Sensitivity of tropospheric ozone to chemical kinetic uncertainties in air masses influenced by anthropogenic and biomass burning emissions

We use a Lagrangian chemical transport model with a Monte Carlo approach to determine impacts of kinetic rate uncertainties on simulated concentrations of ozone, NOy and OH in a high-altitude biomass burning plume and a low-level industrial pollution plume undergoing long-range transport. Uncertainties in kinetic rate constants yield 10–12 ppbv (5th to 95th percentile) uncertainty in the ozone concentration, dominated by reactions that cycle NO and NO2, control NOx conversion to NOy reservoir species, and key reactions contributing to O3 loss (O( D) + H2O, HO2 + O3). Our results imply that better understanding of the peroxyacetylnitrate (PAN) thermal decomposition constant is key to predicting large-scale O3 production from fire emissions and uncertainty in the reaction of NO + O3 at low temperatures is particularly important for both the anthropogenic and biomass burning plumes. The highlighted reactions serve as a useful template for targeting new laboratory experiments aimed at reducing uncertainties in our understanding of tropospheric O3 photochemistry. Plain Language Summary Computer models used to assess and predict how air pollution changes in response to emissions, and how it affects climate and human health, rely on information from laboratory experiments to prescribe the rates at which different atmospheric chemical species react. This laboratory information has uncertainties associated with experimental limitations or constraints. We show how these uncertainties affect confidence in model predictions of tropospheric ozone in two pollution plumes. Ozone is a key air pollutant, harmful to human health and vegetation, as well as a climate warming agent. We identify key reactions that lead to large uncertainty in simulated ozone and demonstrate the importance of low confidence in some reactions at low temperatures in driving large portion of ozone uncertainty. Our work serves as a key basis from which to motivate future lab experiments aimed at reducing uncertainty in our understanding of tropospheric ozone.