Sun Zuozhe, Chen Yaowu, You Genxiang, Han Jiankang
The flow measurement of Glacier No. 1 has been taken since 1980 and data have been analysed on the basic theory of glaciology. Following characteristics are noticeable:1. Both tributaries of Glacier No. 1 have two areas with high speed. At the western one, the first located on c-profile is due to the narrowing of the channel, the second occupies the region beyond i-profile because the cirque back-wall is with steep slope. The variation of the longitudinal velocity profile on the eastern tributary,with high velocity areas occurring near i′-and d′-profile respectively, is less serious than that on the western. The transverse profiles of flow velocity, in general, opposite to the situation of ice motion in valley glacier, show obvious asymmetry which reflects the character of the channel.2. Velocity vectors near the snow-line run parallel to the slope of ice surface, while in accumulation area they are inclined into the ice and in the glacial tongue area they point from inside the ice to ice surface. This is similar to that found in other cirque and valley glaciers. Velocity vectors in Glacier No.1, with exception of b-profile on western tributary, all converge towards flow centre-line. This anomaly in ablation area is caused by the narrowing of the channel in the lower reaches. Divergence of vectors, which should appear in the glacial tongue area, is offset by the convergence.3. Velocity on c-profile at western tributary has a day and night variation with a propertion of 2,42: 1. From measurements we see that as a process ice flow contains a series of jerks.Comparison between the two meassurement years, i. e. 1980-1981 and 1981-1982, shows that the velocity on western tributary became lower, while on eastern tributary, in contrast, went up. Daily mean velocity obtained during ablation seasons in 1980 was 30% less than in 1973. And annual velocity in May 1980-May 1981 was lowered 31-73% than the arerage of 1959-1962. This resulted from the thinning of ice and the flattening of ice slope. Comparison of maps drawn in 1973 and in 1980, shows that thinning of ice mass at different degree took place at both tributaries. In ablation area, the eastern tributary thinned more strongly than the western one, while in accumulation area, conversely. Near the snow-line of the western tributary, ice surface lowered by 8 m, and velocity decreased by 67%.4. There exists obvious emergence velocity on Glacier No. 1. It can offset ice ablation by 0.25-0.5 or so. Thus, it is reasonable to think that in order to keep the balance in ice mass in ablation area, ice must be continuously transported here, It depends on both horizontal and emergence movement components.
