DOI: 10.5061/dryad.sf7m0cgf5
title: KORUS-AQ gridded O3, NOx, and CO observations created using ground station data

description: 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 timeframe of the Korea–US Air Quality (KORUS–AQ) mission
 (May–June 2016). The tenth degree hourly averaged abundances are
 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 was 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 and variability of O3
 throughout South Korea, and of CO and surface NOx in most site–dense urban
 centres (SMA, Cheongju, Gwangju, Daegu, Changwon, and Busan).
description: Inverse Distance Weighting (IDW) to interpolate (NIER) ground
 station chemical abundances to a fine grid (1/20th degree), followed by
 spatial averaging to 10th degree resolution.
description: # KORUS-AQ gridded O3, NOx, and CO observations created using ground
 station
 [https://doi.org/10.5061/dryad.sf7m0cgf5](https://doi.org/10.5061/dryad.sf7m0cgf5) A gridded observational dataset of surface level ozone (O3), carbon monoxide (CO), and nitrogen oxides (NOx) in South Korea during KORUS-AQ time period created using an inverse distance weighting interpolation procedure. ## Description of the data and file structure ### Gridded data products: #### KORUS-AQ\_gridded\_O3\_CO\_NOx\_Q.nc 0.1x0.1 degree gridded hourly O3, CO, and NOx obervations from NIER stations across South Korea during the KORUS. Also includes the effective density of observations for each grid cell (number of stations within 10 km). ### Analysis data: Datasets used to generate results and figures in the associated manuscript. #### Ground\_Station\_Hourly\_O3\_CO\_NOx.nc Hourly averages of the 5 minute individual NIER site O3, CO, and NOx data used to produce the gridded product. Also contains predictions from leave-one-out cross validation #### Olympic\_Park\_Hourly\_O3\_CO\_NOx\_With\_Predictions.nc Hourly O3, CO, and NOx observations at Olympic Park research station interpolated in time to match the NIER station sampling times. #### Taehwa\_Forest\_Hourly\_O3\_CO\_NOx\_With\_Predictions.nc As above, but at Taehwa Forest research station. #### DC-8\_NIER\_Comparison.nc DC-8 transects and corresponding ground observations from the gridded data product. Also provides the number of segments per transect and number of transects per grid cell over the whole KORUS-AQ mission. ### Quality Control #### Raw\_NIER\_Data\_Quality\_Control\_Flags\_O3.nc Quality control flags for O3 NIER ground station data from [10.5067/Suborbital/KORUSAQ/DATA01](10.5067/Suborbital/KORUSAQ/DATA01). Actual data is access-controlled and therefore not included here. Similar files are listed for CO and NOx. ## Sharing/Access information Raw data for dataset production was derived from the KORUS-AQ data archive and ERA5 reanalysis: [10.5067/Suborbital/KORUSAQ/DATA01](10.5067/Suborbital/KORUSAQ/DATA01) [https://doi.org/10.24381/cds.adbb2d47](https://doi.org/10.24381/cds.adbb2d47)