Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison
Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison
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DOI：
10.3189/2013jog12j129
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发表时间：
2013-04
影响因子：
3.4
通讯作者：
F. Pattyn;L. Perichon;G. Durand;O. Gagliardini;L. Favier;R. Hindmarsh;T. Zwinger;Mismip d Participants
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文献类型：
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作者：
F. Pattyn;L. Perichon;G. Durand;O. Gagliardini;L. Favier;R. Hindmarsh;T. Zwinger;Mismip d Participants
摘要 海洋冰盖行为的预测需要能够模拟接地线迁移的模型。我们展示了平面海洋冰盖模型的比对实验结果。通过使用简化的几何配置（无横向变化，无横向阻力的支撑效应）与接地线通量的近似解析解进行比较来进行验证。指定基础滑动参数空间变化的扰动实验允许弯曲接地线的演变，产生支撑效应。实验显示了穿过接地线的压缩和拉伸流动区域，从而使边界层理论无效。研究发现稳态接地线位置取决于物理模型近似的水平。解决接地线需要包含膜应力、足够小的网格尺寸 (<500 m) 或接地线的子网格插值。后者仍然要求标称网格尺寸<5公里。对于较大的网格间距，可以在接地线上施加适当的冰通量参数化，但是短时瞬态行为是不正确的并且与不结合接地线参数化的模型不同。与预测接地线运动相关的数值误差可以显着减少到低于与未来场景中的参数无知和不确定性相关的误差。
Abstract Predictions of marine ice-sheet behaviour require models able to simulate grounding-line migration. We present results of an intercomparison experiment for plan-view 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 buttressing effects from lateral drag). Perturbation experiments specifying spatial variation in basal sliding parameters permitted the evolution of curved grounding lines, generating buttressing effects. The experiments showed regions of compression and extensional flow across the grounding line, thereby invalidating the boundary layer theory. Steady-state grounding-line positions were found to be dependent on the level of physical model approximation. Resolving grounding lines requires inclusion of membrane stresses, a sufficiently small grid size (<500 m), or subgrid interpolation of the grounding line. The latter still requires nominal grid sizes of <5 km. For larger grid spacings, appropriate parameterizations for ice flux may be imposed at the grounding line, but the short-time transient behaviour is then incorrect and different from models that do not incorporate grounding-line parameterizations. The numerical error associated with predicting grounding-line motion can be reduced significantly below the errors associated with parameter ignorance and uncertainties in future scenarios.