56 results match your criteria Atmospheric Chemistry And Physics[Journal]


Modelling black carbon absorption of solar radiation: combining external and internal mixing assumptions.

Atmos Chem Phys 2019 7;19(1):181-204. Epub 2019 Jan 7.

Joint Research Centre (JRC), European Commission, Ispra (VA), 21027, Italy.

An accurate simulation of the absorption properties is key for assessing the radiative effects of aerosol on meteorology and climate. The representation of how chemical species are mixed inside the particles (the mixing state) is one of the major uncertainty factors in the assessment of these effects. Here we compare aerosol optical properties simulations over Europe and North America, coordinated in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII), to 1 year of AERONET sunphotometer retrievals, in an attempt to identify a mixing state representation that better reproduces the observed single scattering albedo and its spectral variation. Read More

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http://dx.doi.org/10.5194/acp-19-181-2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6392454PMC
January 2019
3 Reads

Seasonal ozone vertical profiles over North America using the AQMEII3 group of air quality models: model inter-comparison and stratospheric intrusions.

Atmos Chem Phys 2018 2;18(19):13925-13945. Epub 2018 Oct 2.

Ramboll, 773 San Marin Dr., Suite 2115, Novato, CA 94945, USA.

This study evaluates simulated vertical ozone profiles produced in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) against ozonesonde observations in North America for the year 2010. Four research groups from the United States (US) and Europe have provided modeled ozone vertical profiles to conduct this analysis. Because some of the modeling systems differ in their meteorological drivers, wind speed and temperature are also included in the analysis. Read More

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http://dx.doi.org/10.5194/acp-18-13925-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382018PMC
October 2018
5 Reads

Reanalysis intercomparisons of stratospheric polar processing diagnostics.

Atmos Chem Phys 2018 25;18(18):13547-13579. Epub 2018 Sep 25.

NASA/Goddard Space Flight Center, Greenbelt, MD USA.

We compare herein polar processing diagnostics derived from the four most recent full-input reanalysis datasets: the National Centers for Environmental Prediction Climate Forecast System Reanalysis / Climate Forecast System, version 2 (CFSR/CFSv2), the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), the Japanese Meteorological Agency's Japanese 55-year Reanalysis (JRA-55), and the National Aeronautics and Space Administration's Modern Era Retrospective-analysis for Research and Applications version 2 (MERRA-2). We focus on diagnostics based on temperatures and potential vorticity (PV) in the lower to middle stratosphere that are related to formation of polar stratospheric clouds (PSCs), chlorine activation, and the strength, size, and longevity of the stratospheric polar vortex. Polar minimum temperatures (T) and the area of regions having temperatures below PSC formation thresholds (A) show large persistent differences between the reanalyses, especially in the southern hemisphere (SH), for years prior to 1999. Read More

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http://dx.doi.org/10.5194/acp-18-13547-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6299841PMC
September 2018
1 Read

Modeled deposition of nitrogen and sulfur in Europe estimated by 14 air quality model systems: evaluation, effects of changes in emissions and implications for habitat protection.

Atmos Chem Phys 2018 Jul;18(14):10199-10218

European Commission, Joint Research Centre (JRC), Ispra (VA), Italy.

The evaluation and intercomparison of air quality models is key to reducing model errors and uncertainty. The projects AQMEII3 and EURODELTA-Trends, in the framework of the Task Force on Hemispheric Transport of Air Pollutants and the Task Force on Measurements and Modelling, respectively (both task forces under the UNECE Convention on the Long Range Transport of Air Pollution, LTRAP), have brought together various regional air quality models to analyze their performance in terms of air concentrations and wet deposition, as well as to address other specific objectives. This paper jointly examines the results from both project communities by intercomparing and evaluating the deposition estimates of reduced and oxidized nitrogen (N) and sulfur (S) in Europe simulated by 14 air quality model systems for the year 2010. Read More

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http://dx.doi.org/10.5194/acp-18-10199-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235743PMC
July 2018
5 Reads

Constraining chemical transport PM modeling outputs using surface monitor measurements and satellite retrievals: application over the San Joaquin Valley.

