Laboratory observations of the high temperature creep of polycrystalline ice

• Main Authors: Treverrow, A, Le'Gallais, B, Roberts, J
• Format: Conference Object
• Language: English
• Published: WSL Institute for Snow and Avalanche Research SLF 2019
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Glaciology; Ice Sheet
• Online Access: https://www.polar2018.org/uploads/2/4/6/0/24605948/polar2018_abstractproceedings.pdf; http://ecite.utas.edu.au/134535

The largest source of uncertainty in predictions of future sea level is the contribution arising from the dischargeof ice from the polar ice sheets. A key factor in reducing this uncertainty is to improve the numerical modelsused to predict ice sheet evolution. One important aspect of model development is to improve the constitutiverelationship that describes the rheological properties of ice. Factors influencing creep deformation rates include: the magnitudes of the stresses causing ice to deform;strain-induced anisotropy of polycrystalline ice, and temperature. Creep rates at high temperatures, within 2degrees (K) of the melting point, are constrained by a relatively small number of laboratory observations due tothe inherent difficulties in conducting experiments at such temperatures. We present results from a series of laboratory ice deformation experiments conducted in simple shear attemperatures between -2C and -0.3C at 0.1 MPa (octahedral shear stress). Unlike previous experimentalstudies conducted at temperatures close to the melting point, these experiments were continued through tohigh shear strains (>10% strain) to ensure that anisotropic flow, compatible with the stress configuration, haddeveloped. These data contribute to the continued development of a constitutive relationship for polycrystalline ice thatwill improve the accuracy of ice sheet models and are relevant to model studies utilizing inverse methods toinfer the spatial extent of basal sliding.