title: Temperature dependence of ice-on-rock friction at realistic glacier conditions.
abstract: Using a new biaxial friction apparatus, we conducted experiments of ice-on-rock friction in order to better understand basal sliding of glaciers and ice streams. A series of velocity-stepping and slide-hold-slide tests were conducted to measure friction and healing at temperatures between -20°C and melting. Experimental conditions in this study are comparable to subglacial temperatures, sliding rates and effective pressures of Antarctic ice streams and other glaciers, with load-point velocities ranging from 0.5 to 100 µm s-1and normal stress σn= 100 kPa. In this range of conditions, temperature dependences of both steady-state friction and frictional healing are considerable. The friction increases linearly with decreasing temperature (temperature weakening) from μ = 0.52 at -20°C to μ = 0.02 at melting. Frictional healing increases and velocity dependence shifts from velocity-strengthening to velocity-weakening behaviour with decreasing temperature. Our results indicate that the strength and stability of glaciers and ice streams may change considerably over the range of temperatures typically found at the ice-bed interface.This article is part of the themed issue 'Microdynamics of ice'.
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA mccarthy@ldeo.columbia.edu.
authors.forename: C
authors.identifier: http://orcid.org/0000-0002-5276-5246
authors.initials: C
authors.lastname: McCarthy
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA.
authors.forename: H
authors.initials: H
authors.lastname: Savage
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, New York, NY, USA.
authors.forename: M
authors.initials: M
authors.lastname: Nettles
keywords: basal sliding; frictional healing; glaciers; ice friction