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| Titel |
Analysis of the seasonal and inter-annual variations, and long-term trends of ozone in the metropolitan area of Monterrey, Mexico |
| VerfasserIn |
Iván Yassmany Hernández Paniagua, Kevin C. Clemitshaw, Alberto Mendoza |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121479
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| Publikation (Nr.) |
 EGU/EGU2016-222.pdf |
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| Zusammenfassung |
| Since 1993, high-precision and high-frequency measurements of ambient O3 have been
recorded at 5 sites within the metropolitan area of Monterrey, the third largest city in Mexico.
O3was measured by the Integral Environmental Monitoring System of the Nuevo Leon State
Government using commercially available, conventional UV photometry instrumentation
(precision better than ±1 ppb). The datasets exhibit variations on differing time-scales of
minutes to hours, with evidence of seasonal cycles and inter-annual variability. The O3
diurnal cycles vary with length of daylight, which influences its formation and loss via
photochemistry. No apparent influence is observed in the amplitudes of O3 diurnal cycles
recorded during weekdays with higher emissions from fossil fuel combustion than at
weekends, although larger amplitudes occur at sites with polluted air from industrial areas.
Seasonal cycles are driven by the variation in solar radiation and changes in emissions of
primary precursors, VOCs and NOX. Maximum O3 mixing ratios were recorded in
spring, and minimum values in winter, with a secondary trough during summer due
to the advection of clean air masses from the Gulf of Mexico. The largest spring
maxima are recorded downwind of an industrial area likely due photochemical
processing of VOCs and NOx, with the lowest recorded in a highly populated area due to
reaction of O3 and NO. At all sites, decreasing seasonal amplitudes were observed
during 1993-1998, followed by persistent increases from 1998 to 2014. Wind sector
analyses were carried out by splitting the wind direction into 8 categories (45˚ ). At all
sites, the highest O3 mixing ratios were recorded from the E and SE sectors, with
lowest values recorded in air masses from the W and NW. Wind sector analysis of
primary precursors (such as VOCs, CO, NOX) reveal that sources are dominated by
emissions from industrial regions in Monterrey and surrounding areas. The largest
annual growth rates for the E and SE sectors and for all sites are 0.50 and 0.66 ppb
O3 yr−1, whereas the lowest are 0.36 and 0.25 ppb O3 yr−1,respectively. In the
metropolitan area of Monterrey, O3has increased at an average annual rate of 0.20 ppb O3
yr−1 (p <0.001), which is in marked contrast with the decline of 0.71 ppb O3 yr−1
(p <0.001) observed at Mexico City during the same period and the variable levels at
Guadalajara from 1996 to 2014. The analysed O3 records imply that controls on
primary precursor emissions have been successful in Mexico City, whereas more
measures to improve air quality should be introduced in Guadalajara and Monterrey. |
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