Wavelet-Based Analysis of Characteristics of Summer Rainfall in Nenjiang and Harbin

Based on 48 years of summer rainfall data,Morlet wavelet analysis was done of the sequence of summer rainfall in Nenjiang and Harbin,on a multi-time scale.Results show that in recent years,the summer rainfall in Harbin displayed the most apparent cyclical variation on a 29-38-year scale,the largest modulus,and the strongest energy;and the summer rainfall in Nenjiang did an obvious cyclical variation on a 19-30-year scale,and its energy value is quite large.Both the two cyclical variations showed a trend of being stronger in energy with the time.Presently,both the summer rainfalls in Nenjiang and Harbin are in a long cyclical period of low-water.It is predicted that in a relatively long period the summer rainfall will be lower than the average of the past 48 years.