Research On Ozone Sensitivity Of Eighteen Cities In Henan Province Based On CMAQ-DDM-3D

At present,ozone(O3)has gradually and become the primary pollutant affecting the air quality of summer instead of PM2.5,especially the urbanized regions in China(for example Pearl River Delta,Yangtze River Delta,Beijing-Tianjin-Hebei).The ozone pollution in Henan,which is a typical province of the central China with large population,has been increased in recent years.However lack of relavant researchfor this region has caused an apperant knowlege gap still exist.Therefore,it is necessary to gain fundamental understanding about such topic to fill such gap in order to provide sufficient scientific suggestion for the government in preventing or effective controlling of ozone pollution in this region.This research used the observation data of the eight-hour moving average concentration of ozone from the National Environmental Monitoring Station between 2017 and 2019,combined with correspongding meteorological data from the Natioanl Meteorological Center to study the ozone pollution characteristics and effects of meteorological conditations of 17 cities(except for Jiyuan)in Henan Province.In this study,WRF-CMAQ air quality modelling system has been used to simulate the ozone pollution in Henan Province,the anthropogenic emission rates of the nested simulation domain were modelled with East Asia Emission Inventory(REAS)based on high-precision GDP and population gridded data,China Multi-scale Emission Inventory(MEIC),Henan Province High-resolution Emission Inventory;Simulation results have been validated by the observation data and the modelled O3 spatial distribution in the study area was in consistency with the observation.Additioanlly the high order direct decouple method(HDDM)was used to calculate the sensitivity of ozone to the anthropogenic emission intensity of precursors including VOCs and NOx in 18 cities in Henan Province,and finally the ozone EKMA contours regarding the relative emission rates of these cities have been plotted.From the result of this study,conclusions were drawn as:ozone pollution has the characteristics of higher concentration in northern part of Henan Province and lower concentrations in southern cities.The total number of days with ozone pollution in Henan Province increased gruadually from 2017 to 2019.Ozone pollution has significantly seasonal variation,and mainly occurred in June July and August in summer.During a day,the ozone concentration value increased sharpely in the time interval from 12:00 to 16:00.While the precipitation had a significant removing effect on ozone pollution,and the average wind speed was negatively correlated with ozone pollution.According to the HDDM results including the first-and second-order ozone sensitivity,the cities of Henan Province could be classified into three distinct catagories:industrialized cities including Anyang,Hebi,Puyang,Xinxiang,Shangqiu,Zhengzhou,Kaifeng,Xuchang,and Luohe mainly belonged to VOCs sensitive region,and the main agricultural cities including Nanyang,Sanmenxia,Zhumadian,Xinyang,Pingdingshan,Jiyuan were in the NOx sensitive region,while the remaining cities Zhoukou,Luoyang,and Jiaozuo were classified as transition regime.According to the intepretion of the EMKA contour,for effective ozone controll,optimum emission reduction strategy for industrial cities was found to be 2:1 ratio of VOCs to NOx,and for agricultural cities the optimum ratio was found to be nearly 1:2,while for the remaining transition regime 1:1 emission reduction ratio was suggested.