MRI: Development of a Thermal Melt Probe System for Extensive, Low-Cost Instrument Deployment at the Bed of the Greenland Ice Sheet

这项MRI提案的目的是开发一种低成本的成套仪器，用于研究冰川和冰盖底部的水文系统。估计未来格陵兰冰盖（GIS）的海平面上升的贡献，关键取决于动态冰下水文的定量了解。冰下水文网络中的加压水强烈地调节冰盖在其床上的滑动，即使这些网络在很大范围的时间和空间尺度上响应于输入速率和表面融水的数量而发展。因此，冰盖下的水压力是系统中最重要的动力学和诊断变量。尽管如此重要，但由于现有方法的实际局限性，目前对冰盖下压力（或任何其他冰下变量）的实地测量很少。现有的能够达到这些深度的冰钻和取芯钻机包括成吨的设备和燃料，并由几个或更多人的工作人员操作。因此，如果不显著增加其物流负荷，许多项目就无法获得基底水压的测量值，尽管这些数据与其调查直接相关。研究人员建议开发热融化探测器，以每小时米的速度自动融化冰层。小型化仪器、固态功率控制电子设备和高压电缆的进步现在使可靠、稳健和复杂的基础水压测量和其他变量能够使用小型、后勤轻便的熔体探头。该提案基于一个在海冰和山区冰川中建造和测试的缩尺原型。研究人员计划通过在格陵兰岛西部600-1000米的冰层下放置至少一个探测器来委托新系统，并获取基础水压数据，以作为一系列进一步建议的概念验证。本科生和研究生将在该项目的过程中接受培训。

The aim of this MRI proposal is to develop a low-cost instrumentation package for studying the hydrologic system at the bases of glaciers and ice sheets. Estimating future contributions of the Greenland Ice Sheet (GIS) to sea level rise depends critically on a quantitative understanding of dynamic subglacial hydrology. Pressurized water in subglacial hydrological networks strongly modulates sliding of the ice sheet over its bed, even as those networks evolve in response to input rates and quantities of surface melt water, on a wide range of scales in time and space. The pressure of water beneath the ice sheet is thus the single most important dynamic and diagnostic variable in the system. Despite this importance there are presently very few field measurements of pressure (or any other subglacial variable) beneath ice sheets, because of the practical limitations of existing methods. Existing ice drilling and coring rigs capable of reaching those depths comprise tons of equipment and fuel, and are operated by crews of several or more people. Without dramatically increasing their logistics loads, many projects are therefore unable to acquire measurements of basal water pressure, despite direct relevance of such data to their investigations. The investigators propose to develop thermal melt probes, that would melt their way autonomously down through the ice at speeds of meters per hour. Advances in miniaturized instrumentation, solid-state power-control electronics, and high-voltage cabling now enable reliable, robust and sophisticated measurements of basal water pressure and other variables with small, logistically light melt probes. The proposal is based on a subscale prototype that has been built and tested in sea ice and a mountain glacier. The investigators plan to commission the new system by emplacing at least one probe beneath 600-1000 m of ice in western Greenland and acquiring basal water pressure data to serve as a proof-of-concept for a wide range of further proposals. Undergraduate and graduate students will be trained in the course of this project.