Atmos Chem Phys 2018 Jul;18(17):12891-12913

School of Civil & Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Advances in satellite retrieval of aerosol type can improve the accuracy of near-surface air quality characterization by providing broad regional context and decreasing metric uncertainties and errors. The frequent, spatially extensive and radiometrically consistent instantaneous constraints can be especially useful in areas away from ground monitors and progressively downwind of emission sources. We present a physical approach to constraining regional-scale estimates of PM. Read More

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https://www.atmos-chem-phys.net/18/12891/2018/
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http://dx.doi.org/10.5194/acp-18-12891-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6166888PMC
July 2018
1 Read

Influence of anthropogenic emissions and boundary conditions on multi-model simulations of major air pollutants over Europe and North America in the framework of AQMEII3.

Atmos Chem Phys 2018 ;18(12):8929-8952

European Commission, Joint Research Centre (JRC), Ispra, Italy.

In the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3), and as contribution to the second phase of the Hemispheric Transport of Air Pollution (HTAP2) activities for Europe and North America, the impacts of a 20 % decrease of global and regional anthropogenic emissions on surface air pollutant levels in 2010 are simulated by an international community of regional-scale air quality modeling groups, using different state-of-the-art chemistry and transport models (CTMs). The emission perturbations at the global level, as well as over the HTAP2-defined regions of Europe, North America and East Asia, are first simulated by the global Composition Integrated Forecasting System (C-IFS) model from European Centre for Medium-Range Weather Forecasts (ECMWF), which provides boundary conditions to the various regional CTMs participating in AQMEII3. On top of the perturbed boundary conditions, the regional CTMs used the same set of perturbed emissions within the regional domain for the different perturbation scenarios that introduce a 20 % reduction of anthropogenic emissions globally as well as over the HTAP2-defined regions of Europe, North America and East Asia. Read More

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http://dx.doi.org/10.5194/acp-18-8929-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104647PMC
January 2018
6 Reads

Assessment and economic valuation of air pollution impacts on human health over Europe and the United States as calculated by a multi-model ensemble in the framework of AQMEII3.

Atmos Chem Phys 2018 Apr;18(8):5967-5989

European Commission, Joint Research Centre (JRC), Ispra, Italy.

The impact of air pollution on human health and the associated external costs in Europe and the United States (US) for the year 2010 are modeled by a multi-model ensemble of regional models in the frame of the third phase of the Air Quality Modelling Evaluation International Initiative (AQMEII3). The modeled surface concentrations of O, CO, SO and PM are used as input to the Economic Valuation of Air Pollution (EVA) system to calculate the resulting health impacts and the associated external costs from each individual model. Along with a base case simulation, additional runs were performed introducing 20 % anthropogenic emission reductions both globally and regionally in Europe, North America and east Asia, as defined by the second phase of the Task Force on Hemispheric Transport of Air Pollution (TF-HTAP2). Read More

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http://dx.doi.org/10.5194/acp-18-5967-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070159PMC
April 2018
7 Reads

Impacts of different characterizations of large-scale background on simulated regional-scale ozone over the continental United States.

Atmos Chem Phys 2018 ;18(5):3839-3864

School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea.

This study analyzes simulated regional-scale ozone burdens both near the surface and aloft, estimates process contributions to these burdens, and calculates the sensitivity of the simulated regional-scale ozone burden to several key model inputs with a particular emphasis on boundary conditions derived from hemispheric or global-scale models. The Community Multiscale Air Quality (CMAQ) model simulations supporting this analysis were performed over the continental US for the year 2010 within the context of the Air Quality Model Evaluation International Initiative (AQMEII) and Task Force on Hemispheric Transport of Air Pollution (TF-HTAP) activities. CMAQ process analysis (PA) results highlight the dominant role of horizontal and vertical advection on the ozone burden in the mid-to-upper troposphere and lower stratosphere. Read More

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http://dx.doi.org/10.5194/acp-18-3839-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6071430PMC
January 2018
2 Reads

Long-term trends in total inorganic nitrogen and sulfur deposition in the U.S. from 1990 to 2010.

Atmos Chem Phys 2018 27;18(12):9091-9106. Epub 2018 Jun 27.

US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.

