30a来长江源区冰川变化遥感监测

Glacier Change in Headwaters of the Yangtze River in Recent Three Decades

根据地形图、航空相片和Landsat ETM+数字影像,采用比值阈值法对青藏高原东北部长江源区1969/1971—1999/2002年间的冰川变化进行了研究;同时,选取覆盖同一区域(格拉丹东峰北坡)的Landsat MSS(1973年)、Landsat TM(1992年)以及2景2005/2006年获取的1B级ASTER数字遥感影像,进一步分析源区冰川的连续变化规律。结果表明:①研究区的冰川平均退缩了108.3 m,冰川面积减少了5.3%,其中,色的日峰地区的面积变化率最大,冰川面积减少12.9%;唐古拉山北坡冰川相对处于稳定状态,面积仅减少了4.3%。②格拉丹东峰北坡冰川面积变化速率不均匀,1969—1973年冰川面积变化最快,平均变化量为-1.16 km2.a-1,1973年后冰川变化有所减缓,1973—1992年和1992—2002年平均变化量均为-0.59 km2.a-1,而2002年后冰川面积变化又有所加快,平均变化量为-0.95 km2.a-1。③沱沱河、五道梁和治多3个气象站的气温和降水变化显示,暖季气温升高是导致研究区冰川退缩的主要因素,此外,气温升高的快慢可能是引起上述3个区域冰川变化差异的重要原因之一。

Many researches have shown that most glaciers in the world experienced a general reduction in area due to climate warming in recent decades.The glaciers in headwaters of the Yangtze River in the central-northeast part of Qinghai-Tibetan Plateau are mainly distributed in the north-oriented slopes of Mt.Tanggula and Mt.Sedir and the south-oriented slopes of Mt.Kunlun.In this study,the change of glaciers in the whole headwaters was monitored using the 1∶100 000 topographic maps based on the aerial photographs taken in 1969/1971 and the Landsat ETM＋ imageries in 1999/2002.Moreover,Landsat MSS（1973）,Landsat TM（1992） and 2 scenes 2005 and 2006,ASTER images at level 1B,were used to study the change of glaciers in the Geladandong Peak area in multi-periods.It was found that the most glaciers in the headwaters were in a retreat.In general,the glaciers were retreated by 108.3 m in average,and an area of 68.13 km2 was lost,accounting for 5.3% of the total glacier area.There was a significant difference in glacier change rate among the Mt.Tanggula,Mt.Sedir and Mt.Kunlun.Shrinkage of area of the glaciers was 12.9% in the Mt.Sedir,4.3% in the Mt.Tanggula,and 8.3% in the Mt.Kunlun respectively.The results of glacier change in the Geladandong Peak area in multi-periods showed that the reduction of glacier area was the most significant during 1969-1973,about-1.16 km2·a-1,and the glacier area was enlarged by 0.59 km2·a-1 during 1973-2002.However,the reduction of glacier area was accelerated after 2002 with a change rate of-0.95 km2·a-1.Generally,the larger the glacier area was,the lower the glacier change rate would be.According to the statistic analysis,there was a decreasing logarithm relationship（R2=0.91） between the glacier area and the area reduction rate in the study area.The meteorological data observed by Zhiduo,Tuotuohe and Wudaoliang Glacier meteorological stations revealed that the retreat of glaciers in this area may be mainly caused by the increase of air temperature in warm season,and the different extent of temperature increase may be one of the reasons resulting in the different glacier change rate among the Mts.Tanggula,Mt.Sedir and Mt.Kunlun.