1961-2014年西安市秋淋气候特征分析

利用1961-2014年8-10月西安市7个气象站逐日降水资料,采用降水强度指数分析了西安市秋淋天气气候变化特征.结果表明,20世纪90年代是近50年来西安市秋季9~10月降水量最少的阶段.1961年以来西安市共有23 a出现秋淋多雨时段,20世纪60年代至80年代中期较多,1983年和1984年出现强秋淋;20世纪80年代中期至21世纪10年代初期,只有1992年出现了1次秋淋天气;2011年以来,秋淋呈明显上升、增强趋势.1961-2014年秋淋天气过程平均降水量呈上升趋势,偏多年份主要出现在20世纪80年代初中期和21世纪.厄尔尼诺使秋季9~10月降水量减少,与秋淋天气存在明显的负相关关系.近54年西安市秋淋没有发生显著的气候突变,存在4~6 a、10 a和24 a左右的长振荡周期.

Analysis on Climatic Characteristics of Autumn-rainy in Xi`an from 1961 to 2014

Based on the daily precipitation data of seven meteorological stations in 8-10 month from 1961 to 2014 in Xi`an,using precipitation intensity index,the climatic characteristics of autumn-rainy in Xi`an was analyzed.Results showed that 1990s was the least precipitation phase in the last 54 years on 9-10 month precipitation in autumn in Xi`an.Since 1961,there were 23 years of autumn-rainy period in Xi`an,from 1960s to mid 1980s more,in 1983 and in 1984 strong autumn-rainy;from mid 1980s to early 2010s,only in 1992 there was one autumn-rainy;since 2011,autumn-rainy showed a marked rise and increase trend.From 1961 to 2014,the years with more-than-normal rainfall mainly appeared in early and mid 1980s and 2000s.El Nino made 9-10 month precipitation decrease,and autumn-rainy weather had obvious negative correlation.In the past 54 years,there had been no significant abrupt change in the climate of autumn-rainy in Xi`an,which had long oscillation periods of 4 to 6 years,10 years and 24 years or so.