中国西部冰川度日因子的空间变化特征

Spatial Variation of Degree-day Factors on the Observed Glaciers in Western China

在冰川与积雪消融研究中,度日模型应用较为广泛,该模型是基于冰雪消融与气温,尤其是正积温之间的线性关系建立的。度日因子是该模型的重要参数,反映了单位正积温产生的冰雪消融量,其空间变化特征对于不同模型模拟冰雪消融过程的精度有较大影响。本文根据中国西部不同地区数十条冰川的短期考察和观测资料,分析了西部冰川度日因子的空间变化特征,结果表明:由于青藏高原及其周围地区独特的气候和热量条件,西部冰川度日因子具有明显的区域特征。在同一冰川上,度日因子的空间变化较为明显。从冰川类型来看,与极大陆型及亚大陆型冰川相比,海洋型冰川的度日因子较大。总体看来,西部冰川的度日因子由西北向东南逐渐增大,这与中国西部冰川的气候环境变化趋势是一致的,即在干冷的气候条件下,度日因子较小;而在暖湿的气候条件下度日因子较大。

Degree-day factor is an important parameter of degree-day model which is a widely used method for ice and snow melt computation. Spatial variations of a degree-day factor have great impacts on the accuracy of snow or ice melt modeling. This paper analyzes the spatial variability characteristics of the degree-day factors obtained from the observed glaciers of different regions in western China. Results clearly show that the regional patterns of the degree-day factors are detectable on the observed glaciers of western China due to the unique climatic environment and heat budget of the Tibetan Plateau and the surrounding areas; the factors of maritime glaciers are higher than those of the sub-continental and extremely continental glaciers because of the ablation area covered with a thin debris layer in the maritime glacier; for a single glacier, the degree-day factors are subject to significant small-scale variations. In general, the regional patterns of the degree-day factors are detectable on observed glaciers due to the unique climatic environment and heat budget of the Tibetan Plateau and the surrounding areas. Low degree-day factors can be expected for cold-dry areas, whereas, high degree-day factors can be expected for warm-wet areas in western China.