Collaborative Research: Disentangling runoff- and Terminus-driven Velocity Variations of Fast Flowing Outlet Glaciers

合作研究：解开快速流动的出口冰川径流和终点驱动的速度变化

• 批准号: 2234729
• 负责人: Elizabeth Ultee
• 金额: $ 22.7万
• 依托单位: Middlebury College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-15 至 2027-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2234729&HistoricalAwards=false
• 关键词: Collaborative; Research; Disentangling; runoff; Terminus

Ice loss from the polar ice sheets is the largest anticipated contribution to global mean-sea-level rise in the coming century. A fundamental control on the rate of ice loss is how fast ice flows from ice sheet interiors out to the edges. In the interior of the Greenland Ice Sheet, ice flow responds to liquid water (“runoff") input, which affects how the ice slides over the bedrock beneath. At ocean-terminating "outlet glaciers” around the edges of Greenland, ice flows into the ocean with speed that varies by season. That strong seasonal variation makes it more difficult to determine the extent to which liquid water input is affecting the flow speed. Identifying the relative strength of ocean-driven versus melt-driven ice flow variations is essential for computer models used to forecast future ice loss. It has been difficult to assess those factors in a consistent way because they operate over multiple time scales, thus requiring different methods of observation that could not be directly compared.This proposal seeks to address three key motivating questions: (Q1) How does runoff affect outlet glacier flow over timescales of hours to years?; (Q2) How does glacier geometry affect the response to runoff?; and (Q3) How do runoff- and terminus-driven velocity variations interact? To address these questions, the PIs will combine new field observations at a large marine-terminating outlet glacier with newly available satellite data from multiple sources, using recently developed methods for flexible time series analysis. Multivariate statistical analysis and idealized numerical model experiments will test hypothesized feedbacks between runoff-driven and terminus-driven changes, as well as connect the observational work to more general settings. The PIs will develop open-source software that allows other researchers to replicate their analysis for remote-sensing and in situ data obtained on any glacier. Museum professionals on the team will coordinate with the PIs to develop a special exhibit on the drivers of Arctic glacier change; after initial installation at the University of Alaska Museum of the North, the exhibit will be made available to tour other Arctic museums.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.

极地冰盖的冰流失是未来一个世纪对全球平均海平面上升的最大预期贡献，对冰流失速度的根本控制是冰从冰盖内部流向边缘的速度。在格陵兰冰盖内部，冰流入液态水（“径流”），这会影响冰在格陵兰岛边缘的海洋终止“出口冰川”上滑动的方式。速度那个这种强烈的季节性变化使得确定液态水输入对流速的影响程度变得更加困难，对于用于预测的计算机模型来说，确定海洋驱动与融化驱动的冰流变化的相对强度至关重要。很难以一致的方式评估这些因素，因为它们在多个时间尺度上运行，因此需要无法直接比较的不同观察方法。该提案旨在解决三个关键的激励问题：（Q1）径流如何影响出口冰川流量小时到年的时间尺度？；（问题 2）冰川几何形状如何影响对径流的响应？；（问题 3）径流和终点驱动的速度变化如何相互作用？一个大型海洋终止出口冰川，具有来自多个来源的新可用卫星数据，使用最近开发的灵活时间序列分析方法和理想化数值模型实验，将测试径流驱动和终点驱动之间的开创性反馈。变化，以及将观测工作与更一般的环境联系起来，PI将开发开源软件，使其他研究人员能够复制他们对团队中任何冰川获得的遥感和现场数据的分析。与 PI 合作开发一个关于北极冰川变化驱动因素的特别展览；在阿拉斯加大学北方博物馆首次安装后，该展览将可供其他北极博物馆参观。该奖项反映了 NSF 的法定使命，并已获得被视为值得通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。