Spatial-Temporal Variation Of Glacier Resources In Chinese Tianshan Mountains Based Landsat And Icesat Data

According to the IPCC Fifth Assessment Report,the global warming in the past 132 years has been 0.85°C.With the global climate warming,the resource and environmental problems have become increasingly serious.As a "solid reservoir",glaciers are the most sensitive to climate change,and play an important role in the use of water resources,rising sea levels,and prevention of glacial disasters.Tianshan is located in the central of Xinjiang and is the source region of many rivers in Xinjiang.Therefore,strengthening the monitoring of glacial changes in the Tianshan area is of great significance to the rational use of water resources in Xinjiang and the Tianshan area and the sustainable development of the social economy.This paper uses Landsat TM/ETM remote sensing images,successively uses ratio method and artificial revision to extract the glacial catalogue data of two phases of China's Tianshan area,and uses this data to analyze the characteristics of glacial resources in Tianshan area in the past 28 years.Second,using the ICESat data of 2003-2009 and SRTM DEM data,the characteristics of elevation changes in the Tianshan area in the past 10 years were analyzed.The main conclusions are as follows:(1)In the past 28 years,the glaciers of the Tianshan Mountains in China have generally retreated.The area of glaciers has decreased by 879.73 km2,and the retreat rate has reached-0.52% a-1.The average annual rate of change of glaciers in the four regions of the North Tianshan,South Tianshan,East Tianshan and Central Tianshan Mountains is somewhat different.Among them,the Glacier area of the East Tianshan Mountain has the fastest change,the glacial area has decreased by 55.66 km2,and the retreat rate has reached-0.64%.a-1;followed by Central Tianshan,the glacier area was reduced by 66.58 km2 and the retreat rate was-0.55% a-1;the northern Tianshan glacier area was reduced by 316.03 km2,and the average annual retreat rate was-0.52% a-1;the South Tianshan glacier The area of change was the slowest,the area decreased by 441.46 km2,and the withdrawal rate was only-0.41% a-1.At different altitudes,the area of glaciers is normally distributed;the area of glaciers is related to the orientation of glaciers,with the glaciers in the north facing the greatest changes,and the glaciers in the south and southeast facing the smallest change.(2)In different watersheds in different regions,the change in glacier area also has large differences.By comparing the glacial inventory data of different periods,the Tianshan glacier has continued to shrink.The annual reduction rate of the glacier area in the eastern part of the Tianshan Mountains from 1989 to 2000 was 0.62% a-1,the annual reduction rate of the glacier area from 2000 to 2009 was 0.71% a-1,and the annual reduction rate of the glacier area from 2009 to 2017 was 0.67%-1.The annual reduction rate of glacier area in the southern part of Tianshan Mountain from 1989 to 2009 was 0.41% a-1,and the annual decrease rate of glacier area in 2009-2017 was 0.40% a-1 Comparing the changes in glaciers in typical regions of western China,found that the average annual retreat rate of the glaciers in the Tianshan Mountains in China was-5.23% a-1,which is one of the more regressive mountain ranges.(3)The glacial surface elevation of Tianshan Mountain in 2003-2009 has significantly decreased in different research periods,with an average decrease of 3.99 m.The elevation of the glacier surface in the eastern part of the Tianshan Mountains decreased by an average of 5.02 m between 2003 and 2009.The elevation of the glacier surface in the northern part of the Tianshan Mountains decreased by an average of 4.16 m between 2003 and 2009.The average elevation of the glacier surface in the southern part of the Tianshan Mountains fell by 2.8 m between 2003 and 20009.At different altitudes,there are differences in elevation changes of Tianshan Glacier,possibly due to the presence of surface ridges,which accelerates or inhibits glacial melting.(4)The analysis of meteorological data shows that in the past 50 years,the temperature in summer in the Tianshan Mountains has increased significantly and the precipitation has increased significantly.If we do not consider the lag of the glacial response,it is presumed that the ablation caused by the significant increase in summer temperature is greater than the accumulation caused by precipitation during the year is the main reason for the retreat of the Tianshan glacier.