Assessment of Sectoral NOx Emission Reductions During COVID‐19 Lockdown Using Combined Satellite and Surface Observations and Source‐Oriented Model Simulations. Issue 3 (2nd February 2022)

• Record Type: Journal Article
• Authors: Kang, Mingjie; Zhang, Jie; Cheng, Zhen; Guo, Song; Su, Fangcheng; Hu, Jianlin; Zhang, Hongliang; Ying, Qi
• Is Part Of: Geophysical research letters. Volume 49:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-02
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL095339
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Large emission reductions of anthropogenic nitrogen oxides (NO x ) due to the coronavirus disease 2019 (COVID‐19) lockdown policies in China have been extensively reported since the outbreak, while assessments of sectoral emission changes during that period are still limited. In this study, a source‐oriented community multiscale air quality (CMAQ) model was applied to quantify NO2 concentrations from major emission sectors. A new optimization approach was employed to obtain the sectorial emission reductions using satellite and ground‐level observations as constraints. The optimized emissions significantly improved the model performance of NO2 during the lockdown period. February NO x emission changes varied with regions and sectors, with relatively larger reductions in transportation (286.6 kt) and industrial sources (260.1 kt). The maximum amount of NO x emission reduction occurred in the North China Plain (230.6 kt). Our work presents a quick and reliable technique for assessing sector‐specific emission changes due to short‐term emission control policies. Plain Language Summary: In China, the strict lockdown periods in February 2020 to slow the spread of coronavirus disease 2019 (COVID‐19) led to significant reductions in the emissions of nitrogen oxides (NO x ). While the total amounts of emission reductions have been inferred from surface and satellite observations, studies on the changes from major emission sources such as transportation and industry sectors are still limited. In this study, we use an advanced air quality model to determine the contributions of different emission sectors to NO2 concentrations. A new optimization method is then applied to determine the emission reductions of each sector. The agreement between modeled and observed concentrations improved significantly with the adjusted emission estimations. February NO x emission changes vary with regions and sectors, with relatively larger reductions in transportation (286.6 kt) and industrial sources (260.1 kt). The maximum amount of NO x emission reduction happened in the North China Plain (230.6 kt). Our work presents a quick and reliable technique for assessing sector‐specific emission changes due to short‐term emission control policies. Key Points: A new optimization method coupled with a source‐oriented model was applied to estimate sector‐based NO x emission changes NO x emission changes vary with regions and sectors, with larger reductions in transportation (286.6 kt) and industrial sources (260.1 kt) Our work presents a quick and reliable technique for assessing the actual sectoral NO x emission changes due to short‐term control policies