Model experiments on large tabular iceberg evolution: ablation and strain thinning


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djansen [ at ] awi-bremerhaven.de

Abstract

Antarctic tabular icebergs are important active components of the ice ocean system. To investigate the relevance of inherent ice dynamics to iceberg evolution, we developed a numerical model based on the fundamental equations of ice-shelf flow forced by environmental parameters of the ice-ocean-atmosphere system. First model experiments with idealized icebergs of constant density show that the strain thinning rate for a typical iceberg with a thickness of 250 m and a temperature of 15 °C is about 1 m yr-1. Sensitivity studies for different scenarios of environmental conditions confirmed the reliability of our model. A five year simulation of the evolution of iceberg A 38B yielded a mean decrease of thickness from 220 m to 106.3 m, 95 % of which was caused by basal melting, 1 % by surface melting and 4 % by strain thinning. We found iceberg flow decelerating by about 75 % and ice temperatures being strongly affected by progressive erosion of the relatively warm basal layers and simultaneous warming in the uppermost part. According to the model results, basal melting is the primary cause for change of iceberg geometry during drift, whereas strain thinning is only relevant in cold areas where basal melting is low.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
11232
Cite as
Jansen, D. , Sandhäger, H. and Rack, W. (2005): Model experiments on large tabular iceberg evolution: ablation and strain thinning , Journal of glaciology, 51 (174), pp. 363-372 .


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