1976-2010年祁连山中段岗格尔肖合力雪山冰川退缩和气候变化的关系研究

Climate change and glacier retreat in Ganggeexiaoheli,middle Qilian Mountains using remote sensing data,1976-2010

运用最大似然监督分类法和比值阈值法(TM3/TM5)结合目视解译方法,从1976、1990、2001和2010的MSS、TM、ETM影像中提取了岗格尔肖合力雪山四个时段的冰川边界,并结合距其较近的托勒、野牛沟、祁连、德令哈和刚察5个气象站点1960-2010年年总降水量数据和年平均气温数据进行了分析,得到如下结论:1)岗格尔肖合力冰川变化特征是:a、35年来,冰川处在持续退缩状态;b、近10年来,冰川消融速度加快;c、35年来,规模较大冰川消融分解,而规模较小冰川消失;d、低海拔地区退缩比高海拔地区迅速;e、南坡、东南坡和西南坡退缩较快,北坡、西北坡退缩较慢,其余坡向介于两者之间;2)近半个世纪来的气候变化特征是:a、该区增温趋势较明显;b、该区的降水虽有少量增加,但趋势却很不明显;3)冰川变化与气候变化的关系是:a、35年来,冰川退缩的主要原因是温度的升高;b、近10年来,冰川加速消融反映了2000年后的温度变化特征;c、规模小的冰川对气候变化的反应较敏感;d、低海拔地区的冰川对气候变化的反应较敏感;e、南坡、东南坡和西南坡冰川对气候变化的反应较敏感。

This paper presents an analysis of precipitation and temperature trends and glacier changes in Ganggeexiaoheli of Middle Qilian Mountains.Trend analysis for the period from 1960 to 2010 at five selected meteorological stations showed a pronounced temperature increase.For precipitation,there was a small increase on average,but no clear trend.The glacier outlines of 1976 were delineated using maximum likelihood classification from a Landsat MSS Scene then improved manually.The glacier outlines of 1990,2001 and 2010 were delineated in a semi-automated way using band TM3/TM5 ratio images of Landsat TM or ETM scenes.The decrease in glacier extent was 68.60% between 1976 and 2010 because of temperature rising and a rapid and accelerating shrinkage in the last decade was detected,which was consistent with the temperature increase in the same period.The glacier retreat was not homogeneous.128 of 132 glaciers of 1976 with area less than 3 km2 disappeared and the other four glaciers with area larger than 3 km2 were split into 34 small glaciers in 2010.Shrinkage rate of glaciers with low elevation was higher than that with high elevation,which indicated that glaciers with low elevation were much more sensitive to climate changes.Overall,south,southeast and southwest facing glaciers shrank mostly,which indicated that glaciers on those aspects were more sensitive to climate changes in this region.Given the temperature increase in the future,based on IPCC,the glaciers in this region will continue to retreat.In the short-term,as glaciers retreat and lose mass,they add to a temporary increase in runoff,thereafter their contribution to runoff will be decrease,thereby raising serious sustainability concerns.