Summer ozone episodes in the Greater Madrid area. Analyzing the ozone response to abatement strategies by modelling

The development of ozone control strategies requires analysing the sensitivity of the dispersion model used to changes in emissions of nitrogen oxides (NOX) and volatile organic compounds. The ozone response to variations in road traffic and total anthropogenic emissions is evaluated for two different summer ozone episodes in the Greater Madrid Area (GMA). This study uses the TVM model and a transport/chemistry module in which different chemical mechanisms (EMEP, RACM) are implemented. The results show that the areas of maximum impact and ozone responses are notably influenced by the different transport and dispersion patterns established in the area. However, the contribution of anthropogenic sources other than road traffic is patent in both episodes. Strategies based only on decreasing road traffic emissions were not sufficient for an effective control of the air quality in the GMA. Moreover, certain discrepancies observed in the predicted trends, as a response to these control strategies posed, reflect the importance of variations in the precursors balance. The ozone production regime associated to these ozone episodes and the sensitivity of the ozone response to changes in this balance has been investigated. A chemical indicator has been used to deepen in that evaluation.