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Mechanical and thermodynamical discontinuities in Scandinavian type polythermal glaciers: a modeling study

English title Mechanical and thermodynamical discontinuities in Scandinavian type polythermal glaciers: a modeling study
Applicant Blatter Heinz
Number 115881
Funding scheme Project funding
Research institution Institut für Atmosphäre und Klima ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.05.2007 - 30.04.2009
Approved amount 134'040.00
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All Disciplines (2)

Hydrology, Limnology, Glaciology

Keywords (8)

glaciology; polythermal glaciers; discontinuites; numerical modeling; numerical model; discontinuitiy; polythermal glacier; shear moraines

Lay Summary (English)

Lay summary
Glacier dynamics is not only defined by continuum mechanical processes, such as ice flow and temperature fields, but also by discontinuous processes, such as basal sliding, intraglacial and subglacial hydraulics, englacial phase boundaries and shear planes or thrust faults. One type of thermodynamic discontinuity is the cold-temperate transition surface (CTS). Scandinavian-type polythermal glaciers are mostly temperate, contains a small percentage of liquid water within the ice matrix, with a cold surface layer in the lower accumulation zone and ablation zone. The corresponding transition at the glacier bed may lead to transitions in the basal motion from sliding to non-sliding or nearly stagnant parts, and possibly to entrainment of basal rocky material. This in turn may lead to internal layers with high shear or even thrust faults, along which the debris is transported to the ice surface. The project attempts a combined model and experimental study of some specific processes related to the CTS and internal debris laden layers in Storglaciären, Sweden.
An important part of this investigation is the development of an efficient ice flow model for the generation of flow fields based on observations and model physics. Since model development, model experiments and field observations will be combined, the project not only aims at new modeling tools for glacier studies, but also attempts to strengthen understanding of the investigated processes.
A project of Prof. N. Iverson, Iowa, in cooperation with P. Jansson, Sweden, attempts an extended observation program in connection with the internal discontinuities on the ice tongue of Storglaciären. We intend to measure strain profiles through a debris layer, which emerges about 300 m upglacier from the ice tongue. With these observations, we obtain the basic information on the rheological properties of debris laden ice, which in turn gives the input on the transition conditions across the layer for the numerical modeling. One goal of the study is to understand the entrainment of rock debris or organic material into the basal ice and the formation of englacial debris layers. This may be used to interprete findings of material on glacier surfaces their origin and may help to reconstruct past extents of the glacier.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
107480 Mechanical and thermodynamical discontinuities in Scandinavian type polythermal glaciers: a modeling study 01.05.2005 Project funding