应用去趋势互相关分析法对比分析了香港地区2011年7月2日-19日(其中,7月2日-10日为连续晴天,7月11日-19日为连续阴雨天)9个监测站点近地面NO2与O3互相关性及时间尺度特征.研究表明,香港地区近地面NO2与O3浓度波动的相关性在一定时间尺度内具有长期持续性特征,且这两种污染物浓度波动的相关性随时间衰减过程并不遵循经典的马尔可夫随机过程(即相关性随时间呈现指数衰减),而是以幂律形式随时间缓慢衰减.统计分析表明,香港地区9个监测站点NO2与O3相互作用的DCCA标度指数在空间上服从正态分布.此外,为了研究不同太阳辐射对NO2与O3相互作用的时间尺度的影响,对夏季阴雨天和晴天NO2与O3相关性进行了对比分析.结果表明,在不同天气条件下,太阳辐射对NO2与O3相互作用的时间尺度存在显著差异.同时,进一步结合光化学反应机制以及人类日常生活规律探讨了导致此种差异的原因,认为其差异性可能与总日照时数、每日太阳总辐射等因素有关.本研究有助于进一步加强对大气O3污染演化复杂规律的认识.
Temporal scaling properties of O3 and NO2 evolution at nine air automatic monitoring stations of Hong Kong were explored by using detrended cross-correlation analysis method, during a typical summer period (from July 2 to February 19, 2011).The results show that both in continuous sunny days and rainy days, the cross-correlation of O3 and NO2 exhibited long-term persistence, and the decay process of O3 and NO2 with time does not follow the classical stochastic Markov process (ie, the exponential decay of correlation with time),but in the form of power-law. Statistical analysis showed that, the scaling exponents of O3 and NO2 evolution of the nine monitoring stations obey normal distribution. In addition, in order to study the impact of solar radiation on different time scales of O3 and NO2, a comparative study of the correlation of O3 and NO2 in the continuous sunny days and rainy days. It shows that, under different weather conditions, there were significant differences in solar radiation on the time scale of the interaction between O3 and NO2. Further, an analysis to the photochemical reaction mechanism and the law of human life was made, we suggest that total sunshine claration and daily solar radiation may be the reasons for the differences. We hope this study will be of help to further understanding O3 pollution evolution process.