Changes in Air Temperature and Evaporation in Xinjiang during Recent 50 Years

After lot of researches, it is found that the climate in northwest China is changing from the warm-dry type to the warm-wetting type since 1987. In this paper, the two important climatic factors, i.e., the air temperature and the evaporation in the different regions of Xinjiang in recent 50 years are analyzed, and the scientific facts affecting the climate change from the warm dry type to the warm-wetting type are discussed. Based on the observation data collected by 77 hydrologic and meteorological stations in Xinjiang, the analyzed results show that the air temperature in Xinjiang has increased in recent 50 years, and the average increase amplitude is 0.27 ℃.10·a -1 . The average annual temperature has obviously increased since 1987 than that before 1986, especially the increase amplitudes are as high as 0.6～1.6 ℃ in the western and northern parts of north Xinjiang and in east Xinjiang. The change amplitude of air temperature is highest in winter and lowest in summer, however, the air temperature increases generally in all the seasons. The change of the annual evaporation and the aridity index in Xinjiang is in a decrease trend, which reveals that the signals of climate wetting have occurred.