Influence of transboundary air pollutants from China on the high-PM₁₀ episode in Seoul, Korea for the period October 16-20, 2008

This study examines the extraordinarily long-lasting episode of high concentrations of particulate matter with diameter <10μm (PM₁₀) in Seoul, Korea over the period October 16-20, 2008. The concentration of PM₁₀ increased up to 197.2μgm^-3 and continually stayed above the daily environmental control standard value (100μgm^-3) for the period. Satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) showed pronounced transport of aerosols from China to the Korean peninsula prior to the high-PM₁₀ episode. The updraft of air pollutants from the source region in China, transport by westerlies, and subsequent descent to Seoul metropolitan regions are examined in the context of horizontal and vertical airflows. The connection between PM₁₀ concentration over the Chinese source region and the Seoul target area is verified by wind back trajectory analysis. The meteorological conditions favorable for maintenance of the high PM₁₀ levels are investigated through the analysis of weather maps and low-level stability. In this high-PM₁₀ episode, the stagnant high-pressure system over Korea may play a decisive role in the descent and accumulation of air pollutants. The influence of transboundary air pollutants from China on the air quality in Korea and relevant meteorological environment found in the present study will provide a theoretical underpinning to potential cooperation between East Asian countries in monitoring and controlling atmospheric conditions.