Abstract: By using summer precipitation and annual precipitation sequence data last 51 years(1951-2001) from Changchun weather station,the temporal-frequency multi-time scale and jump features of summer and annual precipitation(1951-2001) in Changchun were analyzed based on complex Morlet wavelet.The results showed that the time scales of the summer and annual precipitation time series were uneven in time domain,the local characteristics were obvious.Summer precipitation time series were 5 and 15 years periods.Annual precipitation time series were 5 years,8 years,16 years and 22 years periods.The annual precipitation and summer precipitation are very similar in terms of time scales and cycle characteristics.

Key words: Morlet wavelet, Morlet wavelet, Precipitation, Time series, Multi-time scale