Investigation of the Ozone Production in the Seoul Metropolitan Area Using Observations and Modeling Results from the KORUS-AQ Campaign

In-situ chemical production of ozone (O₃) in urban environments is controlled through the interactions of NO_x (NO + NO₂) with radicals in either propagating or terminating the O₃ production. Observations collected over the Seoul Metropolitan Area (SMA) during the NASA/NIER Korea-United States Air Quality (KORUS-AQ) campaign are used here to investigate this interaction. The observations indicate a missing source of reactivity which impacts both the production of O₃ and peroxy nitrates (PNs). Furthermore, the production of PNs is a net sink of O₃ in SMA but will become a net source of O₃ outside SMA. The observationally constrained in-situ O₃ production is utilized to update the emissions and chemistry of the GEOS-Chem chemical transport model. Though improvements in emissions increase the VOCs and thus O₃ for GEOS-Chem, the model is still missing PNs. Investigation in the missing PNs is being conducted and its impact on the in-situ O₃ production for SMA and surrounding areas.