Analysis on the Change Trend of Temperature and Precipitation in Xi'an during the Period of 1961-2009

Based on the average annual and monthly temperature and precipitation data observed in Xi'an during the period from 1961 to 2009,in this paper climate change in Xi'an in recent 49 years was analyzed.The conclusions are as follows: annual temperature was increased with an increase rate of 0.3 ℃/10 a;the change of seasonal temperature was different: the seasonal temperature was increased with increase rates of 0.54 ℃/10 a,0.42 ℃/10 a and 0.23 ℃/10 a in spring,winter and autumn respectively.Monthly temperature in January was also increased with an increase rate of 0.23 ℃/10 a,and that in July was significantly increased since the 1980s.Annual precipitation was in a decrease trend;seasonal precipitation was significantly decreased in spring and autumn,it was decreased with a decrease rate of 14.8 mm/10 a in spring,but it was significantly increased with an increase rate of 21.8 mm/10 a in summer,and it was slightly increased in winter;precipitation in flood season was also increased significantly in the 1980s and during the period from 2001 to 2009.There was a good correlation between seasonal temperature and precipitation in spring,summer and autumn,but the correlations between annual temperature and precipitation and between seasonal temperature and precipitation in winter were not significant.