Investigation of the summer 2018 European ozone air pollution episodes using novel satellite data and modelling

• Published in: Atmospheric Chemistry and Physics
• Main Authors: R. J. Pope, B. J. Kerridge, M. P. Chipperfield, R. Siddans, B. G. Latter, L. J. Ventress, M. A. Pimlott, W. Feng, E. Comyn-Platt, G. D. Hayman, S. R. Arnold, A. M. Graham
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: Physics; QC1-999; Chemistry; QD1-999; North Atlantic
• Online Access: https://doi.org/10.5194/acp-23-13235-2023; https://doaj.org/article/14af8c78293246708a49793f19384b30

In the summer of 2018, Europe experienced an intense heatwave which coincided with several persistent large-scale ozone ( O 3 ) pollution episodes. Novel satellite data of lower-tropospheric column O 3 from the Global Ozone Monitoring Experiment-2 (GOME-2) and Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite showed substantial enhancements in 2018 relative to other years since 2012. Surface observations also showed ozone enhancements across large regions of continental Europe in summer 2018 compared to 2017. Enhancements to surface temperature and the O 3 precursor gases carbon monoxide and methanol in 2018 were co-retrieved from MetOp observations by the same scheme. This analysis was supported by the TOMCAT chemistry transport model (CTM) to investigate processes driving the observed O 3 enhancements. Through several targeted sensitivity experiments we show that meteorological processes, and emissions to a secondary order, were important for controlling the elevated O 3 concentrations at the surface. However, mid-tropospheric ( ∼ 500 hPa ) O 3 enhancements were dominated by meteorological processes. We find that contributions from stratospheric O 3 intrusions ranged between 15 %–40 %. Analysis of back trajectories indicates that the import of O 3 -enriched air masses into Europe originated over the North Atlantic, substantially increasing O 3 in the 500 hPa layer during summer 2018.