Enhanced PM2.5 Decreases and O3 Increases in China During COVID-19 Lockdown by Aerosol-Radiation Feedback

Jia Zhu; Lei Chen; Hong Liao; Hao Yang; Yang Yang; Xu Yue

doi:10.1029/2020GL090260

Enhanced PM_2.5 Decreases and O₃ Increases in China During COVID-19 Lockdown by Aerosol-Radiation Feedback

Geophys Res Lett. 2021 Jan 28;48(2):e2020GL090260. doi: 10.1029/2020GL090260. Epub 2021 Jan 18.

Authors

Jia Zhu¹, Lei Chen^{1

2}, Hong Liao¹, Hao Yang¹, Yang Yang¹, Xu Yue¹

Affiliations

¹ Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology School of Environmental Science and Engineering Nanjing University of Information Science & Technology Nanjing China.
² Key Laboratory of Meteorological Disaster Ministry of Education Joint International Research Laboratory of Climate and Environment Change Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology Nanjing China.

Abstract

We apply an online-coupled meteorology-chemistry model (WRF-Chem) embedded with an improved process analysis to examine aerosol-radiation feedback (ARF) impacts on effectiveness of emission control due to Coronavirus Disease 2019 (COVID-19) lockdown over North China Plain. Emission reduction alone induces PM_2.5 decrease by 16.3 μg m^-3 and O₃ increase by 10.2 ppbv during COVID-19 lockdown. The ARF enhances PM_2.5 decrease by 2.7 μg m^-3 (16.6%) and O₃ increase by 0.8 ppbv (7.8%). The ARF-induced enhancement of PM_2.5 decline is mostly attributed to aerosol chemistry process, while enhancement of O₃ rise is ascribed to physical advection and vertical mixing processes. A set of sensitivity experiments with emission reductions in different degrees indicate that the ARF-induced enhancements of PM_2.5 declines (O₃ rises) follow a robust linear relationship with the emission-reduction-induced PM_2.5 decreases. The fitted relationship has an important implication for assessing the effectiveness of emission abatement at any extent.

Keywords: COVID‐19; O3; PM2.5; aerosol‐radiation feedback; emission reduction.