Role of the position of the North Atlantic jet in the variability and odds of extreme PM10 in Europe

Abstract

We have analysed the impact of the North Atlantic jet on the winter PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) concentrations in Europe during a 10-year period. For this purpose we have extracted the daily latitude and strength of the jet from a reanalysis dataset and surface PM10 observations from the AirBase network. We show that the detection of the jet over the eastern North Atlantic (0°–15° W) is preferred compared to the whole North Atlantic basin as this maximises the signal on the PM10 concentrations. Four preferred jet positions have been identified over that region and season: southern (south of 41° N), central-southern (between 41° N and 51° N), central-northern (between 51° N and 63° N) and northern (north of 63° N). According to our results, the jet latitude exerts a stronger influence than the jet strength on the mean PM10 levels. We also examine the impact of the jet positions on the full distribution of PM10 as well as on the odds of PM10 extremes (exceedances of the local winter 95th percentiles). The latter is done through a logistic regression model which considers the effect of the persistence of extremes and different time lags for the jet position. The northern position is associated with enhanced PM10 concentrations (on average ∼9 μg m−3) over northwestern/central Europe and threefold increases in the odds of PM10 extremes at most sites in the region. Similar increases have been found for PM10 in southern Europe when the jet is in its central-northern position. In both cases, the rise in the PM10 concentrations is associated with anticyclonic conditions over those regions and the impact on PM10 extremes is maximised for time lags of around 1–2 days. On the other hand, the central-southern and southern jet positions yield large PM10 decreases (on average around −9 μg m−3) in northwestern/central Europe and southern Europe, respectively.