Nitrogen dioxide decline and rebound observed by GOME-2 and TROPOMI during COVID-19 pandemic

Song Liu; Pieter Valks; Steffen Beirle; Diego G Loyola

doi:10.1007/s11869-021-01046-2

Nitrogen dioxide decline and rebound observed by GOME-2 and TROPOMI during COVID-19 pandemic

Air Qual Atmos Health. 2021;14(11):1737-1755. doi: 10.1007/s11869-021-01046-2. Epub 2021 Aug 28.

Authors

Song Liu^{1

2}, Pieter Valks¹, Steffen Beirle³, Diego G Loyola¹

Affiliations

¹ Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Methodik der Fernerkundung (IMF), Oberpfaffenhofen, Germany.
² Present Address: School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
³ Max Planck Institute for Chemistry, Mainz, Germany.

Abstract

Since its first confirmed case in December 2019, coronavirus disease 2019 (COVID-19) has become a worldwide pandemic with more than 90 million confirmed cases by January 2021. Countries around the world have enforced lockdown measures to prevent the spread of the virus, introducing a temporal change of air pollutants such as nitrogen dioxide (NO₂) that are strongly related to transportation, industry, and energy. In this study, NO₂ variations over regions with strong responses to COVID-19 are analysed using datasets from the Global Ozone Monitoring Experiment-2 (GOME-2) sensor aboard the EUMETSAT Metop satellites and TROPOspheric Monitoring Instrument (TROPOMI) aboard the EU/ESA Sentinel-5 Precursor satellite. The global GOME-2 and TROPOMI NO₂ datasets are generated at the German Aerospace Center (DLR) using harmonized retrieval algorithms; potential influences of the long-term trend and seasonal cycle, as well as the short-term meteorological variation, are taken into account statistically. We present the application of the GOME-2 data to analyze the lockdown-related NO₂ variations for morning conditions. Consistent NO₂ variations are observed for the GOME-2 measurements and the early afternoon TROPOMI data: regions with strong social responses to COVID-19 in Asia, Europe, North America, and South America show strong NO₂ reductions of $\sim$ 30-50% on average due to restriction of social and economic activities, followed by a gradual rebound with lifted restriction measures.

Supplementary information: The online version contains supplementary material available at 10.1007/s11869-021-01046-2.

Keywords: COVID-19; GOME-2; Harmonized retrieval; TROPOMI; Tropospheric NO2.