重庆市近11年空气污染指数变化的小波变换分析

Wavelet Transformation Analysis of Chongqing Air Pollution Index Change in Recent 11 Years

运用一维连续Modet小波变换法分析重庆市近11年逐日空气污染指数的多尺度演变特征、主周期、突变点和变化因素。结果表明：重庆市空气污染指数在不同时间尺度有不同的变化规律，变化主周期为300d左右；空气污染状况受地形和气象因素影响，呈“冬重夏轻”格局；春分、秋分前后是一年中空气污染轻重状况转换的突变点；2005年后重庆市空气污染逐渐减轻，但冬季有加重趋势。实践证明，小波变换法是研究空气污染指数时间序列变化的有效分析方法。

To explore the multi-scale variations, primary period and influencing factors in Chongqing air pollution index change,the continuous Morlet wavelet transformation method is used to analyze the time series of daily air pollution index in recent 11 years. The result shows that the air pollution index varies at diverse time-scales. The primary period of the daily variations of air pollution index is around 300 d. Due to topographical and meteorological conditions, the air pollution is serious in winter and minor in summer at most scales. The inflection points of serious-light transformation of air pollution index in a year are the vernal and autumnal equinoxes. The air pollution in Chongqing is reduced after 2005, yet it has a increasing trend in winter. Facts show that wavelet analysis method is an effective method for multi-scale variations of air pollution index.