Links of climate variability in Arctic sea ice, Eurasian teleconnection pattern and summer surface ozone pollution in North China

Summer surface O-3 pollution has rapidly intensified in China in the recent decade, damaging human and ecosystem health. In 2017, the summer mean maximum daily average 8 h concentration of ozone was greater than 150 mu g m(-3) in North China. Based on the close relationships between the O-3 concentration and the meteorological conditions, a daily surface O-3 weather index was constructed, which extends the study period to the historical period before 2007 and the projected future. Here, we show that in addition to anthropogenic emissions, the Eurasian teleconnection pattern (EU), a major globally atmospheric teleconnection pattern, influences surface O-3 pollution in North China on a timescale of climate. The local meteorological conditions associated with the EU positive phase supported intense and efficient photochemical reactions to produce more surface O-3. The associated southerlies over North China transported surrounding O-3 precursors to superpose local emissions. Increased solar radiation and high temperatures during the positive EU phase dramatically enhanced O-3 production. Furthermore, due to the close connection between the preceding May Arctic sea ice (SI) and summer EU pattern, approximately 60% of the interannual variability in O-3-related weather conditions was attributed to Arctic sea ice to the north of Eurasia. This finding will aid in understanding the interannual variation in O-3 pollution, specifically the related meteorological conditions.