NSF-NERC: THwaites Offshore Research (THOR)

NSF-NERC：THwaites 离岸研究中心 (THOR)

• 批准号: 1738942
• 负责人: Julia Wellner
• 金额: $ 101.56万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1738942&HistoricalAwards=false
• 关键词: NSF; NERC; THwaites; Offshore; Research

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. Satellite observations extending over the last 25 years show that Thwaites Glacier is rapidly thinning and accelerating. Over this same period, the Thwaites grounding line, the point at which the glacier transitions from sitting on the seabed to floating, has retreated. Oceanographic studies demonstrate that the main driver of these changes is incursion of warm water from the deep ocean that flows beneath the floating ice shelf and causes basal melting. The period of satellite observation is not long enough to determine how a large glacier, such as Thwaites, responds to long-term and near-term changes in the ocean or the atmosphere. As a result, records of glacier change from the pre-satellite era are required to build a holistic understanding of glacier behavior. Ocean-floor sediments deposited at the retreating grounding line and further offshore contain these longer-term records of changes in the glacier and the adjacent ocean. An additional large unknown is the topography of the seafloor and how it influences interactions of landward-flowing warm water with Thwaites Glacier and affects its stability. Consequently, this project focuses on the seafloor offshore from Thwaites Glacier and the records of past glacial and ocean change contained in the sediments deposited by the glacier and surrounding ocean.Uncertainty in model projections of the future of Thwaites Glacier will be significantly reduced by cross-disciplinary investigations seaward of the current grounding line, including extracting the record of decadal to millennial variations in warm water incursion, determining the pre-satellite era history of grounding-line migration, and constraining the bathymetric pathways that control flow of warm water to the grounding line. Sedimentary records and glacial landforms preserved on the seafloor will allow reconstruction of changes in drivers and the glacial response to them over a range of timescales, thus providing reference data that can be used to initiate and evaluate the reliability of models. Such data will further provide insights on the influence of poorly understood processes on marine ice sheet dynamics. This project will include an integrated suite of marine and sub-ice shelf research activities aimed at establishing boundary conditions seaward of the Thwaites Glacier grounding line, obtaining records of the external drivers of change, improving knowledge of processes leading to collapse of Thwaites Glacier, and determining the history of past change in grounding line migration and conditions at the glacier base. These objectives will be achieved through high-resolution geophysical surveys of the seafloor and analysis of sediments collected in cores from the inner shelf seaward of the Thwaites Glacier grounding line using ship-based equipment, and from beneath the ice shelf using a corer deployed through the ice shelf via hot water drill holes.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.

该项目为美国国家科学基金会 (NSF) 和英国自然环境研究委员会 (NERC) 发起的联合倡议做出了贡献，该倡议旨在大幅改进对源自西部思韦茨冰川的冰损失和海平面上升的十年和长期预测南极洲。 过去 25 年的卫星观测表明，思韦茨冰川正在迅速变薄并加速。在同一时期，思韦茨接地线（冰川从海底转变为漂浮的点）已经后退。海洋学研究表明，这些变化的主要驱动因素是来自深海的温水入侵，这些温水在漂浮冰架下方流动并导致基底融化。卫星观测的时间还不够长，无法确定像思韦茨这样的大型冰川如何响应海洋或大气的长期和近期变化。因此，需要从前卫星时代开始的冰川变化记录来建立对冰川行为的整体了解。在后退的接地线和更远的近海处沉积的海底沉积物包含了冰川和邻近海洋变化的长期记录。另一个巨大的未知数是海底的地形以及它如何影响向陆地流动的温水与思韦茨冰川的相互作用并影响其稳定性。因此，该项目重点关注思韦茨冰川近海的海底，以及冰川和周围海洋沉积物中包含的过去冰川和海洋变化的记录。通过交叉研究，思韦茨冰川未来的模型预测的不确定性将大大减少。对当前接地线的海上进行学科调查，包括提取温水入侵的十年到千年的变化记录，确定前卫星时代的历史接地线迁移，并限制控制温水流向接地线的测深路径。海底保存的沉积记录和冰川地貌将允许重建驱动因素的变化以及冰川在一定时间尺度上对它们的响应，从而提供可用于启动和评估模型可靠性的参考数据。这些数据将进一步深入了解人们知之甚少的过程对海洋冰盖动力学的影响。该项目将包括一套综合的海洋和冰下架研究活动，旨在建立思韦茨冰川接地线向海的边界条件，获取变化的外部驱动因素的记录，提高对导致思韦茨冰川崩溃过程的了解，以及确定接地线迁移和冰川底部条件过去变化的历史。这些目标将通过海底高分辨率地球物理调查以及使用船载设备从思韦茨冰川接地线内陆架海上收集的岩芯中收集的沉积物以及使用通过部署在冰架下方的岩芯进行分析来实现。该奖项反映了 NSF 的法定使命，并且通过使用基金会的智力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

