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Palaeoclimatic evolution and present conditions of the Greenland Ice Sheet in the vicinity of Summit : An approach by large-scale modelling

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タイトル: Palaeoclimatic evolution and present conditions of the Greenland Ice Sheet in the vicinity of Summit : An approach by large-scale modelling
著者: Greve, R. 著作を一覧する
Weis, M. 著作を一覧する
Hutter, K. 著作を一覧する
キーワード: Ice sheets
palaeoclimate modelling
dating of ice cores
発行日: 1998年
出版者: Gordon and Breach
誌名: Palaeoclimates : data and modelling
巻: 2
号: 2-3
開始ページ: 133
終了ページ: 161
抄録: Using the three-dimensional numerical model SICOPOLIS for polythermal land-based ice sheets in the shallow ice approximation, simulations are performed to determine the velocity, temperature and water-content distributions as well as the evolution of the free surface, the cold-temperate-transition surface (CTS) and the basal surface within the Greenland Ice Sheet through time for a climate driving as determined by the (smoothed) GRIP palaeotemperature record. The model is driven by the temperature at the free surface, the global sea level and the geothermal heat flow 5 km below the basal surface. It uses plausible parameterizations for the accumulation and ablation rates, the basal sliding law and the constitutive behaviour (power-law rheology), in which the fluidity difference between glacial and interglacial ice is accounted for by appropriate enhancement factors. Computations that cover 250,000 years of climate history are performed with various sets of parameters to find optimal present conditions when compared with available data. To this end a misfit index is defined, and parameterizations are chosen so as to minimize it. It is shown that dating the ice at depth is crucially dependent on the “flux of age” into the base. However, other parameterizations such as the geothermal heat flow or the basal drag in the sliding law etc. equally influence the present geometry of the ice sheet. We investigate the results of the best-fit simulation with particular attention to the vicinity of Summit, the highest point of the Greenland Ice Sheet at 72°34'N, 37°38'W, in whose vicinity the two deep ice cores GRIP and GISP2 were drilled. For these boreholes, time series for the ice thickness and the basal temperature, present temperature-depth profiles and present age-depth profiles are presented. Furthermore, the ice-surface topography and the ice thickness in the vicinity of Summit is shown, and a comparison with high-resolution RES data is performed.
資料タイプ: article (author version)
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: Greve Ralf


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