天山托木尔峰科其喀尔巴西冰川表面运动速度特征分析

Change of the Surface Velocity of Koxkar Baxi Glacier Interpreted from Remote Sensing Data,Tianshan Mountains

天山托木尔峰科其喀尔巴西冰川是典型的树枝状山谷冰川,利用3组(6期)ASTER遥感影像通过COSI-corr软件反演了该冰川表面运动速度.与花杆测量数据进行对比,反演冰川表面运动速度平均绝对误差为3.1m.a-1,相对误差为11.9%,二者在空间上的分布基本一致,表明其反演精度符合要求.在此基础上,分析冰川表面运动速度空间分布及年际变化特征,结果表明:从空间分布看,冰川上部至末端的表面运动速度在横剖面上均具有从中部向边缘逐渐减少的特征;冰川运动速度具有在积累区随海拔降低逐渐增大,而在消融区则随海拔降低逐渐减小,符合冰川运动的一般规律.2001-2006年间科其喀尔巴西冰川海拔3 600m以上区域表面运动速度增大,而以下区域则呈减小趋势.

Climate warming has been resulting in continuous retreat of glaciers and ice sheet.However,there are some glaciers and ice sheets exhibiting some kinds of surprising behaviors,such as rapid advance or surging.Many of them result from glacier/ice sheet motion,as the discharge of ice mass is largely dependent on the flow velocity of glacier and ice sheet.In this study,the Koxkar Baxi Glacier,located in south slopes of the Tomur Peak in Tianshan Mountains,Northwest China was selected for glacier surface flow velocity study based on COSI-corr software and optical remote sensing images.The three pairs of ASTER images taken in 2001.01.12/2002.03.04,2005.05.06/2006.8.13 and 2006.02.22/2007.01.04 were used for velocity extracting.Glacier flow velocity data observed by D-GPS based on the 54 stakes during May to September 2009 was used for accuracy assessment of the velocity extracting from ASTER images during 2006/2007.A mean absolute error of 3.1 m·a-1（11.9%） is obtained,which,in general,indicates that the glacier flow velocity extracted from ASTER can be used to analyze the spatial distribution and change of surface flow velocity.It was found that glacier reaches its maximum flow velocity near the center part,and the velocity decreases towards both lateral margins.In a longitudinal profile,ice flow velocity in the accumulation area increases down to the equilibrium line,while decreases towards the glacier terminal.The maximum velocity,117.9 m·a-1,was found at 4 500 m a.s.l.near the equilibrium line altitude,while the minimum velocity,1.3 m·a-1,was located at the glacier terminal and lateral margin in 2006/2007.There was a significant increase of glacier flow velocity in the altitude above 3 600 m a.s.l.from 2001/2002 to 2005/2006 and 2006/2007,as well as a remarkable decrease below 3 600 m a.s.l.