Variations in Hard‐Bedded Topography Beneath Glaciers
Variations in Hard‐Bedded Topography Beneath Glaciers
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DOI：
10.1029/2021jf006326
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
J. Woodard;L. Zoet;N. Iverson;C. Helanow
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文献类型：
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作者：
J. Woodard;L. Zoet;N. Iverson;C. Helanow
冰川床的形态是其滑动速度和随之产生的冰下侵蚀速率的一级控制因素。因此，限制冰川下预期的河床形状范围将改善对冰川滑动速度的估计。为了估计冰下床形态的变化，我们利用地面激光扫描和摄影测量技术相结合产生的点云，构建了10个高分辨率（10厘米）的冰川前区域数字高程模型。前冰期地区位于瑞士阿尔卑斯山脉和加拿大落基山脉，主要由各种岩性（火成岩、沉积岩和变质岩）的无碎屑基岩组成。我们测量了八种不同的空间参数，旨在描述冰川下产生的床形态。利用概率密度函数、Bhattacharyya系数、主成分分析和贝叶斯统计模型研究了这些空间参数的显著性。我们发现参数跨越相似的范围，但参数概率密度函数的均值和标准差通常是不同的。这些结果表明，基岩上的冰川流动可能导致向共同床形态的收敛。然而，与每个位置相关的不同属性阻止了形态的统一。
The morphology of glacier beds is a first‐order control on their slip speeds and consequent rates of subglacial erosion. As such, constraining the range of bed shapes expected beneath glaciers will improve estimates of glacier slip speeds. To estimate the variability of subglacial bed morphology, we construct 10 high‐resolution (10 cm) digital elevation models of proglacial areas near current glacier margins from point clouds produced through a combination of terrestrial laser scanning and photogrammetry techniques. The proglacial areas are located in the Swiss Alps and the Canadian Rockies and consist of predominantly debris‐free bedrock of variable lithology (igneous, sedimentary, and metamorphic). We measure eight different spatial parameters intended to describe bed morphologies generated beneath glaciers. Using probability density functions, Bhattacharyya coefficients, principal component analysis, and Bayesian statistical models we investigate the significance of these spatial parameters. We find that the parameters span similar ranges, but the means and standard deviations of the parameter probability density functions are commonly distinct. These results indicate that glacier flow over bedrock may lead to a convergence toward a common bed morphology. However, distinct properties associated with each location prevent morphologies from being uniform.