NOx Emission Changes Over China During the COVID‐19 Epidemic Inferred From Surface NO2 Observations. Issue 19 (2nd October 2020)

• Record Type: Journal Article
• Authors: Feng, Shuzhuang; Jiang, Fei; Wang, Hengmao; Wang, Haikun; Ju, Weimin; Shen, Yang; Zheng, Yanhua; Wu, Zheng; Ding, Aijun
• Is Part Of: Geophysical research letters. Volume 47:Issue 19(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-02
• Subjects: EnKF data assimilation -- NOX emission changes -- inversion -- WRF/CMAQ model -- COVID‐19; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL090080
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The COVID‐19 epidemic has substantially limited human activities and affected anthropogenic emissions. In this work, daily NO x emissions are inferred using a regional data assimilation system and hourly surface NO2 measurement over China. The results show that because of the coronavirus outbreak, NO x emissions across the whole mainland China dropped sharply after 31 January, began to rise slightly in certain areas after 10 February, and gradually recover across the country after 20 February. Compared with the emissions before the outbreak, NO x emissions fell by more than 60% and ~30% in many large cities and most small to medium cities, respectively. Overall, NO x emissions were reduced by 36% over China, which were mainly contributed by transportation. Evaluations show that the inverted changes over eastern China are credible, whereas those in western China might be underestimated. These findings are of great significance for exploring the reduction potential of NO x emissions in China. Plain Language Summary: In this study, we quantitatively estimate the impact of the COVID‐19 lockdown on NO x emissions over China based on nationwide surface hourly NO2 monitoring data. We find that NO x emissions dropped sharply after 31 January and began to gradually recover after 20 February across the country; NO x emissions fell by more than 60% in many large cities and decreased by ~30% in most small to medium cities. Across the whole mainland China, NO x emissions were reduced by 36% due to the COVID‐19 lockdown. Key Points: The spatiotemporal variations of NO x emissions across mainland China during COVID‐19 well inferred from surface NO2 observations NO x emissions fell by more than 60% in many large cities and by 36% across the whole mainland China due to the lockdown NO x emissions dropped sharply after 31 January and began to gradually recover after 20 February across the country