Results of the Marine Ice Sheet Model Intercomparison Project, MISMIP
Results of the Marine Ice Sheet Model Intercomparison Project, MISMIP
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DOI：
10.5194/tc-6-573-2012
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发表时间：
2012-01-01
期刊：
影响因子：
5.2
通讯作者：
Vieli, A.
中科院分区：
文献类型：
--
作者：
Pattyn, F.;Schoof, C.;Vieli, A.
对海洋冰盖行为的预测需要能够稳健地模拟接地线迁移的模型。我们展示了海洋冰盖模型相互比较实验的结果。通过使用简化的几何构型（无侧向变化，无侧向支撑效应）与接地线通量的近似解析解进行比较来进行验证。在向下倾斜的基底上的冰盖存在唯一的稳态接地线位置，而在过深的基底上会出现滞后现象，并且稳定的稳态接地线位置仅出现在向下倾斜的部分。基于浅冰近似（不考虑拉伸应力）的模型，除非在接地线处施加适当的冰通量参数化，否则无法重现近似解析结果。对于考虑拉伸应力的“陆架流”模型，模型结果之间的差异主要是由于空间离散化的选择。移动网格方法被发现是捕捉接地线演化最准确的方法，因为它们明确地追踪接地线。自适应网格细化可以进一步提高准确性，包括在粗分辨率下通常表现不佳的固定网格模型。具有接地线嵌套网格表示的固定网格模型能够生成准确的稳态位置，但在瞬态过程中可能不准确。在相互比较中仅包含了一个全斯托克斯模型，因此“陆架流”模型作为全斯托克斯模型近似的准确性仍有待详细确定，特别是在瞬态过程中。
Predictions of marine ice-sheet behaviour require models that are able to robustly simulate grounding line migration. We present results of an intercomparison exercise for marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no effects of lateral buttressing). Unique steady state grounding line positions exist for ice sheets on a downward sloping bed, while hysteresis occurs across an overdeepened bed, and stable steady state grounding line positions only occur on the downward-sloping sections. Models based on the shallow ice approximation, which does not resolve extensional stresses, do not reproduce the approximate analytical results unless appropriate parameterizations for ice flux are imposed at the grounding line. For extensional-stress resolving 'shelfy stream' models, differences between model results were mainly due to the choice of spatial discretization. Moving grid methods were found to be the most accurate at capturing grounding line evolution, since they track the grounding line explicitly. Adaptive mesh refinement can further improve accuracy, including fixed grid models that generally perform poorly at coarse resolution. Fixed grid models, with nested grid representations of the grounding line, are able to generate accurate steady state positions, but can be inaccurate over transients. Only one full-Stokes model was included in the intercomparison, and consequently the accuracy of shelfy stream models as approximations of full-Stokes models remains to be determined in detail, especially during transients.