Weather & Climate conditions affecting air quality over Korea

Abstract

Air quality directly affects human health and the ecosystem and the economically growing East Asia is one of the largest aerosol emitters. Emissions aside, weather condition leads to a favorable condition for high concentrations of aerosol occurrence and formation. The weather conditions of poor ventilation due to atmospheric stagnant, which is a potential factor that could worsen air quality. In Part1, we examined the long-term changes in the near-surface wind speed and its link with how the air in northeast Asia may or may not have become increasingly stagnant since 1958. To explain the long-term change, we used 59 years atmospheric data. We found a negative correlation between the near-surface wind speed and the static stability over the Yellow Sea and the western part of South Korea. Moreover, the near-surface wind speed has shown a declining trend with increased static stability, while their negative correlation appears to strengthen in recent years. Further investigations using historical global climate models single-forcing experiments suggested that long-term enhanced stabilization in the atmosphere due to global warming caused by anthropogenic greenhouse gases, implying future of atmospheric stagnant condition and its potential implication on regional air quality. In Part2, we investigated the relationship between synoptic weather patterns, which is relatively short-term weather change, and surface ozone concentration over South Korea. To determine a dominant synoptic weather type, we used Spatial Synoptic Classification (SSC) data. We found that dry moderate (DM), dry tropical (DT), and moist tropical (MT) are commonly associated with high ozone, especially DT type has a high efficiency of ozone production in high levels of concentration. The weather properties in DT type have shown the long-term increasing trend of 2m temperature and decreasing trend of relative humidity, implying long-term air quality change due to climate change. The efficiency of high ozone occurrence estimated that mean daily maximum eight-hour ozone concentrations (MDA8 O3) may increase by 3.5% (7.5%) with DT frequency increased by doubled (tripled). We concluded that synoptic weather and its long-term trends play important roles in recent increased surface ozone in South Korea. In Part3, we validate the relationship between synoptic weather patterns and regional air quality using PM10 concentration over South Korea. We found that DM and dry polar (DP) occurs frequently with high PM cases during winter. It is interesting to note that the DP type is also associated with the non-high PM range, because of its dominant pattern in the winter with prevailing northerly winds. On the other hand, DM and DT are found highly corelated with the high PM cases during spring. The circulation system characteristics with the high PM cases have shown a weak northwesterly wind field in the DM weather type during winter and strengthened static stability in the lower troposphere in the DM and DT weather types during spring. Furthermore, a major source of pollutants is originated from China with high values of mean PM10 concentrations during winter and spring seasons. We concluded that synoptic weather and its variation with lead time play important roles in regional high PM cases in South Korea. Finally, our results demonstrated that atmospheric stagnant due to weather and climate change are a likely connection to regional air quality over Korea.