Observed annual surface ozone maxima and minima in northern and central Europe from 1990–2015 — latitude dependence and temporal trends

Ground-level ozone is an air pollutant that, despite reductions in precursor emission in Europe, still represents a risk to vegetation and human health. This study is based on observations of ozone concentrations ([O3]) from 25 European monitoring stations, north of the Alps within the EMEP network, during the 26-year period from 1990–2015. We analyzed the maximum and minimum hourly [O3] as well as the seasonal cycle in relation to latitude. In addition, temporal trends were studied. The maximum [O3] increased towards the south of the study area, while the yearly minimum of daytime mean increased towards the north. There was a strong correlation between the day of year when the maximum [O3] occurred and latitude: the maximum [O3] occurred earlier in the north. The maximum daytime [O3] decreased at all stations while the minimum daytime [O3] increased at most stations during the studied time period.