基于ALOSPALSAR的喜马拉雅山冰川流速分布及变化

Distribution and Variation of Glacier Velocity in Himalayas based on ALOS PALSAR

基于2007年12月至2010年2月的12景ALOS PALSAR数据,结合SRTM,应用特征跟踪方法对喜马拉雅山冰川3个时段的流速进行了估算。结果表明,2007年冬季、2009年夏季和2009年冬季冰川流速均在0～300m·a-1之间,冰川积累区仅在夏季有较明显的运动,而冰舌部分的运动在任何季节都较为明显,并且长冰舌冰川流速沿主流线向下缓慢减小,而短冰舌冰川沿主流线向下流速不断波动变化,甚至增加。4个坡向中,东坡冰川流速最大,东南坡和西南坡次之,北坡冰川流速最小,除了与气候因素相关外,还与地形因素密切相关,从4个坡向的坡度大小来看,北坡坡度最小,也是造成北坡冰川流速最小的主要原因之一。冰川存在年际变化,即冰川冬季平均流速有所增加,增加的冰川流速在-5～18m·(2a)-1之间,并且面积大的冰川流速变化较小,面积小的冰川流速变化较大。同时冰川流速也存在季节性变化,夏季流速整体比冬季流速要大,冰川主流线上流速在夏季时波动较强烈,并且会出现多个峰值,而冬季主流线流速则较为平缓,但主流线上平均流速季节性差异并不明显。4条典型冰川流速年际变化、季节变化与研究区冰川总体特征相似,并且流速与气候特征和冰川形状之间都有密切的关系。冰川前进与退缩特征不明显,研究区冰川总体上处于平衡状态。

Based on the 12 scenes ALOS PALSAR data from December 2007 to February 2010, combined with SRTM,we estimated the glacier velocityof the Himalayasin three periods by feature tracking method. The results show that glacier velocity of the winter of 2007, the summer of 2009 and the winter of 2009 were between 0-300 m·a^-1 ,and accumulation area of the glacier have obvious movement only in summer,butthe movement of the glacier tongue is obviousin any season.Long tongue glacier velocity decreas- esslowlyalong the mainstream line,while the short tongue glacier velocity fluctuatesalong the mainstream line,and even increases. The glacier in east aspecthas the largest velocity. The glaciervelocity in southeast aspect and the southwest aspect are second,and glacier velocity is minimum in the north aspect.In addition to climatic factors, it also closely relates to terrain factors. In terms of the slope of the four aspects, the north aspecthas the smallest slope, andit is one of the main causes of the smallest glacier velocity in the north aspect. There is an inter-annual variation of glaciers, that is, mean velocity of glaciers increases in winter,and the increased velocities are between -5-18 m·（2a）^-1.The glacier with small areavaries great ly,and the glacier with large area varies little. Meanwhile, the glacier velocity also has seasonal variation. The overall velocity in summer is larger than that in winter. The velocity in mainstream line fluctuates strongly in summer, and there are many peaks, but velocity in winteris gentle. However, the seasonal varia- tion of the mean velocity in mainstream line is not obvious. The inter-annual variation and seasonal variation of the four typical glacier velocities are similar to those of the glaciers in the study area.There is a close relationship between velocity and climate and the shape of the glacier.The characteristics of glacier advance and retreat are not obvious, and the glaciers in the study area are in equilibrium.