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

Authors: Hubbard, Bryn P.; Hubbard, Alun; Mader, Heidy M.; Tison, Jean-Louis; Grust, Karin; Nienow, Peter W.

Source: Annals of Glaciology, Volume 37, Number 1, 1 June 2003 , pp. 1-6(6)

Publisher: International Glaciological Society

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Abstract:

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 <5 m. In contrast, a single-layered model constrained with a hardness of 1.2 a-1 bar-3 overestimates the current measured long-section area by 31%, having a rms ice-thickness error of 15.0 m. Under the retreat modelling scenario, which gauges the response of the glacier to an imposed 75m rise in equilibrium-line altitude (ELA), the multi-layered model predicts a long-section area reduction of 78%. This contrasts with a reduction of 64% for the single-layered model (hardness = 7.0 a-1 bar-3) and 85% for the single-layered model (hardness = 1.2 a-1 bar-3).

Document Type: Research Article

DOI: http://dx.doi.org/10.3189/172756403781815474

Publication date: June 1, 2003

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  • The Annals of Glaciology is a peer-reviewed, thematic journal published 2 to 4 times a year by the International Glaciological Society (IGS). Publication frequency is determined and volume/issue numbers assigned by the IGS Council on a year-to-year basis and with a lead time of 3 to 4 years. The Annals of Glaciology is included in the ISI Science Citation Index from volume 50, number 50 onwards.

    Themes can be on any aspect of the study of snow and ice. Individual members can make a suggestion for a theme for an Annals issue to the Secretary General, who will forward it to the IGS Publications Committee. The IGS Publication Committee will make a recommendation for an individual themed Annals issue, together with a potential Annals Chief Editor for that issue, to IGS Council. The IGS Council will make the decision whether to proceed, taking into account the spread of topics and the overall capacity for publication of pages in Annals.

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