基于合成孔径雷达技术及DEM的公格尔山冰川动力特征分析

冰川流速是冰川动力状况的重要标志,利用合成孔径雷达技术能快速获得大范围冰川的表面流速.利用日本高级陆地观测卫星(ALOS)相控阵型合成孔径雷达L波段(PALSAR)及欧洲太空局的ENVISAT/ASAR数据的特征匹配方法获得帕米尔高原公格尔山区冰川表面流速,并结合合成孔径雷达干涉相干与不同时期数字高程模型对公格尔山区典型冰川动力进行分析,获得研究区不同时间基线冰川表面相干性、表面流速以及基于不同时相DEM的典型冰川表面高程变化信息.结果表明:30 a来克拉牙依拉克冰川表面高程下降了(15±12.1)m,表碛区域近期运动速度变化不大;其木干冰川平均表面高程几乎无变化,但2007-2011年夏季表面流速明显减缓,靠近末端附近部分区域可能已经演化为非活动区;姜满加尔冰川位于西风带的迎风坡,积累区面积大,冰川流速较快,无表碛覆盖,但表面高程仍下降了(8.8±12.7)m.编号为5Y663D0009的冰川冰舌表碛覆盖区可能已经演化为非活动区,30 a来表面高程下降(8.6±12.0)m.综合分析表明,冰川规模特别是积累区面积的大小及所处位置、地形对冰川演化具有重要影响.

Analysis of the glacier dynamics features in Kongur Mountain based on SAR technology and DEMs

Glacier surface velocities are the indicators of glacier dynamics. To understand the regional dynamics of glaciers which are hard to be observed in-situ, remote sensing methods such as Synthetic Aperture Radar technology is convenient and feasible. In this research, feature tracking with ALOS/PALSAR and ENVISAT/ASAR data was employed to obtain glacier surface velocities in the Kongur Mountain, Pamirs. Dynamics were analyzed for four glaciers based on the surface velocities, interferometry coherence and digital elevation models with 30 years interval. Information of glacier surface velocities, coherence maps and elevation changes were obtained. It is found that glacier surface elevation had decreased down by 15±12.1 m for the Kelayayilake Glacier, by 8.8±12.7 m for the Jiangmanjiaer Glacier and by 8.6±12.0 m for the glacier coded 5Y663D0009. However, for the Qimugan Glacier, the surface elevation had changed nothing (equal to the difference of SRTM DEM and Topographic DEM in stable area). From 2007 to 2011, the surface velocities of these glaciers had changed little, except the glacier coded 5Y663D0009, which was inactive according to the analysis of glacier surface velocities along transverse and central flow lines. Furthermore, glaciers with broad accumulation areas changed slowly than those with small ones. It is suggested that monitoring glacier flow rates and elevation changes can provide a useful proxy for glacier dynamics when no other mass-balance information available, and regional glacier dynamics change can be understood by glacier surface velocities, interferometry coherence and topographic measurements. It is also found that area (especially for magnitude of accumulation area), location and topography of a glacier are determining factors of the glacier evolution.