Research On Glacier And Climate Change In The Eastern Kunlun Mountains Based On Remote Sensin

Based on Chinese glacier inventory, satellite images (Landsat TM, Landsat ETM+), SRTM DEM and climatic data of the metrological stations, this paper discusses the extent of glacier in the eastern Kunlun Mountains from1990to2010, Bukatage and Malan ice caps from1973to2010and analyzes the climate changes of research area between1960and2010. The main results are as follows:(1) This paper extracted glacier outlines from satellite image scenes during1990to2010by using a semi-automated method applied to band ratios (TM4/TM5), with some necessary manual editing to correct the outline of ice-lake contacts and debris. The results showed that the area of glacier in the eastern Kunlun Mountains presented obviously shrinking trend and decreased12.03%from1990to2010; it was retreating at the rate of0.6%every year.140glaciers had entirely disappeared since1990; retreat rate between1990and2000was faster than that from2000to2010. According to glacier changes in three parts, shrinkage rate of the northern glacier was the fastest, and the least ratio was in the southern part. Ice volume reduced34.228km3during20years which was equivalent to31.489km3water. Glaciers, small-scale and northward, shrank faster than others, which indicated glacier size、geographic position and topography influence the behavior of the glaciers and the behavior were different in spatial distribution.(2) Annual mean temperature experienced upward trend in general from1960to2010, increased almost4℃:Variation trend of temperature in different period was rise-decrease-rise and the lowest level had recorded since1983, the highest level began in2006. As for annual precipitation during50years, it had indistinctively positive correlation with altitude. However, annual precipitation showed the longitudinal-latitudinal distribution pattern which annual precipitation increased linearly with longitude, was inverse correlated to latitude, the distribution of the trend of annual precipitation gradually decreased from southeast to northwest. Although annual precipitation went up and down depending on year, the general trend still gradually increased; it also presented remarkable stage characteristics in annual precipitation between1960and2010, increased81.5mm.(3) Studying on Bukatage and Malan ice caps from1973to2010based on satellite images (Landsat RBV、Landsat MSS、Landsat TM、Landsat ETM+). The results indicated that the total area of the Bukatage ice caps decreased23.34km2from1973to2010which accounted for5.42%of glacier area in1973, with annual diminution rate of up to0.14%. Bukatage ice caps had experienced a general shrinkage from1976to2010after slight rise (1973-1976). Malan Ice Caps had experienced a general shrinkage; the total glacier area lost12.31km2from1973to2010, representing a loss of6.04%of the original glacier coverage in1973; annual reduction rate was0.16%, but the rate of glacier shrinkage varied in different period. The processes of glacier retreat, including fast-slow-fast-slow and not significant in recent decades, reflected a transitional period of glacier change. By analyzing of Bukatage and Malan ice caps in northern and southern slops, there were significant differences of glacier variation in direction due to topographic condition、 geographic position and the scale of glacier. These differences were different from each other that southern glacier in Bukatage feng shrank more significantly than northern glacier while northern glacier in Malan shrinking more fast than southern glacier.(4) This paper analyzed the response of glacier variation to climate change. Annual average temperature in both areas increased from1960to1980, which was followed by decrease in the1980s, and then went up again until2010. The similar pattern was found in winter average temperature. From1960to1970, summer average temperate in both areas experienced a slight drop, then they grew over the next10years; there was a decrease in the middle of1980s, after that, they saw a steady rise. As for annual precipitation, there were increases before drop in both areas. However, the situation in two areas had some difference that annual precipitation in Bukatage had increased since1980s while that in Malan began to go up from1990s. A comparative analysis between glacier variation and climate changes showed the response of glacier variation to climate change could not be brought out, with a lag of a further10years. Increase in summer average temperature had more impact on glacier retreat, increase trend of annual precipitation could not compensate for the mass loss due to the ablation in response to summer temperature increase during the same period. In other words, rising summer average temperature and declining annual precipitation could accelerate glacial ablation.(5) Analyzing the relationship between the glacier variation and temperature, precipitation in regional scale in eastern Kunlun Mountains. There were a negative correlativity of glacier changes and temperature and a positive correlativity of glacier change and precipitation. To reflect climate change from1980to1990that temperature increased dramatically and precipitation grew slightly, glacier retreated between1990and2000. The period between1990and2000, the variation trend of temperature did not increase as obviously as the precipitation; even so, temperature was still a dominant factor for affecting glacier change, glacier area continued to decrease in size during1990to2000. In contrast with eastern part, west part experienced more remarkable warming during30years in wet and dry season. Annual precipitation had entered a long period of relatively abundant since1990s, which showed basic characteristics that annual precipitation grew more significantly in two sides than that in the middle, and annual precipitation in southern displayed more marked increasing tendency than that in northern. Consequently, annual precipitation in northwestern part increased the most slowly in the whole area. According to increasing range of temperature and precipitation, western glacier was affected mainly by temperature while the influence of precipitation on eastern glacier was marked. The corresponding relationship between glacier variation and climate change, however, could not apply simply to eastern Kunlun Mountains because there were a great amount of reasons why glacier may fluctuate.