Response of lakes to climate change in Xainza basin Tibetan Plateau using multi-mission satellite data from 1976 to 2008

Changes in the lake areas of Xainza basin in the past 33 years (1976 to 2008) were studied using Landsat data from Multispectral Scanners (1973-1977), Thematic Mapper (1989-1992, 2007-2009), and Enhanced Thematic Mapper Plus (1999-2002). The results indicated that lakes in the study area evidently expanded from 1976 to 2008, with total expansion of 1512.64 km(2). The mean annual air temperature presented an upward trend with certain fluctuations from 1966 to 2008. The air temperature rise rates in the cold season (0.31A degrees C/10a) were higher than those in the hot season (0.24A degrees C/10a), in the Xainza station example. Precipitation exhibited evident seasonal differences. Mean annual precipitation in hot season is 281.48 mm and cold season is 32.66 mm from 1966 to 2008 in study area. Precipitation in the hot season was the major contributor to the increase in annual precipitation. Grey relational analysis (GRA) was used to study the response of lake areas to climatic factors. The mean air temperature and precipitation were selected as compared series, and the lake areas were regarded as the reference series. The grey relational grade (GRG) between compared series and reference series were calculated through GRA. The results indicated that changes in lake areas were mainly affected by climatic factors in the hot season. Lakes in this region were classified into three grades, namely, Grades I, II, and III according to the recharge source and elevation. The GRGs of each series varied for different grade lakes: the area of Grade III lakes were the most relevant to the hot season factors, the GRGs of precipitation and air temperature were 0.7570 and 0.6606; followed by the Grade II lakes; Grade I lakes were more sensitive to the air temperature.