Processes of fast glacier flow

冰川快速流动过程

• 批准号: 357193-2013
• 负责人: Schoof, Christian
• 金额: $ 3.5万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=572767
• 关键词: Processes; fast; glacier; flow

Ice sheets and glaciers are the biggest potential source of future sea level rise. Mountain glaciers also play an important role in regional water supplies, especially through providing water during dry summers, while continent-sized ice sheets such as those in Greenland and Antarctica have multple impacts on the world's climate system beyond sea level change. Ice flow is a key component in determining how much ice there is on the planet: faster ice flow tends to lead to thinner, smaller ice masses, and potentially even to the complete disappearance of a glacier or ice sheet. Yet relatively little is known about how the fastest glacial flow phenomena on Earth work - ice streams in Antarctica, surging glaciers, and fast-flowing glaciers that teminate in the ocean. The proposed research aims to unravel the physics behind these phenomena. It will focus on the role that melt water plays in speeding up ice flow. Most fast glacier flow is caused by lubrication of the base of the ice by melt water that reaches the bed. To quantify the effect of water, it is however not enough to know how much of it reaches the bed: we also have to know how it drains along the bed. Highly pressurized water will weaken the contact between ice and rock, and permit faster sliding. My research will use mathematical modelling techniques in combination with direct observations at the bed of a valley glacier to determine the physics that controls water pressure under the ice, and to introduce that physics into ice flow simulations to better predict its effects on fast ice flow phenomena. Alongside this focus on water, I will develop novel modelling techniques to capture the breaking-off of icebergs, and the effect that this has through removing constrictions on ice flow that slow ice discharge into the oceans. I am motivated in this effort by the fact that the parts of Greenland and Antarctica that are losing mass fastest are invariably outlet glaciers that terminate in the ocean, where the loss of a floating ice tongue (or `ice shelf') has removed a constriction to ice flow. Future projections of ice discharge will crucially depend on being to understand how and why floating ice tongues break off, and my work will aim to produce predictive models for the underlying physics.

冰盖和冰川是未来海平面上升的最大潜在来源。山地冰川在区域供水方面也发挥着重要作用，特别是通过在干燥的夏季提供水，而格陵兰岛和南极洲等大陆大小的冰盖对世界气候系统的影响超出了海平面变化的范围。冰流是决定地球上有多少冰的一个关键因素：更快的冰流往往会导致更薄、更小的冰块，甚至可能导致冰川或冰盖的完全消失。然而，对于地球上最快的冰川流动现象——南极洲的冰流、汹涌的冰川和在海洋中终止的快速流动的冰川——是如何运作的，人们知之甚少。这项提议的研究旨在揭示这些现象背后的物理学原理。它将关注融化的水在加速冰流方面所起的作用。大多数快速的冰川流动是由于到达冰层底部的融水对冰层底部的润滑造成的。然而，为了量化水的影响，仅仅知道有多少水到达河床是不够的：我们还必须知道它是如何沿着河床排出的。高压水将削弱冰和岩石之间的接触，并允许更快的滑动。我的研究将使用数学建模技术，结合在山谷冰川床上的直接观察，以确定控制冰下水压的物理特性，并将该物理特性引入冰流模拟，以更好地预测其对快速冰流现象的影响。除了对水的关注，我还将开发新的建模技术来捕捉冰山的断裂，以及通过消除阻碍冰流的限制来减缓冰流入海洋的影响。我之所以这样做，是因为格陵兰岛和南极洲的部分冰川质量损失最快，它们总是以海洋为终点的出口冰川，在海洋中，漂浮冰舌（或“冰架”）的消失消除了对冰流的限制。未来对冰流的预测将关键取决于我们对漂浮冰舌断裂的方式和原因的理解，而我的工作将旨在为潜在的物理现象建立预测模型。