近23年来北天山冰川面积变化对气候的响应

Response of glacier area variation to climate change in northern Tianshan Mountains in the past 23 years

利用1989、1998、2011年的Landsat TM、ETM+遥感影像为数据源,运用比值阈值法(b3/b5)结合目视解译方法,提取了北天山3个时段的冰川边界,并在地理信息系统技术支持下分析了该区域冰川的变化情况。研究表明:北天山整体变化幅度较大,冰川表现为萎缩的趋势,近23年来冰川面积减小了14.93%。分析认为,较大的变化率是由于研究区面积<1km2的冰川数量占总数的比重较大(近80%)造成的。同时分析了北天山冰川空间结构特征,<0.5km2面积的冰川对气候变化最为敏感,消融率最高,1～5km2面积的冰川对消融总量贡献比例最大。依据分形理论对未来冰川变化进行初步预测,分析认为研究区冰川的消融率仍保持比较高的状态。

The northern Tianshan Mountain region was selected to search a method for delineating glacier extent by Landsat TM,ETM＋ image of 1989,1998 and 2011.The study area for glaciers was extracted by using the remote sensing image processing and analyzing method,and the changes of glaciers in the study area were analyzed under the support of the geographic information systems technology.The results indicate that the amplitude of the whole change of glaciers in northern Tianshan Mountain is large and glaciers have retreated rapidly during the study period 1989 to 2011.In the study period,the total area for the investigated glaciers have reduced by 14.93%.The paper analyzed the reasons of the large change rate of glaciers,and the results indicate that the large change rate of glaciers is caused by the large proportion of small glaciers,whose glaciers smaller than 1km2 for nearly 80% in total glaciers in northern Tianshan.At the same time,the distribution characteristics of spatial structure for the glaciers in the northern Tianshan were analyzed,and the results show that those glaciers with area smaller than 0.5km2 have the highest degree of response to climate change.Meanwhile,the ablation of glaciers with area from 1km2 to 5km2 account for the largest percentage of the total ablation.Finally,based on the fractal theory,the future changes were analyzed,it shows that the melting rate of glaciers in the study area will remain high affected by the climate warming which is mainly caused by the area and length changes of these glaciers.