Author(s)

P. Jiménez & J. M. Baldasano

Abstract

The forecast of Ozone peaks has very important applications, such as control by authorities of the level of this pollutant, and it is also a necessary tool in Environmental Impact Assessment. Determinists and statistical models can estimate these levels, but they are very expensive to develop and apply, and it takes a long time to run the model. In this paper the authors suggest the use of an empirical model, proposed by Chang and Rudy [2], where it is related the ratio non-methane organic gases/nitrogen oxides (NMOG/NOx) with the tropospheric Ozone levels reached. The model has been validated with data from different stations over Catalonia (Spain). Finally, it can be concluded that the model is a reasonably effective tool to predict tropospheric Ozone peaks and the range of concentrations that are going to be reached, although the system tends to slightly overestimate the mean values of Ozone. The model works better in NMOG-rich regime than in low values of NMOG/NOx ratio, so the fit of the model to real data is higher in non-urban stations than in those placed in populated area where emissions of NOx are proportionally higher. 1 Introduction There are four air quality control stations in Catalonia (Spain) that register simultaneously NMOG, NOx and Ozone: two urban stations (Barcelona-Sagrera and Sabadell) and two non-urban stations (Constanti and Sant Celoni). Data used respond to episodes of Ozone that took place in August, 14-15,2000 and August, 13-16, 2001. Peak levels of Ozone are in the range of 0-160 pg/m3, while NOx and NMOG concentrations reach 135 pg/m3 and 1 ppmC, respectively. Data employed for validating the model match up to episodes of Ozone corresponding

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