Relationship between synoptic weather pattern and surface Particulate Matter (PM) during winter and spring seasons over South Korea

Regional air quality over East Asia, including South Korea, has been a center of public attention recently because of a few episodes in which very high particulate matter (PM) concentrations have been observed. Predicting PM variation with lead time of a few hours up to days is one of the key areas that the governments are working on because it can benefit from early warning system to short-term mitigation effort. In this study, the influence of synoptic weather conditions on regional air quality was investigated with the occurrence frequencies of PM episodes as a function of various synoptic weather patterns during winter and spring. (1) During winter, dry moderate (DM) types occur frequently alongside high PM cases (24-h mean PM₁₀ concentration > ). The composite weather map showed a weak northwesterly wind field as a potential cause. On the contrary, it is interesting to note that dry polar (DP) types can be associated with low PM cases (24-h mean PM₁₀ concentration < ) as well as high PM depending on near-surface wind speed. (2) Furthermore, during spring, DM and dry tropical (DT) types were found to be highly correlated with high (much higher) PM concentrations, likely because of the enhanced static stability in the lower troposphere. It should be noted that PM concentration depends on the lower atmospheric stability. The close relationship between synoptic weather patterns and PM concentration suggests that synoptic weather can play an important role in regional air quality.