Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 and 2003 field campaigns

Velasco, Erik; Lamb, Berton L.; Westberg, H.; Allwine, E.; Sosa, G.; Arriaga‐Colina, J. L.; Jobson, B. T.; Hoole, Alexander; Prazeller, Peter; Knighton, W. B.; Rogers, T. M.; Grütter, Michel; Herndon, S. C.; Kolb, C. E.; Zavala, M.; Foy, B. de; Volkamer, Rainer; Molina, Luisa T.; Molina, M. J.

doi:10.5194/acpd-6-7563-2006

Cited by 63 publications

(139 citation statements)

References 38 publications

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“…Other possible reasons for the difference include different estimations of VOC emissions and different meteorological conditions during the simulated events. It has also been suggested that vertical mixing is too rapid in the CIT model used here (Velasco et al, 2007), which can also lead to a more NO x -sensitive simulation, but report good agreement with NO y measurements, suggesting that errors in vertical mixing may not be large. West et al (2004) and Lei et al (2007) Lei et al were also supported by measurement-based analyses, although with some uncertainty (Velasco et al, 2005(Velasco et al, , 2007.…”

Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 95%

“…It has also been suggested that vertical mixing is too rapid in the CIT model used here (Velasco et al, 2007), which can also lead to a more NO x -sensitive simulation, but report good agreement with NO y measurements, suggesting that errors in vertical mixing may not be large. West et al (2004) and Lei et al (2007) Lei et al were also supported by measurement-based analyses, although with some uncertainty (Velasco et al, 2005(Velasco et al, , 2007. It is also possible that the different emissions adjustments used by West et al andLei et al reflect reductions in ambient VOC between 1997 and.…”

Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 95%

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

Sillman

West

2009

Atmos. Chem. Phys.

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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.

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Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 95%

Section: Implications For Ozone-precursor Sensitivitymentioning

confidence: 95%

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

Sillman

West

2009

Atmos. Chem. Phys.

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“…Jimenez et al (2003) demonstrated that the spatial and temporal distribution of CO and NO x follows that of the traffic, while Pfeffer (1994) and Perrino et al (2002) showed that the mean concentrations of gaseous pollutants at very busy junctions are considerably higher than those of areas that are not directly affected by road traffic. Ambient NMVOC levels are mainly affected by motor vehicle emissions where high levels of aromatic hydrocarbons (toluene, benzene and xylenes) have been detected and associated with diverse public transport systems (Velasco et al, 2007; …”

Section: Urban Scalementioning

confidence: 99%

Transport impacts on atmosphere and climate: Land transport

Uherek¹,

Halenka²,

Borken‐Kleefeld³

et al. 2010

Atmospheric Environment

311

151

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a b s t r a c tEmissions from land transport, and from road transport in particular, have significant impacts on the atmosphere and on climate change. This assessment gives an overview of past, present and future emissions from land transport, of their impacts on the atmospheric composition and air quality, on human health and climate change and on options for mitigation.In the past vehicle exhaust emission control has successfully reduced emissions of nitrogen oxides, carbon monoxide, volatile organic compounds and particulate matter. This contributed to improved air quality and reduced health impacts in industrialised countries. In developing countries however, pollutant emissions have been growing strongly, adversely affecting many populations. In addition, ozone and particulate matter change the radiative balance and hence contribute to global warming on shorter time scales. Latest knowledge on the magnitude of land transport's impact on global warming is reviewed here.In the future, road transport's emissions of these pollutants are expected to stagnate and then decrease globally. This will then help to improve the air quality notably in developing countries. On the contrary, emissions of carbon dioxide and of halocarbons from mobile air conditioners have been globally increasing and are further expected to grow. Consequently, road transport's impact on climate is gaining in importance. The expected efficiency improvements of vehicles and the introduction of biofuels will not be sufficient to offset the expected strong growth in both, passenger and freight transportation. Technical measures could offer a significant reduction potential, but strong interventions would be needed as markets do not initiate the necessary changes. Further reductions would need a resolute expansion of low-carbon fuels, a tripling of vehicle fuel efficiency and a stagnation in absolute transport volumes. Land transport will remain a key sector in climate change mitigation during the next decades.

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“…More recently, Velasco et al (2007) have reported intercomparison results from a PTR-MS, GC-FID and a commercial DOAS instrument for several days of measurements from an auxiliary monitoring site in Mexico City during the MCMA 2003 field experiment. The comparison showed good agreement, with the exception of benzene measurements by the commercial DOAS, which were greater than the PTR-MS and GC-FID measurements in the early afternoon when ozone levels were high.…”

mentioning

confidence: 99%

Comparison of aromatic hydrocarbon measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

et al. 2010

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Abstract.A comparison of aromatic hydrocarbon measurements is reported for the CENICA supersite in the district of Iztapalapa during the Mexico City Metropolitan Area field experiment in April 2003 (MCMA 2003). Data from three different measurement methods were compared: a Proton Transfer Reaction Mass Spectrometer (PTR-MS), long path measurements using a UV Differential Optical Absorption Spectrometer (DOAS), and Gas Chromatography-Flame Ionization analysis (GC-FID) of canister samples. The principle focus was on the comparison between PTR-MS and DOAS data. Lab tests established that the PTR-MS and DOAS calibrations were consistent for a suite of aromatic compounds including benzene, toluene, p-xylene, ethylbenzene, 1,2,4-trimethylbenzene, phenol and styrene. The point sampling measurements by the PTR-MS and GC-FID showed good correlations (r=0.6), and were in reasonable agreement for toluene, C 2 -alkylbenzenes and C 3 -alkylbenzenes. The PTR-MS benzene data were consistently high, indicating interference from ethylbenzene fragmentation for the 145 Td drift field intensity used in the experiment. Correlations between the open-path data measured at 16-m height over a 860-m path length (retroreflector in 430 m distance), and the point measurements collected at 37-m sampling height were best for benzene (r=0.61), and reasonably good for toluene, C 2 -alkylbenzenes, naphthalene, styrene, cresols and phenol (r>0.5). There was good agreement between DOAS and PTR-MS measurements of benzene after correction for the Correspondence to: B. T. Jobson (tjobson@wsu.edu) PTR-MS ethylbenzene interference. Mixing ratios measured by DOAS were on average a factor of 1.7 times greater than the PTR-MS data for toluene, C 2 -alkylbenzenes, naphthalene and styrene. The level of agreement for the toluene data displayed a modest dependence on wind direction, establishing that spatial gradients -horizontal, vertical, or both -in toluene mixing ratios were significant, and up to a factor of 2 despite the fact that all measurements were conducted above roof level. Our analysis highlights a potential problem in defining a VOC sampling strategy that is meaningful for the comparison with photochemical transport models: meaningful measurements require a spatial fetch that is comparable to the grid cell size of models, which is typically a few 10 km 2 . Long-path DOAS measurements inherently average over a larger spatial scale than point measurements. The spatial representativeness can be further increased if observations are conducted outside the surface roughness sublayer, which might require measurements at altitudes as high as 10s of metres above roof level.

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Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 and 2003 field campaigns

Cited by 63 publications

References 38 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

Transport impacts on atmosphere and climate: Land transport

Comparison of aromatic hydrocarbon measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

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