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J. A. Åström¹, T. I. Riikilä², T. Tallinen2, T. Zwinger¹, D. Benn^3,4, J. C. Moore^5,6,7, and J. Timonen²

 

¹CSC – IT Center for Science, P.O. Box 405, 02101, Esbo, Finland;

²Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), 40014, Jyväskylä, Finland;

³Department of Geology, University Centre in Svalbard, 9171 Longyearbyen, Norway;

⁴School of Geography and Geosciences, University of St Andrews, Fife, KY16 8ST, UK;

⁵State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing, China;

⁶Arctic Centre, University of Lapland, PL122, 96100 Rovaniemi, Finland;

⁷Department of Earth Sciences, Uppsala University, Villavägen 16, Uppsala, 75236, Sweden.

 

Abstract

A particle-based computer simulation model was developed for investigating the dynamics of glaciers. In the model, large ice bodies are made of discrete elastic particles which are bound together by massless elastic beams. These beams can break, which induces brittle behaviour. At loads below fracture, beams may also break and reform with small probabilities to incorporate slowly deforming viscous behaviour in the model. This model has the advantage that it can simulate important physical processes such as ice calving and fracturing in a more realistic way than traditional continuum models. For benchmarking purposes the deformation of an ice block on a slip-free surface was compared to that of a similar block simulated with a Finite Element full-Stokes continuum model. Two simulations were performed: (1) calving of an ice block partially supported in water, similar to a grounded marine glacier terminus, and (2) fracturing of an ice block on an inclined plane of varying basal friction, which could represent transition to fast flow or surging. Despite several approximations, including restriction to two-dimensions and simplified water-ice interaction, the model was able to reproduce the size distributions of the debris observed in calving, which may be approximated by universal scaling laws. On a moderate slope, a large ice block was stable and quiescent as long as there was enough of friction against the substrate. For a critical length of frictional contact, global sliding began, and the model block disintegrated in a manner suggestive of a surging glacier. In this case the fragment size distribution produced was typical of a grinding process.

 

PUBLISHED BY: THE CRYOSPHERE, 2013, 7: 1591-1602.

 

DOWNLOAD PDF: http://www.the-cryosphere.net/7/1591/2013/tc-7-1591-2013.pdf