Nitrogen oxides and ozone in Portugal: trends and ozone estimation in an urban and a rural site

Fernández-Guisuraga, José Manuel; Castro, Amaya; Alves, Célia; Calvo, Ana; Alonso-Blanco, Elisabeth; Blanco-Alegre, Carlos; Rocha, Alfredo; Fraile, R.

Nitrogen oxides and ozone in Portugal: trends and ozone estimation in an urban and a rural site

2016

This study provides an analysis of the spatial distribution and trends of NO, NO₂ and O₃ concentrations in Portugal between 1995 and 2010. Furthermore, an estimation model for daily ozone concentrations was developed for an urban and a rural site. NO concentration showed a significant decreasing trend in most urban stations. A decreasing trend in NO₂ is only observed in the stations with less influence from emissions of primary NO₂. Several stations showed a significant upward trend in O₃ as a result of the decrease in the NO/NO₂ ratio. In the northern rural region, ozone showed a strong correlation with wind direction, highlighting the importance of long-range transport. In the urban site, most of the variance is explained by the NO₂/NOX ratio. The results obtained by the ozone estimation model in the urban site fit 2013 observed data. In the rural site, the estimated ozone during extreme events agrees with observed concentration.

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