Tools for quantifying the role of basal processes in glacier dynamics

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Funds are requested to purchase tools to aid in quantifying the role basal processes play in determining glacier flow, stability, and climate response characteristics.  These tools will provide (1) rapid access to the glacier bed, allowing a variety of instruments to be installed there; (2) year-round control of subglacial instruments, allowing in situ measurement of mechanical and hydrological conditions at the glacier bed; (3) all-weather high precision survey capability, allowing surface flow rates to be related to instrument records of basal motion; and (4) year-round measurement of local environmental conditions, which will aid in quantifying meltwater input to the subglacial drainage system.  This equipment will help establish a new research program that aims to observe and quantify the strong interaction between mechanical processes and hydrological conditions present beneath weak-bedded valley glaciers.   Data obtained from the field component of the program will be used to constrain numerical models of basal processes, with the long-term goal of improving the treatment of the basal boundary condition for ice-dynamics models.  This will allow more accurate determination of the response of ice sheets (both past and present) to climate change, and will elucidate the behaviours of modern-day ice streams, surging glaciers, and tidewater glaciers.      Glaciers that are underlain by soft, deformable sediments move by some combination of ice deformation, sediment deformation and basal sliding.  These last two components of flow can contribute greatly to the motion of ice masses.  In addition, erosional processes at the ice-bed contact determine the physical effect that glaciers and ice sheets have on the bedrock topography.  Because high subglacial water pressures facilitate both glacier sliding and sediment deformation, basal motion is strongly influenced by hydrological conditions at the glacier bed.  An improved knowledge of the relationship between mechanical processes and hydrological conditions at the bed is thus key to understanding both the dynamics of ice masses and their effect on the landscape.