Spatiotemporal analysis on the impact of COVID-19 pandemic on NO2 emission in China

ABSTRACT

Based on the high-resolution TROPOMI data, this paper analyzed the spatial distribution of NO2 column density during the COVID-19 outbreaking period in China, and revealed the spatial variations in the NO2 changes during the year-on-year and month-on-month COVID-19 pandemic. The analysis showed that during the pandemic, the nationwide decline in NO2 column density compared to the NO2 level during the same period in 2019 (year-on-year) and during one-month before (month-on-month) the pandemic reached 40.46% and 50.09%, respectively. The economically developed and populous urban agglomerations had a significant decrease in emissions. Specifically, provinces with high historical NO2 emissions, including Jiangsu, Henan, Shandong, Zhejiang, etc., were more affected by the epidemic. Hubei showed the lowest NO2 column density (1.63×1015molec/cm2) during the epidemic period among the central and eastern provinces, with the NO2 decrease compared to the NO2 level during the same period in 2019 and during one-month before the pandemic greater than 50%. Regarding different cities in Hubei, the influence of the COVID-19 pandemic on the surrounding cities, e.g. Wuhan and Xiaogan, was much greater than that on the western mountainous cities, e.g. Shiyan and Enshi. The measurements of NO2 concentration at the ground-based national air quality monitoring stations also showed a consistent spatiotemporal trend with satellite observations, indicating that the "top-down" remote sensing method can efficiently reflects the intensity of air pollution emissions and the level of socio-economic activities in different regions. © 2021, Editorial Board of China Environmental Science. All right reserved.