The response of Antarctic ice streams to tidal forcing

冰从南极洲内部向海洋的运输主要是通过几条快速流动的冰流的通量，这些冰流的行为在很大程度上受其底部和沿冰-海洋界面的接地点的条件的影响。冰速对变化的基础条件的响应是预测未来气候变化行为的一个关键挑战。最近的观测表明，冰流的运动对10公里以上的海潮很敏感（Gudmundsson 2006, Minchew et al. 2017），这表明冰川冰的流动、侧缘剪切加热和冰下沉积物孔隙压力变化之间存在耦合。该项目旨在通过使用高分辨率的冰川运动测量，在空间和时间上响应潮汐强迫，了解粘性冰与冰下till的压力依赖流变的非线性耦合。该项目结合了卫星和GPS观测的冰流运动变动性的分析，以响应一些关键的南极地点的潮汐强迫，以及冰川冰在多孔弹性冰下till上运动的简化模型（Hewitt等人，in press）。简单的物理模型和最先进的观测相结合，结合了两个快速发展的科学领域，孔隙力学和遥感，以解决与流体饱和冰下沉积物力学有关的冰盖演变的基本问题。

The transport of ice from the interior of Antarctica to the oceans is dominated by the flux through several fast-flowing ice streams whose behaviour is greatly influenced by the conditions at their base and at grounding points along the ice-ocean interface. The response of the ice velocity to changing basal conditions presents a key challenge for predicting future behaviour in a changing climate. Recent observations have shown that the motion of ice streams is sensitive, over 10s of kilometres, to ocean tides (Gudmundsson 2006, Minchew et al. 2017) suggesting a coupling between the flow of glacial ice, shear heating at lateral margins, and pore pressure changes in subglacial sediment. This project aims to understand the nonlinear coupling of viscous ice with the pressure-dependent rheology of the subglacial till through the use of highly resolved measurements of glacial motion, both spatially and temporally, in response to the tidal forcing.This project combines analysis of satellite and GPS observations of the variability of ice stream motion in response to tidal forcing at a number of key Antarctic sites, along with simplified models of the motion of glacial ice over a poro-elastic subglacial till (Hewitt et al, in press). This combination of simple physical models and state-of-the-art observations combines two rapidly evolving scientific fields, poromechanics and remote sensing, to address fundamental questions in ice sheet evolution related to the mechanics of fluid-saturated subglacial sediments.