Incorporating Glacial Blisters into Models of Subglacial Drainage

将冰川水泡纳入冰下排水模型

• 批准号: 2747405
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2747405
• 关键词: Incorporating; Glacial; Blisters; into; Models

Glaciers are currently undergoing major changes in their structure due to climate change; new features are appearing which are not well understood for which better models are needed. As the global climate has warmed, so has the prevalence of meltwater lakes on the surfaces of glaciers during warmer seasonal fluctuations. Such 'supraglacial' lakes can drain rapidly (on the order of hours) through fractures in the ice with the meltwater then collecting in 'subglacial' lakes. These, in turn, force a gap between the ice and bedrock causing the glacier to rise locally with the water stored below in a pool under pressure - such features are known as 'glacial blisters' due to their structure.These sudden drainage events can flood a pre-existing subglacial drainage system with an overwhelming influx of water. Near the glacier terminus large channels in the drainage system are able to carry water away quickly, reducing the effects of such events. However, further inland such expansive channels don't usually exist. Thus, inland blisters can drain on the order of days, at a much slower pace than they are initially formed.It is recognised that the quantity of water flowing through a subglacial drainage system can significantly affect the ice sheet motion due to lubrication at the base of a glacier. However, how to incorporate blister drainage into glacial hydrology models remains an open area and any potential link between this and increased ice velocity has not yet been established through mathematical models. The aim of this project is to extend current subglacial drainage system models to incorporate the effects of lakes driven by supraglacial drainage. In extending the models we can then attempt to observe if there are any significant changes on the overall glacier behaviour. For example, during drainage, one might see that larger channels are formed further inland to enable water to drain form blisters more quickly. Alternatively one might observe that longer term drainage leads to greater lubrication at the base of the glacier hence resulting in faster motion at the surface.On the length scale of a blister, the ice can be modelled under an elastic deformation but on the scale of the glacier a more sensible choice would be to treat the ice as viscous. Marrying these two models, or indeed using a more complex visco-elastic setup, will form a major part of this project.This project falls within the EPSRC Continuum Mechanics research area, specifically in relation to modelling fluid and solid mechanics. It will involve fundamental aspects of fluid flow and deformations within a porous medium. It has the potential to better our understanding of what causes an increase in glacier velocity and thus overall glacier melting and calving rates that lead to global sea level rise. Given the rapidly changing climate has increased the occurrence of glacier ponding, modelling the effects of drainage (and hence refining our models) will enable us to better predict the effects the warming atmosphere will have on the reduction of global glacier coverage.

由于气候变化，冰川目前正在经历其结构的重大变化;新的特征正在出现，这些特征尚未得到很好的理解，需要更好的模型。随着全球气候变暖，在温暖的季节波动期间，冰川表面的融水湖也普遍存在。这种“冰上”湖泊可以通过冰的裂缝迅速排水（大约几个小时），融水然后收集在“冰下”湖泊中。这反过来又迫使冰和基岩之间产生间隙，导致冰川局部上升，水储存在压力下的水池中-这种特征因其结构而被称为“冰川水泡”。这些突然的排水事件可能会淹没先前存在的冰下排水系统。在冰川终点附近，排水系统中的大型渠道能够迅速将水带走，减少此类事件的影响。然而，在更远的内陆，这种广阔的渠道通常不存在。因此，内陆水泡可以在几天的时间内排出，速度比它们最初形成的速度慢得多。人们认识到，由于冰川底部的润滑作用，流经冰下排水系统的水量可以显著影响冰盖运动。然而，如何将水泡排水纳入冰川水文模型仍然是一个开放的领域，这与冰速增加之间的任何潜在联系尚未通过数学模型建立。该项目的目的是扩展当前的冰下排水系统模型，以纳入冰上排水驱动的湖泊的影响。在扩展模型时，我们可以尝试观察整个冰川行为是否有任何重大变化。例如，在排水过程中，人们可能会看到更大的通道形成在内陆，使水能够更快地从水泡中排出。另外，人们可能会观察到，长期的排水导致冰川底部更大的润滑，从而导致表面更快的运动。在水泡的长度尺度上，冰可以在弹性变形下建模，但在冰川的尺度上，更明智的选择是将冰视为粘性。结合这两个模型，或者使用更复杂的粘弹性设置，将构成该项目的主要部分。该项目福尔斯EPSRC连续介质力学研究领域，特别是与建模流体和固体力学有关。它将涉及多孔介质内流体流动和变形的基本方面。它有可能使我们更好地了解是什么原因导致冰川速度增加，从而导致全球海平面上升的整体冰川融化和崩解率。鉴于快速变化的气候增加了冰川积水的发生，模拟排水的影响（从而改进我们的模型）将使我们能够更好地预测气候变暖对全球冰川覆盖率减少的影响。