Ice-flow characteristics over a rough bedrock: implications for ice-core interpretation
Recent observations in western Dronning Maud Land, Antarctica, point to a relatively high bedrock roughness in the area of the future EPICA drilling site. It is commonly accepted that such a roughness does not favor the interpretation of deep ice cores as basal ice-sheet interactions might disturb t...
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| Format: | Report |
| Language: | English |
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Department of Geography, Vrije Universiteit Brussel
2002
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| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2945 http://id.nii.ac.jp/1291/00002945/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2945&item_no=1&attribute_id=18&file_no=1 |
| Summary: | Recent observations in western Dronning Maud Land, Antarctica, point to a relatively high bedrock roughness in the area of the future EPICA drilling site. It is commonly accepted that such a roughness does not favor the interpretation of deep ice cores as basal ice-sheet interactions might disturb the bottom ice layers. The present study aims at examining the ice-flow characteristics over a strongly undulating bed and investigates its influence on age-depth profiles in the ice sheet.For this purpose a high-resolution time-dependent two-dimensional flowline model was developed (horizontal gridsize ≦ 1km), taking into account all relevant stresses at such a small scale. The model is solved on a fixed finite-difference grid, and compared with a similar model, solving the velocity field according to the shallow-ice approximation. The analysis is presented for sinusoidal bedrock undulations with amplitude-to-wavelength ratio comparable to those observed by radio-echo sounding (D.Steinhage et al., Ann. Glaciol., 29, 267, 1999). Calculations are performed over a period of 300 ka. Results demonstrate that the influence of a high bed roughness on the age-depth profiles is not only confined close to the bed, but near the surface as well, which might affect the interpretation of shallow ice cores. |
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