Articles | Volume 12, issue 15
https://doi.org/10.5194/acp-12-6983-2012
https://doi.org/10.5194/acp-12-6983-2012
Research article
 | 
02 Aug 2012
Research article |  | 02 Aug 2012

Can a global model reproduce observed trends in summertime surface ozone levels?

S. Koumoutsaris and I. Bey

Abstract. Quantifying trends in surface ozone concentrations is critical for assessing pollution control strategies. Here we use observations and results from a global chemical transport model to examine the trends (1991–2005) in daily maximum 8-h average concentrations in summertime surface ozone at rural sites in Europe and the United States (US). We find a decrease in observed ozone concentrations at the high end of the probability distribution at many of the sites in both regions. The model attributes these trends to a decrease in local anthropogenic ozone precursors, although simulated decreasing trends are overestimated in comparison with observed ones. The low end of observed distribution show small upward trends over Europe and the western US and downward trends in Eastern US. The model cannot reproduce these observed trends, especially over Europe and the western US. In particular, simulated changes between the low and high end of the distributions in these two regions are not significant. Sensitivity simulations indicate that emissions from far away source regions do not affect significantly summer ozone trends at both ends of the distribution in both Europe and US. Possible reasons for discrepancies between observed and simulated trends are discussed.

Download
Altmetrics
Final-revised paper
Preprint