The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)

The impact of model resolution on the simulated Holocene retreat of the southwestern Greenland ice sheet using the Ice Sheet System Model (ISSM)
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模型分辨率对使用冰盖系统模型（ISSM）模拟格陵兰岛西南部冰盖全新世退缩的影响

DOI：
10.5194/tc-13-879-2019
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发表时间：
2018
期刊：
The Cryosphere
影响因子：
--
通讯作者：
L. Caron
L. Caron
中科院分区：
--
文献类型：
--
作者：
J. Cuzzone;N. Schlegel;Mathieu Morlighem;E. Larour;J. Briner;H. Seroussi;L. Caron

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抽象的。制约格陵兰岛变化的地质档案 全新世冰盖（GrIS）为冰盖模型提供了目标， 测试对过去气候变化的敏感性和模式制定。甚至 随着数据模型比较变得越来越普遍，许多模型模拟 在过去，GrIS的行为依赖于具有粗糙 水平分辨率（≥10 km）。在这项研究中，我们探讨了 模拟西南地区撤退性质的模式分辨率 全新世期间的格陵兰岛。四个模拟进行使用冰 板材系统模型（ISSM）：三种使用统一网格和水平网格 分辨率为20、10和5 km，以及使用非均匀网格的网格， 分辨率范围为2至15公里。我们发现模拟撤退可以 在不同水平分辨率的模型之间差异很大， 取决于河床地形的分辨率在地势低洼地区， 起伏，水平分辨率在模拟中起着微不足道的作用 不同的撤退，而每一个模型，而不是类似的反应， 由表面质量平衡（SMB）驱动的撤退。相反，在床 地形复杂，地势高，如峡湾，分辨率较低的模型（10和20公里）模拟不切实际的撤退， 冰面下降与河床地形中的隆起相交， 否则使用较高分辨率的网格将其解析为槽。我们 结果强调了高分辨率网格在 模拟复杂河床地形区域的后退，但也表明， 使用非均匀网格的模型可以节省计算资源， 粗化非复杂河床地形区域的网格， 主要驱动撤退。此外，这些结果强调， 当调整模型参数以匹配时，必须与冰盖模型一起使用 重建的边缘，特别是对于区域中的低分辨率模型 其中复杂的河床地形难以分辨。
Abstract. Geologic archives constraining the variability of the Greenland ice sheet (GrIS) during the Holocene provide targets for ice sheet models to test sensitivities to variations in past climate and model formulation. Even as data–model comparisons are becoming more common, many models simulating the behavior of the GrIS during the past rely on meshes with coarse horizontal resolutions (≥10 km). In this study, we explore the impact of model resolution on the simulated nature of retreat across southwestern Greenland during the Holocene. Four simulations are performed using the Ice Sheet System Model (ISSM): three that use a uniform mesh and horizontal mesh resolutions of 20, 10, and 5 km, and one that uses a nonuniform mesh with a resolution ranging from 2 to 15 km. We find that the simulated retreat can vary significantly between models with different horizontal resolutions based on how well the bed topography is resolved. In areas of low topographic relief, the horizontal resolution plays a negligible role in simulated differences in retreat, with each model instead responding similarly to retreat driven by surface mass balance (SMB). Conversely, in areas where the bed topography is complex and high in relief, such as fjords, the lower-resolution models (10 and 20 km) simulate unrealistic retreat that occurs as ice surface lowering intersects bumps in the bed topography that would otherwise be resolved as troughs using the higher-resolution grids. Our results highlight the important role that high-resolution grids play in simulating retreat in areas of complex bed topography, but also suggest that models using nonuniform grids can save computational resources through coarsening the mesh in areas of noncomplex bed topography where the SMB predominantly drives retreat. Additionally, these results emphasize that care must be taken with ice sheet models when tuning model parameters to match reconstructed margins, particularly for lower-resolution models in regions where complex bed topography is poorly resolved.