表碛覆盖型冰川的提取方法及变化

Extraction method and change of debris-covered glaciers

表碛覆盖型冰川是山地冰川的一种特殊类型,表碛的存在使得其对气候变化呈现出不同的响应特征。基于2011—2020年Landsat TM/ETM+/OLI遥感影像和ASTER DEM数据,在综合分析表碛光谱、地形和地表温度特征基础上提出TDSI(temperature NDDI slope ice)方法,并将其用于提取中国境内托木尔冰川等6条大陆型冰川和雅弄冰川等3条海洋型冰川。结果表明:基于TDSI方法提取表碛覆盖型冰川的总体精度为91.23%,其中大陆型和海洋型表碛覆盖冰川的精度分别为91.20%和90.97%。2011—2020年6条大陆型冰川和3条海洋型冰川面积平均减少0.06%和0.11%,而表碛面积分别增加了11.92%和18.35%。大陆型冰川表碛主要分布在其中值海拔以下,而海洋型冰川表碛分布范围更广,近10年间二者均呈现向冰川上部扩张趋势。气温上升是冰川消融退缩和表碛增加的主要原因,同时冰川流速变化和终碛湖演变也对表碛变化有一定影响。

As a special type of mountain glacier,debris-covered glaciers show different response to climate change due to the presence of debris.By analyzing the spectral characteristics,topographic and surface tempera⁃ture of debris,we proposed a new method for automatically delineating debris-covered glacier,i.e.,TDSI(temperature NDDI slope ice).Based on the Landsat TM/ETM+/OLI remote sensing images and ASTER DEM data from 2011 to 2020,the TDSI method was used to extract six continental glaciers in Karakoram Range and Tien Mountains and three maritime glaciers in Nyainqentanglha Range.The results show:the overall area accu⁃racy of the TDSI method for extracting the debris-covered glaciers is 91.23%,with 91.20%and 90.97%for continental and maritime debris-covered glaciers,respectively.The area of six continental glaciers and three maritime glaciers decreased by 0.06%and 0.11%on average from 2011 to 2020,while the area of debris in⁃creased by 11.92%and 18.35%.The debris of continental glaciers are mainly located below median altitude,while the distributions of maritime glaciers’debris are more extensive.During the past decade,the debris of both continental glaciers and maritime glaciers showed an obvious tendency of expanding to the upper part of gla⁃ciers.Rising temperature is the main reason for the decrease in glacier and the increase in debris.Meanwhile the change of ice velocities and the evolution of proglacial lakes near glacier terminus have a certain influence on the debris changes.