The time evolution of aerosol composition over the Mexico City plateau

Kleinman, Lawrence I.; Springston, Stephen; Daum, P. H.; Lee, Y. N.; Nunnermacker, L. J.; Senum, G.; Wang, J. X.; Weinstein-Lloyd, J.; Alexander, M. L.; Hubbe, J. M.; Ortega, John; Canagaratna, Manjula R.; Jayne, John T.

doi:10.5194/acp-8-1559-2008

Cited by 260 publications

(252 citation statements)

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“…Tai, are much lower than the values at Miyun, predicted by a model to be 0.4-0.7 . Our range is even lower than that of the NO x / NO y ratio reported by Kleinman et al (2008) over the Mexico City plateau of between 0.11 and 0.83. From these findings, it was concluded that air at Mt.…”

Section: Overview Of Mtx200findingscontrasting

confidence: 49%

“…Tai, around 50 ppbv ppbv −1 , shown as the slope of Fig. 4a, is 1.4 times that at Lin'an (30-40, Wang et al, 2002, about twice that at Changping (20-30, T. and in a plume from Mexico City (20.6, Kleinman et al, 2008), and five or more times that in US vehicular emissions (6-10, Parrish et al, 2002;Parrish, 2006). The large CO / NO y ratio at Mt.…”

Section: Overview Of Mtx200findingsmentioning

confidence: 99%

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Overview of the Mount Tai Experiment (MTX2006) in central East China in June 2006: studies of significant regional air pollution

et al. 2013

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We conducted an intensive field campaign at the summit of Mt. Tai (36.26° N, 117.11° E, 1534 m above sea level), Shandong Province, located at the center of central East China, during the period 28 May to 30 June 2006, to study seasonal maxima of regional air pollution with respect to ozone (O₃) and aerosols. The specific objectives, campaign design, and major findings are summarized. High concentrations of O₃ and its precursors, and aerosols, were detected and studied in the context of annual variations. Most importantly, we identified that emissions from regional-scale open crop residue burning after the harvesting of winter wheat, together with photochemical aging, strongly increased the concentrations of O₃, aerosols, and primary pollutants in this month of year. Studies of in situ photochemical activity, regional source attribution of O₃, O₃–aerosol interactions, validation of satellite observations of tropospheric NO₂, behaviors of volatile organic compounds and organic/inorganic aerosol species, loss rates of black carbon (BC), and instrument inter-comparisons are also summarized. The observed BC levels must have a strong impact on the regional climate

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Section: Overview Of Mtx200findingscontrasting

confidence: 49%

Section: Overview Of Mtx200findingsmentioning

confidence: 99%

Overview of the Mount Tai Experiment (MTX2006) in central East China in June 2006: studies of significant regional air pollution

et al. 2013

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“…The higher levels of f 44 and absence of a trend with f 60 in the "downwind" plume indicate OA is more heavily oxidised than in the fresher "source" plumes. This contrast in oxygenation is linked to other changes between plumes, including apparent photochemical age, which in this instance is represented by the −log(NO x / NO y ) ratio (Kleinman et al, 2008;DeCarlo et al, 2008). Levels of the ratio are significantly elevated in the "downwind" plume from B626 (Fig.…”

