Issues with Understanding Atmospheric Oxidation and Ozone Production during KORUS-AQ

South Korea and its environs release a rich mixture of gases and aerosol particles into the atmosphere. This mixture interacts with hydroxyl (OH) and hydroperoxyl (HO₂), determining the production rates for both ozone and secondary particles. During KORUS-AQ, we measured OH and HO₂ with the Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) as part of the large instrument suite on the NASA DC-8 aircraft. These measurements are compared to OH and HO₂ calculated with a photochemical box model that is constrained by the simultaneous chemical and meteorological measurements. As in previous urban field studies, the observed-to-modeled HO₂ ratio is greater for greater NO amounts, which may imply that ozone production at morning rush hour is greater than currently modeled. In this presentation, we discuss the ozone production rate (P(O₃)) that is calculated from measured and modeled HO₂ and organic peroxyl (RO₂) and its implications for ozone pollution in South Korea, particularly Seoul.