Characteristics of Multi-day PM2.5 Episode from 2015 to 2021 in Seoul

초록

Examining PM2.5 mass and species concentration monitoring data, all multi-day PM2.5 episodes from 2015 to 2021 in Seoul were analyzed to identify common meteorological and chemical characteristics and determine causes. Among the five multi-day PM2.5 episodes identified, four of them took place during the winter and early spring and one in autumn. The weak and western wind pattern mainly blew with a wind speed of 1 similar to 3 m/sec. The particulate nitrate mainly composed of PM2.5 mass during the multi-day PM2.5 episodes. Higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) during the multi-day PM2.5 episodes were obtained and compared to those during the non-episode, implying domination of sulfate and nitrate over precursors during the multi- day PM2.5 episodes. Observation in Baengnyeong, up-wind region and remote site, were used to estimate long- range transport of PM2.5 toward Seoul with coefficient of divergence. Also, correlation between NOR and temperature were used to assess long-range transport of PM2.5.

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