气候变化所导致的冰川加速消融及冰川冰储量的减少将显著影响区域水资源和水循环,而冰川厚度的变化是反映这一过程的关键指标. 利用ICESat/GLAS 数据与SRTMDEM 数据,并结合冰面差分GPS 实测数据, 通过监测喜马拉雅山脉西段纳木那尼冰川的冰面高程变化,来估算其冰川厚度变化. 在方法上, 首先利用非冰川区的ICESat 高程数据对SRTM DEM 高程精度进行评价, 然后选择控制点对SRTM DEM 进行配准并再次评价, SRTM DEM 水平位置偏移为138 m, 配准后的SRTM DEM与ICESat 高程差平均值为-0.1 m, 标准差为11 m, 最后利用校准后的SRTM DEM与ICESat/GLAS, 计算2000~2009年纳木那尼冰面高程的变化. 研究结果表明, 纳木那尼冰川在2000~2009年间的平均减薄速率为0.630.32 m/a, 这与利用差分 GPS 测得的2008~2010年间冰川平均减薄速率0.650.25 m/a 接近. 研究结果也发现纳木那尼冰川的减薄速率整体上随着海拔的升高而逐渐减小. 普兰县气象资料分析表明纳木那尼冰面的快速消融主要是由当地气温升高所致.
英文摘要:
Glacier melting plays a significant role in regional water resources and the hydrological cycle in a warming climate. Glacier surface elevation change is one of the key indicators of climate change. The surface elevation changes of the NaimonaNyi Glacier in the western Himalaya was monitored based on ICESat (Ice, Cloud, and Elevation Satellite)/GLAS (Geoscience Laser Altimeter System) and SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model), which was verified by in-situ investigations using differential GPS field measurements on the glacier. The vertical accuracy of SRTM DEM was evaluated according to ICESat data in the ice free area. SRTM DEM was co-registered to the Google Earth using several controlling points. The SRTM DEM is offset by 138 m on the horizontal. The average difference and standard deviation between the co-registered SRTM DEM and ICESat footprints are ?0.7 and 11 m, respectively. Based upon these data, the surface elevation change of NaimonaNyi glacier was calculated by comparing results from ICESat/GLAS and co-registered SRTM DEM from 2000 to 2009. Results show that the average annual lowering rate of NaimonaNyi glacier was 0.630.32 m/a, matching with the in-situ observed result of 0.650.25 m/a from differential GPS field measurements between 2008 and 2010. Results also showed that the glacier lowering rate of the NaimonaNyi Glacier decreased with increasing altitude. The meteorological data show that rising temperature is the major controlling factor causing accelerated glacier melting in this region.