The impact of spatially-variable basal properties on outlet glacier flow
The impact of spatially-variable basal properties on outlet glacier flow
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DOI：
10.1016/j.epsl.2019.03.026
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发表时间：
2019-06-01
影响因子：
5.3
通讯作者：
Holschuh, Nicholas
中科院分区：
文献类型：
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作者：
Koellner, Stephen;Parizek, Byron R.;Holschuh, Nicholas
空间可变的基流法建议从思韦茨冰川，南极洲西部的地球物理数据产生模拟的冰流响应变暖，显着不同的响应通常假设的空间均匀流动的法律，未来海平面上升的影响。与许多冰盖出口不同，思韦茨流过而不是沿着突出的地形流动，硬的风暴面，其中形状阻力被认为给出了低应力指数的基底流动规律，软的背风侧冰碛可能给出接近塑性的行为。将PSU 2-D高阶流线模型应用于一系列理想化的Thwaites状地形，我们测试了近塑性、近粘性和空间可变的基底流变学对强制接地线演变的影响。与以前的研究结果一致，对于空间均匀的基底流变学，接地线后退的时间和速率强烈依赖于床指数，其中塑性流变学促进在电流接地线处的更长稳定性，但是一旦不稳定则更快地消退。此外，我们发现，撤退的混合流变床是敏感的波长的基础地形。对于出口冰川流穿过长波长隆起（大于或类似于10 km），行为福尔斯之间的均匀粘性和塑料床，但更接近塑料。然而，在较短波长的地形，有时，接地线撤退是慢于任何一个均匀流变端元。因此，在冰盖模型中准确地考虑可变的基底条件对于改进退缩的时间和幅度的预测至关重要。(C)2019作者由爱思唯尔公司出版。这是一篇开放获取的文章，获得了CC BY-NC-ND许可证（http：//creativecommons.org/licenses/by-nc-nd/4.0/）。
The spatially variable basal flow law suggested by geophysical data from Thwaites Glacier, West Antarctica produces modeled ice-flow response to warming that differs notably from the response of commonly assumed spatially uniform flow laws, with implications for future sea-level rise. Unlike many ice-sheet outlets, Thwaites flows across rather than along prominent topography, with hard stoss faces where form drag is understood to give a low-stress-exponent basal flow law and soft lee-side tills likely to give nearly-plastic behavior. Applying the PSU 2-D higher-order flowline model to a range of idealized Thwaites-like topographies, we test the impact of nearly plastic, nearly viscous, and spatially variable basal rheology on forced grounding-line evolution.In agreement with previous findings, for spatially uniform basal rheology, the timing and rate of grounding-line retreat depend strongly on the bed exponent, with plastic rheology promoting longer stability at the current grounding line but faster retreat once destabilized. Additionally, we find that retreat over mixed-rheology beds is sensitive to the wavelength of the basal topography. For outlet glacier flow across long-wavelength bumps (greater than or similar to 10 km), behavior falls between that for uniform viscous and plastic beds, yet closer to plastic. However, over shorter-wavelength topography, at times, grounding line retreat is slower than for either uniform-rheology end-member. Accurately accounting for variable basal conditions in ice-sheet models thus is critical for improving projections of both the timing and magnitude of retreat. (C) 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).