Rapid retreat of Thwaites Glacier in the pre-satellite era

前卫星时代思韦茨冰川快速退缩

• DOI: 10.1038/s41561-022-01019-9
• 发表时间: 2022-09
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: Graham, Alastair G. C.;Wåhlin, Anna;Hogan, Kelly A.;Nitsche, Frank O.;Heywood, Karen J.;Totten, Rebecca L.;Smith, James A.;Hillenbrand, Claus;Simkins, Lauren M.;Anderson, John B.;et al
• 通讯作者: et al

Revealing the former bed of Thwaites Glacier using sea-floor bathymetry: implications for warm-water routing and bed controls on ice flow and buttressing

使用海底测深揭示思韦茨冰川的前床：对温水路径和冰床控制对冰流和支撑的影响

• DOI: 10.5194/tc-14-2883-2020
• 发表时间: 2020-01
• 期刊: The Cryosphere
• 作者: Hogan, Kelly A.;Larter, Robert D.;Graham, Alastair G.;Arthern, Robert;Kirkham, James D.;Totten Minzoni, Rebecca;Jordan, Tom A.;Clark, Rachel;Fitzgerald, Victoria;Wåhlin, Anna K.;et al
• 通讯作者: et al

Sedimentary Signatures of Persistent Subglacial Meltwater Drainage From Thwaites Glacier, Antarctica

南极洲思韦茨冰川持续冰下融水排放的沉积特征

• DOI: 10.3389/feart.2022.863200
• 发表时间: 2022-05
• 期刊: Frontiers in Earth Science
• 影响因子: 2.9
• 作者: Lepp, A. P.;Simkins, L. M.;Anderson, J. B.;Clark, R. W.;Wellner, J. S.;Hillenbrand, C;Smith, J. A.;Lehrmann, A. A.;Totten, R.;Larter, R. D.;et al
• 通讯作者: et al

Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica

南极洲西部思韦茨冰架下温水流动的路径和改变

• DOI: 10.1126/sciadv.abd7254
• 发表时间: 2021-04
• 期刊: Science Advances
• 影响因子: 13.6
• 作者: Wåhlin AK;Graham AGC;Hogan KA;Queste BY;Boehme L;Larter RD;Pettit EC;Wellner J;Heywood KJ
• 通讯作者: Heywood KJ

Ice front retreat reconfigures meltwater-driven gyres modulating ocean heat delivery to an Antarctic ice shelf

冰锋退缩重新配置融水驱动的环流，调节海洋热量输送到南极冰架

• DOI: 10.1038/s41467-022-27968-8
• 发表时间: 2022-01-13
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Yoon ST;Lee WS;Nam S;Lee CK;Yun S;Heywood K;Boehme L;Zheng Y;Lee I;Choi Y;Jenkins A;Jin EK;Larter R;Wellner J;Dutrieux P;Bradley AT
• 通讯作者: Bradley AT