资源环境科技发展态势分析平台

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 approximately 30% in many large cities and most small‐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.