长三角地区汛期暴雨时空特征分析

为揭示长三角地区汛期暴雨时空特征,利用该地区20个气象测站1959—2005年逐日降水数据,统计不同测站年汛期(5月—9月)暴雨量、暴雨日数,采用数据场、线性趋势法、Mann-Ken-dall非参数检验法及Morlet小波方法对其进行分析。结果表明,长三角地区可分为南区、中区、北区3个空间区域。47 a来各分区汛期暴雨量呈先减少再增加的趋势,整体上呈增加趋势,但均不显著,只有中区在1998—2003年间出现超过α=0.05显著性水平的变化特征。各分区均存在25 a左右的准周期震荡,且具有全域性;从20世纪80年代开始短时间尺度周期(小于20 a)有延长趋势,但不稳定。

Spatial and Temporal Feature Analysis of Rainstorms in Flood Season in Yangtze River Delta Region

To reveal spatial and temporal feature of rainstorms in flood season in Yangtze river delta region,using the daily precipitation data of 20 meteorological stations in Yangtze river delta region during the 1959-2005,the annual flood season(from May to September) rainstorms quantity and days in different stations were obtained by statistical method.Spatial and temporal features of rainstorms were studied by using data field,linear trend method,Mann-Kendall non-parameter test and Morlet wavelet method.The results show that the region can be divided into 3 subregions: southern,central and northern subregions.In the past 47 years,the flood season rainstorms quantity of each partition reduced firstly and then increased,and it was tending to increase throughout the period.Only the central subregion appeared more than α=0.05 significant level of change characteristics in 1998-2003.Each subregion had the quasi-periodic concussion of 25 years or so in the past 47 years.From the 1980s,the short time scale cycles(less than 20 years) were tending to prolong,but they were unstable.