Using peroxy radical measurements from chemical amplifiers to quantify ozone production rates in the troposphere

Ozone (O₃) is a criteria air pollutant in the troposphere and powerful oxidant that damages cellular tissue along our respiratory tract, causing distress, and crops and other plants, decreasing primary productivity in the environment. O₃ is also a greenhouse gas that is responsible for ~12% of the anthropogenic global warming since 1750. Unlike other criteria air pollutants that have major primary emission sources, O₃ is entirely a secondary pollutant and has a complicated non-linear dependence on its precursors nitrogen oxides (NO_x) and volatile organic compounds (VOCs). For instance, lowering some O₃ precursors can actually increase local O₃ concentrations under certain conditions. Ozone concentrations observed at monitoring sites not only depend on the local chemistry but also on the transport of air masses containing O₃ from other locations, and on dry deposition. It is therefore essential to clearly understand how these physicochemical processes impact ozone budgets to design efficient mitigation measures at targeted sites.

Simultaneous measurements of ozone production rates, P(O₃), and ozone concentrations can provide a detailed picture of the ozone budget at a monitoring site, including a critical assessment of the O₃-driving processes mentioned above. In this study, we will present how a chemical amplifier can be used to infer P(O₃) from peroxy radical measurements and we will discuss the reliability of this methodology. We will present results from ozone production experiments that were performed in the SAPHIR atmospheric chamber during the ROxCOMP (ROx Comparison) campaign. We will show how P(O₃) values inferred from the chemical amplifier compare to values derived from observed O_x (O₃+NO₂) changes in the chamber for various experiments using contrasting conditions of VOCs and NO_x.

Acknowledgments. This work is supported by the French national research agency (ANR) under LABEX-CaPPA (ANR-11-LABX-005-01), the CPER-CLIMIBIO program, the French national program LEFE/CHAT INSU and the Hauts-de-France region of France. This project has received funding from the European Union’s Horizon 2020 research and innovation programme through the ATMO-ACCESS Integrating Activity under grant agreement No 101008004.