Section: Tracer Evolution During Bortasmentioning

confidence: 97%

Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires

et al. 2015

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Abstract. Airborne measurements of biomass burning organic aerosol (BBOA) from boreal forest fires reveal highly contrasting properties for plumes of different ages. These measurements, performed using an Aerodyne Research Inc. compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) during the BORTAS (quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment in the summer of 2011, have been used to derive normalised excess organic aerosol (OA) mass concentrations ( OA / CO), with higher average ratios observed closer to source (0.190 ± 0.010) than in the far-field (0.097 ± 0.002). The difference in OA / CO between fresh and aged plumes is influenced by a change in dominant combustion conditions throughout the campaign. Measurements at source comprised 3 plume interceptions during a single research flight and sampled largely smouldering fires. Twentythree interceptions were made across four flights in the farfield, with plumes originating from fires occurring earlier in the campaign when fire activity had been more intense, creating an underlying contrast in emissions prior to any transformations associated with aging. Changing combustion conditions also affect the vertical distribution of biomass burning emissions, as aged plumes from more flaming-dominated fires are injected to higher altitudes of up to 6000 m. Proportional contributions of the mass-to-charge ratio (m/z) 60 and 44 peaks in the AMS mass spectra to the total OA mass (denoted f 60 and f 44 ) are used as tracers for primary and oxidised BBOA, respectively. f 44 is lower on average in near-field plumes than those sampled in the far-field, in accordance with longer aging times as plumes are transported a greater distance from source. However, high levels of O 3 / CO and −log(NO x / NO y ) close to source indicate that emissions can be subject to very rapid oxidation over short timescales. Conversely, the lofting of plumes into the upper troposphere can lead to the retention of source profiles after transportation over extensive temporal and spatial scales, with f 60 also higher on average in aged plumes. Evolution of OA composition with aging is comparable to observations of BB tracers in previous studies, revealing a consistent progression from f 60 to f 44 . The elevated levels of oxygenation in aged plumes, and their association with lower average OA / CO, are consistent with OA loss through evaporation during aging due to a combination of dilution and chemical processing, while differences in combustion conditions throughout the campaign also have a significant influence on BBOA production and composition.

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“…-Three compact Time-of-Flight Aerosol Mass Spectrometers (C-ToF-AMS) Kleinman et al, 2008;Herndon et al, 2008;de Gouw et al, 2009). …”

Section: Instruments Deployed To Mexico City For the First Timementioning

confidence: 99%

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

et al. 2010

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Abstract. MILAGRO (Megacity Initiative: Local And Global Research Observations) is an international collaborative project to examine the behavior and the export of atmospheric emissions from a megacity. The Mexico City Metropolitan Area (MCMA) -one of the world's largest megacities and North America's most populous city -was selected as the case study to characterize the sources, concentrations, transport, and transformation processes of the gases and fine particles emitted to the MCMA atmosphere and to evaluate the regional and global impacts of these emissions. The findings of this study are relevant to the evolution and impacts of pollution from many other megacities.The measurement phase consisted of a month-long series of carefully coordinated observations of the chemistry and physics of the atmosphere in and near Mexico City duringCorrespondence to: L. T. Molina (ltmolina@mit.edu) March 2006, using a wide range of instruments at ground sites, on aircraft and satellites, and enlisting over 450 scientists from 150 institutions in 30 countries. Three ground supersites were set up to examine the evolution of the primary emitted gases and fine particles. Additional platforms in or near Mexico City included mobile vans containing scientific laboratories and mobile and stationary upward-looking lidars. Seven instrumented research aircraft provided information about the atmosphere over a large region and at various altitudes. Satellite-based instruments peered down into the atmosphere, providing even larger geographical coverage. The overall campaign was complemented by meteorological forecasting and numerical simulations, satellite observations and surface networks. Together, these research observations have provided the most comprehensive characterization of the MCMA's urban and regional atmospheric composition and chemistry that will take years to analyze and evaluate fully.Published by Copernicus Publications on behalf of the European Geosciences Union. L. T. Molina et al.: Mexico City emissions and their transport and transformationIn this paper we review over 120 papers resulting from the MILAGRO/INTEX-B Campaign that have been published or submitted, as well as relevant papers from the earlier MCMA-2003 Campaign, with the aim of providing a road map for the scientific community interested in understanding the emissions from a megacity such as the MCMA and their impacts on air quality and climate. This paper describes the measurements performed during MILAGRO and the results obtained on MCMA's atmospheric meteorology and dynamics, emissions of gases and fine particles, sources and concentrations of volatile organic compounds, urban and regional photochemistry, ambient particulate matter, aerosol radiative properties, urban plume characterization, and health studies. A summary of key findings from the field study is presented.

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The time evolution of aerosol composition over the Mexico City plateau

Cited by 260 publications

References 58 publications

Overview of the Mount Tai Experiment (MTX2006) in central East China in June 2006: studies of significant regional air pollution

Overview of the Mount Tai Experiment (MTX2006) in central East China in June 2006: studies of significant regional air pollution

Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

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