Estimate of ablation rate of glacier ice under a supraglacial debris layer
Estimate of ablation rate of glacier ice under a supraglacial debris layer
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DOI：
10.1111/1468-0459.00097
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发表时间：
1999-12
影响因子：
1.5
通讯作者：
M. Nakawo;B. Rana
中科院分区：
文献类型：
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作者：
M. Nakawo;B. Rana
在被碎屑覆盖的冰川上，很难直接测量碎屑层下的烧蚀率，因为冰川表面高度不均匀，而且各地的烧蚀率差异很大。考虑到冰川顶部有碎屑层的热量收支情况，可以根据地表温度和碎屑表面的热通量估计碎屑层的“热阻”，并根据热阻和气象数据估算下面冰川冰的消融率。该方法在尼泊尔喜马拉雅山脉朗唐河谷的利荣冰川上进行了试验，利用陆地卫星的热带估计了碎片顶面的表面温度分布。这样估计的融水量与1985年季风季和1996年季风季前至1996年季风季期间冰川盆地的观测流量数据相符。调查还显示，该流域的流量远大于降雨量，并认为冰川消融对河流流量的贡献很大，因为冰川萎缩。
The ablation rate under a debris layer is very difficult to measure directly at debris-covered glaciers, because the surface is highly heterogeneous, and the ablation rate varies tremendously from place to place. Heat budget considerations with a debris layer on top of glacier ice suggested that ‘thermal resistance’ of the debris layer could be estimated from surface temperature and the heat fluxes at the debris surface, and the ablation rate of the underlying glacier ice from the thermal resistance and meteorological data. The method was tested at the Lirung Glacier in Langtang Valley, Nepal Himalayas, using the thermal band of LANDSAT satellite for estimating surface temperature distribution of the debris top surface. The amount of melt water thus estimated was compatible with the observed discharge data from the glacier basin for periods of the monsoon season in 1985 and the pre-monsoon to the monsoon season in 1996. The investigation also revealed that the amount of discharge was much larger than the amount of precipitation over the basin, and it was suggested that the melt water from the debris-covered glacier contributes significantly to the river flow as a result of the shrinkage of the glacier.