基于Matlab小波分析的南京北郊大气O_3浓度变化特征研究

Observational Study of Ozone Concentrations in Northern Suburb of Nanjing Based on Matlab Wavelet Analysis

以2008年南京北郊大气中O3质量浓度观测资料和常规观测资料为基础,利用Matlab小波分析工具,对O3浓度的年时间序列进行分析,得出该地区的O3日均浓度的变化特征:春、夏季节O3浓度大于秋、冬季节,最高浓度出现在春末夏初,最低浓度出现在冬季;并且全年共有5个突变点;弱高压的天气系统、较高的温度、较低的湿度和晴朗少云的天气是造成南京北郊O3浓度突变的主要气象因素。结合HYSPLIT气流后向轨迹模拟,对污染源来源进行追踪,结果表明:南京北郊O3高浓度污染来源主要分为本地局地污染和外来污染物输送两类;垂直方向上,O3的区域尺度或中尺度的输送主要稳定在混合层的底层。

Based on the O3 and meteorological data observed in northern suburb of Nanjing in 2008,the time series and the variation characteristics of the daily averaged O3 was analyzed with a Matlab wavelet method.The results indicated that the O3 concentration in spring and summer were higher than that in autumn and winter.And the daily maximum and minimum values were presented in late spring to early summer and winter respectively.There were five O3 concentration mutation points during the whole year.The mutational variation of the O3 concentration was caused by the high-pressure system,high temperature,low humidity and the sunny and cloudless climate.The source of the pollutants was studied with a HYSPLIT pollutant dispersion model.The results showed that the pollution source leaded to the higher level of O3 concentration was mostly come form the local pollutant and transportation of outer pollutant,and the transportation of the O3 in regional scale or mesoscale was mainly stabilized at the bottom of mixing layer in the vertical direction.