江苏省夏季暴雨的时空变率特征及其与不同类型ENSO的联系

利用1961—2016年江苏省70个站点的逐日降水资料和暴雨定义,分析了江苏省半个世纪以来暴雨发生的年代际时空变化特征,并分析了不同分布型El Nino发展年份对江苏省夏季降水和暴雨的影响特征。结果表明江苏省暴雨主要集中在6—8月,暴雨日数占全年的73.6%,尤其又以7月为最多;暴雨总的分布特点为苏北多于苏南,淮北西北部及苏南东部最少;江苏暴雨发生频次具有明显的年代际变化,且各地区暴雨的年代际变化有一定差异,频发期为1960s、1990s至今,尤其是1990s以来,全省暴雨增多趋势明显,且2011年之后雨带明显南移;东部型El Nino发展年份较中部型El Nino年份的环流形势更有利于导致江苏夏季降水偏多,尤其是沿江苏南地区与常年同期均值有显著性差异。

Spatial and temporal variation characteristics of summer rainstorm in Jiangsu Province and its relationship with different types of ENSO

Based on the daily precipitation data and the definition of rainstorm in 70 stations in Jiangsu Province from 1961 to 2016, this paper analyzes the interdecadal spatiotemporal variation characteristics of rainstorms in Jiangsu Province in the past half century, and the characteristics of the impact of the development years of ENSO of different distribution patterns on summer precipitation and rainstorms in Jiangsu Province. The results show that the rainstorms in Jiangsu Province are mainly concentrated in June and August, and the number of rainstorm stations accounts for 73.6% of the whole year, especially in July. The rainstorms in the northern Jiangsu are more than that of southern Jiangsu, and are least in Northwest of the northern Huaihe area and the East of the southern Jiangsu. The frequency of rainstorms shows obvious interdecadal variations, and the interdecadal variations of the regional rainstorms are different. The frequent periods of rainstorms are the 1960s and the period from 1990s to the present. In particular, since the 1990s, a marked increase has been shown in the number of rainstorms across the province, and the rain belt has obviously moved southward since 2011. Compared with the central ENSO years, the circulation of eastern ENSO years is more favorable to lead to more precipitation in Jiangsu Province in summer. In particular, there is a significant difference between the precipitation and the mean value of the same period in the southern Jiangsu Province.