Spatial variability in the water content and rheology of temperate glaciers: Glacier de Tsanfleuron, Switzerland

The physical properties of eight ice cores recovered from along a flowline at Glacier de Tsanfleuron, Switzerland, have led to the identification of three distinctive internal zones. We use variations in the bulk ionic chemistry of these zones to approximate their relative liquid-water concentrations and ice viscosities. Results suggest that relative bulk water concentration and ice softness vary by over an order of magnitude between the zones. Implications of this variability for predictions of the glacier's response to climate change are evaluated by incorporating these relative softnesses into a multi-layered (two-dimensional) model of ice flow. Model output is compared with that from an identical model constrained with a spatially uniform ice viscosity under advance and retreat modelling scenarios. The former scenario is used to tune viscosity by growing a glacier to its present long-section geometry, resulting in best-fit ice hardness values of 1.2 a-1 bar-3 for the englacial ice in the multi-layered model and 7.0 a-1 bar-3 for all of the ice in the single-layered model. Both result in close approximations to the current long profile, yielding rms deviations between measured and modelled ice thicknesses that are