The Ice Temperature of Bogda Fan-Shaped Diffluence Glacier in Bogda Area, Tian Shan
Ren Jiawen (Lanzhou Institute of Glaciology and Cryopedology, Academia Sinica)
Although the glaciers in Bogda area of Tian Shan were investigated in past years, the ice temperature observation was carried out only for the first time. During the joint expedition to Bogda area by Chinese and Japanese glaciologists, a 20 m deep hole was bored with steam drill at some 3750 m a. s. 1. in the upper ablation area of the Bogda Fan-shaped Diffluence Glacier on July 29, 1981. Seventeen thermal resistor thermometers were put into the hole at intervals of 1-2 m, and four observations were taken respectively on 8, 11, 13 and 15 August. Analysis of the records shows that there was a zero temperature layer of liquid water at least 0.5 m deep on the glacier surface in summer. The ice temperature dropped with the increase in depth, and the lowest, being about -3℃, located in the layer 4-7 m deep. Below this layer, temperature went up in a vertical gradient γ=0.148℃/m, and reached the pressure melting point at about 26 m deep. Besides, it was calculated that the equilibrium temperature at the lower limit of the active layer at the equilibrium line of the glacier T0 (l6)E equals to -3.4??. Thus, there might be temperate ice in the lower layer of the glacier. The ice temperature of Bogda Fan-shaped Diffluence Glacier may be higher than other glaciers in Northwest China. Further observation of this glacier may provide new informations for the classification of the continental type glaciers in China.