Complex motion of Greenland Ice Sheet outlet glaciers with basal temperate ice.
Complex motion of Greenland Ice Sheet outlet glaciers with basal temperate ice.
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DOI：
10.1126/sciadv.abq5180
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发表时间：
2023-02-10
期刊：
影响因子：
13.6
通讯作者：
中科院分区：
文献类型：
--
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与冰盖运动相关的不确定性困扰着海平面上升预测。这种不确定性很大程度上源于对物理过程的不完美描述，包括底部滑动和内部冰变形，冰盖模型在很大程度上无法重现基于钻孔的观测。在这里，我们模拟了格陵兰岛快速移动(Sermeq Kujalleq/Store Glacier)和缓慢移动(Isunnguata Sermia)冰盖环境中的孤立三维域。通过结合真实的地质统计模拟地形，我们表明在这两种情况下都会自然形成空间高度可变的温带冰层(压力熔点处的冰要软得多)，同时形成的冰运动模式与使用平滑变化的BedMachine地形获得的冰运动模式有很大差异。温带冰在深海槽中垂直延伸(>；100米)，但在基岩高度上显著变薄(<；5米)，基本滑移率达到地表速度的>；90或约5%，这取决于地形和温带层厚度。开发这种复杂运动的净影响的参数化可以提高预测冰盖模式的真实性。地质统计学上真实的地形迫使格陵兰出口冰川出现复杂的底部滑动和变形模式。
Uncertainty associated with ice sheet motion plagues sea level rise predictions. Much of this uncertainty arises from imperfect representations of physical processes including basal slip and internal ice deformation, with ice sheet models largely incapable of reproducing borehole-based observations. Here, we model isolated three-dimensional domains from fast-moving (Sermeq Kujalleq/Store Glacier) and slow-moving (Isunnguata Sermia) ice sheet settings in Greenland. By incorporating realistic geostatistically simulated topography, we show that a spatially highly variable layer of temperate ice (much softer ice at the pressure-melting point) forms naturally in both settings, alongside ice motion patterns which diverge substantially from those obtained using smoothly varying BedMachine topography. Temperate ice is vertically extensive (>100 meters) in deep troughs but thins notably (<5 meters) over bedrock highs, with basal slip rates reaching >90 or <5% of surface velocity dependent on topography and temperate layer thickness. Developing parameterizations of the net effect of this complex motion can improve the realism of predictive ice sheet models. Geostatistically realistic topography forces complex patterns of basal slip and deformation in Greenland outlet glaciers.
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