Collaborative Research: Modeling ice-ocean Interaction for the Rapidly Evolving Ice Shelf Cavities of Pine Island and Thwaites Glaciers, Antarctica

合作研究：对南极洲松岛和思韦茨冰川快速演变的冰架空腔的冰-海洋相互作用进行建模

• 批准号: 1643285
• 负责人: Ian Joughin
• 金额: $ 56.2万
• 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: 2017
• 资助国家: 美国
• 起止时间: 2017-07-15 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1643285&HistoricalAwards=false
• 关键词: Collaborative; Research; Modeling; ice; ocean

The West Antarctic Ice Sheet contains enough ice to raise global sea levels by 3-4 meters. Ice-sheet volume falls, and sea level increases, when more ice is lost to the ocean by glacier flow than is replaced by snowfall. Glacier speed is reduced when ice shelves, which are the floating extensions of the ice sheets, are present. Processes that affect ice shelf thickness and extent therefore influence the rates of grounded ice loss and sea-level rise. West Antarctica is currently losing ice, at an accelerating rate, with most loss occurring in the Amundsen Sea region via discharge from Pine Island and Thwaites glaciers. This loss was initiated by increased circulation of relatively warm ocean water beneath these glacier's ice shelves, causing them to thin by melting. However, this melting also depends on how the changing shape of the ice shelves affects the ocean circulation beneath them and the speeds of the grounded glaciers upstream. Limited understanding of these processes leads to uncertainties in estimates of future ice loss. This interdisciplinary project brings together glaciologists and oceanographers from three US institutions to study the interactions between changing glacier flow, ice shelf shape and extent, and ocean circulation. Data and numerical models will be used to identify the key processes that determine how rapidly this region can shed ice. The project team will train postdocs and graduate students in cutting-edge modeling techniques, and educate the public about Antarctic ice loss through talks, school science fairs, and Seattle Science Center's annual Polar Science Weekend. The project team will conduct simulations, using a combination of ice-sheet and ocean models, to reduce uncertainties in projected ice loss from Pine Island and Thwaites glaciers by: (i) assessing how ice-shelf melt rates will change as the ice-shelf cavities evolve through melting and grounding-line retreat, and (ii) improving understanding of the sensitivity of sub-shelf melt rates to changes in ocean state on the nearby continental shelf. These studies will reduce uncertainty on ice loss and sea-level rise estimates, and lay the groundwork for development of future fully-coupled ice-sheet/ocean models. The project will first develop high-resolution ice-shelf-cavity circulation models driven by modern observed regional ocean state and validated with estimates of melt derived from satellite observations. Next, an ice-flow model will be used to estimate the future grounding retreat. An iterative process with the ocean-circulation and ice-flow models will then simulate melt rates at each stage of retreat. These results will help assess the validity of the hypothesis that unstable collapse of the Amundsen Sea sector of West Antarctica is underway, which was based on simplified models of melt rate. These models will also provide a better understanding of the sensitivity of melt to regional forcing such as changes in Circumpolar Deep Water temperature and wind-driven changes in thermocline height. Finally, several semi-coupled ice-ocean simulations will help determine the influence of the ocean-circulation driven melt over the next several decades. These simulations will provide a much-improved understanding of the linkages between far-field ocean forcing, cavity circulation and melting, and ice-sheet response.

