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Dynamics of the Antarctic ice sheet and environmental change
Pattyn, F.; Decleir, H.; Willaert, D. (1997). Dynamics of the Antarctic ice sheet and environmental change, in: Caschetto, S. (Ed.) Belgian research programme on the Antarctic: scientific results of phase III (1992-1996): 3. Glaciology and climatology. pp. A3/03/002/1-65
In: Caschetto, S. (Ed.) (1997). Belgian research programme on the Antarctic: scientific results of phase III (1992-1996): 3. Glaciology and climatology. Belgian scientific research programme on Antarctica. Federal Office for Scientific, Technical and Cultural Affairs: Brussel. 149 pp.
In: Belgian scientific research programme on Antarctica. Belgian Science Policy Office: Brussel.
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| Auteurs | | Top |
- Pattyn, F.
- Decleir, H.
- Willaert, D.
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| Abstract |
In this study we examined (i) the stability of the ice sheet in East Dronning Maud Land and Enderby Land where it is drained by a large fast-flowing continental ice stream (Shirase Glacier) and (ii) the regional behavior of the Antarctic ice sheet in East Dronning Maud Land in function of environmental change over a period of the last 200,000 years. Both tasks were accomplished by numerical modeling of the ice sheet system and by satellite remote sensing. For this purpose, a high resolution two-dimensional time-dependent flow line model was developed, taking into account grounded ice, ice shelf and ice stream mechanics, basal motion and isostatic adjustment. Furthermore the two-dimensional temperature field is calculated and coupled to the flow field. The model is numerically solved on a fine grid, which is unequally spaced both in the horizontal and vertical directions. An analysis of ice stream dynamics under different basal conditions revealed a thermally regulated cyclic behavior, strongly related to the hydraulic conditions at the bed. Applying this mechanism to Shirase Glacier, a possible explanation is given tor the rapid ice sheet thinning which is at present observed in Shirase Drainage Basin. Our modeling experiments showed that this thinning could not be solely attributed to the local imbalance due to Holocene ice sheet retreat. For the paleo-reconstruction of the ice sheet in East Dronning Maud Land, the model was forced with the climate signal in the past and eustatic sea-level variations. The outcome of the experiments was then compared to the geomorphological evidences on past glacier stands in the Sør Rondane Mountains. Results of the 'best fit' scenario showed that the present ice sheet in the Sør Rondane is close to its maximum position of the last glacial-interglacial period, which corroborates the small differences found between the level of present active and Last Glacial Maximum moraines. The model experiments also indicate glacier variations over the last 200,000 years of the order of 100-150 m, which are however very dependent on the position on the glacier (seaward, inland, inside the mountain range) highlighting the damming effect of the coastal mountains. Finally a method is presented to inter surface glacier velocities trom sequential satellite imagery and successfully applied to the ice fall area of a glacier in the Sør Rondane. |
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