Ice Dynamics at the Intersection of the West and East Antarctic Ice Sheets

南极西部和东部冰盖交汇处的冰动力学

• 批准号: 1744649
• 负责人: Knut Christianson
• 金额: $ 62.89万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744649&HistoricalAwards=false
• 关键词: Ice; Dynamics; Intersection; West; East

The response of the Antarctic ice sheet to climate change is a central issue in projecting global sea-level rise. While much attention is focused on the ongoing rapid changes at the coastal margin of the West Antarctic Ice Sheet, obtaining records of past ice-sheet and climate change is the only way to constrain how an ice sheet changes over millennial timescales. Whether the West Antarctic Ice Sheet collapsed during the last interglacial period (~130,000 to 116,000 years ago), when temperatures were slightly warmer than today, remains a major unsolved problem in Antarctic glaciology. Hercules Dome is an ice divide located at the intersection of the East Antarctic and West Antarctic ice sheets. It is ideally situated to record the glaciological and climatic effects of changes in the West Antarctic Ice Sheet. This project will establish whether Hercules Dome experienced major changes in flow due to changes in the elevation of the two ice sheets. The project will also ascertain whether Hercules Domes is a suitable site from which to recover climate records from the last interglacial period. These records could be used to determine whether the West Antarctic Ice Sheet collapsed during that period. The project will support two early-career researchers and train students at the University of Washington. Results will be communicated through outreach programs in coordination the Ice Drilling Project Office, the University of Washington's annual Polar Science Weekend in Seattle, and art-science collaboration.This project will develop a history of ice dynamics at the intersection of the East and West Antarctic ice sheets, and ascertain whether the site is suitable for a deep ice-coring operation. Ice divides provide a unique opportunity to assess the stability of past ice flow. The low deviatoric stresses and non-linearity of ice flow causes an arch (a "Raymond Bump") in the internal layers beneath a stable ice divide. This information can be used to determine the duration of steady ice flow. Due to the slow horizontal ice-flow velocities, ice divides also preserve old ice with internal layering that reflects past flow conditions caused by divide migration. Hercules Dome is an ice divide that is well positioned to retain information of past variations in the geometry of both the East and West Antarctic Ice Sheets. This dome is also the most promising location at which to recover an ice core that can be used to determine whether the West Antarctic Ice Sheet collapsed during the last interglacial period. Limited ice-penetrating radar data collected along a previous scientific surface traverse indicate well-preserved englacial stratigraphy and evidence suggestive of a Raymond Bump, but the previous survey was not sufficiently extensive to allow thorough characterization or determination of past changes in ice dynamics. This project will conduct a dedicated survey to map the englacial stratigraphy and subglacial topography as well as basal properties at Hercules Dome. The project will use ground-based ice-penetrating radar to 1) image internal layers and the ice-sheet basal interface, 2) accurately measure englacial attenuation, and 3) determine englacial vertical strain rates. The radar data will be combined with GPS observations for detailed topography and surface velocities and ice-flow modeling to constrain the basal characteristics and the history of past ice flow.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

