Improvement And Application Of Response Surface Modeling Technology And O₃ Source Contribution Analysis Method

In recent years,due to the rapid urbanization and industrialization,the photochemical smog pollutions characterized by the high concentration of ozone?O₃?in the Pearl River Delta?PRD?region has become more and more severe.Accurately presenting the nonlinearities between ambient ozone?O₃?and the emissions of nitrogen oxides?NO_X?and volatile organic compound?VOC?,identifing the O₃-NO_X-VOC sensitivities,and quantifing the source contribution are the prerequisites for an effective O₃ control strategy.An Enhanced polynomial functions Response Surface Model?Epf-RSM?was firstly developed by integrating the hill-climbing adaptive method into the optimized Extended Response Surface Model?ERSM?system.Then,the Epf-RSM coupled with the sectoral linear fitting technique?Epf-RSM-SL?,which could single out the best suitable polynomial function for each grid cell,was bulid to present the response of O₃concentrations to multi-region and multi-sector precursor emission changes.Moreover,a new differential method?DM?was developed for analyzing the source contribution based on the prediction of the Epf-RSM-SL system.A series of validations were performed for evalidating the performances of Epf-RSM?Epf-RSM-SL,and DM.The results showed that?1?compared with the conventional pf-ERSM?polynomial functions based ERSM?,Epf-RSM could effectively reduce the errors in the margin and the transition areas;?2?the O₃ concentrations predicted by Epf-RSM-SL system agreed well with Community Multi-scale Air Quality simulation results;and?3?in comparision with the brute-force method?BFM?,DM could overcome the issue of nonlinear quantification.Finally,the Epf-RSM-SL system and DM were applied for O₃ sensitivity and source contribution analysis in July and October 2015 over the Pearl River Delta?PRD?region of China.Diagnosis of the O₃-NO_X-VOC sensitivity indicated that the O₃ formation in most regions of the PRD was in NO_X-limited regimes in July;in October,the initial VOC-limited or transition regime was found that would transit to NOx-limited regime when the emission reductions of NO_X were more than 22-44%.Investigation of the source contribution suggested that NO_x emissions were the dominated contributor when turning-off the anthropogenic emissions,occupying 85.42?94.90%and 52.61?75.37%of the peak O₃ responses in July and October respectively in the receptor regions of the PRD;the NO_X emissions from on-road mobile source?NO_X?ORM?in Guangzhou?GZ?,Zhongshan?ZS?,and Dongguan&Shenzhen?DG&SZ?were the main contributors.Consequently,the reinforced control of NO_X?ORM is highly recommended to lower the ambient O₃ in the PRD effectively.