L. Liu, L. Liu, J. Wu, S. Liu, X. Li, J. Zhou, T. Feng, Y. Qian, J. Cao, J. Cao, X. Tie, G. Li
||Atmospheric Chemistry and Physics, 2019, Vol.19 , pp.8189-8207
||Directory of Open Access Journals
Although stringent emission mitigation strategies havebeen carried out since 2013 in Beijing–Tianjin–Hebei (BTH), China, heavyhaze with high levels of fine particulate matter (PM 2.5 ) stillfrequently engulfs the region during wintertime and the nitrate contributionto PM 2.5 mass has progressively increased. N2O5 heterogeneous hydrolysis is the most important pathway of nitrateformation at nighttime. In the present study, the WRF-Chem model is appliedto simulate a heavy haze episode from 10 to 27 February 2014 in BTH toevaluate contributions of N2O5 heterogeneous hydrolysis tonitrate formation and effects of organic coating. The model generallyperforms reasonably well in simulating meteorological parameters, airpollutants,... and aerosol species against observations in BTH. N2O5 heterogeneous hydrolysis with all the secondary organicaerosol assumed to be involved in coating considerably improves the nitratesimulations compared to the measurements in Beijing. On average, organiccoating decreases nitrate concentrations by 8.4 % in BTH during anepisode, and N2O5 heterogeneous hydrolysis with organiccoating contributes about 30.1 % of nitrate concentrations. Additionally,the reaction also plays a considerable role in the heavy haze formation,with a PM 2.5 contribution of about 11.6 % in BTH. Sensitivity studiesalso reveal that future studies need to be conducted to predict the organicaerosol hygroscopicity for accurately representing the organic coatingeffect on N2O5 heterogeneous hydrolysis.