Efficiency of Urban Ozone Photochemistry during the 2023 AEROMMA and CUPiDS Airborne Field Campaigns

Wyndom Chase,
CU ANYL 3rd year, Brown group

"The summer 2023 Airborne Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) and Coastal Urban Plume Dynamics (CUPiDS) field campaigns provided extensive in-situ observations of ozone (O­­­_­­­3) and its precursors in the largest United States urban areas (New York City, Chicago, and Los Angeles). We present the distribution of O­­­_­­­3 in these megacities, along with the distribution of its precursor nitrogen oxides (NO_­­­x = NO + NO₂) and total reactive nitrogen (NO_­­­y), as measured from the NASA DC-8 and NOAA Twin Otter aircraft platforms during AEROMMA and CUPiDS, respectively. Several metrics calculated from in-situ trace gas measurements can aid the understanding of the photochemical regimes in which O_­­­3 production takes place. The O­­­_­­­3 production efficiency (OPE) is a measure of the amount of O_­­­3 produced per unit NO­_­­­x that is emitted and oxidized and is often taken as the ratio of enhanced O_­­­3 or O_­­­x (= O_­­­3 + NO₂) to NO_­­­z (= NO_­­­z - NO_x) within an urban plume transect. The spatial and temporal variability of OPE probes the evolution of O­­­_­­­3 sensitivity within a given urban area. Comparison of this metric between urban areas, in this case New York City, Chicago, and Los Angeles, elucidates differences or similarities across major U.S. urban areas. This analysis establishes a foundation for future work that will incorporate additional O­­­_­­­3 sensitivity metrics, as well as chemical box modeling and remote sensing observations, to gain greater insight into the current landscape of U.S. O_­­­3 photochemical pollution."