Excess deposition (including both wet and dry deposition) of nitrogen and sulfur are detrimental to ecosystems. Recent studies have investigated the spatial patterns and temporal trends of nitrogen and sulfur wet deposition, but few studies have focused on dry deposition due to the scarcity of dry deposition measurements. Here, we use long-term model simulations from the coupled WRF-CMAQ model covering the period from 1990 to 2010 to study changes in spatial distribution as well as temporal trends in total (TDEP), wet (WDEP) and dry deposition (DDEP) of total inorganic nitrogen (TIN) and sulfur (TSO). Read More

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6069975PMC
http://dx.doi.org/10.5194/acp-18-9091-2018DOI Listing
June 2018
1 Read

Nonlinear response of tropical lower stratospheric temperature and water vapor to ENSO.

Atmos Chem Phys 2018 5;18(7):4597-4615. Epub 2018 Apr 5.

NASA Goddard Space Flight Center, Greenbelt, MD, USA.

A series of simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model are analyzed in order to assess interannual and sub-decadal variability in the tropical lower stratosphere over the past 35 years. The impact of El Niño-Southern Oscillation on temperature and water vapor in this region is nonlinear in boreal spring. While moderate El Niño events lead to cooling in this region, strong El Niño events lead to warming, even as the response of the large scale Brewer Dobson Circulation appears to scale nearly linearly with El Niño. Read More

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http://dx.doi.org/10.5194/acp-18-4597-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6041696PMC
April 2018
1 Read
5.050 Impact Factor

Southeast Atmosphere Studies: learning from model-observation syntheses.

Atmos Chem Phys 2018 22;18(4):2615-2651. Epub 2018 Feb 22.

Geophysical Fluid Dynamics Laboratory-National Oceanic and Atmospheric Administration, Princeton, NJ, USA.

Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Read More

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http://dx.doi.org/10.5194/acp-18-2615-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6020695PMC
February 2018
6 Reads

Coupling of organic and inorganic aerosol systems and the effect on gas-particle partitioning in the southeastern US.

Atmos Chem Phys 2018 Jan;18(1):357-370

Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA.

Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1. Read More

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http://dx.doi.org/10.5194/acp-18-357-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6020690PMC
January 2018
4 Reads

Karymsky volcano eruptive plume properties based on MISR multi-angle imagery, and volcanological implications.

Atmos Chem Phys 2018 20;18(6):3903-3918. Epub 2018 Mar 20.

Climate and Radiation Laboratory, Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

Space-based, operational instruments are in unique positions to monitor volcanic activity globally, especially in remote locations or where suborbital observing conditions are hazardous. The Multi-angle Imaging SpectroRadiometer (MISR) provides hyper-stereo imagery, from which the altitude and microphysical properties of suspended atmospheric aerosols can be derived. These capabilities are applied to plumes emitted at Karymsky volcano from 2000 to 2017. Read More

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http://dx.doi.org/10.5194/acp-18-3903-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5996395PMC

Impact of intercontinental pollution transport on North American ozone air pollution: an HTAP phase 2 multi-model study.

Atmos Chem Phys 2017 May;17:5721-5750

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.

The recent update on the US National Ambient Air Quality Standards (NAAQS) of the ground-level ozone (O/ can benefit from a better understanding of its source contributions in different US regions during recent years. In the Hemispheric Transport of Air Pollution experiment phase 1 (HTAP1), various global models were used to determine the O source-receptor (SR) relationships among three continents in the Northern Hemisphere in 2001. In support of the HTAP phase 2 (HTAP2) experiment that studies more recent years and involves higher-resolution global models and regional models' participation, we conduct a number of regional-scale Sulfur Transport and dEposition Model (STEM) air quality base and sensitivity simulations over North America during May-June 2010. Read More

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http://dx.doi.org/10.5194/acp-17-5721-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954439PMC
May 2017
26 Reads

The potential effects of climate change on air quality across the conterminous U.S. at 2030 under three Representative Concentration Pathways.

Atmos Chem Phys 2018 ;18(20):15471-15489

Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA.

The potential impacts of climate change on regional ozone (O) and fine particulate (PM) air quality in the United States are investigated by linking global climate simulations with regional scale meteorological and chemical transport models. Regional climate at 2000 and at 2030 under three Representative Concentration Pathways (RCPs) is simulated by using the Weather Research and Forecasting (WRF) model to downscale 11-year time slices from the Community Earth System Model (CESM). The downscaled meteorology is then used with the Community Multiscale Air Quality (CMAQ) model to simulate air quality during each of these 11-year periods. Read More

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https://www.atmos-chem-phys.net/18/15471/2018/
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http://dx.doi.org/10.5194/acp-18-15471-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6453137PMC
January 2018
2 Reads

Two-scale multi-model ensemble: is a hybrid ensemble of opportunity telling us more?

