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.

基底滑动是大多数温带冰川运动的主要形式，它导致冰川涌动，导致冰川侵蚀河床，并往往控制着整个冰川的质量分布。冰川的变形速度场可以有一定的信心建模，但没有工作模型可以准确预测冰川的滑动运动。事实上，可能进入滑动模型的变量尚未完全确定。从理论上讲，滑动是由升高的水压和河床处的水储存促进的。然而，以前的现场项目将滑动速率与压力或储存量相关联，其中大多数关联与压力有关。这些观测项目只使用有限的空间和时间分布的测量数据，将滑动和冰下条件联系起来。这使得这项任务非常困难，因为冰下排水系统是短暂的，内部冰动力学（例如，纵向耦合）使冰川对下边界变化的反应复杂化。主要研究人员将进行一项多方面的研究，重点是冰下水文和冰动力系统之间耦合的时间/空间变化，他们认为这是对滑动动力学新认识的关键。他们将在阿拉斯加东南部的温带山谷冰川Bench Glacier进行实地考察。将使用各种类型的仪器收集一套全面的数据集，包括测量基底水压、表面运动、内部变形、滑动速度、河床视频观测以及关于冰下水流的段塞、泵和示踪实验。这些数据将包括至少三个以前没有涉及的要素，从而能够对冰下水文学和冰川运动之间的联系进行新的探索：1）将在两个长度尺度上收集数据，包括跨越整个冰川的测量和侧重于一小段冰川的详细测量; 2）测量将在至少一年的时间内进行，以便对短周期和长周期进行调查; 3）自动测量仪器将允许对冰川运动进行不间断的高时间分辨率研究。在第一个野外季节，他们将专注于长尺度（公里），测量跨越冰川长度的位置的基础条件和速度。数据将被用来研究床和冰动力学之间的纵向耦合。在第二个实地季节，他们将处理一个短的长度尺度（10-100米），使当地的观测能够放在区域进程的背景下。这将使地表隆起的测量结果能够与冰动力学和水文学进行充分比较，以调查隆起的原因。由此产生的数据集和分析将用于测试和完善冰下水流的概念和数字模型，并建立水文学和冰动态之间的联系。