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INSIGT: Investigating Shear-margin Interactions with Grounding-line Transitions

INSIGT：研究剪切裕度与接地线过渡的相互作用

基本信息

批准号：
1744758
负责人：
Jenny Suckale
金额：
$ 41.42万
依托单位：
Stanford University
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：
2018-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744758&HistoricalAwards=false
关键词：
INSIGT Investigating Shear margin Interactions

项目摘要

Antarctica is losing most of its mass through rapid and localized ice flow in outlet glaciers and ice streams. While the position and width of outlet glaciers are often largely controlled by the underlying landscape (e.g., ice flow through gaps in mountains), ice streams flow mostly over sedimentary basins with little or no topographic control on their lateral boundaries. Despite these differences, both ice streams and outlet glaciers are potentially prone to unstable retreat. One of the key mechanisms responsible for this rapid ice loss is the marine ice-sheet instability, in which continued retreat may be induced in areas where the bathymetry slopes inland. This instability has been primarily studied for outlet glaciers with lateral topographic bounds on ice flow. Consequently, this project explores the effect and applicability of the marine ice-sheet instability to ice streams without those topographic bounds on their margins.The goal of this project is to understand whether and how the mechanism of the marine ice-sheet instability applies to ice streams. To achieve this goal, the team will study how ice streams respond to the retreat of the grounding line, where ice loses contact with the bed and starts floating in the ocean. The team will focus on understanding the coupling between grounding-line retreat and ice-stream lateral boundaries rather than initiation of grounding-line retreat. It is hypothesized that both the width and flow speed of ice streams would be affected by retreat, because ice-stream dynamics are extremely sensitive to the force-balance between the bed, margins, and driving stress. More specifically, the team hypothesizes that the bed slope is less relevant in the case of ice streams than it is for outlet glaciers, because ice streams have the potential to widen in response to retreat, exacerbating ice loss even in the absence of a landward sloping bed. This mechanism, however, depends on the resistance to both widening and flow acceleration, which is sensitively dependent on the subglacial hydrology between ice and the sedimentary layer underneath. The team will test its hypothesis through a customized numerical modeling approach developed for this purpose and will compare model predictions to observational constraints from past ice flow in the Siple Coast region of West Antarctica.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.

南极洲正在通过出口冰川和冰流中快速和局部的冰流失去大部分质量。虽然出口冰川的位置和宽度通常在很大程度上受底层景观的控制（例如，冰流通过山脉中的缺口），冰流主要流经沉积盆地，其横向边界很少或没有地形控制。尽管存在这些差异，但冰流和出口冰川都可能倾向于不稳定的退缩。造成这种快速冰损失的一个关键机制是海洋冰盖的不稳定性，在水深向内陆倾斜的地区，可能会引起持续的退缩。这种不稳定性主要研究了出口冰川与冰流的横向地形边界。因此，本计画将探讨海洋冰盖不稳定性对无地形边界的冰流的影响与适用性，其目的是了解海洋冰盖不稳定性的机制是否以及如何适用于冰流。为了实现这一目标，该团队将研究冰流如何对接地线的撤退做出反应，在那里冰失去了与床的接触，并开始漂浮在海洋中。该团队将专注于了解接地线撤退和冰流横向边界之间的耦合，而不是接地线撤退的开始。据推测，冰流的宽度和流速都会受到后退的影响，因为冰流动力学对河床、边缘和驱动应力之间的力平衡非常敏感。更具体地说，研究小组假设，冰流的河床坡度与出口冰川的相关性较低，因为冰流有可能因退缩而变宽，即使没有向陆地倾斜的河床，也会加剧冰的流失。然而，这种机制取决于对加宽和流动加速的阻力，而这又敏感地取决于冰和下面的沉积层之间的冰下水文。该团队将通过为此目的开发的定制数值模拟方法来测试其假设，并将模型预测与南极洲西部西普尔海岸地区过去冰流的观测约束进行比较。该奖项反映了NSF的法定使命，并被认为值得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来支持。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Modelling thermomechanical ice deformation using an implicit pseudo-transient method (FastICE v1.0) based on graphical processing units (GPUs)

使用基于图形处理单元 (GPU) 的隐式伪瞬态方法 (FastICE v1.0) 对热机械冰变形进行建模

DOI：
10.5194/gmd-13-955-2020
发表时间：
2020
期刊：
Geoscientific Model Development
影响因子：
5.1
作者：
Räss, Ludovic;Licul, Aleksandar;Herman, Frédéric;Podladchikov, Yury Y.;Suckale, Jenny
通讯作者：
Suckale, Jenny

Water pressure fluctuations control variability in sediment flux and slip dynamics beneath glaciers and ice streams

水压波动控制冰川和冰流下方沉积物通量和滑移动力学的变化