Atmos Chem Phys 2018 ;18:2727-2744

Eurasia Institute of Earth Sciences, Istanbul Technical University, Istanbul, Turkey.

In this study we introduce a consisting of air quality models operating at both the global and regional scale. The work is motivated by the fact that these different types of models treat specific portions of the atmospheric spectrum with different levels of detail, and it is hypothesized that their combination can generate an ensemble that performs better than mono-scale ensembles. A detailed analysis of the hybrid ensemble is carried out in the attempt to investigate this hypothesis and determine the real benefit it produces compared to ensembles constructed from only global-scale or only regional-scale models. Read More

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https://www.atmos-chem-phys.net/18/8727/2018/
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http://dx.doi.org/10.5194/acp-18-8727-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452644PMC
January 2018
1 Read

Long-term trends in the ambient PM- and O-related mortality burdens in the United States under emission reductions from 1990 to 2010.

Atmos Chem Phys 2018 ;18(20):15003-15016

Computational Exposure Division, National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.

Concentrations of both fine particulate matter (PM) and ozone (O) in the United States (US) have decreased significantly since 1990, mainly because of air quality regulations. Exposure to these air pollutants is associated with premature death. Here we quantify the annual mortality burdens from PM and O in the US from 1990 to 2010, estimate trends and inter-annual variability, and evaluate the contributions to those trends from changes in pollutant concentrations, population, and baseline mortality rates. Read More

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http://dx.doi.org/10.5194/acp-18-15003-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436631PMC
January 2018

Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States.

Atmos Chem Phys 2018 31;18(17):12613-12637. Epub 2018 Aug 31.

School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are important precursors of secondary organic aerosol (SOA), but the amounts and pathways of SOA generation from these precursors are not well constrained by observations. We propose that the less-oxidized oxygenated organic aerosol (LO-OOA) factor resolved from positive matrix factorization (PMF) analysis on aerosol mass spectrometry (AMS) data can be used as a surrogate for fresh SOA from monoterpenes and sesquiterpenes in the southeastern US. Read More

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http://dx.doi.org/10.5194/acp-18-12613-2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6402345PMC
August 2018
1 Read

Observation- and Model-Based Estimates of Particulate Dry Nitrogen Deposition to the Oceans.

Atmos Chem Phys 2017 5;17(13):8189-8210. Epub 2017 Jul 5.

Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida, USA.

Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO) and ammonium (NH) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ~2900 observations of aerosol NO and NH concentrations, acquired from sampling aboard ships in the period 1995 - 2012, are used to assess the performance of modelled N concentration and deposition fields over the remote ocean. Read More

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http://dx.doi.org/10.5194/acp-17-8189-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5685536PMC
July 2017
9 Reads

NO emission trends over Chinese cities estimated from OMI observations during 2005 to 2015.

Atmos Chem Phys 2017 1;17(15):9261-9275. Epub 2017 Aug 1.

Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China.

Satellite NO observations have been widely used to evaluate emission changes. To determine trends in NO emission over China, we used a method independent of chemical transport models to quantify the NO emissions from 48 cities and 7 power plants over China, on the basis of Ozone Monitoring Instrument (OMI) NO observations during 2005 to 2015. We found that NO emissions over 48 Chinese cities increased by 52% from 2005 to 2011 and decreased by 21% from 2011 to 2015. Read More

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http://dx.doi.org/10.5194/acp-17-9261-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5664226PMC
August 2017
5 Reads

The spectral signature of cloud spatial structure in shortwave irradiance.

Atmos Chem Phys 2016 Nov 28;16(21):13791-13806. Epub 2016 Sep 28.

Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA.

In this paper, we used cloud imagery from a NASA field experiment in conjunction with three-dimensional radiative transfer calculations to show that cloud spatial structure manifests itself as a spectral signature in shortwave irradiance fields - specifically in transmittance and net horizontal photon transport in the visible and near-ultraviolet wavelength range. We found a robust correlation between the magnitude of net horizontal photon transport () and its spectral dependence (slope), which is scale-invariant and holds for the entire pixel population of a domain. This was surprising at first given the large degree of spatial inhomogeneity. Read More

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http://dx.doi.org/10.5194/acp-16-13791-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562414PMC
November 2016
10 Reads

Comprehensive atmospheric modeling of reactive cyclic siloxanes and their oxidation products.

