11 Aug 2022
11 Aug 2022
Status: this preprint is currently under review for the journal ACP.

Decoupling impacts of weather conditions on interannual variations in concentrations of criteria air pollutants in south China – constraining analysis uncertainties by using multiple analysis tools

Yu Lin1, Leiming Zhang2, Qinchu Fan3, He Meng4, Yang Gao1,3,5, Huiwang Gao3,5, and Xiaohong Yao1,3,5 Yu Lin et al.
  • 1Sanya Oceanographic Institution (Ocean University of China), Yazhou Bay Science & Technology City, Sanya, China
  • 2Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, ON, M3H 5T4, Canada
  • 3Key Laboratory of Marine Environment and Ecology (MoE), Ocean University of China, Qingdao, China
  • 4Qingdao Eco-Environment Monitoring Center of Shandong Province, Qingdao, China
  • 5Laboratory for Marine Ecology and Environmental Sciences, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China

Abstract. In this study, three methods including the random forest (RF) algorithm, boosted regression trees (BRTs) and the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) were adopted for investigating emission-driven interannual variations in concentrations of air pollutants including PM2.5, PM10, O3, NO2, CO, SO2 and (NO2+O3) monitored in six cities in south China from May 2014 to April 2021. The first two methods were used to calculate the deweathered hourly concentrations, and the third one was used to calculate decomposed hourly residuals. To constrain the uncertainties in the calculated deweathered or decomposed hourly values, a self-developed method was applied to calculate the range of the deweathered percentage changes (DePCs) of air pollutant concentrations in annual scale. Emission-driven trends and emission-driven percentage changes (PCs) during the whole seven-year period were generated with the four methods being applied to analyzing the data. The consistency in the trends between the RF-deweathered and BRTs-deweathered concentrations and the ICEEMDAN-decomposed residuals of an air pollutant in a city reaches approximately 70 % of all the studied cases, but that in the PCs reaches only approximately 30 % of all the cases. The remaining cases with inconsistent trends and/or PCs indicated large uncertainties produced by one or more of the three methods. The calculated PCs from the deweathered concentrations and decomposed residuals were thus combined with the corresponding range of DePCs calculated from the self-developed method to gain the robust range of DePCs where applicable. Building on the robust ranges, the mitigation effects were discussed.

Yu Lin et al.

Status: open (until 07 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-502', Zongbo Shi, 30 Aug 2022 reply

Yu Lin et al.

Model code and software

The code of DePC calculation Yu Lin

Video supplement

An example of construction activities Yu Lin and Xiaohong Yao

Yu Lin et al.


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Short summary
In order to assess the effectiveness of existing emission control strategies, we extracted emission-driven trends in concentrations of air pollutants by separately applying three methods and analyzed their uncertainties. We found consistent trends in approximately 70 % of the study cases, the effects of emission-driven took the lead in the overall changes. The effects of mitigation measures and weather perturbations were also discussed.