天山乌鲁木齐河源1号冰川夏季消融期内反射率的变化

Variations of Albedo on the Glacier No. 1 at the Headwater of Urumqi River, Tianshan Mountains, During the Summer Ablation Period

The variations of the albedo on the glacier No. 1 were investigated during the summer ablation period in 1983. In the wide ablation area situated under snow-line of the glacier where granular snow and glacial ice appeared, main factors controlling the variation of the albedo are the rate of dusting and thickness of snow-cover. The albedo decreased with the increase of grain size and water content of granular snow for thick snow layer. Owing to the effect of snowfall on the albedo of glacier surface remains longer at higher elevations, so that frequent snowfall and subsequent melting cause large variation of albedo during the summer ablation period, especially in the lower part of the glacier. Based on analysis and computation of spatial variation of main affecting factors and real field observed data at the HB-1 and OS-2 Sites as well as along glacial cross-section (from A to G), the groph reflecting relationship between the albedo and altitude of the locality has been constructed. On their basis, the distribution chart of mean value of glacial albedo was plotted in figure. Corresponding to the variations in the field of albedo, the albedo of the physical surface of east-branch of Glacier No 1 changed from 70% to 25% during the sumu.er ablation period.