Analysis On Elevation Change Of The Typical Glaciers In Qinghai-Tibet Plateau In Recent 50 Years With Multi-source Data

Glaciers are highly sensitive to climate change,and their dynamic changes have received extensive attention from domestic and foreign scholars against the backdrop of current global warming.Glacier elevation is one of the important parameters for glacier dynamic changes,and the characteristics of glacier elevation changes are closely related to glacier velocity,meteorological factors,and attribute information.The Qinghai-Tibet Plateau is one of the centers for the development of mountain glaciers in low-latitude regions on Earth,and it is also the main source of glacier formation in China.Exploring the spatial and temporal distribution characteristics of typical glacier elevation changes on the Qinghai-Tibet Plateau is of great significance.Early elevation data was scarce,and there were correspondingly fewer studies on glacier elevation changes.Moreover,most elevation change analyses for glaciers on the Qinghai-Tibet Plateau were limited to a few glaciers in a single geographical unit.In response to the lack of data and the single study area,this thesis selected 28 glaciers covering a large area of the Qinghai-Tibet Plateau,extracted DEM data using Hexagon KH-9 remote sensing images,and used differential processing with multiple sources of DEM data such as NASA DEM and AST14 DEM to obtain the results of glacier elevation changes in the study area for two periods,1973-2000 and 2000-2022.The thesis further explores the elevation changes of typical glaciers on the Qinghai-Tibet Plateau in combination with multiple driving factors.The main contents of the thesis are as follows:(1)DEM extraction based on Hexagon KH-9 stereo image pairsWe established a process for extracting DEM data based on high-resolution Hexagon KH-9 remote sensing images from 1973 to 1980,including data preprocessing,stereo image pair extraction of DEM,and DEM accuracy assessment.The feasibility of using KH-9 data in glacier elevation change research was demonstrated.(2)Differential processing based on multiple sources of DEM dataWe used KH-9 DEM data,NASA DEM data,AST14 DEM data,and DEM data extracted from ZY3 images for differential processing of multiple sources of DEM data,obtaining the elevation change results of typical glaciers on the Qinghai-Tibet Plateau during the two periods of 1973-2000 and 2000-2022.The characteristics of glacier elevation change in different regions were found to be different,and there were certain differences in elevation change at different times.(3)Spatiotemporal distribution characteristics of glacier elevation changeWe discussed the spatiotemporal distribution characteristics of glacier elevation change from multiple perspectives,revealing differences in elevation change of different glaciers in the same region.The results showed that the spatiotemporal distribution of glacier elevation changes varied in different regions,with significant elevation changes in typical glaciers in the Karakoram and Pamir Plateau regions,and weak elevation changes in typical glaciers in southeastern Tibet and the Himalayan region.(4)Multi-driving factor analysis of glacier elevation changeWe used geographic detectors to analyze the elevation change characteristics of 28 glaciers in the study area based on glacier flow velocity,meteorological factors,and glacier attributes.We concluded that glacier flow velocity and precipitation are the main controlling factors of glacier elevation change.The thesis contains 35 figures,12 tables,and a total of 91 references.