江淮梅雨的多尺度特征及其与厄尔尼诺和大气环流的联系

The Multiscale Characteristics of Meiyu in the Changjiang-Huaihe River Valley and Its Association with the El Nino and the General Circulation

利用小波变换,分析了江淮流域夏季降水的多尺度特征和存在的周期,通过对Nino3区海温、西太平洋副高以及亚洲纬向环流指数的小波变换,分析了它们与江淮流域夏季降水的多尺度联系。结果表明,整个江淮流域的降水具有明显的年际和年代际变化特征,年际变化主要表现为3～4a、5～6a和7～8a的周期,年代际变化则表现为12～13a、16～17a和27a的周期。南片和北片以及长江中游和下游之间所具有的特征是不尽相同的。相对于亚洲纬向环流指数而言,Nino3区海温对江淮流域降水的影响较为重要。Nino3区的海温与江淮流域降水的联系,在一些时段是同位相的,而在另一些时段是反位相的。

The multiscale characteristics and period of summer precipitation in the Changjiang-Huaihe River valley have been analyzed by using the wavelet transformation.Through the wavelet transformation of Nino3 SSTA,indices of west Pacific subtropic high and Asian zonal circulation,the multiscale associations between them and rainfall in the Changjiang-Huaihe River valley have been investigated.The results suggest that precipitation of the Changjiang-Huaihe River valley has obvious interannual and interdecadal variation characters.The interannual peorids are found in 2～3, 5～6 and 7～8 year. The interdecadal periods are found in 12～13, 16～17 and 27 year.The characters of the south and north regions,as well as those of the middle and lower reaches of the Changjiang River,are different.The impact of Nino3 SSTA on rainfall in the Changjiang-Huaihe River valley is more significant than the impact of Asian zonal circulation.The association of the Nino3 SSTA,as well as the indices of western Pacific subtropic high,with rainfall in the Changjiang-Huaihe River valley is in-phase in some periods,but out-of-phase in other periods.