Large Reductions in Satellite-Derived and Modelled European Lower Tropospheric Ozone During and After the COVID-19 Pandemic (2020–2022)

Abstract. Activity restrictions during the COVID-19 pandemic caused large reductions in ozone (O₃) precursor emissions. Studies showed large O₃ reductions in the 2020 spring-summer Northern Hemisphere free troposphere coinciding with this emission reduction period. Here, we provide an insight into the European satellite-derived tropospheric O₃ record updated to mid-2023. Rutherford Appleton Laboratory (RAL) retrieval products show large negative anomalies in the spring-summer periods of 2020–2022, with the largest in 2022, and smaller reductions in 2023. The Infrared Atmospheric Sounding Interferometer (IASI) showed peak reductions compared to monthly averages of 2.2 DU (11.0 %), 1.7 DU (8.4 %) and 2.8 DU (14.6 %) in 2020, 2021 and 2022, respectively. Scaling model emissions, based on activity reduction data, yields large negative anomalies peaking in May 2020 and 2021. Emissions reduction was the greater influence, explaining ~65 % of the decrease, however, the meteorological impact was substantial, driven by a reduced stratosphere-troposphere O₃ exchange flux.