Long-term evaluation of atmospheric composition reanalyses from CAMS, TCR-2, and MERRA-2 over South Korea: Insights into applications, implications, and limitations

A 16-year (2003–2018) evaluation of CO, NO2, SO2, O3, and PM10 from three reanalysis products (CAMS, TCR-2, MERRA-2) against independent observations intercomparison among reanalyses are performed over South Korea. All show significant persistent biases in the five pollutants, but partly capture decreasing trends increasing O3 period. CAMS outperforms TCR-2 MERRA-2 terms area-averaged climatology all species except for SO2. SO2 is best reproduced TCR-2. The long-term averaged spatial distributions pollutants reveal that their largely influenced by a priori emissions. larger cold months than warm months. average daily correlations between bias-corrected data found to be reasonably high some species: 0.74–0.82 CAMS, 0.66 0.7 MERRA-2. Although generally shows lower it potential correction emissions through assimilation can improve its performance at seasonal interannual time scales. It recommended bias applied use regional air quality modeling as initial/boundary conditions or other relevant studies because each product has throughout season/year. vertical profiles during KORUS-AQ campaign indicates captures aerosols underestimates NO2.