Study on the effects of artificial oases to the climate change trend

The previous studies on the effects of artificial oases to the climatic environment were mainly based on the comparison of the observed data from very few sites in short periods (for several days or several months) and the analysis on the differences of the climatic factors between oases. and deserts as well as the mechanism of energy exchange. In this paper, the representative series reflecting the climatic background change and the climatic series representing the different oases are developed by carefully selecting the observed data from some meteorological stations where the change of the observation environment is slight, the regions are sparsely populated, and the large-scale water and land exploitations are not undertaken yet. The change ratio differences of the interannual change trends of 10 climatic factors, such as the air temperature, precipitation, vapour pressure, evaporation and wind speed, are analyzed, and the compositive effects of oasis development to the long-term climate change are researched. The results show that the climatic environmental effects caused by oasis development are significant in affecting the local long-term climate change trend. In summer, the increase trend of the mean air temperature in the oases is lower than that of the background change trend, and the change trends of air temperature are in a slight decrease status in some oases, such as in the oases in the Turpan-Shanshan-Toksun Basin and the Yarkant River watershed. The oases play an obvious restraining role in the increase trend of the maximum temperature, in which the change trends of the maximum temperature are in a slight decrease status in the oases in the Yarkant River watershed and the middle reaches of Tarim River. The oases play a certain active role in increasing the minimum temperature, and the oasis effects make the diurnal-nocturnal temperature difference become smaller and smaller. In summer, the oases play an obvious role in increasing the air vapour pressure, and make the evaporation potential become lower and lower and the precipitation be increased to a certain extent. The most significant aspect of the oasis effects is the change of wind speed, that is the average wind speed and the occurring days of gales are sharply reduced in the oases.