Tropospheric NO(2) and O(3) Response to COVID‐19 Lockdown Restrictions at the National and Urban Scales in Germany

This study estimates the influence of anthropogenic emission reductions on nitrogen dioxide ([Formula: see text]) and ozone ([Formula: see text]) 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) [Formula: see text] concentrations by 23 [Formula: see text] (& 16 [Formula: see text]) between March 21 and June 30, 2020 after accounting for meteorology, whereas the corresponding mean in‐situ [Formula: see text] concentration increased by 4 [Formula: see text] between March 21 and May 31, 2020, and decreased by 3 [Formula: see text] in June 2020, compared to 2019. In the winter and spring, the degree of [Formula: see text] saturation of ozone production is stronger than in the summer. This implies that future reductions in [Formula: see text] emissions in these metropolitan areas are likely to increase ozone pollution during winter and spring if appropriate mitigation measures are not implemented. TROPOMI [Formula: see text] 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 [Formula: see text] emissions from agricultural soils.