Observed trends in ground-level O3 in Monterrey, Mexico, during 1993-2014: Comparison with Mexico City and Guadalajara Academic Article in Scopus uri icon

abstract

  • © 2017 Author(s). Here, we present an assessment of long-term trends in O 3 and odd oxygen (O 3 CNO 2 ) at the industrial Monterrey metropolitan area (MMA) in NE Mexico. Diurnal amplitudes in O x (AVd) are used as a proxy for net O 3 production, which is influenced by the NO 2 photolysis rate. No significant differences in the AV d are observed between weekends and weekdays, although the largest AVd values are observed at sites downwind of industrial areas. The highest O 3 mixing ratios are observed in spring, with minimum values in winter. The largest annual variations in O 3 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 O 3 precursors revealed that the dominant sources of emissions are located in the industrial regions within the MMA and surrounding area. Significant increasing trends in O 3 in spring, summer, and autumn are observed depending on site location, with trends in annual averages ranging between 0.19 and 0.33 ppbyr. 1. Overall, from 1993 to 2014, within the MMA, O 3 has increased at an average rate of 0.22 ppbyr..1 (p0:01), which is in marked contrast with the decline of 1.15 ppbyr..1 (p0:001) 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).

publication date

  • July 31, 2017