近40年来天山东段冰川变化及其对气候的响应

Response of glacier variations in the eastern Tianshan Mountains to climate change,during the last 40 years

利用经1959/1961年航片校正的地形图、1972年航片和1992年TM、2001年ETM+遥感影像,通过遥感图像处理和人工目视解译,分析了天山东段哈尔里克山区1959/1961-2001年的冰川变化。结果表明,1959/1961-2001年冰川面积和储量减少量分别占1959/1961年的11.4%和12.3%。其中,20世纪50年代末到70年代初,冰川退缩幅度大,冰川面积和储量年减少率分别约为0.51%和0.508%,20世纪70年代初到90年代初,退缩大幅减缓,冰川面积和储量年减少率为0.1%和0.13%,90年代以后退缩速度又有加剧趋势,冰川面积和储量年减少率增加到0.31%和0.34%。对流域气象站气候资料分析发现,1959/1961-1972年的冰川面积减少率大,主要与1959-1966年时段气温偏高、而降水偏少有关。升温幅度的增大是影响20世纪90年代初以来研究区冰川退缩加剧的根本原因。

Mountain glaciers are one of potential climate indicators because they are sensitive to climate changes Glacier area and volume variations in the Karlik Mountain, the eastern Tianshan Mountains, from 1959/1961 to 2001 were analyzed in this paper. The topographic maps of 1 ： 100 000 scales in 1959/1961, 1972 aerial photographs and satellite images （Landsat TM and ETM ＋ ） from 1992 and 2001 was used to map the surface area of glaciers and in this region through a process of manual digitizing on a false color composite of bands 5, 4, 3 （ red, green, blue）. Glacier volumes were calculated using the experience formula developed by Liu and others, based on the relation between glacier area and volume. The results indicate that the glacier area and volume over the Karlik Mountain shrunk by 11.4% and 12.3%, respectively, in the last 40 years. The rate of the glacier area decrease was 0.51% ·a^-1 over the interval 1959/1961 - 1972,and decreased to 0.1% ·a^-1 between 1972 and 1992, but increased by about three times （0.31% ·a^-1 ） from 1992 to 2001, which indicated accelerated glacier retreat in recent decades. In the same way, the volume of the Karlik mountain glaciers was reduced with the rates of 0.508% ·a^-1 from 1959/1961 to1972, 0.13% ·a^-1 during 1972 -1992, and 0.34% ·a^-1 from 1992 to 2001, respectively. Glacier changes in the eastern Tianshan Mountains have a significant response to increasing summer temperatures. Analysis of the climate records of over the last 40 years from the Yiwu meteorological station also showed a precipitation rise in winter and summer from 1959, but these could not compensate for the mass loss due to ablation. The large shrinkage of Karlik mountain glaciers from 1959/1961 to 1972 can be attributed to the warm and dry climatic events during 1959 -1966. The sharp increase in summer air temperature resulted in the accelerated glacier recession in this region since the 1990s.