24 Mar 2022
24 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Attribution of surface ozone to NOx and VOC sources during two different high ozone events

Aurelia Lupaşcu1, Noelia Otero1,a, Andrea Minkos2, and Tim Butler1,3 Aurelia Lupaşcu et al.
  • 1Institute for Advanced Sustainability Studies (IASS), Potsdam, 14467, Germany
  • 2German Environment Agency, 06844 Dessau-Roßlau, Germany
  • 3Freie Universität Berlin, Institut für Meteorologie, Berlin, Germany
  • anow at: Oeschger Centre for Climate Change Research (OCCR), Bern, Switzerland

Abstract. Increased tropospheric ozone (O3) and high temperatures affect human health during heat waves. Here, we perform a source attribution that considers separately the formation of German surface ozone from emitted NOx and VOC precursors during two peak ozone events that took place in 2015 and 2018 which were associated with elevated temperatures. Results showed that the peak ozone concentrations can be primarily attributed to nearby emissions of anthropogenic NOx (from Germany and immediately neighboring countries) and biogenic VOC. Outside of these high ozone episodes, baseline ozone concentrations are attributed primarily to long-range transport, with ozone due to remote anthropogenic NOx emissions and methane oxidation adding to the tropospheric ozone background. We show that a significant contribution to modeled O3 coming from German NOx or VOC emissions occurs mostly in southern Germany, emphasizing that the production of ozone depends on the local interplay among NOx and VOC precursors. Shipping activities in the Baltic and North Seas have a large impact on ozone predicted in coastal areas, yet a small amount of ozone from these sources can also be seen far inland, showing the importance of transported ozone on pollution levels. We have also shown that changes in circulation patterns during the peak O3 episodes observed in Germany during the 2015 and 2018 heatwaves can affect the contribution of different NOX emission sources to total O3, thus the possible influence of multiple upwind source regions should be accounted for when mitigation strategies are designed. Our study also highlights the good correlation between ozone coming from German biogenic VOC emissions and total ozone, although the diurnal variation in the ozone coming from biogenic sources is not dominated by the diurnal variation in biogenic emissions, and the peaks of ozone from biogenic sources are disconnected from local emission peaks. This suggests that the formation of O3 from local German biogenic VOC emissions is not the sole factor that influences the ozone formation and other meteorological and chemical processes affect the diel variation of ozone having a biogenic origin. Overall, this study helps to understand the importance of a source attribution method to understand the sources of O3 in Germany and can be a useful tool that will help to design effective mitigation strategies.

Aurelia Lupaşcu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-189', Anonymous Referee #1, 21 Apr 2022
  • RC2: 'Comment on acp-2022-189', Anonymous Referee #2, 26 May 2022

Aurelia Lupaşcu et al.

Aurelia Lupaşcu et al.


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Short summary
Ground-level ozone is an important air pollutant that affects human health, ecosystems, and climate. Ozone is not emitted directly, but rather formed in the atmosphere through chemical reactions involving two distinct precursors. Our results provide detailed information about the origin of ozone in Germany during two peak ozone events that took place in 2015 and 2018, thus improving our understanding of ground-level ozone.