Collaborative Research: Linking Subglacial Hydrology and Sliding Dynamics Through Variations Along the Glacier Length

合作研究：通过沿冰川长度的变化将冰下水文学和滑动动力学联系起来

• 批准号: 0443750
• 负责人: Joel Harper
• 金额: $ 37.57万
• 依托单位: University of Montana
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0443750&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; Subglacial; Hydrology

ABSTRACTHarperOPP-0118488PfefferOPP-0118721Basal sliding is the principle form of movement of most temperate glaciers and leads to glacier surging, causes glaciers to erode their beds, and often controls the overall glacier's mass distribution. A glacier's deformational velocity field can be modeled with some confidence, but there are no working models that will accurately predict the sliding motion of glaciers. In fact, the variables that would potentially go into a sliding model have not been fully established. Theoretically, sliding is promoted by both elevated water pressure and water storage at the bed. Previous field programs, however, have correlated sliding rate with either pressure or storage, with the majority of associations made with pressure. These observational programs have correlated sliding and subglacial conditions by using only limited spatially and temporally distributed measurements. This has made the task very difficult because the subglacial drainage system is transient and internal ice dynamics (e.g., longitudinal coupling) complicate the glacier's response to change at its lower boundary. The Principal Investigators will conduct a multifaceted study focusing on time/space variability in coupling between the subglacial hydrology and ice dynamics system which they believe is key to a new understanding of sliding dynamics. They will conduct a field campaign on the Bench Glacier, a temperate valley glacier in southeast Alaska. Various types of instrumentation will be used to collect a comprehensive data set of measurements of basal water pressure, surface motion, internal deformation, sliding velocity, video observations of the bed, and slug, pump, and tracer experiments on subglacial water flow. These data will include at least three elements which have not been previously addressed, thus enabling new explorations of the linkages between subglacial hydrology and glacier motion: 1) data will be collected at two length scales, including measurements spanning the entire glacier and detailed measurements focused on a small reach; 2) measurements will be made over a time period of at least a year, allowing short to long period cycles to be investigated; and 3) an automated survey instrument will allow for uninterrupted high-time resolution studies of glacier motion. During the first field season, they will focus on the long length scale (kilometers), with measurements of basal conditions and velocity made at locations spanning the length of the glacier. Data will be used to investigate the longitudinal coupling between the bed and ice dynamics. During the second field season, they will address a short length scale (10-100 meters), enabling local observations to be placed within the context of regional processes. This will permit measurements of surface uplift to be fully compared with both ice dynamics and hydrology to investigate the cause of the uplift. The resulting data set and analyses will be used to test and refine conceptual and numerical models for subglacial water flow and to establish links between hydrology and ice dynamics.

Apptractharperopp-011848888888888872118721Basal滑动是大多数温带冰川运动的主要形式，并导致冰川迅速飙升，导致冰川侵蚀床，并且经常控制整体冰川的质量分布。冰川的变形速度场可以以某种置信度进行建模，但是没有工作模型可以准确预测冰川的滑动运动。实际上，可能会进入滑动模型的变量尚未完全确定。从理论上讲，滑动是通过床上升高的水压和水存储来推动的。但是，先前的现场程序与压力或存储的滑动速率与压力的大多数关联相关。这些观察计划仅通过仅使用有限的空间和时间分布的测量值将滑动和冰山下条件相关联。这使任务变得非常困难，因为亚冰标排水系统是短暂的，并且内部冰动力学（例如纵向耦合）使冰川对其下边界的变化反应变得复杂。首席研究人员将进行一项多方面的研究，重点介绍了冰川水文学和冰动力学系统之间耦合的时间/空间可变性，他们认为这对于对滑动动力学有了新的了解的关键。他们将在阿拉斯加东南部的温带谷冰川板凳冰川上进行野外运动。各种类型的仪器将用于收集基础水压，表面运动，内部变形，滑动速度，床的视频观察以及SLUG，泵和示踪剂实验的全面数据集。这些数据将包括至少以前尚未解决的三个要素，从而对亚冰川水文和冰川运动之间的联系进行新的探索：1）数据将以两个长度尺度收集，包括涵盖整个冰川和详细测量的测量值； 2）将在至少一年的时间段内进行测量，从而可以研究短期至长期的周期； 3）自动调查工具将允许对冰川运动的高级分辨率研究。在第一个野外季节，它们将集中在长度尺度（公里）上，并在跨越冰川长度的位置进行了基础条件和速度的测量。数据将用于研究床和冰动力学之间的纵向耦合。在第二个野外季节中，他们将解决一个短长的比例（10-100米），从而使本地观察值能够在区域过程的背景下进行。这将允许与冰动力学和水文学进行完全比较表面隆升的测量，以研究升高的原因。所得的数据集和分析将用于测试和完善冰川下水流的概念和数值模型，并在水文和冰动力学之间建立联系。