Abstract:

The variation characteristics of the annual precipitation in Da’an area of Jilin Province from 1959 to 2007 were discussed based on wavelet analysis method. The analysis result shows that the annual precipitation sequence of Da’an area represents a non-uniform time-scale distribution in its calculation period with a obvious local features, in which 4-6 years scale mainly occurred in the period of 1959-1969 and the year after 1984, the 10-12 years scale mainly occurred in the period of 1965-1999 and the 20-25 years scale occurred throughout the calculation period. In different time scales, the alternated change is different in the situation that the precipitation on the high side and low side. Simultaneously, the analysis shows that the sequence of precipitation of the region has a main period of 4 years, 10 years and 21 years, and the period of 4 years is the first main period.

Key words: wavelet transformation, Da’an area, Morlet wavelet, multiple time scales;precipitation