近20年长江源头各拉丹东冰川变化及其对气候变化的响应

Stepped-up melt of glaciers in the headwaters of Geladandong and its response to climate warming in recent 20 years

基于1992、2002、2008年三个时相TM数字遥感影像和1：10万地形图数据,通过目视解译方法提取冰川面积,研究了青藏高原腹地长江源头各拉丹东地区冰川变化问题。结果表明：各拉丹东地区总冰川面积自1992年以来呈持续下降趋势,面积由1992年的931.59km2减少至2002年的927.66km2,至2008年时缩减至915.13km2。1992~2008年冰川面积共减少了16.46km2,年平均递减约1.03km2,总面积减少约1.77%。2002-2008年总面积下降约1.35%,约为1969-2000年的31a间冰川消融面积的80%,表明近二十年青藏高原腹地冰川退缩速率明显加快。进一步分析发现,面积较小的冰川其消融或退缩速度更快,面积较大的则相对较为缓慢。在总体退缩趋势下,2号冰川末端部分地区2002年出现了增长趋势,其变化趋势表现为：退缩-短暂前进-退缩。对影响冰川变化气候因子分析表明,近几十年青藏高原地区升温所引起的气候变暖是影响20世纪90年代中期以来该地区冰川加速消融的根本原因,气候显著变暖冰川明显退缩。

Dynamic change of Geladandong glaciers in area of headwaters of the Yangtze River in the hinterland of Qinghai-Tibetan Plateau were analyzed by using the 1992,2002,2008 Landsat satellite TM image and 1：100,000 topographic map and the method of man-machine visual conversation discriminated glaciers area manually.It was found that the total area of glaciers showed a distinctly decreasing trend since 1992.Glacier area was 931.59km2,927.66km2,and 915.13km2in 1992,2002 and 2008 respectively.Reduced area was about 1.77% from 1992 to 2008 and about 1.35% during 2002 ~ 2008 which was approximately 80% area that decreased from 1969 to 2000.It indicated the decrease rate of glacier area was significant greater than previous period in the hinterland of Qinghai-Tibetan Plateau.Furthermore,the results showed a greater melting pace in smaller glacier area than larger area.The pattern of some glaciers variation can be summarized as follows： ＂ Withdrawal-short-term advance-retreat＂.The glacier variation respond to temperature and precipitation showed a strong corresponding in this area,it is implied that climate warming dominated a quickly decreases of glacier area since mid-1990s.