基于SAR的表碛覆盖型冰川边界定位研究

A Study of the Debris-covered Glacier Limit Based on SAR

使用光学图像进行表碛覆盖型冰川边界判断相对比较困难。采用日本高级陆地观测卫星(ALOS)携带的L波段相控阵型合成孔径雷达(PALSAR)数据的干涉相干对表碛覆盖型冰川边界进行判断,并使用ALOS PALSAR数据的特征匹配方法获得表面流速进行验证分析,发现公格尔山区5Y663D0009冰川表碛覆盖区呈现高相干性且运动速度十分缓慢,表明该表碛区域可能已经演化成非活动区;而该冰川中碛覆盖区则表现出低相干性,运动速度比较高(5 m/a),表明相干性是有效的判断依据,利用PALSAR数据相干性及获得的表面流速可以区分表碛覆盖型冰川活动与非活动区域,使气候波动情景下该类型冰川的动态变化监测成为可能并对该方法的可靠性与不确定性进行了探讨。

Due to the difficulties in outlining glacier using optical imagery methodology hampered by debris-cover,a new method using the combination of interferometric coherence and surface velocity to delineate debris-covered glacier limits is presented.Coherence images from difference interferometry of ALOS PALSAR data were classified using Maximum Likelihood classifiers（ML） based on Iterative Self-Organization cluster algorithm（ISO） to discern glacier limit from non-glacier area.The results were compared with historic limit from aerial photos and validated by GPS ground-truth data.The surface velocity derived from SAR feature-tracking was employed to validate the results and to discuss the glacier dynamic change.The glacier（coded 5Y663D0009） in Kongur Mountains was tested.We find that the long glacier tongue shows high coherence with low surface velocities while the middle moraine area shows low coherence with higher surface velocities.This implies that the interferometric coherence is a confident judgment for active or inactive debris-covered glacier area.This will make it possible to monitor glacier dynamic change under climate warming.The reliability and uncertainty were discussed.