Roles of Uncontrollable VOC Emissions in the Regional Air Quality of the Seoul Metropolitan Area

Roles of natural (uncontrollable) reactive gas emissions in the suburbs of East Asian megacities have been highlighted in determining secondary pollutant formation processes. We will discuss oxidation capacity controlled by anthropogenic-biogenic interactions by presenting a trace gas observational dataset from a forest research site near the Seoul Metropolitan Area (SMA). As uncertainty in isoprene-OH interaction from low to intermediate NO conditions has not been fully resolved yet, we will particularly highlight implications of uncertainty in OH levels to ozone production regimes and OVOC production potentials using an observationally constrained 0-D box model (UWCM v 2.1). Multiple scenarios such as different isopreneperoxy radical photochemistry schemes are adapted for the assessments. In addition, the evaluation of NO₂ overestimation by a conventional chemiluminescence instrument with a Mo-converter routinely utilized NO₂ observations in East Asia will be also discussed by comparing observational datasets from a Thermo 42i NO_x analyzer and a LGR CRDS NO₂ instrument from summer to fall. The discussion will be evolved to assess potential uncertainty caused by the overestimation from the previous regional photochemistry assessment studies.