On air pollutant variations in the cases of long-range transport of dust particles observed in central Korea in the leeside of China in 2010
The occurrence and transport of dust storms and anthropogenic air pollutants in East Asia have been monitored using the meteorological satellite data of the National Oceanic and Atmospheric Administration (NOAA) and ground-based measurements at Cheongwon, a background observation site in central Korea. The nine cases, measured over 14 days, of natural dust particles caused by dust storms originating from northern China and Mongolia were observed at Cheongwon in the spring, autumn, and winter of 2010. In addition, seven cases, measured over 18 days, of anthropogenic dust particles originating from eastern China were observed over the course of a year. In those cases of natural and anthropogenic dust particles observed at Cheongwon, the level of particle matter (PM) with a diameter of ≤10 μm (PM10) (100 μgm−3 day−1) or PM2.5 (50 μgm−3 day−1) exceeded the air quality standards of Korea for 5 and 6 days, respectively. At the same time, CO concentrations rose higher due to long-range transport, while CO levels in the cases of anthropogenic dust particles (954 ppb) rose higher compared with the cases of natural dust particles (812 ppb). While gusty north–northwesterly winds were blowing in the front side of high-pressure systems, an increase in CO concentrations along with the influx of dust storms was observed at Cheongwon in the three natural dust particle cases with continental background airflow (n-CBAs). However, the other six natural dust particle cases with continental polluted airflow (n-CPAs) were also observed where mass concentrations of TSP, PM10 and PM2.5, and CO increased simultaneously after the CO concentrations rose and fell before dust storms had flowed in, showing double peaks. The mass concentrations of total suspended particle (TSP), PM10, and PM2.5 were high, and the PM2.5/TSP mass concentration ratio was high in n-CPAs, compared with n-CBAs. However, the anthropogenic dust particle cases with continental polluted airflow (a-CPA) are affected by air pollutants transported from eastern China by warm southwesterly winds, since central Korea is located in the rear side of the high-pressure system and in the foreside of the low-pressure system. Also, the anthropogenic dust particle cases with regionally polluted airflow (a-RPA) were observed in central Korea due to a stagnant high-pressure system for several days in the Yellow Sea region. In a-CPA, the mass concentrations of TSP, PM10, and PM2.5; the PM2.5/TSP mass concentration ratio; and the CO concentrations were all higher than in a-RPA.