Assessing ice-cliff backwasting and its contribution to total ablation of debris-covered Miage glacier, Mont Blanc massif, Italy
Assessing ice-cliff backwasting and its contribution to total ablation of debris-covered Miage glacier, Mont Blanc massif, Italy
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DOI：
10.3189/2014jog13j045
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发表时间：
2014-02
影响因子：
3.4
通讯作者：
T. Reid;B. Brock
中科院分区：
文献类型：
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作者：
T. Reid;B. Brock
摘要 连续的表面碎片覆盖极大地减少了冰川的消融，但在太陡而无法容纳碎片的冰崖上可能会出现高融化率。本研究基于现场测量、物理融化模型和使用高分辨率 (1 m) 数字高程模型 (DEM) 绘制的冰崖地图，评估了 2010 年和 2011 年意大利勃朗峰地块 Miage 冰川总体消融的冰崖回流影响。短期模型计算与测量的熔化速率非常匹配。模型敏感性分析表明，悬崖坡度和反照率对烧蚀的影响比太阳加热碎片增强的长波入射或受庇护的悬崖底部湍流通量的减少更为重要。 DEM 分析表明，冰崖最多占冰川碎片覆盖区域 1 m 像素的 1.3%，但分布式模型的应用表明，冰崖约占总消融量的 7.4%。我们得出的结论是，冰崖对碎片覆盖的冰川的消融做出了重要贡献，即使它们的空间范围非常小。
Abstract Continuous surface debris cover strongly reduces the ablation of glaciers, but high melt rates may occur at ice cliffs that are too steep to hold debris. This study assesses the contribution of ice-cliff backwasting to total ablation of Miage glacier, Mont Blanc massif, Italy, in 2010 and 2011, based on field measurements, physical melt models and mapping of ice cliffs using a high-resolution (1 m) digital elevation model (DEM). Short-term model calculations closely match the measured melt rates. A model sensitivity analysis indicates that the effects of cliff slope and albedo are more important for ablation than enhanced longwave incidence from sun-warmed debris or reduced turbulent fluxes at sheltered cliff bases. Analysis of the DEM indicates that ice cliffs account for at most 1.3% of the 1 m pixels in the glacier’s debris-covered zone, but application of a distributed model indicates that ice cliffs account for ~7.4% of total ablation. We conclude that ice cliffs make an important contribution to the ablation of debris-covered glaciers, even when their spatial extent is very small.