1974—2020年海螺沟冰川变化遥感监测

Remote sensing monitoring of Hailuogou Glacier change from 1974 to 2020

位于青藏高原东南边缘的海螺沟冰川是典型的季风海洋性冰川,对气候变化响应极为敏感,研究海螺沟冰川现状及变化趋势具有重要的现实意义。本文以Landsat系列遥感影像为数据源,基于遥感和地理信息技术,采用波段比值阈值法和目视解译相结合的方法提取1974年、1991年、2000年、2009年、2020年5期冰川边界,并结合数字高程数据分析了在全球变暖大背景下近46年来海螺沟冰川长度、总面积、表碛覆盖范围和不同朝向冰川覆盖单元变化特征。结果表明:(1)1974—2020年冰川长度缩短1087 m,年平均退缩速率为0.15%,其中,2000年后冰川末端退缩速度不断加快。(2)1974—2020年冰川面积减少0.55 km^(2),面积变化率为-2.19%,年平均退缩率为0.05%,其中2000—2009年减少最多,约为0.23 km^(2),面积变化率为-0.93%,年平均退缩率为0.10%。(3)不同朝向冰川也呈不同程度的退缩状态,其中偏东向冰川面积萎缩速率最快。冰川分布呈东多西少、南多北少的特点,且各朝向冰川面积分布与1974—2020年对应朝向面积总萎缩量存在正相关关系。(4)自2000年后海螺沟冰川西北部、东北部和西南部表碛覆盖面积不断增大,预测未来海螺沟冰川表碛将处于持续扩张的状态。

Hailuogou Glacier,located on the southeast edge of Tibetan Plateau,is a typical monsoonal maritime glacier,which is extremely sensitive to climate change.It is of great practical significance to recognize the pres⁃ent situation and changing trend of glaciers.In this paper,Landsat series remote sensing images are used as data sources,based on remote sensing and geographic information technology,band ratio threshold method and visu⁃al interpretation method are used to extract the glacier boundaries of five periods in 1974,1991,2000,2009 and 2020.Combined with digital elevation data,the variation characteristics of glacier length,total area,coverage of debris and glacier cover units in different directions in Hailuogou in recent 46 years are analyzed.The results showed that:(1)From 1974 to 2020,the glacier length shortened by 1087.10 m,and the average annual re⁃treat rate was 0.15%,among which the retreat rate at the end of the glacier accelerated continuously after 2000.(2)From 1974 to 2020,the area of glaciers in the study area decreased by 0.55 km^(2),with the area change rate of-0.52%and the annual average retreat rate of 0.03%,among which from 2000 to 2009,the largest decrease was about 0.23 km^(2),the area change rate of-0.93%and the annual average retreat rate of 0.10%.(3)Glaciers in different directions are also shrinking in different degrees,and the area of glaciers in the east direction is shrinking fastest.The distribution of glaciers is characterized by more in the east and less in the south and less in the north,and there is a positive correlation between the area distribution of glaciers in each orientation and the total shrinkage of corresponding orientation areas from 1974 to 2020.(4)Through comparative analysis,it is found that the debris in the northwest,northeast and southwest of Hailuogou Glacier increases after 2000 and fur⁃ther increases after 2009.It is predicted that the debris cover of Hailuogou Glacier will continue to expand in the future.