Remote Sensing Analysis Of The Dynamic Change Of Glacier On The Tibet Plateau

Current global warming has become a hot issue of concern, and higher temperatures will affect even lead to a variety of ecological and environmental problems. As an important part of the cryosphere, glaciers are closely related to the change of climate. The rising temperatures and shrinking glaciers are always global issues in recent decades. As the largest modern glacier distribution in mid-low latitudes regions of the world, the change of Tibetan Plateau glaciers affects the runoff of rivers recharged by glacier, and further affect the sustainable development of Western China in a large extent.With the development of remote sensing technology, more and more efficient methods have been found for study of glacier monitoring and changes. Selected the Tibetan Plateau as study area, based on Landsat remote sensing data, digital elevation model data(DEM), and China Glacier Inventory and so on, this paper obtained the area of multi temporal glacier in the study area by combination of the technology of Envi, IDL, Arcgis. The Tibetan Plateau is divided into different areas and then conduct comparative analysis of changes in glacier, and analyze the changes in response to climate change. Research results are as follows:(1) It is found by analysis and comparison of the glacial area extraction method: The Normalized Difference Snow Index(NDSI) and band rationing is commonly used method in recent years, experiments show that the band rationing has higher precision and can identify thin snow. Band rationing is the ultimate choice for this paper and it was improved by combination of the Normalized Difference Water Index(NDWI) and DEM data. Finally, the glacier area range of the study area in 1990, 2000 and 2010 were obtained.(2) In order to achieve glaciers by one division, the basin was divided by hydrologic analysis tools in Arcgis based on Digital Elevation Model(DEM) Data. The Tibet Plateau is divided into four regions, named Qiangtang Plateau, Qaidam Basin, the Yangtze River, and the Hexi Corridor inland, and their Glacier attribute and changes will be analyzed in this paper. Glacier in four regions sustained recession trends from 1990 to 2010, but the glacier retreat in different research areas is not the same: glacier area reduced from 8 020.3km2 to 7 756.8 km2 in Qiangtang plateau, the average annual shrink rate was 0.16%/a; glacier area of Qaidam Basin reduced from 1 942.9km2 to 1 676.6 km2, the average annual shrink rate was 0.69%/a; the Yangtze River reduced from 2 527.6km2 to 1 581.4 km2, the average annual shrink rate was 1.87%/a, and the Hexi Corridor inland reduced from 1 424.5km2 to 984.1km2, the average annual shrink rate was 1.55%/a.(3) Temperature and precipitation are the main impact factors for the glacier area changes. The temperature and precipitation of study area from 1985 to 2015 show that, the average annual temperature turn out to be fluctuated overall increase trend, the average annual precipitation showed an increasing trend and existed regional differences. After analysis of the relationship between glacier area and the air temperature and precipitation, the following conclusion can be obtained: the increase of annual average temperature is the main influencing factor of glacier retreat under the condition of precipitation in a slight increase or in a state of equilibrium, and the higher the temperature, the faster the glacier retreat; the increase of precipitation will slow down the glacier retreat when the temperature rises in a little scale.