins that separate the fast flowing glacier from the slow-moving ice that surrounds it. To test the hypothesis the team will set up an ice observatory at two sites on the eastern shear margin of Thwaites Glacier. The team argues that weak topographic control makes this shear margin susceptible to outward migration and, possibly, sudden jumps in response to the drawdown of inland ice when the grounding line of Thwaites Glacier retreats. The ice observatory is designed to produce new and comprehensive constraints on important englacial properties, which include ice deformation rates, ice crystal fabric, ice viscosity, ice temperature, ice liquid-water content and basal melt rates. The ice observatory will also establish basal conditions, including thickness and porosity of any subglacial sediment layer and the deeper marine sediments. Furthermore, the team will develop new knowledge with an unparalleled emphasis on the consequences of variations in these properties for ice flow, including a direct assessment of the spatial and temporal scales on which they vary. These knowledge will be obtained from interdisciplinary field-based geophysical platforms, including 3D active-source seismic surveys, 2D active-source seismic transects, networks of GPS and complementary passive broadband seismometers, and autonomous radar systems deployed with phased arrays to detect rapidly deforming internal layers and liquid water in the ice and at the bed. Datasets will be incorporated into numerical models developed on different spatial scales. One will focus specifically on shear margin dynamics, the other on how shear margin dynamics can influence ice flow in the whole drainage basin. Upon completion, the project will have confirmed whether the eastern shear margin of Thwaites Glacier can migrate rapidly, as hypothesised, and if so what the impacts will be in terms of sea level rise in this century and beyond.

全球科学界认为，南极西部冰盖对沿海环境和城市来说是最重大的风险，因为它可能对未来海平面上升做出巨大贡献。 WAIS 带来的风险更加严重，因为它与变暖的海洋直接接触，而且其反向床坡使冰层容易遭受长期不稳定的退缩。尽管自 20 世纪 70 年代初以来，科学家们就已经意识到 WAIS 的不稳定环境，但直到现在才变得明显，几个大型流域盆地中的冰流正在经历动态变化，这与（尽管不确定）持续且可能不可阻挡的解体的开始是一致的。当今科学界面临的两个基本全球挑战包括了解 WAIS 稳定性的控制，以及通过改进冰流计算机模拟来更准确地预测海平面上升。在 TIME 项目中，我们通过以下方式直接解决这两个挑战：a）使用前沿技术观察快速变形的剪切边际，假设对思韦茨冰川流域的冰流未来演变施加强有力的控制，b）使用观测记录开发重要过程的参数化，这些过程尚未在用于预测南极对海平面上升的贡献的冰盖模型中实施。TIME 将测试关键假设 通过思韦茨冰川流域的冰流的未来演变受到剪切边际动力学的控制，剪切边际将快速流动的冰川与其周围缓慢移动的冰分开。为了验证这一假设，该团队将在思韦茨冰川东部剪切边缘的两个地点建立一个冰观测站。研究小组认为，薄弱的地形控制使得剪切裕度容易向外迁移，并且当思韦茨冰川的接地线后退时，可能会因内陆冰层的消退而突然跳跃。冰观测站旨在对重要的冰川特性产生新的综合约束，包括冰变形率、冰晶结构、冰粘度、冰温度、冰液水含量和基础融化速率。冰观测站还将建立基础条件，包括冰下沉积物层和更深海洋沉积物的厚度和孔隙度。此外，该团队将开发新知识，特别强调这些特性变化对冰流的影响，包括直接评估它们变化的空间和时间尺度。这些知识将从跨学科的基于现场的地球物理平台获得，包括3D主动源地震勘测、2D主动源地震横断面、GPS网络和互补的无源宽带地震仪，以及部署有相控阵的自主雷达系统，以检测快速变形的内层以及冰层和地床中的液态水。数据集将被纳入在不同空间尺度上开发的数值模型中。一个将特别关注剪切边缘动力学，另一个将关注剪切边缘动力学如何影响整个流域的冰流。完成后，该项目将确认思韦茨冰川东部剪切边缘是否能够像假设的那样快速迁移，如果是的话，将对本世纪及以后的海平面上升产生什么影响。

项目成果

Inferring Ice Fabric From Birefringence Loss in Airborne Radargrams: Application to the Eastern Shear Margin of Thwaites Glacier, West Antarctica

从机载雷达图中的双折射损失推断冰结构：在南极洲西部思韦茨冰川东部剪切边缘的应用

• DOI: 10.1029/2020jf006023
• 发表时间: 2021
• 期刊: Journal of Geophysical Research: Earth Surface
• 作者: Young, T. J.;Schroeder, D. M.;Jordan, T. M.;Christoffersen, P.;Tulaczyk, S. M.;Culberg, R.;Bienert, N. L.
• 通讯作者: Bienert, N. L.

Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide deep ice core site

• DOI: 10.5194/tc-2020-264
• 发表时间: 2020-09
• 作者: T. J. Young;C. Martín;P. Christoffersen;D. Schroeder;S. Tulaczyk;E. Dawson

Polarimetric radar-sounding to infer and quantify shear margin ice fabric anisotropy

偏振雷达探测推断和量化剪切裕度冰织物各向异性

• DOI: 10.5194/egusphere-egu21-2107
• 发表时间: 2021
• 作者: Young T

Rapid and accurate polarimetric radar measurements of ice crystal fabric orientation at the Western Antarctic Ice Sheet (WAIS) Divide ice core site

• DOI: 10.5194/tc-15-4117-2021
• 发表时间: 2021-08
• 期刊: The Cryosphere
• 作者: T. J. Young;C. Martín;P. Christoffersen;D. Schroeder;S. Tulaczyk;E. Dawson

Radar-derived ice fabric anisotropy and implications on flow enhancement along the Thwaites Glacier Eastern Shear Margin

雷达衍生的冰结构各向异性及其对思韦茨冰川东部剪切边缘流动增强的影响

• DOI: 10.5194/egusphere-egu23-2178
• 发表时间: 2023
• 作者: Young T