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

University Of Washington, Seattle WA

Investigators

Abstract

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.