Observed versus simulated OH reactivity during KORUS-AQ campaign: Implications for emission inventory and chemical environment in East Asia

We present a holistic examination of tropospheric OH reactivity (OHR) in South Korea using comprehensive NASA DC-8 airborne measurements collected during the Korea–United States Air Quality field study and chemical transport models. The observed total OHR (tOHR) averaged planetary boundary layer (PBL, <2.0 km) free troposphere was 5.2 s−1 2.0 campaign, respectively. These values were higher than calculated (cOHR, 3.4 s−1, 1.0 s−1) derived from trace-gas observations, indicating missing fractions PBL 35% 50%, Incorporating nonobserved secondary species observationally constrained box model increased cOHR to 4.0 1.3 troposphere. Simulated (sOHR, 2.7 0.8 substantially lower both tOHR by as much 60%. This underestimate substantial marine marginal sea (Yellow Sea). then discuss potential causes unaccounted OHR. First, we suggest improving accuracy reaction kinetics, which vary significantly available literature. Second, underestimated emissions anthropogenic CO oxygenated volatile organic compounds East Asia contributed discrepancy between sOHR. In addition, biogenic emitted may contribute regional Typical models these sources, leading large fraction. Despite this discrepancy, found that simulated concentrations comparable with those campaign because slow recycling rates models; therefore, predicted less formation photochemical oxidation products such ozone.