南极冰盖对气候变化的反应是预测全球海平面上升的核心问题。尽管大量关注集中在南极冰盖沿海边缘的持续快速变化上，但获得过去的冰淇淋和气候变化的记录是限制冰盖在千禧年时间表上如何变化的唯一方法。南极冰盖是否在最后一次冰河期间倒塌（〜130,000至116，000年前），当时温度比今天温暖略高，这仍然是南极冰川学的一个主要未解决问题。大力神圆顶是位于南极和南极西部冰盖的交叉路口的冰鸿沟。理想情况下，可以记录南极西部冰盖变化的冰​​川学和气候影响。该项目将确定大力神圆顶是否由于两个冰盖的高度变化而导致流量发生了重大变化。该项目还将确定赫拉克勒斯圆顶是否是从最后一次冰河间回收气候记录的合适地点。 这些记录可用于确定在此期间西南极冰盖是否崩溃。该项目将支持华盛顿大学的两名早期研究人员和培训学生。结果将通过协调的宣传计划进行冰钻项目办公室，华盛顿大学在西雅图的年度极地科学周末以及艺术科学合作进行传播。该项目将在东南极冰盖的交汇处发展冰动力学史，并确定该地点是否适合进行深层冰期的操作。 ICE Divides提供了一个独特的机会来评估过去冰流的稳定性。 冰流的低偏斜应力和非线性导致稳定冰层下方的内部层中的拱形（“雷蒙德碰撞”）。 这些信息可用于确定稳定冰流的持续时间。由于水平冰流速度缓慢，冰划分还可以保留旧的冰，内部分层反映了由于迁移而导致的过去流量条件。大力神圆顶是一个冰鸿沟，可以很好地保留东部和西南极冰盖几何形状的过去变化的信息。该圆顶也是最有前途的位置，可以在该地点恢复冰芯，该冰芯可用于确定在最后一次冰河期间是否在南极冰盖倒塌的位置。沿着先前的科学表面遍历收集的有限的冰渗透雷达数据表明，保存完好的英语地层和暗示了雷蒙德颠簸的证据，但先前的调查不足以允许对冰动力学的过去变化进行彻底表征或确定。该项目将进行一项专门的调查，以绘制Hercules Dome的Eng -Racial地层和冰川亚地形以及基础特性。该项目将使用基于地面的冰渗透雷达到1）图像内层图像和冰层基底界面，2）准确测量熟衰减，3）确定Eng-Racial垂直应变速率。雷达数据将与GPS观测值结合使用，以详细的地形和表面速度和冰流建模，以限制基础特征和过去冰流的历史。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估来通过评估来获得支持的。

项目成果

ImpDAR: an open-source impulse radar processor

• DOI: 10.1017/aog.2020.44
• 发表时间: 2020-04
• 期刊: Annals of Glaciology
• 影响因子: 2.9
• 作者: D. Lilien;B. Hills;Joshua Driscol;R. Jacobel;K. Christianson

A site for deep ice coring at West Hercules Dome: results from ground-based geophysics and modeling

西赫拉克勒斯圆顶深冰取芯地点：地面地球物理学和建模的结果

• DOI: 10.1017/jog.2022.80
• 发表时间: 2022
• 期刊: Journal of Glaciology
• 影响因子: 3.4
• 作者: Fudge, T. J.;Hills, Benjamin H.;Horlings, Annika N.;Holschuh, Nicholas;Christian, John Erich;Davidge, Lindsey;Hoffman, Andrew;O'Connor, Gemma K.;Christianson, Knut;Steig, Eric J.
• 通讯作者: Steig, Eric J.

Response of Water Isotopes in Precipitation to a Collapse of the West Antarctic Ice Sheet in High-Resolution Simulations with the Weather Research and Forecasting Model

天气研究和预报模型高分辨率模拟中降水中的水同位素对南极西部冰盖崩塌的响应

• DOI: 10.1175/jcli-d-22-0647.1
• 发表时间: 2023
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Dütsch, Marina;Steig, Eric J.;Blossey, Peter N.;Pauling, Andrew G.
• 通讯作者: Pauling, Andrew G.

Scars of tectonism promote ice-sheet nucleation from Hercules Dome into West Antarctica

• DOI: 10.1038/s41561-023-01265-5
• 发表时间: 2023-10-12
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Hoffman，Andrew O.;Holschuh，Nicholas;Christianson，Knut
• 通讯作者: Christianson，Knut

A framework for attenuation method selection evaluated with ice-penetrating radar data at South Pole Lake

• DOI: 10.1017/aog.2020.32
• 发表时间: 2020-04
• 期刊: Annals of Glaciology
• 影响因子: 2.9
• 作者: B. Hills;K. Christianson;N. Holschuh