南极西部冰盖含有的冰足以使全球海平面上升 3-4 米。当冰川流向海洋流失的冰量多于降雪替代的冰量时，冰盖体积就会下降，海平面就会上升。当冰架（冰盖的浮动延伸部分）存在时，冰川速度会降低。因此，影响冰架厚度和范围的过程会影响地面冰损失和海平面上升的速度。南极洲西部目前正在加速流失冰，其中大部分流失发生在阿蒙森海地区，是由派恩岛和思韦茨冰川排放造成的。这种损失是由于这些冰川冰架下方相对温暖的海水循环增加导致冰架融化而变薄所致。然而，这种融化还取决于冰架形状的变化如何影响其下方的海洋环流以及上游接地冰川的速度。对这些过程的了解有限导致对未来冰损失的估计存在不确定性。这个跨学科项目汇集了来自三个美国机构的冰川学家和海洋学家，研究不断变化的冰川流量、冰架形状和范围以及海洋环流之间的相互作用。数据和数值模型将用于确定决定该地区结冰速度的关键过程。该项目团队将培训博士后和研究生掌握尖端建模技术，并通过讲座、学校科学博览会和西雅图科学中心的年度极地科学周末向公众宣传南极冰盖流失的情况。项目团队将结合冰盖和海洋模型进行模拟，通过以下方式减少预计松岛和思韦茨冰川冰损失的不确定性：(i) 评估冰架融化速率将如何随着冰架融化而变化。空洞通过融化和接地线后退而演变，并且（ii）提高对亚大陆架融化速率对附近大陆架海洋状态变化的敏感性的了解。这些研究将减少冰损失和海平面上升估计的不确定性，并为未来完全耦合的冰盖/海洋模型的开发奠定基础。该项目将首先开发由现代观测到的区域海洋状态驱动的高分辨率冰架腔环流模型，并通过卫星观测得出的融化估计进行验证。接下来，将使用冰流模型来估计未来的接地撤退。然后，海洋环流和冰流模型的迭代过程将模拟撤退每个阶段的融化速率。这些结果将有助于评估南极洲西部阿蒙森海部分正在发生不稳定崩溃的假设的有效性，该假设基于融化速率的简化模型。这些模型还将更好地了解融化对区域强迫的敏感性，例如环极深水温度的变化和风驱动的温跃层高度的变化。最后，一些半耦合冰海模拟将有助于确定未来几十年海洋环流驱动的融化的影响。这些模拟将大大加深对远场海洋强迫、空腔环流和融化以及冰盖响应之间联系的理解。

项目成果

Ice shelf basal melt rates from a high-resolution DEM record for Pine Island Glacier, Antarctica

来自南极洲松岛冰川高分辨率 DEM 记录的冰架基础融化速率

• DOI: 10.5194/tc-2018-209
• 发表时间: 2018-10
• 期刊: The Cryosphere Discussions
• 作者: Shean, David E.;Joughin, Ian R.;Dutrieux, Pierre;Smith, Benjamin E.;Berthier, Etienne
• 通讯作者: Berthier, Etienne

West Antarctic Ice Sheet retreat in the Amundsen Sea driven by decadal oceanic variability

海洋年代际变化驱动阿蒙森海西南极冰盖退缩

• DOI: 10.1038/s41561-018-0207-4
• 发表时间: 2018-10
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: Jenkins, Adrian;Shoosmith, Deb;Dutrieux, Pierre;Jacobs, Stan;Kim, Tae Wan;Lee, Sang Hoon;Ha, Ho Kyung;Stammerjohn, Sharon
• 通讯作者: Stammerjohn, Sharon

Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018

1994年至2018年南极洲盖兹地区动态失衡普遍加剧

• DOI: 10.1038/s41467-021-21321-1
• 发表时间: 2021-02
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Selley, Heather L.;Hogg, Anna E.;Cornford, Stephen;Dutrieux, Pierre;Shepherd, Andrew;Wuite, Jan;Floricioiu, Dana;Kusk, Anders;Nagler, Thomas;Gilbert, Lin;et al
• 通讯作者: et al

Ocean-induced melt volume directly paces ice loss from Pine Island Glacier

海洋引起的融化量直接影响松岛冰川的冰损失

• DOI: 10.1126/sciadv.abi5738
• 发表时间: 2021-10
• 期刊: Science Advances
• 影响因子: 13.6
• 作者: Joughin, Ian;Shapero, Daniel;Dutrieux, Pierre;Smith, Ben
• 通讯作者: Smith, Ben

West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing

南极西部冰损失受内部气候变化和人为强迫的影响

• DOI: 10.1038/s41561-019-0420-9
• 发表时间: 2019-09
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: Holland, Paul R.;Bracegirdle, Thomas J.;Dutrieux, Pierre;Jenkins, Adrian;Steig, Eric J.
• 通讯作者: Steig, Eric J.