Atmos Chem Phys 2017 Jul 10;17(13):8357-8370. Epub 2017 Jul 10.

Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA 52242, USA.

Cyclic volatile methyl siloxanes (cVMSs) are important components in personal care products that transport and react in the atmosphere. Octamethylcyclotetrasiloxane (D), decamethylcyclopentasiloxane (D), dodecamethylcyclohexasiloxane (D), and their gas-phase oxidation products have been incorporated into the Community Multiscale Air Quality (CMAQ) model. Gas-phase oxidation products, as the precursor to secondary organic aerosol from this compound class, were included to quantify the maximum potential for aerosol formation from gas-phase reactions with OH. Read More

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http://dx.doi.org/10.5194/acp-17-8357-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6368090PMC

Chemical transport model simulations of organic aerosol in southern California: model evaluation and gasoline and diesel source contributions.

Atmos Chem Phys 2017 Mar;17(6):4305-4318

Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.

Gasoline- and diesel-fueled engines are ubiquitous sources of air pollution in urban environments. They emit both primary particulate matter and precursor gases that react to form secondary particulate matter in the atmosphere. In this work, we updated the organic aerosol module and organic emissions inventory of a three-dimensional chemical transport model, the Community Multiscale Air Quality Model (CMAQ), using recent, experimentally derived inputs and parameterizations for mobile sources. Read More

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https://www.atmos-chem-phys.net/17/4305/2017/
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http://dx.doi.org/10.5194/acp-17-4305-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070158PMC
March 2017
7 Reads

Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project - Part 1: calibration, urban enhancements, and uncertainty estimates.

Atmos Chem Phys 2017 ;17

NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.

We report continuous surface observations of carbon dioxide (CO) and methane (CH) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO and CH measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally. Read More

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http://dx.doi.org/10.5194/acp-17-8313-2017DOI Listing
January 2017

Assessing the impact of anthropogenic pollution on isoprene-derived secondary organic aerosol formation in PM collected from the Birmingham, Alabama, ground site during the 2013 Southern Oxidant and Aerosol Study.

Atmos Chem Phys 2017 ;16(0):4897-4914

Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.

In the southeastern US, substantial emissions of isoprene from deciduous trees undergo atmospheric oxidation to form secondary organic aerosol (SOA) that contributes to fine particulate matter (PM). Laboratory studies have revealed that anthropogenic pollutants, such as sulfur dioxide (SO), oxides of nitrogen (NO ), and aerosol acidity, can enhance SOA formation from the hydroxyl radical (OH)-initiated oxidation of isoprene; however, the mechanisms by which specific pollutants enhance isoprene SOA in ambient PM remain unclear. As one aspect of an investigation to examine how anthropogenic pollutants influence isoprene-derived SOA formation, high-volume PM filter samples were collected at the Birmingham, Alabama (BHM), ground site during the 2013 Southern Oxidant and Aerosol Study (SOAS). Read More

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http://dx.doi.org/10.5194/acp-16-4897-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145830PMC
January 2017
12 Reads

Evaluation and error apportionment of an ensemble of atmospheric chemistry transport modeling systems: multivariable temporal and spatial breakdown.

Atmos Chem Phys 2017 ;17(4):3001-3054

European Commission, Joint Research Centre (JRC), Directorate for Energy, Transport and Climate, Air and Climate Unit, Ispra (VA), Italy.

Through the comparison of several regional-scale chemistry transport modeling systems that simulate meteorology and air quality over the European and North American continents, this study aims at (i) apportioning error to the responsible processes using timescale analysis, (ii) helping to detect causes of model error, and (iii) identifying the processes and temporal scales most urgently requiring dedicated investigations. The analysis is conducted within the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII) and tackles model performance gauging through measurement-to-model comparison, error decomposition, and time series analysis of the models biases for several fields (ozone, CO, SO, NO, NO, PM, PM, wind speed, and temperature). The operational metrics (magnitude of the error, sign of the bias, associativity) provide an overallsense of model strengths and deficiencies, while apportioning the error to its constituent parts (bias, variance, and covariance) can help assess the nature and quality of the error. Read More

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https://www.atmos-chem-phys.net/17/3001/2017/
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http://dx.doi.org/10.5194/acp-17-3001-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105295PMC
January 2017
26 Reads

Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol.

