Modeling Study of Source Contributions and Emission Control Effects During a Heavy Ozone Pollution Event in Zhongshan City
In this paper,WRF-CMAQ model and NAQPMS model of the Zhongshan air quality forecasting and early warning system were used to analyze the ozone(O3)pollution process,source apportionment and emission control effects of a heavy O3 pollution event in Zhongshan City in September 2022.The WRF-CMAQ simulations showed reasonable agreement with the meteorological,nitrogen dioxide and O3 observations.This O3 pollution event was mainly caused by adverse meteorological conditions such as the downdraft around the typhoon and the continental high pressure.The contribution percentages of local emissions and regional transport to the O3 concentration in Zhongshan were 20.5％and 79.5％,with regional transport dominated.In terms of emission sectors,the two largest contributors to O3 in Zhongshan were transportation and solvent sources,with an average contribution of 39.6％and 35.6％,respectively.The contribution of industrial sources cannot be ignored,with an average contribution of 9.9％.Modeling results showed that emission reduction in Zhongshan alone cannot eliminate the heavy pollution days,indicating that emission reduction in a single city is difficult to resist the regional large-scale pollution event,and regional joint prevention and control is needed to deal with ozone pollution event.The effects of joint emission reductions in the key cities of Pearl River Delta including Zhongshan,Guangzhou,Dongguan,Foshan,Jiangmen and Shenzhen were evaluated by model sensitivity simulations.The greater of the intensity of emission reduction will get the more obvious of the improvement of air quality.When the emission reduction ratio reaches 100％,the pollution days of moderate and above levels will be eliminated,but there are still pollution days of mild level.It indicates that substantial emission reduction can significantly reduce the O3 peak concentrations and pollution days,but it is still difficult to fully resist the impact of extreme adverse meteorological conditions.
Zhongshanozonenumerical simulationsource analysisemission control
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