Tropospheric NO2 and O3 Response to COVID-19 Lockdown Restrictions at the National and Urban Scales in Germany

Vigneshkumar Balamurugan; Jia Chen; Zhen Qu; Xiao Bi; Johannes Gensheimer; Ankit Shekhar; Shrutilipi Bhattacharjee; Frank N Keutsch

doi:10.1029/2021JD035440

Tropospheric NO₂ and O₃ Response to COVID-19 Lockdown Restrictions at the National and Urban Scales in Germany

J Geophys Res Atmos. 2021 Oct 16;126(19):e2021JD035440. doi: 10.1029/2021JD035440. Epub 2021 Sep 27.

Authors

Vigneshkumar Balamurugan¹, Jia Chen¹, Zhen Qu², Xiao Bi¹, Johannes Gensheimer¹, Ankit Shekhar³, Shrutilipi Bhattacharjee⁴, Frank N Keutsch^{2

5}

Affiliations

¹ Environmental Sensing and Modeling Technical University of Munich (TUM) Munich Germany.
² School of Engineering and Applied Science Harvard University Cambridge MA USA.
³ Department of Environmental Systems Science ETH Zurich Zurich Switzerland.
⁴ Department of Information Technology National Institute of Technology Karnataka Surathkal India.
⁵ Department of Chemistry and Chemical Biology Harvard University Cambridge MA USA.

Abstract

This study estimates the influence of anthropogenic emission reductions on nitrogen dioxide ( ${N O}_{2}$ ) and ozone ( $O_{3}$ ) concentration changes in Germany during the COVID-19 pandemic period using in-situ surface and Sentinel-5 Precursor TROPOspheric Monitoring Instrument (TROPOMI) satellite column measurements and GEOS-Chem model simulations. We show that reductions in anthropogenic emissions in eight German metropolitan areas reduced mean in-situ (& column) ${N O}_{2}$ concentrations by 23 $%$ (& 16 $%$ ) between March 21 and June 30, 2020 after accounting for meteorology, whereas the corresponding mean in-situ $O_{3}$ concentration increased by 4 $%$ between March 21 and May 31, 2020, and decreased by 3 $%$ in June 2020, compared to 2019. In the winter and spring, the degree of ${N O}_{X}$ saturation of ozone production is stronger than in the summer. This implies that future reductions in ${N O}_{X}$ emissions in these metropolitan areas are likely to increase ozone pollution during winter and spring if appropriate mitigation measures are not implemented. TROPOMI ${N O}_{2}$ concentrations decreased nationwide during the stricter lockdown period after accounting for meteorology with the exception of North-West Germany which can be attributed to enhanced ${N O}_{X}$ emissions from agricultural soils.

Keywords: COVID‐19; GEOS‐Chem; NOX‐saturated; emission reduction; nitrogen oxide; ozone.