Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

Zavala, M.; Lei, W.; Molina, Mario J.; Molina, Luisa T.

doi:10.5194/acp-9-39-2009

Cited by 38 publications

(14 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results from Zavala et al (2009) suggest that CO and VOC emissions from mobile sources decreased by approximately 40% over this time period while NO x emissions remained unchanged. Marley et al (2007) also reported evidence of a significant decrease in emissions of light olefins based on changes in ambient PAN concentrations.…”

Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 93%

Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models

Sillman

West

2009

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract.We use results of a 3-D photochemistry/transport model for ozone formation in Mexico City during events in 1997 to investigate ambient concentrations of reactive nitrogen in relation to ozone-precursor sensitivity. Previous results from other locations suggest that ratios such as O 3 /NO y and H 2 O 2 /HNO 3 might provide measurement-based indicators for NO x -sensitive or VOC-sensitive conditions. Mexico City presents a different environment due to its high concentrations of VOC and high level of pollutants in general. The model predicts a correlation between PAN and O 3 with relatively high PAN/O 3 (0.07), which is still lower than measured values. The model PAN is comparable with results from a model for Paris but much higher than were found in Nashville in both models and measurements. The difference is due in part to the lower temperature in Mexico City relative to Nashville. Model HNO 3 in Mexico City is unusually low for an urban area and PAN/HNO 3 is very high, probably due to the high ratio of reactivity-weighted VOC to NO x . The model predicts that VOC-sensitive chemistry in Mexico is associated with high NO x , NO y and NO x /NO y and with low O 3 /NO y and H 2 O 2 /HNO 3 , suggesting that these indicators work well for Mexico City. The relation between ozone-precursor sensitivity and either O 3 /NO z or O 3 /HNO 3 is more ambiguous. VOC-sensitive conditions are associated with higher O 3 /HNO 3 than would be found in NO x -sensitive conditions, but model O 3 /HNO 3 associated with both NO xsensitive and VOC-sensitive chemistry is higher in Mexico than in other cities. The model predicts a mixed pattern of ozone-precursor sensitivity in Mexico City, with VOCsensitive conditions in the morning and NO x -sensitive in the afternoon, in contrast to results from other models for more recent events that predicted strongly VOC-sensitive conditions throughout the day. The difference in predicted ozoneCorrespondence to: S. Sillman (sillman@umich.edu) precursor sensitivity is most likely due to different emission rates and to changes in emissions over time. The model with mixed sensitivity predicts much lower ambient NO x and NO x /NO y than the strongly VOC-sensitive model.

show abstract

Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 93%

Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models

Sillman

West

2009

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Long-term analysis of ambient pollutants (Stephens et al, 2008;Zavala et al, 2009b) and Fig. 1 in this work indicate that despite the impressive 75% increase of the vehicle fleet over the 2000-2006 period, the ambient concentrations of CO and NO x have not increased proportionally.…”

Section: Impact Of Older High Emission Vehiclesmentioning

confidence: 98%

Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions.We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20-28% for CO and 14-20% for NO. However, we identify a probable EI discrepancy of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be unCorrespondence to: M. Zavala (miguelz@mce2.org) derpredicted by factors of 3 for HCHO and 2 for CH 3 CHO. Our on-road measurement-based estimate of annual emissions of organic mass from PM 1 particles suggests a severe underprediction (larger than a factor of 4) of PM 2.5 mobile emissions in the inventory.Analyses of ambient CO, NO x and CO/NO x concentration trends in the MCMA indicate that the early morning ambient CO/NO x ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades due to reductions in CO levels rather than by NO x . These trends, together with the analysis of fuel sales and fleet size, suggest that the relative contribution of diesel vehicles to overall NO x levels has increased over time in the city. Despite the impressive increase in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NO x have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality improvement strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles.

show abstract

“…In particular, several modeling studies have been conducted in the past to understand the O 3 -NOx-VOC relationship that exists at several locations of its airshed at different times using CTMs. Even though there has been some controversy in the chemical regimes that these studies suggest for Mexico City (Torres-Jardón et al, 2009), recent studies that have applied CTMs conclude that this megacity is likely VOC-sensitive (Lei et al, 2007;Tie et al, 2007;Zavala et al, 2009;Song et al, 2010). However, Stephens et al (2008), following an observational-based approach, suggest that during working days the regime is NOx-sensitive, while during the week-ends a VOC-sensitive regime exists (which has grown stronger in the last decade).…”

Section: Introductionmentioning

confidence: 96%

Ozone sensitivity to its precursor emissions in northeastern Mexico for a summer air pollution episode

Sierra

Vanoye

Mendoza

2013

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

A summer episode was modeled to address the expected response of ambient air O 3 to hypothetical emission control scenarios in northeastern Mexico, and in particular in the Monterrey Metropolitan Area (MMA). This region is of interest because the MMA holds one of the worst air quality problems in the country and levels of air pollutants in the rest of northeastern Mexico are starting to be a concern. The MM5-SMOKE-CMAQ platform was used to conduct the numerical experiments. Twenty-four control scenarios were evaluated, combining the level of emission controls of O 3 precursors (NOx and volatile organic compounds [VOCs]) from 0% to 50%. For the MMA, VOC-only controls result in the best option to reduce O 3 concentrations, though the benefit is limited to the urban core. This same strategy results in negligible benefits for the rest of northeastern Mexico. NOx controls result in an increase in O 3 concentration within the MMA of up to 20 ppbv and a decrease at downwind locations of up to 11 ppbv, with respect to the basecase scenario. Indicator ratios were also used to probe for NOx-sensitive and VOC-sensitive areas. Locations with an important influence of NOx point sources (i.e., Monclova and Nava/Acuña) are quite sensitive to changes in NOx emissions. Border cities in the Rio Bravo/Grande Valley tend to be marginally NOx-sensitive. Overall, the MMA seems to be dominated by a VOC-sensitive regime, while the rest of the region would tend to have a NOx-sensitive response. The results obtained serve to expand the current knowledge on the chemical regimes that dominate this region (VOC-or NOx-sensitive), and thus could help guide public policies related to emission regional control strategies.Implications: Updated information on the expected response of ambient air O 3 to emission changes in northeastern Mexico is presented. Results suggest that emission control strategies for the Monterrey Metropolitan Area should focus on VOC reductions or combined VOC-NOx reductions, while the Lower Rio Bravo/Grande Valley border has a negligible response to the emission scenarios tested. Changes in NOx emissions from Carbon II, a 1,400-MW coal-fired electric utility, would have a nonnegligible transboundary effect.

show abstract

Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

Cited by 38 publications

References 30 publications

Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models

Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models

Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

Ozone sensitivity to its precursor emissions in northeastern Mexico for a summer air pollution episode

Contact Info

Product

Resources

About