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 (O-3) has not been revealed. This study aimed to reveal the relationship between the WNPSH and O-3 levels across the Korean Peninsula. For this purpose, a linear regression analysis was performed to assess WNPSH-related variations in observed O-3 concentrations at 151 air quality monitoring sites during 2001-2015. The results showed that enhanced WNPSH contributed to the observed increase in O-3 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 O-3 level. This implies that summer O-3 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.