Gridded surface O ₃ , NO _<i>x</i> , and CO abundances for model metrics from the South Korean ground station network

Abstract. We present gridded surface air quality datasets over South Korea for three key species – ozone (O3), carbon monoxide (CO), and nitrogen oxides (NOx) – during the time frame of the Korea–US Air Quality (KORUS-AQ) mission (May–June 2016). Mixing ratios for the key species were mapped to 0.1° × 0.1° grid cells (hourly resolution), which were constructed from the 300+ air quality network sites using inverse distance weighting with simple declustering. Cross-comparing the interpolated fields against the site data that were used to create them reveals high prediction skill for O3 (80 %) throughout South Korea and moderate skill (60 %) for CO and NOx on average in densely observed regions after individual mean bias corrections. The gridded O3 and CO interpolations predict the NASA DC-8 observations in the planetary boundary layer (PBL) with high skill (80 %) in the Seoul Metropolitan Area (SMA) after subtracting the mean bias. DC-8 NOx observations were much less predictable on account of consistently negative vertical gradients within the PBL. Our gridded products capture the mean of and variability in O3 throughout South Korea and the mean of and variability in CO and surface NOx in most site-dense urban centres (SMA, Cheongju, Gwangju, Daegu, Changwon, and Busan).