吉林省夏季极端降水事件特征分析

利用吉林省46个气象站1961-2010年逐日降水资料,采用百分位定义极端事件阈值的方法,对吉林省极端降水事件的时空分布及变化趋势特征进行了分析。结果表明:(1)吉林省极端降水事件主要发生在夏季,其中5%的降水日数贡献了该季度25%～30%的降水量;夏季极端降水强度以通化地区最强、东部山区最弱,极端降水频率东部山区最大、西北部最小;(2)吉林省100mm以上的极端大暴雨天气也时有发生,通化地区南部发生几率最大,约为4～6 a一遇;中部一带约为8～10a一遇;西北平原区和东部山区出现大暴雨概率很小。(3)近50a吉林省夏季极端降水事件稍有增多的趋势,而强度变化趋势不明显,但存在明显的地域差别,西北部表现为频率减少、强度减弱,中部和东南部表现为频率增多、强度增强。(4)极端降水事件存在年代际差异,20世纪70年代极端降水频率最小,90年代极端降水强度最大,60年代初期极端降水强度存在由强转弱的突变。

Characteristic analysis of summer extreme precipitation events in Jilin Province

With daily precipitation data of 46 observational stations in Jilin Province from 1961 to 2010 and the 95th percentile as the threshold of extreme precipitation,the characteristics of the space-time distribution and variation tendencies of summer extreme precipitation events were analyzed.The results show that:(1) Extreme precipitation events in Jilin Province mostly happen in summer,and 5% rain days contribute about 25%-30% of total summer precipitation.The maximum mean intensity of summer extreme precipitation is in Tonghua area and the minimum is in eastern mountain areas,while the maximum frequency of summer extreme precipitation is in eastern mountain areas and the minimum is in Northwest areas.(2) Heavy rainstorms over 100mm often happen in summer once 4-6 years in south Tonghua area and 8-10 years in central Jilin Province while less likely to happen in other areas.(3) The summer extreme precipitation frequency shows a slightly increasing tendency without distinct intensity variation tendencies in recent 50 years.Both frequency and intensity of the summer extreme precipitation have decreasing tendency at most observational stations in northwest Jilin and increasing tendency at most stations in the Middle and Southeast Jilin.(4) The summer extreme precipitation events varied in every decade.The frequency was the least during the 1970s and the intensity was the most intensive during the 1990s.Extreme precipitation intensity had a mutation from higher to lower in early 1960s.