1964—2010年青藏高原长江源各拉丹冬地区冰川变化及其不确定性分析

Variation and Uncertainty Analysis of the Glaciers in the Past 50 Years in Geladandong of Tibetan Plateau

利用1964年美国CORONA间谍卫星影像和1976-2010年的Landsat MSS/TM/ETM+遥感影像,对青藏高原长江源各拉丹冬地区的冰川进行监测,获得每10a间隔的冰川面积数据,并对冰川制图中的不确定性进行了评估.由于冰川表面比较洁净,认为该地区冰川变化的不确定性主要由分辨率(Landsat)和人为操作差异造成,误差可达1%～2%.通过对比发现:1964-2010年间,各拉丹冬地区冰川面积总体上减少了45.75km2,相对变化为6.80%,冰川年平均变化速度约为0.99km2·a-1,相对变化速度为0.15%·a-1;该地区冰川总体退缩较为缓慢,但部分冰川变化显著,在138条冰川中,有14条大冰川存在较为明显的变化.在过去的近50a中,该地区的冰川并不是都呈退缩状态,先后有9条冰川出现过前进的现象,其中有1条冰川一直处于前进状态,长江源头冰川(姜古迪如北支冰川)先后出现过两次前进,分别发生在1964-1977年间和2000-2010年间.

The dataset of glacierized area in Geladandong,with 10 years interval,was established on the CORONA satellite images in 1964 and the Landsat MSS/TM/ETM images from 1976 to 2010.As the glacierized surface is relatively clean,the uncertain of glacierized area,about 1%-2% of the total area,mainly caused by the satellite image resolution(Landsat) and different operators.The contrast of glacierized area in different periods shows that the total glacierized area in Geladandong decreased by 45.75 km2 from 1964 to 2010 and the relative change amount was 6.80%;the annual average change rate was 0.99 km2·a-1 and the relative change rate was 0.15%·a-1.Generally the glacier in Geladandong retreated slowly.Among 138 glaciers there are 14 ones having significant changed in the past 50 years and not all the glaciers having retreated.Nine glaciers had advanced at different periods and one of them advances all the time.There is a glacier at the source of the Yangtze River(north branch of Jianggudiru Glacier) having advanced twice during the periods of 1964-1977 and 2000-2010.