Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 9163-9185, 2017
https://doi.org/10.5194/acp-17-9163-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
31 Jul 2017
Observed trends in ground-level O3 in Monterrey, Mexico, during 1993–2014: comparison with Mexico City and Guadalajara
Iván Y. Hernández Paniagua1,2, Kevin C. Clemitshaw3, and Alberto Mendoza1 1Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterrey, Av. Eugenio Garza Sada 2501, Monterrey, N.L., 64849, México
2Centro de Ciencias de la Atmosfera, Universidad Nacional Autónoma de México, Ciudad de México, México
3Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
Abstract. Here, we present an assessment of long-term trends in O3 and odd oxygen (O3 + NO2) at the industrial Monterrey metropolitan area (MMA) in NE Mexico. Diurnal amplitudes in Ox (AVd) are used as a proxy for net O3 production, which is influenced by the NO2 photolysis rate. No significant differences in the AVd are observed between weekends and weekdays, although the largest AVd values are observed at sites downwind of industrial areas. The highest O3 mixing ratios are observed in spring, with minimum values in winter. The largest annual variations in O3 are typically observed downwind of the MMA, with the lowest variations generally recorded in highly populated areas and close to industrial areas. A wind sector analysis of mixing ratios of O3 precursors revealed that the dominant sources of emissions are located in the industrial regions within the MMA and surrounding area. Significant increasing trends in O3 in spring, summer, and autumn are observed depending on site location, with trends in annual averages ranging between 0.19 and 0.33 ppb yr−1. Overall, from 1993 to 2014, within the MMA, O3 has increased at an average rate of 0.22 ppb yr−1 (p < 0. 01), which is in marked contrast with the decline of 1.15 ppb yr−1 (p < 0. 001) observed in the Mexico City metropolitan area (MCMA) for the same period. No clear trend is observed from 1996 to 2014 within the Guadalajara metropolitan area (GMA).

Citation: Hernández Paniagua, I. Y., Clemitshaw, K. C., and Mendoza, A.: Observed trends in ground-level O3 in Monterrey, Mexico, during 1993–2014: comparison with Mexico City and Guadalajara, Atmos. Chem. Phys., 17, 9163-9185, https://doi.org/10.5194/acp-17-9163-2017, 2017.
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In this study, we describe trends in ground-level O3 within the Monterrey metropolitan area (MMA) during 1993–2014. A wind sector analysis of mixing ratios of O3 precursors revealed that the dominant sources of emissions are located in the industrial regions within the MMA and surrounding area. During 1993–2014, O3 increased within the MMA, whereas within Mexico City it decreased. The number of exceedances of the O3 standard will very likely increase.
In this study, we describe trends in ground-level O3 within the Monterrey metropolitan area...
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