Variation Characteristics of Ozone Pollution and Their Relationship with Sunshine and Precipitation in Chengde City

Meng Xuqin; Tong Jun; Zhang Xiaohui; Wang Duo; Peng Jiuhui; Tan Guoming

doi:10.16765/j.cnki.1673-7148.2023.06.012

Abstract：Using the hourly data of NO2,CO,SO2,O3 of four ambient air quality monitoring sta-tions and the meteorological data in Chengde City from 2017 to 2020,as well as the methods of Pearson correlation analysis and mathematical statistics,this paper analyzes the distribution characteristics of pol-lutants,the occurrence law of the daily extreme value of O3 and its correlation with related factors in Chengde city,especially the influence of precipitation and sunshine on it.The results show that:(1)From 2017 to 2020,the number of substandard air quality in Chengde City showed a trend of first in-creasing and then decreasing,but the proportion of O3 was increasing year by year.(2)The daily maxi-mum O3-8h concentration ρ(O3-8 h max)mainly appeared around 18:00 from March to October.The daily maximum O3 concentration ρ(O3 max)appeared around 16:00 from March to May and from August to Oc-tober,and appeared around 14:00 in June and July.In terms of the daily minimum O3 concentrationρ(O3 min),it usually appeared around 06:00.(3)The correlation coefficients between ρ(O3 min)andρ(O3-8 h max)of the previous day and that very day were 0.614 and 0.502,respectively.The O3 pollution had continuity under suitable conditions.(4)Except for the lack of sunshine in March and insufficient sunshine in June,the maximum value of monthly average ρ(O3-8h max)occurred in sunny enough weath-er.The ρ(O3-8 h max)in sunshine deficiency and precipitation weather showed a negative growth.(5)During the precipitation processes lasting for different days,the average value of ρ(O3-8 h max)before the precipitation was higher than after the precipitation,and the daily average values of ρ(NO2),ρ(SO2)and ρ(CO)are basically reduced as precipitation went on,while the average value of ρ(O3 min)increased on the first day of precipitation and decreased on the next day.(6)The scavenging effect of precipitation on O3 at different times was that of the whole day＞that before 13:00＞that after 13:00.When ρ(O3-8h max)was higher than 160 μg/m3,the increase and decrease of p(O3-8 h max)caused by the precipi-tation before 13:00 were respectively＜2 mm and 2～6 mm,while ρ(O3-8 h max)was affected by the occur-rence time of precipitation after 13:00,and 91.3％ of precipitation occurred between 18:00 and 00:00.With the increase of precipitation before 13:00,the number of days with ρ(O3-8 h max)in the range of 100 to 160 µg/m3 decreased,and the number of days with ρ(O3-8 h max)less than 100 μg/m3 increased.