The role of tributaries in glacier surges

支流在冰川涌动中的作用

• 批准号: 1107491
• 负责人: Martin Truffer
• 金额: $ 54.48万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-11-01 至 2016-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1107491&HistoricalAwards=false
• 关键词: role; tributaries; glacier; surges

A glacier surge is characterized by a sudden increase in speed by one to two orders of magnitude and often leads to a significant movement of the terminus of the glacier. While the role of subglacial hydraulics during the surge has been well documented, the issue of surge initiation has remained unsolved. Also, the related question of why some glaciers surge and others do not remains open. This proposal will investigate whether the special geometry of many Alaska Range glaciers allows particularly large shear stresses to develop that eventually allow a surge to occur. The proposed work would focus on the Black Rapids Glacier on the Denali Fault in the eastern Alaska Range. The investigators contend that understanding glacier surges can also make a fundamental contribution to understanding of the basal boundary condition, which remains a major question in glaciology. As numerical models of ice flow are becoming more sophisticated, the issue of the basal boundary condition will have to be revisited and it is important to understand the strong non-linear aspects that lead to the switch from quiescence to surge. Lessons learned from surge initiation can also be applied to other situations where ice flows fast under high stress conditions, such as at fast outlet glaciers. The fieldwork would include radar to accurately map the base of the glacier, airborne lidar to generate a full digital elevation model of the surface of the glacier, GPS measurements of ice velocity, meteorological stations for climate data and ice ablation, and cameras to monitor the marginal lakes for drainage. These observations will be fully integrated with and complemented by a three-dimensional flow model of the glacier. The proposed work would form the core of a PhD thesis with training in field methods, data analysis, and numerical modeling. Scientific results will be presented at national and international meetings and in the peer-reviewed literature. Because glacier research tends to attract great interest among the general public, and Black Rapids is familiar to many Alaskans, this project is well-suited to public outreach. Outreach efforts will be coordinated through the institute's Information Office, which regularly schedules well-attended public talks and provides news columns about the institute's science activities.

冰川涌动的特点是速度突然增加一到两个数量级，往往导致冰川终点的显著移动。虽然冰下水力学在涌浪过程中的作用已经有了很好的文献记载，但涌浪启动的问题仍然没有解决。此外，为什么一些冰川激增而另一些冰川没有激增的相关问题仍然悬而未决。这项提案将调查许多阿拉斯加山脉冰川的特殊几何形状是否允许特别大的剪切应力发展，最终允许激增发生。拟议的工作将侧重于阿拉斯加山脉东部德纳里断层上的黑急流冰川。研究人员认为，了解冰川涌动也可以为理解基础边界条件做出根本性的贡献，这仍然是冰川学中的一个主要问题。由于冰流的数值模型正变得越来越复杂，基础边界条件的问题将不得不重新考虑，重要的是要了解强非线性方面，导致从静止到浪涌的切换。从浪涌启动中吸取的经验教训也可以应用于在高应力条件下冰快速流动的其他情况，例如快速出口冰川。实地工作将包括精确绘制冰川底部地图的雷达，生成冰川表面完整数字高程模型的机载激光雷达，冰速度的GPS测量，气候数据和冰消融的气象站，以及监测边缘湖泊排水的摄像机。这些观测结果将与冰川三维流动模型充分结合并得到补充。拟议的工作将构成博士论文的核心，并接受现场方法、数据分析和数值建模方面的培训。科学成果将在国家和国际会议上以及在同行审查的文献中介绍。由于冰川研究往往会引起公众的极大兴趣，而且许多阿拉斯加人都熟悉黑急流，因此这个项目非常适合公众宣传。外联工作将通过研究所的信息办公室进行协调，该办公室定期安排参加人数众多的公开讲座，并提供有关研究所科学活动的新闻专栏。