Year-round changes in tropospheric nitrogen dioxide caused by COVID-19 in China using satellite observation

The lockdown policy deals a severe blow to the economy and greatly reduces the nitrogen oxides (NOx) emission in China when the coronavirus 2019 spreads widely in early 2020. Here we use satellite observations from Tropospheric Monitoring Instrument to study the year-round variation of the nitrogen dioxide (NO2) tropospheric vertical column den-sity (TVCD) in 2020. The NO2 TVCD reveals a sharp drop, followed by small fluctuations and then a strong rebound when compared to 2019. By the end of 2020, the annual average NO2 TVCD declines by only 3.4% in China mainland, much less than the reduction of 24.1% in the lockdown period. On the basis of quantitative analysis, we find the rebound of NO2 TVCD is mainly caused by the rapid recovery of economy especially in the fourth quarter, when con-tribution of industry and power plant on NO2 TVCD continues to rise. This revenge bounce of NO2 indicates the emission reduction of NOx in lockdown period is basically offset by the recovery of economy, revealing the fact that China's economic development and NOx emissions are still not decoupled. More efforts are still required to stimulate low-pollution development. (c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

The lockdown policy in China during the spread of coronavirus in early 2020 severely impacted the economy and led to a significant reduction in nitrogen oxides (NOx) emissions. Satellite observations showed a sharp drop in nitrogen dioxide (NO2) levels, followed by small fluctuations and a strong rebound compared to 2019. The rebound of NO2 was mainly driven by the rapid economic recovery, particularly in the industrial and power sectors. This indicates that the emission reduction during the lockdown was offset by the economic recovery, highlighting the need for further efforts to promote low-pollution development.