Sensitivity of a Greenland ice sheet model to ice flow and ablation parameters: consequences for the evolution through the last climatic cycle
Sensitivity of a Greenland ice sheet model to ice flow and ablation parameters: consequences for the evolution through the last climatic cycle
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格陵兰冰盖模型对冰流和消融参数的敏感性：上一个气候周期演变的后果
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
A. Letréguilly
中科院分区：
文献类型：
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作者：
C. Ritz;A. Fabre;A. Letréguilly
抽象的。灵敏度实验进行测试的影响，鲜为人知的模型参数的模拟格陵兰冰盖的三维数值模式，包括冰内的机械和热过程的装置。两种类型的实验进行：稳态气候条件和模拟在过去的气候周期与气候强迫来自GRIP记录。实验表明，冰盖最大高度取决于冰流参数（变形系数、滑动律系数、地热通量），当冰流速度快时，冰盖最大高度较低。另一方面，最大高度对烧蚀强度不敏感，因此在气候循环期间，它是由累积速率的变化驱动的。冰盖的扩展表现出相反的敏感性：它几乎不受冰流速的影响，大消融系数的冰覆盖面积较小。对于较冷的气候，当没有消融时，冰盖的延伸取决于海平面。一个有趣的结果是，随着时间的变化的高度在冰分水岭（首脑会议）不依赖于我们测试的参数。本模拟冰盖的气候循环实验结果进行比较，以找到一组参数，使模拟和测量的几何形状之间的最佳拟合与目前测量的冰盖。与最常用的参数集相比，似乎必须使用更高的消融率系数。
Abstract. Sensitivity experiments are conducted to test the influence of poorly known model parameters on the simulation of the Greenland ice sheet by means of a three dimensional numerical model including the mechanical and thermal processes within the ice. Two types of experiments are performed: steady-state climatic conditions and simulations over the last climatic cycle with a climatic forcing derived from the GRIP record. The experiments show that the maximum altitude of the ice sheet depends on the ice flow parameters (deformation and sliding law coefficients, geothermal flux) and that it is low when the ice flow is fast. On the other hand, the maximum altitude is not sensitive to the ablation strength and consequently during the climatic cycle it is driven by changes in accumulation rate. The ice sheet extension shows the opposite sensitivity: it is barely affected by ice flow velocity and the ice covered area is smaller for large ablation coefficients. For colder climates, when there is no ablation, the ice sheet extension depends on the sea level. An interesting result is that the variations with time of the altitude at the ice divide (Summit) do not depend on the parameters we tested. The present modelled ice sheets resulting from the climatic cycle experiments are compared with the present measured ice sheet in order to find the set of parameters that gives the best fit between modelled and measured geometry. It seems that, compared to the parameter set most commonly used, higher ablation rate coefficents must be used.