Characteristics and Synoptic Patterns of PM2.5-O3 Complex Pollution in Chaozhou City
Based on the Chaozhou urban area's hourly air quality concentration data from 2014 to 2020,the annual,monthly and daily variation characteristics of PM2.5-O3 complex pollution were analyzed.The reanalysis data were used to classify the weather situation,and combined with the meteorological data from Chaozhou National Station in the corresponding period,the relationship between PM2.5-O3 and synoptic patterns and meteorological factors was analyzed in this paper.The results showed that the annual mean ρ(PM2.5),ρ(O3-8 h)and the number of days of complex pollution in the Chaozhou urban area showed a decreasing trend during 2014-2020.The highest monthly mean ρ(PM2.5)appeared in March,the highest monthly mean ρ(O3-8 h)appeared in October,and the lowest of both pollutants appeared in June.The most complex pollution occurred from October to April of the following year.PM2.5 and O3 pollution had certain interactions.When the daily average concentration of one pollutant was higher,the concentration of the other pollutant was correspondingly higher,and the daily range of pollutant concentration also increased.When air pollution was severe,the peak time of O3 appeared at 15:00,and the peak time of PM2.5 appeared at 19:00-20:00.The weather patterns that caused the complex pollution in Chaozhou were mainly the degenerative ridge of high pressure,anticyclone,subtropical high and degenerative ridge of high pressure,and uniform pressure field,which mainly appeared in autumn,winter and spring,and a few appeared in early summer.The four weather types appeared in different seasons,but generally speaking,sunny and dry weather was the main meteorological factor for the occurrence of complex pollution.