Characteristics of regional climate change and pattern analysis on Ordos Plateau

The characteristics of precipitation, temperature and their combination determine the special ecological environment pattern of Ordos Plateau. Analyzing its evolutionary trend attributes to understanding the succession process of the ecological environment of Ordos Plateau and has crucial instructional significance on the ecological restoration research being conducted in this region. Four time scales, arranging from ten days, one month, one season growing season contrasting to non-growing season) to one year were adopted to analyze the climate data which included nearly 30 years and were collected by eight weather stations on Ordos Plateau. The results indicated that the mean annual temperature and the mean monthly temperature of February, September and December, had increased significantly during the late 30 years. The annual precipitation did not show significant changes but its distribution pattern had changed obviously. The ratio of precipitation of major growing season (May-October) to annual precipitation had increased distinctively, and five counties' precipitation reached statistically significant level. And the ratio of precipitation of latter growing season (September) to one year decreased significantly while the ratio of non-growing season (November-next April) to one year changed insignificantly. The results showed that maybe the interaction of increased mean temperature and insignificant change of precipitation in non-growing season was one of the reasons why the desertification of the region was deteriorating in recent years. Using some factors closely relating to vegetation succession such as mean annual temperature, mean annual precipitation, distributive pattern of precipitation, mean temperature of the coldest month, mean temperature of the warmest month, precipitation of the warmest month, mean temperature of growing season, precipitation of growing season, potential evapotranspiration(PET) and radiative dryness index(RDI), to synthetically analyze the climate characteristics of Ordos Plateau. The regionalized Ordos Plateau to three synthetical climate types were recognized as follows: Type I, semi-humid and low evaporation(including Jungar Banner, Dongsheng City and Ejin Horo Banner), Type II, semi-arid, semi-humid and moderate evaporation(including Uxin Banner and Dalad Banner), Type III, arid and high evaporation(including Hanggin Banner, Otog Banner and Otog Qian Banner).