Fig. 5: Performances of K_ACheMS v2.0 for PM2.5 predictions over South Korea.

The first column presents levels of observed PM2.5 from AIR KOREA, while the second, the third, and the fourth columns respectively present PM2.5 predictions from K_ACheMS v2.0 and two operational PM2.5 prediction systems at NIER and ECMWF. Red, yellow, green, and blue colors indicate ‘very bad (very unhealthy)’, ‘bad (unhealthy)’, ‘moderate’, and ‘good’ air qualities, respectively, in terms of Korean PM2.5 standards. The PM2.5 prediction service using operational K_ACheMS v2.0 was launched on 1 Jan., 2022 and has been operated continuously since then. The first, second, and third rows are PM2.5 observations and predictions taken at noon on 10 Jan., 23 Jan., and 11 Feb., 2022, respectively.