中天山穆什科托夫冰川跃动特征及控制机理分析

Characteristics and Control Mechanism of Mushketov Glacier Surging, Central Tianshan

天山地区孕育着大量的跃动型冰川,目前该地区冰川跃动过程及跃动控制机制尚不明确。利用Landsat、Sentinel-1A、TerraSAR-X/TanDEM-X等多源遥感数据获得了中天山穆什科托夫冰川跃动前后的表面特征、流速和高程变化。结果表明:(1)该冰川主干表面流速从2017年夏末开始增加,在冬季流速达到最大峰值,约为4.4 m d^(-1),2018年夏末急剧减小;(2)2000—2012年冰川积蓄区平均增厚9.23±4.62 m,跃动前锋形成,而冰舌部分是以减薄为主;2012—2014年冰舌部分持续减薄,中上游仍以积累为主,增厚约1.23±0.91 m;2014—2018年冰川积蓄区出现明显减薄,最大减薄42.6±1.82 m,接收区高程显著增加,最高隆起75.6±1.82 m。根据冰川表面流速及高程变化特征,确认2017—2018年为该冰川跃动活跃期;结合冰川流动定律,认为穆什科托夫冰川跃动主要受冰下水文控制。根据现有的资料及数据,推断该冰川跃动间隔约为60 a。

The Tian Shan region hosts a large number of surge-type glacier,Detailed surge process and control mechanism analysis are still unclear for surge glaciers in Tian Shan.In this paper,the surface velocity and digital elevation models of the Mushketov Glacier in the central Tian Shan are obtained by feature-tracking of Sentinel-1A SAR data and differential Interferometry of TerraSAR-X/TanDEM-X,respectively.Geodetic method was employed to calculate the glacier surface elevation change.The results show that the surface velocity of the main stream of the glacier has increased significantly since the end of summer in 2017,reached its peak in winter,up to 4.4 m d^(-1)and decreased sharply at the end of summer in 2018.The middle and upper reaches of glacier from 2000 to 2012 are accumulated,with an average thickening of 9.23±4.62 m,and the ice tongue thinned dramatically;From 2012 to 2014,the ice tongue continued to thin,the average thickness of reservoir area increased by 1.23±0.91 m;From 2014 to 2018,the glacier reservoir area was significantly thinned,with the maximum decrease of 42.6±1.82 m,the elevation of the receiving area increased significantly,and the highest uplift was 75.6±1.82 m.According to the change of elevation and the characteristics of flow velocity and analysis of glacier surge mechanism using glacier flow law,we concluded that the Mushkotov Glacier surged from 2017 to 2018,and the surge is mainly controlled by hydrological conditions.Combined with the available history data,it is inferred that the glacial surge interval is about 60 years.