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一个核心问题。虽然人们的注意力都集中在南极西部冰盖沿海边缘持续的快速变化上，但获得过去冰盖和气候变化的记录是限制冰盖在千年时间尺度上变化的唯一方法。西南极冰盖是否在最后一次间冰期（约130，000至116，000年前）崩溃，当时气温略高于今天，仍然是南极冰川学中未解决的主要问题。大力士冰穹（Hercules Dome）是位于东南极洲和西南极洲冰盖交汇处的冰分水岭。它是记录西南极冰盖变化的冰川学和气候影响的理想地点。该项目将确定大力神圆顶是否由于两个冰盖的海拔变化而经历了流量的重大变化。该项目还将确定赫拉克勒斯圆顶是否是恢复末次间冰期气候记录的合适地点。 这些记录可以用来确定西南极冰盖是否在这一时期崩溃。该项目将支持两名早期职业研究人员，并培训华盛顿大学的学生。研究结果将通过与钻冰项目办公室、华盛顿大学在西雅图举办的年度极地科学周末以及艺术与科学合作的外联项目进行交流。该项目将研究东南极冰盖和西南极冰盖交汇处的冰动力学历史，并确定该地点是否适合进行深冰取芯作业。 冰分裂提供了一个独特的机会，以评估过去的冰流的稳定性。 冰流的低偏应力和非线性导致稳定冰分水岭下的内部层中出现拱形（“雷蒙德隆起”）。 该信息可用于确定稳定冰流的持续时间。由于缓慢的水平冰流速度，冰鸿沟也保存了旧冰与内部分层，反映了过去的流动条件所造成的鸿沟迁移。大力士冰穹是一个冰分水岭，它的位置很好，可以保留东南极冰盖和西南极冰盖过去几何形状变化的信息。这个圆顶也是最有希望恢复冰芯的位置，冰芯可以用来确定南极西部冰盖是否在最后一次间冰期崩溃。有限的冰穿透雷达数据收集沿着以前的科学表面导线显示保存完好的冰内地层和证据暗示雷蒙德凹凸，但以前的调查不够广泛，允许彻底的特点或确定过去的变化冰动力学。该项目将进行一项专门的调查，以绘制冰内地层和冰下地形以及赫拉克勒斯圆顶的基础特性。该项目将使用地基冰穿透雷达1）成像内部层和冰盖基底界面，2）准确测量冰内衰减，3）确定冰内垂直应变率。雷达数据将与GPS观测相结合，以获得详细的地形和表面速度，并建立冰流模型，以限制基础特征和过去冰流的历史。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.

Geophysics and Thermodynamics at South Pole Lake Indicate Stability and a Regionally Thawed Bed

南极湖的地球物理学和热力学表明稳定性和区域性解冻床

• DOI: 10.1029/2021gl096218
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Hills, Benjamin H.;Christianson, Knut;Hoffman, Andrew O.;Fudge, T. J.;Holschuh, Nicholas;Kahle, Emma C.;Conway, Howard;Christian, John E.;Horlings, Annika N.;O’Connor, Gemma K.
• 通讯作者: O’Connor, Gemma K.

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