Effect of summer accumulation on glacier mass balance on the Tibetan Plateau revealed by mass-balance model
Effect of summer accumulation on glacier mass balance on the Tibetan Plateau revealed by mass-balance model
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DOI：
10.3189/172756500781832945
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发表时间：
2000-01-01
影响因子：
3.4
通讯作者：
Ageta, Y
中科院分区：
文献类型：
--
作者：
Fujita, K;Ageta, Y
利用能量平衡模型，结合水再冻结过程，讨论了青藏高原冷基冰川的特征和敏感性，其中夏季风为冰川提供了大部分物质输入。该模型较好地反映了1992/93年青藏高原小东克玛底冰川物质平衡的观测结果。我们的数据显示，冷冰川的质量平衡不能简单地用表面质量/热量平衡来描述，因为大约20%的渗透水被重新冻结，因此不会从冰川中流失。模型计算表明，干旱环境中的冰川可以保持其质量，因为季风在融化季节提供降水。夏季降雪使地面水汽通量保持较高水平，对消融有很大的抑制作用。然而，计算也清楚地表明，由于夏季的积累，高原上的冰川比其他地区的冰川更脆弱。在季风气候中，变暖不仅会导致堆积的减少，而且会导致消融的急剧增加，同时还会导致地表辐射的降低。因此，尽管高原上及其周边的冰川可以通过夏季积累来维持，但它们比冬季积累型冰川更容易受到变暖的影响。
The characteristics and sensitivities of a cold-based glacier on the Tibetan Plateau, where the summer monsoon provides most of the mass input to glaciers, are discussed using an energy-balance model, incorporating the process of water refreezing. The model accurately represents the observational results related to the mass balance of Xiao Dongkemadi glacier on the central plateau during 1992/93. Our data revealed that the mass balance of cold glaciers cannot simply be described by the surface mass/heat balances, because about 20% of infiltrated water is refrozen and thus does not run off from the glacier. Model calculations demonstrate that glaciers in an arid environment can maintain their mass since the monsoon provides precipitation during the melting season. Snowfall in summer keeps surface albedo high and largely restrains ablation. Nevertheless, the calculations also make clear that glaciers on the plateau are more vulnerable than those of other regions because of summer accumulation. In the monsoon climate, warming would cause not only a decrease in accumulation but also a drastic increase in ablation in combination with surface-albedo lowering. Therefore, although glaciers on and around the plateau can be sustained by summer accumulation, they are more vulnerable to warming than winter-accumulation-type glaciers.