西安市气温和降水变化趋势分析

利用西安市1961-2009年的月平均气温与降水资料，对西安市气候特征及动态变化进行分析。结果显示：年平均气温及春、秋、冬季气温呈上升趋势，增温率分别为0.3 ℃/10 a，0.54 ℃/10 a，0.23 ℃/10 a和0.42 ℃/10 a，春、冬季升温明显。1月平均气温总趋势上升，升温率为0.23 ℃/10 a，20世纪80年代开始7月升温明显。年降水量有减少倾向，春、秋季降水明显减少，其中春季减少率为-14.8 mm/10 a，而夏季降水明显增加，增长率为21.8 mm/10 a，冬季降水小幅度增加。80年代及2001-2009年汛期年均降水较多。春、夏、秋季气温与降水有较好的相关性，而全年及冬季气温与降水相关规律不明显。

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.