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Series
  • ATMOSPHERIC CHEMISTRY AND PHYSICS
Date Range
2013 2016

The notable increase in biofuel usage by the road transportation sector in Brazil during recent years has significantly altered the vehicular fuel composition. Consequently, many uncertainties are currently found in particulate matter vehicular emission profiles. In an effort to better characterise the emitted particulate matter, measurements of aerosol physical and chemical properties were undertaken inside two tunnels located in the São Paulo Metropolitan Area (SPMA). The tunnels show very distinct fleet profiles: in the Jânio Quadros (JQ) tunnel, the vast majority of the circulating fleet are light duty vehicles (LDVs), fuelled on average with the same amount of ethanol as ...

Contributors
Brito, J., Rizzo, L. V., Herckes, Pierre, et al.
Created Date
2013-12-17

Primary emissions from anthropogenic and biogenic sources as well as secondary formation are responsible for the pollution levels of ambient air in major urban areas. These sources release fine particles into the air that negatively impact human health and the environment. Organic molecular markers, which are compounds that are unique to specific PM[subscript 2.5] sources, can be utilized to identify the major emission sources in urban areas. In this study, 43 representative PM[subscript 2.5] samples, for both daytime and nighttime periods, were built from individual samples collected in an urban site of the Monterrey metropolitan area (MMA) during the spring ...

Contributors
Mancilla, Y., Mendoza, A., Fraser, Matthew, et al.
Created Date
2016-01-26

Megacities are major sources of anthropogenic fossil fuel CO[subscript 2] (FFCO[subscript 2]) emissions. The spatial extents of these large urban systems cover areas of 10 000 km[superscript 2] or more with complex topography and changing landscapes. We present a high-resolution land–atmosphere modelling system for urban CO[subscript 2] emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO[subscript 2] emission product, Hestia-LA, to simulate atmospheric CO[subscript 2] concentrations across the LA megacity at spatial resolutions as fine as ∼ 1 km. We evaluated multiple WRF configurations, selecting one that ...

Contributors
Feng, Sha, Lauvaux, Thomas, Newman, Sally, et al.
Created Date
2016-07-22

Urban land–atmosphere interactions can be captured by numerical modeling framework with coupled land surface and atmospheric processes, while the model performance depends largely on accurate input parameters. In this study, we use an advanced stochastic approach to quantify parameter uncertainty and model sensitivity of a coupled numerical framework for urban land–atmosphere interactions. It is found that the development of urban boundary layer is highly sensitive to surface characteristics of built terrains. Changes of both urban land use and geometry impose significant impact on the overlying urban boundary layer dynamics through modification on bottom boundary conditions, i.e., by altering surface energy ...

Contributors
Song, Jiyun, Wang, Zhi-Hua, Ira A. Fulton Schools of Engineering, et al.
Created Date
2016-05-24

Atmospheric radiocarbon ([superscript 14]C) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the absence of [superscript 14]C in fossil fuel reservoirs. The high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric [superscript 14]C analysis has greatly increased the potential for using such measurements to evaluate bottom-up emissions inventories of fossil fuel CO[subscript 2] (CO[subscript 2]ff), as well as those for other co-emitted species. Here we use observations of [superscript 14]CO[subscript 2] and a series of primary hydrocarbons and combustion tracers from discrete air samples collected between June 2009 and ...

Contributors
LaFranchi, B. W., Petron, G., Miller, J. B., et al.
Created Date
2013-11-15

Combustion-derived aerosols in the marine boundary layer have been poorly studied, especially in remote environments such as the open Atlantic Ocean. The tropical Atlantic has the potential to contain a high concentration of aerosols, such as black carbon, due to the African emission plume of biomass and agricultural burning products. Atmospheric particulate matter samples across the tropical Atlantic boundary layer were collected in the summer of 2010 during the southern hemispheric dry season when open fire events were frequent in Africa and South America. The highest black carbon concentrations were detected in the Caribbean Sea and within the African plume, ...

Contributors
Pohl, K., Cantwell, M., Herckes, Pierre, et al.
Created Date
2014-07-18

Urban environments are the primary contributors to global anthropogenic carbon emissions. Because much of the growth in CO[subscript 2] emissions will originate from cities, there is a need to develop, assess, and improve measurement and modeling strategies for quantifying and monitoring greenhouse gas emissions from large urban centers. In this study the uncertainties in an aircraft-based mass balance approach for quantifying carbon dioxide and methane emissions from an urban environment, focusing on Indianapolis, IN, USA, are described. The relatively level terrain of Indianapolis facilitated the application of mean wind fields in the mass balance approach. We investigate the uncertainties in ...

Contributors
Cambaliza, M. O. L., Shepson, P. B., Caulton, D. R., et al.
Created Date
2014-09-02

Large urban emissions of greenhouse gases result in large atmospheric enhancements relative to background that are easily measured. Using CO[subscript 2] mole fractions and Δ[superscript 14]C and δ[superscript 13]C values of CO[subscript 2] in the Los Angeles megacity observed in inland Pasadena (2006–2013) and coastal Palos Verdes peninsula (autumn 2009–2013), we have determined time series for CO[subscript 2] contributions from fossil fuel combustion (C[subscript ff]) for both sites and broken those down into contributions from petroleum and/or gasoline and natural gas burning for Pasadena. We find a 10 % reduction in Pasadena C[subscript ff] during the Great Recession of 2008–2010, ...

Contributors
Newman, Sally, Xu, Xiaomei, Gurney, Kevin, et al.
Created Date
2016-03-22

Recent advances in fossil fuel CO[subscript 2] (FFCO[subscript 2]) emission inventories enable sensitivity tests of simulated atmospheric CO[subscript 2] concentrations to sub-annual variations in FFCO[subscript 2] emissions and what this implies for the interpretation of observed CO[subscript 2]. Six experiments are conducted to investigate the potential impact of three cycles of FFCO[subscript 2] emission variability (diurnal, weekly and monthly) using a global tracer transport model. Results show an annual FFCO[subscript 2] rectification varying from −1.35 to +0.13 ppm from the combination of all three cycles. This rectification is driven by a large negative diurnal FFCO[subscript 2] rectification due to the ...

Contributors
Zhang, Xia, Gurney, Kevin, Rayner, Peter, et al.
Created Date
2016-02-19

In this study, WRF-Chem is utilized at high resolution (1.333 km grid spacing for the innermost domain) to investigate impacts of southern California anthropogenic emissions (SoCal) on Phoenix ground-level ozone concentrations ([O[superscript 3]]) for a pair of recent exceedance episodes. First, WRF-Chem control simulations, based on the US Environmental Protection Agency (EPA) 2005 National Emissions Inventories (NEI05), are conducted to evaluate model performance. Compared with surface observations of hourly ozone, CO, NO[superscript X], and wind fields, the control simulations reproduce observed variability well. Simulated [O[superscript 3]] are comparable with the previous studies in this region. Next, the relative contribution of ...

Contributors
Li, Jialun, Georgescu, Matei, Hyde, Peter, et al.
Created Date
2015-08-21