念青唐古拉山现代冰川1999—2015年期间动态变化遥感研究

利用1999年ETM、2014/2015年GF-1为主的2期遥感影像作为数据源,采用人机交互解译的方法完成了2期冰川编目成果,并对最近15年(1999—2015)念青唐古拉山冰川变化进行分析。结果显示,从1999年至2015年间,念青唐古拉山脉冰川呈退缩趋势,以东段海洋型冰川退缩为主,西段亚大陆型冰川相对稳定。冰川总面积减少了56. 32km2,减少变化率为0. 67%;有10条冰川消失,减少变化率为0. 16%;冰储量减少5. 315 km3,减少变化率为0. 78%。调查结果还显示,念青唐古拉山地区冰川各朝向均呈退缩趋势,偏南向和东向冰川数量与面积减少大于偏北向和西向的;平均坡度在20°～35°范围的冰川数量和面积减少最多;海拔介于4 500～5 500 m区间的冰川面积退缩最明显。在恒河流域和萨尔温江流域的冰川消退最显著。总体上,不同规模冰川均有退缩,规模≤5. 0 km2的冰川是念青唐古拉山地区退缩最多的。冰川退缩与气候变化关系密切。选取念青唐古拉山脉附近3个气象台站,对最近50多年以来的年均气温和年降水量变化分析表明,自1961年以来,念青唐古拉山年均气温呈显著上升趋势,而降水量变化不一,有增有减。气温上升而降水减少,可能是导致念青唐古拉山地区东段冰川退缩的一个因素。

Dynamic Variation of Glaciers in Nyainqentanglha Mountain During 1999-2015:Evidence from Remote Sensing

Using the two-phase remote sensing images based on ETM in 1999 and mainly GF-1 in 2014/2015, two phases of glacier inventory are completed by manual/automatic interpretation methods, and the glacial change in the past 15 years in the Nyainqentanglha Mountain is summarized. The results show that the glaciers were retreating in the mountain from 1999 to 2015, some of which retreated in the east, and the subcontinent was relatively stable in the west. The area covered by the glacier reduced for a total amount of 56.32 km², representing a reduction rate of 0.67%. Ten glaciers have disappeared, representing a reduction rate of 0.16%. The ice volume loss is 5.315 km³, representing a reduction rate of 0.78%. On one hand, the glaciers are retreating in every directions, and the number and size of the glaciers decrease more in the south and east than in the north and west. The number and size of the glaciers decrease mostly in the average slope of 20° to 35°. On the other hand, the size decrease is most significant at the elevations of 4,500 to 5,500 m. Analogously, the glacial size decreased is obvious in the Ganges Basin, followed by the Salween River Basin, where the glaciers are most concentrated. The recession of the glaciers with sizes of ≤5.0 km² are most obvious among the glaciers of other sizes. There is a close relation between the glacial retreat and climate change. The annual average temperature and precipitation changes from three meteorological stations near the mountain over the past 50 years show that the annual average temperature has increased significantly, while the precipitation has fluctuated since 1961. The temperature rise and precipitation drop in the east may have been one of the reasons behind the more severe glacial retreat in the east(than in the west) during this period.