Subglacial drainage and slip modeling in Antarctica: relating lakes to ice discharge

南极洲的冰下排水和滑移模型：将湖泊与冰排放联系起来

• 批准号: 1043481
• 负责人: Timothy Creyts
• 金额: $ 32.59万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1043481&HistoricalAwards=false
• 关键词: Subglacial; drainage; slip; modeling; Antarctica

1043481/CreytsThis award supports a project to develop models of subglacial hydrology in order to understand dynamics of water movement, lake drainage, and how drainage affects ice slip over deformable till with the goal of understanding present and future behavior of fast flowing regions of Antarctica. Drainage of subglacial water falls into two broad categories: distributed and channelized. In distributed systems, water is forced out along the ice?bed interface. Conversely, in channelized systems water is drawn toward a few major arteries. Observations of lake filling and draining sup- port changes in subglacial water flow and suggest a switch from a low to high discharge state or vice versa. Filling or draining can move the subglacial system from one type of drainage morphology to the other. A switch of drainage type will affect slip along the ice-bed interface because distributed morphologies tend to cause enhanced sliding whereas channelized morphologies tend to cause enhanced coupling of the ice-bed interface. Conditions beneath fast flowing ice streams of West Antarctica are ideal for switching between subglacial drainage morphologies. Fast flowing ice in West Antarctica commonly rests on sub- glacial tills and is coincident, in some areas, with observed subglacial lake filling and draining. The goal of the work is to develop the next generation of spatially distributed hydraulic models that capture lake filling and draining phenomena and investigate the effects on subglacial till. Models will be theoretical, process-based descriptions of water drainage and till failure along fast flowing ice streams. Models will be based on balance of mass, momentum, and energy. Building on previous studies, we will incorporate two dimensional movement of water to investigate distributed basal hydrology, distributed basal hydrology coupled to channels, and couple these models with till deformation. These models will provide a framework for determining how lake draining and filling affects ice discharge by providing a constraints on ice?bed coupling. The intellectual merit of the work is that it will advance knowledge about drainage of water subglacially beneath Antarctica and how water affects ice motion. Our modeling provides a unique opportunity to understand the role subglacial hydrology plays in the dynamics of key outlet glaciers and ice streams. The broader impacts of the work include training for one postdoctoral scientist and training for a summer student in simple laboratory techniques for analog experiments. In addition, the proposal dovetails into an existing polar education and outreach plan by including a component of physical, numerical, and scale models in programs developed for high school and middle school classroom visits, teacher workshops and community events. Additionally, because knowledge of glacial hydrology is increasing rapidly, we will convene a workshop on observations and models of subglacial hydrology to facilitate transfer of knowledge and ideas.

1043481/Creys该奖项支持一个开发冰下水文学模型的项目，以了解水运动的动力学、湖泊排水以及排水如何影响冰滑过可变形的冰层，目的是了解南极洲快速流动区现在和未来的行为。冰川下水的排水分为两大类：分布式和沟道化。在分布式系统中，水沿着冰床界面被挤出。相反，在通道化系统中，水被引向几条主要动脉。对湖泊充填和排泄的观察支持了冰下水流的变化，并提出了从低流量状态到高流量状态或从高流量状态到高流量状态的转换。充填或排水可以将冰下系统从一种类型的排水形态转移到另一种类型。排水类型的切换将影响沿冰床界面的滑动，因为分布的形态往往会导致更强的滑动，而沟道化的形态往往会导致冰床界面的耦合增强。南极洲西部快速流动的冰流下的条件是在冰下排水形态之间切换的理想条件。在南极西部，快速流动的冰通常停留在冰下冰层上，在某些地区，与观测到的冰下湖泊的充填和排出是一致的。这项工作的目标是开发下一代空间分布的水力模型，捕捉湖泊填塞和排水现象，并调查对冰下耕作的影响。模型将是理论上的、基于过程的描述，描述快速流动的冰川上的排水和倒塌。模型将基于质量、动量和能量的平衡。在前人研究的基础上，我们将结合水的二维运动来研究分布式基础水文，分布式基础水文耦合到河道，并将这些模型与TIL变形进行耦合。这些模型将提供一个框架，通过提供对冰床耦合的约束，确定湖泊排水和填埋如何影响冰的排放。这项工作的学术价值在于，它将促进人们对南极洲冰层下的水的排水以及水如何影响冰运动的了解。我们的模型提供了一个独特的机会来理解冰下水文学在主要出口冰川和冰流动态中所起的作用。这项工作的更广泛影响包括对一名博士后科学家的培训，以及对一名暑期学生的模拟实验简单实验室技术的培训。此外，该提案与现有的极地教育和推广计划相吻合，在为高中和中学课堂访问、教师研讨会和社区活动开发的项目中纳入了物理、数字和比例模型的组成部分。此外，由于有关冰川水文学的知识正在迅速增加，我们将召开一次关于冰川下水文学观测和模型的研讨会，以促进知识和思想的交流。