Primary tabs

Investigation of ozone production sensitivity to NOx

Project Abstract: 
Ozone is a greenhouse gas and a primary constituent of urban smog, irritating the respiratory system and damaging the vegetation. The current understanding of ozone chemistry in the troposphere indicates that net ozone production, P(O3), occurs when peroxy radicals (HO2+RO2) react with NO producing NO2, whose photolysis leads to O3 formation. P(O3) values can be calculated from peroxy radical concentrations, either from ambient measurements or box model outputs. These two estimation methods often disagree for NOx mixing ratios higher than a few ppb, questioning our ability to measure peroxy radicals under high NOx conditions or indicating that there are still unknowns in our understanding of the radical and ozone production chemistry. The proposed work intends to investigate ozone production rates in air masses exhibiting low levels of NOx but high levels of biogenic VOCs. The sampled air will be perturbed by an addition of NOx to investigate how P(O3) changes with increasing NOx levels.
Investigator(s): 
Years Active: 
2015
Methods: 
We will deploy a new instrument developed in Mines Douai (France) to measure ozone production rates in undisturbed air masses as well as air masses perturbed by an addition of NOx. Complementary instruments will also be deployed to measure important ozone precursors: 2 online gas chromatographs for VOCs and an OH reactivity instrument based on the Comparative Reactivity Method. This set of measurements will be used to model ozone production using box modeling for comparison with the measurements.