Analysis of Meiyu Characteristics and General Circulation Over the Changjiang-Huaihe River Valley in Recent 116 Years
On the basis of the Meiyu characters and NCEP/NCAR reanalysis daily data from 1885 to 2000,The inter-annual and inter-decadal charaeteristics of Meiyu Characters were investigated in terms of harmonic analysis, maximum entropy spectrum analysis, wavelet analysis and composite analysis method and so on. The results show that there are prominent inter-annual and inter-decadal variations of Meiyu characters. The tendencies of onset, end and length of Meiyu are increasing with remarkable long-term evolutions, but no evident trend for precipitation and intensity of Meiyu. There are different time scale oscillations for Meiyu characters, such as quasi-24-year,quasi-5-year and quasi-3-year periodic oscillations for onset of Meiyu and quasi-35-year,quasi-22-year,quasi-5-year′s for end of Meiyu and quasi-40-year,quasi-15-year,quasi-9-year,quasi-3-year′s for precipitation of Meiyu. South Asia high and western Pacific subtropical high are stronger in rich Meiyu years than those in poor Meiyu years over the Changjiang-Huaihe region during the Meiyu period.