Impact of the Western North Pacific Subtropical High on summer surface ozone in the Korean Peninsula

The Western North Pacific Subtropical High (WNPSH) is a crucial circulation system affecting the East Asian summer monsoon region including the Korean Peninsula, but its linkage to surface ozone (O3) has not been revealed. This study aimed to reveal the relationship between the WNPSH and O3 levels across the Korean Peninsula. For this purpose, a linear regression analysis was performed to assess WNPSH-related variations in observed O3 concentrations at 151 air quality monitoring sites during 2001-2015. The results showed that enhanced WNPSH contributed to the observed increase in O3 levels during summer (June-July-August), with the opposite trend during weakened WNPSH years. We found that anomalous precipitation due to altered circulation patterns mainly contributed to changes in O3 level. This implies that summer O3 in Korea is highly sensitive to interannual atmospheric variability. Our results may be useful for revealing the effects of climate variability on air quality in the East Asian region.