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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=549961
• 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，特别是通过在干旱的夏季提供水，而格陵兰和南极洲等大陆规模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关键组成部分：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完全消失。然而，人们对地球上最快的冰川流动现象--南极洲的冰流、汹涌的冰川以及在海洋中终结的快速流动的冰川--如何运作知之甚少。这项研究旨在揭示这些现象背后的物理学原理。它将集中在融水在加速冰流中所起的作用。大多数快速的冰川流动是由于到达冰床的融水润滑了冰的底部。然而，要量化水的影响，仅仅知道有多少水到达河床是不够的：我们还必须知道水是如何沿着河床沿着排出的。高压水会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直接观察在一个山谷冰川的床，以确定物理控制冰下的水压，并引入冰流模拟，以更好地预测其对快速冰流现象的影响物理。 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，以及通过消除冰流上的收缩来减缓冰排入海洋的效果。我之所以这样做，是因为格陵兰岛和南极洲质量损失最快的部分总是终止于海洋的出口冰川，在那里，漂浮的冰舌（或“冰架”）的消失消除了对冰流的限制。未来对冰排放的预测将主要取决于理解漂浮冰舌如何以及为什么会断裂，我的工作将旨在为潜在的物理学产生预测模型。