| AR4 and AR5 of IPCC have pointed out that global warming is happening in a fact. The rate of sea level rise is 1.7mm·a-1 from 1901 to 2010. The change of cryosphere is the fastest and most effective indicator in the five spheres global climate system. Cryosphere is the most sensitive sphere to climate system, and cryosphere is the main factor of global sea level change. AR5 pointed out that the sea level rises in 0.76 mm·a-1 due to the glacier melting. AR4 noted that cryosphere makes 30%-60% contribution. AR5 forecasted responsibly that future temperatures continue to rise, and glacial retreat will continue. China is the most developed areas in the low-latitude cryosphere. The area of glacier is 59425km2. Over the past 100 years, the cryosphere has been significantly shrinking in our country. Because of the accelerated retreat of glacier, glacier floods and glacial lake outbursting and other disasters happen which will lead to river water increased in the short term. At last, it will use up the resources of glaciers in the long term,and then it will affect agricultural production. Large scale of glacier monitor can be implemented by the development of satellite technology. In addition, Landsat image lasts long time scale which can be used to monitor a long period of glacier change.The research focuses on the glacier change from 1977 to 2013 in West Kunlun which is the second maximum glacierized centers in Tibetan Plateau. Landsat images were used to extrat the glacier information in 1977,1993,2002,2010,2013, respectively. We use the methods composed by maximum likelihood supervised classification and NDSI to extract clean glacier, and take advantage of thermal infrared images to extract debris covered glaciers, in order to map the glacier boundary. Finally, we analyze the change of the results including glacier area, length, terminal altitude, and the area of moraine lake in 1977-2013. We use the feature tracking method to estimate the surface velocity of Duofeng glacier. On this basis, we analyze the relationship between glacier change and climate change.The main conclusions include:(1) There are 445 glaciers in 2013, and area is 3000.39 km2. Indicating that study area is composed by large glacier. The length of glacier is negatively related to the terminal altitude. Glaciers distribute more at 5600-6600m. Glaciers on northern slope are larger than on southern slope. (2) Glacier area is 3091.51km2,3052.64km2,3028.23km2,3009.33km2 and 3000.39km2 in 1977-2013, respectively. Area of debris-covered glacier is 0.79km2 in 1993,1.86km2 in 2013 among glacier area. The glacier area decreased by 2.95% with a rate of 2.55km2·a-1 between 1977 and 2013. The reducution of glacier volume is about 20-21km3 which equals to 19km3 water equivalent. (3) Glaciers distribute more concentrated with the increasing altitude and the glacier located in the 6200-6300m is at most. (4) There are 17 of the 20 glaciers which glacier length retreat shorter in 1977-2013,9 changed significantly. There are 13 glaciers terminus altitude increased. 1977-2013, the area of 21 glaciers decreased by 58.85 km2(2.70%) from 1977 to 2013, and its rate of change is slightly lower than the rate of study area(2.9%) that mainly due to two large glaciers large-scale advancing. (5) Duofeng glacier is the fastest retreating glacier with 50m·a-1, and teminus altituderised by 199m. In 1993-2002, the speed of Duofeng glacier retreat was up to 100m·a-1. At the same time, Duofeng glacier was also the biggest declined in area with 7.57km2(3.08%). The largest rate of change is the left branch of Xikunlun glacier, up to 6.64%. (6) Glacier in north of west kunlun mountains retreated more obvious than southern slope. There are 12 glacier in north and 9 in south of 21 large glaciers. The glacier in northern slope is 1287.40km2 which is 1.45 times of southern slope with area but reduced area is 2.65 times. (7) Moraine Lake area has expanded from 1993 to 2013. Several lakes appeared due to the retreat at the end of glaciers. Most of the existing moraine lakes expansion slowly which due to the glacier retreat. (8) The velocity of Duofeng glacier was both lower than 100m·a-1, and it was 8m·a-1 higher in 2001-2002 than 2013-2014. The velocity at the sides is lower than the axis of the glacier. It was found that glacier reaches its maximum flow velocity near the center part, and the velocity decreases towards both lateral margins. (9) The temperature show rised tendency in 1977-2013. Glacier recession is in close relationship with temperature rise in the study area. |
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