Study On Remotely Sensed Monitoring Of The Synergic Evolution Of Alpine Glacier-glacier Lakes And Their Response Mechanism To The Climate Change In The Arid Areas

Glaciers are considered to be sensitive indicators and memories of climate change and are closely related to water resources,sea level changes and natural disasters.Due to the global warming,the vast majority of glaciers in the mountainous areas of western China are retreating,and the rate of retreat is accelerated after the 1980 s.The glacier lake is a lake formed by retreating alpine glaciers.The expansion and atrophy of glacier lakes is closely related to glaciers and climate change.The glacier lake outburst flood is one of the common natural disasters in alpine areas.For China's western arid zone,glaciers and glacier lakes are also an important freshwater resources.It is of great significance to dynamically monitor glaciers and the glacier lakes,and reveal the synergistic evolution between them and their response mechanism with climate change.The rapid development of 3S technology,especially remote sensing technology,provides a powerful technical means for large-scale monitoring of glaciers and the glacier lakes.In this paper,the Bogda region and Youyi Feng region,located in the central and north parts of Xinjiang province,were choose as the study area.The distribution information of glaciers and the glacier lakes in the study area was extracted based on the remote sensing data,which were acquired in 1970 s,1990s,2000 s and 2010,respectively.The variation characteristics of the glaciers and glacier lakes were analyzed.Based on the temperature and precipitation data from 1970 to 2010,the relationship between glaciers and glacier lakes changes and their response mechanism with climate change were discussed.The main research results are as follows:?1?We proposed the automatic remote sensing information extraction methodology for the glaciers and glacier lakes in alpine area.Considering the meteorological characteristics and terrain conditions in alpine areas,a cloud/cloud shadow detection method was developed,which realized the effective recognition and extraction of cloud/cloud shadow in snow covered images.Based on the "global-local" iterative remote sensing information extraction framework,the glacier and glacier lake information extraction methods were developed by fusing multi-temporal cloud covered images within a specific period of time.It overcame the interference in extracting glaciers and glacier lake information in the alpine areas,and improved the efficiency of extraction process.?2?We analyzed and revealed the temporal-spatial variation characteristics and regional differences of glaciers based on nearly 40 years of remote sensing images in the study area.Long time series observation data were constructed based on CORONA,Landsat MSS,Landsat TM and Landsat ETM+.Based on the results of multi-temporal glacier remote sensing information extraction,the temporal and spatial variation characteristics of glaciers in the Bogda region and the Youyi Feng region were analyzed according to the factors such as area,quantity,scale and aspect,and the regional differences of these two regions were discussed.The results shows that:?1?The glaciers in the Youyi Feng region and the Bogda region generally showed a shrinking trend.From 1972 to 2010,the glaciers in Youyi Feng region were retreated by 64.87 km².Its change proportion was 16.39% and the retreat rate was 1.66 km².a^-1.The Bogda glacier area retreated 47.74 km²,the ratio of which was 23.46%,and the retreat rate was 1.22 km².a^-1.?2?For different scale grades,Two groups of glaciers with size of 0.1-0.5 km² and >5 km² showed the largest area reduction in Youyi Feng region,accounting for 70.09% of overall area changes,while the largest area reduction in Bogda region was found in the range of 1-5 km²,accounting for 42.61% of overall area changes.?3?For different aspects,glaciers within east and southeast aspects in Youyi Feng region showed the largest area reduction,accounting for 63.01% of the overall area changes.While the glacier within north aspect in Bogda region showed the most glacier shrinkage,accounting for 33.68% of the overall area changes.?3?We also revealed the long-term temporal-spatial variation characteristics and regional differences of glacier lakes.The temporal and spatial variation characteristics and regional differences of glacier lake were compared and analyzed,and the following conclusions were drawn:?1?From 1972 to 2010,the glacier lakes in the two study areas both showed an increasing trend,and the area of glacier lakes in the Youyi Feng region increased by 26.34 km²,the average annual growth rate was 0.91%.The area of glacier lakes in Bogda increased by 3.04 km²,the average annual growth rate of which was 1.76%.As a whole,the increased area of glacier lakes in Youyi Feng region was larger than that in the Bogda region,but the growth rate in the Bogda region was higher.?2?For different scales,glacier lakes with size of ? 0.1 km² had the largest increase both in the two study areas.the Youyi Feng region increased by 11.78 km²,accounting for 44.72% of its total increase,while the Bogda region increased by 1.36 km 2,accounting for 44.74% of the total.?3?There were differences between the two study areas for different aspects.The increase rate of glacier lakes in south aspect of the Youyi Feng region was larger than that of the north aspect,while the Bogda region was opposite,and the increase rate of the glacier lakes in south aspect was larger than that of the south slope.?4?Based on the analysis of climate change characteristics in the past 40 years,this paper explored the synergistic evolution patterns of glacier-glacier lakes system,and their response to climate change.Based on the meteorological data,the climate change characteristics and their differences for different study areas were analyzed.Through the coupling analysis between the characteristics of climate change and that of the temporal-spatial variation of glacier-glacier lakes system,we try to reveal the synergistic evolution patterns of the glacier-glacier lake system and their intrinsic driving forces.Furthermore,by comparing the evolution patterns of glacier-glacier lakes system in different study areas,the differences in the responses of glacier-glacier lakes system to climate change were explored.The preliminary results showed that,the temperature and precipitation showed an increasing tendency both in the Youyi Feng region and the Bogda region from 1970 s to 2010 s.The continuous increase in temperature is the main factor for glacier melting,which further caused the growing area of glacier lakes.From 1970 s to 2010 s,the glaciers of Youyi Feng region retreated by 64.87 km²,and the area of glacier lakes increased by 26.34 km².The Bogda glaciers retreated by 47.74 km²,and the glacier lakes increased by 3.04 km².The glacier retreat and the area increase of glacier lakes in the Youyi Feng region were more obvious than that in the Bogda region.The main reason was that the temperature rise in the Youyi Feng region was more obvious than that of Bogda region in summer.Due to the influences of terrain and different temperature rise in summer and winter,The glaciers in the south aspect retreated faster than other aspects in Youyi Feng region,with a retreat rate of 0.82 km².a^-1.while the fastest retreat rate of glaciers was found in the north aspect in Bogda region,with a retreat rate of 0.71 km².a^-1.The effect of glaciers retreat on the small and medium-sized glaciers lakes was more prominent.The glacier lakes with sizes of ? 0.1 km² in Youyi Feng region increased by 11.78 km²,accounting for 44.72% of the total growth;The glacier lakes with sizes of ?0.1 km² increase1.36 km² in Bogda region,accounting for 44.74%.Glacier retreat and glacier lake growth in the Youyi Feng region and the Bogda area were the result of global warming.