Adaptive mesh refinement versus subgrid friction interpolation in simulations of Antarctic ice dynamics
Adaptive mesh refinement versus subgrid friction interpolation in simulations of Antarctic ice dynamics
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DOI：
10.1017/aog.2016.13
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发表时间：
2016-09-01
影响因子：
2.9
通讯作者：
Ng, E. G.
中科院分区：
文献类型：
--
作者：
Cornford, S. L.;Martin, D. F.;Ng, E. G.
至少在传统的静水冰盖模型中，可以通过修改离散化方案来减少与接地线动力学相关的数值误差。这些涉及更改接近接地线的基础牵引力和/或驱动应力的积分公式，并在 MISMIP3d 实验中表现出较低（如果仍然是一阶）误差。 MISMIP3d 可能无法代表真实冰流的多样性，因为它缺乏强大的侧向应力，并且在接地线上施加了很大的基础牵引力。我们使用 BISICLES 自适应网格冰盖模型研究整个南极冰盖极端强迫模拟背景下的分辨率敏感性，该模型具有两种方案：原始处理方案和修改基础牵引力离散化的方案。对于给定的网格间距，第二种方案确实提高了精度 - 大约提高了两倍。 1公里分辨率还是有必要的。例如，在较粗分辨率的模拟中，思韦茨冰川后退的速度非常缓慢，以至于其他冰流改变了其树干的方向。相比之下，与。 1公里的网格，同一冰川退缩的速度要快得多，并在任何此类转移发生之前一个世纪引发了南极西部崩塌的最后阶段。
At least in conventional hydrostatic ice-sheet models, the numerical error associated with grounding line dynamics can be reduced by modifications to the discretization scheme. These involve altering the integration formulae for the basal traction and/or driving stress close to the grounding line and exhibit lower - if still first-order - error in the MISMIP3d experiments. MISMIP3d may not represent the variety of real ice streams, in that it lacks strong lateral stresses, and imposes a large basal traction at the grounding line. We study resolution sensitivity in the context of extreme forcing simulations of the entire Antarctic ice sheet, using the BISICLES adaptive mesh ice-sheet model with two schemes: the original treatment, and a scheme, which modifies the discretization of the basal traction. The second scheme does indeed improve accuracy - by around a factor of two - for a given mesh spacing, but. 1 km resolution is still necessary. For example, in coarser resolution simulations Thwaites Glacier retreats so slowly that other ice streams divert its trunk. In contrast, with. 1 km meshes, the same glacier retreats far more quickly and triggers the final phase of West Antarctic collapse a century before any such diversion can take place.