基于SAR影像的喜马拉雅山珠穆朗玛峰地区冰川运动速度特征及其影响因素分析

合成孔径雷达(synthetic aperture radar, SAR)具有其全天候、全天时、穿云透雾的工作能力, 广泛应用于山地冰川动态监测中. 利用2006年6-9月三期ALOS/PALSAR雷达影像, 采用偏移量跟踪技术, 提取了喜马拉雅山珠穆朗玛峰(珠峰)区域的冰川运动速度, 分析了区域内冰川运动速度空间差异及其影响因素. 结果表明: 研究区31条山谷冰川平均运动速度为9.3 cm·d^-1, 总体上以珠峰-洛子峰南北向山脊线为界限, 东侧和东南侧冰川日均运动速度(11.1 cm·d^-1)普遍高于北部和西北部冰川日均运动速度(5.4 cm·d^-1). 冰川消融区非表碛区冰川平均运动速度为表碛覆盖区平均运动速度的2.2倍, 冰面湖的发育在一定程度上加剧冰川运动速度波动. 在气候与非气候因子共同作用和相互间的此消彼长中, 研究区65%的冰川的运动速度自中值高度往下显著减小, 16%的冰川自中值高度往下呈显著增大趋势, 19%冰川消融区运动速度无显著变化趋势.

Characteristics and influence factors of glacier surface flow velocity in the Everest region,the Himalayas derived from ALOS/PALSAR images

Synthetic Aperture Radar(SAR) has been widely applied in mountain glaciers dynamic monitoring in advantages of working with all-weather, all-time and penetrating cloud and mist. In this paper, the glacier flow velocity was derived with feature-tracking procedures and the spatial difference and influence factors of glacier flow velocity in the Everest region, the Himalayas were analyzed based on three ALOS/PALSAR images. It is shown that the average flow velocity of the 31 valley glaciers in the study area is 9.3 cm·d^-1. Generally, bounded by the north-south Everest-Lhotse ridge line, the glaciers on the east and south-east sides are more active than the glaciers on the north and north-west sides, with average velocity of 11.1 cm·d^-1 and 5.4 cm·d^-1, respectively. In the ablation area, flow velocity on non-debris covered ice is about 2.2 times larger than that on debris covered ice. Furthermore, the development of supra-glacial lakes accelerates the fluctuation of glacier flow velocity to some extent. Under combined action and inter-shift of climate and non-climatic factors, flow velocity of 65% of the glaciers decreases significantly from the median height down to glacier terminal, while 16% of them increases significantly, and the remaining 19% have no significant variation.