[Wavelet analysis on SO2 pollution index changes of Shanghai in recent 10 years]

Based on the continuous Mexican Hat wavelet transformation of time series of daily SO2 pollution index during last 10 years in Shanghai, the multiscale variations, primary period, catastrophe point and influencing factors are analyzed. The result shows that periodical fluctuation of SO2 pollution index varies at diverse time-scales, and the primary period of the daily variations is about 100 days; pollution pattern takes on serious in winter and light in summer in most scales due to meteorological conditions, and the catastrophe point of serious-light transformation of SO2 pollution index in a year is vernal and autumnal equinox; energy demand and socioeconomic development result in more seriousness in recent years and half result with twice the effort of endeavors of pollution elimination. Wavelet analysis is an effective method to time series of SO2 pollution index, also to multiscale variations of other pollutants.