Atmos Chem Phys 2017 ;17(3):2103-2162

Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA.

Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Read More

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http://dx.doi.org/10.5194/acp-17-2103-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104845PMC
January 2017
10 Reads

Advanced error diagnostics of the CMAQ and Chimere modelling systems within the AQMEII3 model evaluation framework.

Atmos Chem Phys 2017 ;17(17):10435-10465

European Commission, Joint Research Centre (JRC), Directorate for Sustainable Resources, Food and Security Unit, Ispra (VA), Italy.

The work here complements the overview analysis of the modelling systems participating in the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) by focusing on the performance for hourly surface ozone by two modelling systems, Chimere for Europe and CMAQ for North America. The evaluation strategy outlined in the course of the three phases of the AQMEII activity, aimed to build up a diagnostic methodology for model evaluation, is pursued here and novel diagnostic methods are proposed. In addition to evaluating the "base case" simulation in which all model components are configured in their standard mode, the analysis also makes use of sensitivity simulations in which the models have been applied by altering and/or zeroing lateral boundary conditions, emissions of anthropogenic precursors, and ozone dry deposition. Read More

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https://www.atmos-chem-phys.net/17/10435/2017/
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http://dx.doi.org/10.5194/acp-17-10435-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104839PMC
January 2017
19 Reads

Impacts of aerosol direct effects on tropospheric ozone through changes in atmospheric dynamics and photolysis rates.

Atmos Chem Phys 2017 ;17(16):9869-9883

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

Aerosol direct effects (ADEs), i.e., scattering and absorption of incoming solar radiation, reduce radiation reaching the ground and the resultant photolysis attenuation can decrease ozone (O) formation in polluted areas. Read More

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http://dx.doi.org/10.5194/acp-17-9869-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104653PMC
January 2017
5 Reads

On the implications of aerosol liquid water and phase separation for organic aerosol mass.

Atmos Chem Phys 2017 ;17(1):343-369

Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA USA.

Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to organic carbon (OM/OC) ratios are high such that separation relative humidities (SRH) are below the ambient relative humidity (RH). As OM/OC ratios in the SE US are often between 1. Read More

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http://dx.doi.org/10.5194/acp-17-343-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104851PMC
January 2017
2 Reads

Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment.

Atmos Chem Phys 2017 ;17:1881-1899

CNR-Institute of Atmospheric Pollution Research, Area della Ricerca di Roma 1, Via Salaria km 29 300, Monterotondo, 00015 Rome, Italy.

Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental . However, little is known about the fraction of Hg bound to particulate matter (Hg) released from BB, and the factors controlling this fraction are also uncertain. Read More

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http://dx.doi.org/10.5194/acp-17-1881-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070161PMC
January 2017

Extending the Community Multiscale Air Quality (CMAQ) Modeling System to Hemispheric Scales: Overview of Process Considerations and Initial Applications.

Atmos Chem Phys 2017 ;17:12449-12474

National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.

The Community Multiscale Air Quality (CMAQ) modeling system is extended to simulate ozone, particulate matter, and related precursor distributions throughout the Northern Hemisphere. Modelled processes were examined and enhanced to suitably represent the extended space and time scales for such applications. Hemispheric scale simulations with CMAQ and the Weather Research and Forecasting (WRF) model are performed for multiple years. Read More

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http://dx.doi.org/10.5194/acp-17-12449-2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5907506PMC
January 2017
5 Reads

Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network.

Atmos Chem Phys 2016 Sep;16(18):11915-11935

Department of Environmental Science, Aarhus University, Aarhus, Denmark.

Long-term monitoring of data of ambient mercury (Hg) on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS) project was funded by the European Commission (http://www.gmos. Read More

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http://dx.doi.org/10.5194/acp-16-11915-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145827PMC
September 2016
6 Reads

Co-benefits of global and regional greenhouse gas mitigation on U.S. air quality in 2050.

Atmos Chem Phys 2016 1;16(15):9533-9548. Epub 2016 Aug 1.

Environmental Sciences and Engineering Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.

Policies to mitigate greenhouse gas (GHG) emissions will not only slow climate change, but can also have ancillary benefits of improved air quality. Here we examine the co-benefits of both global and regional GHG mitigation on U.S. Read More

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http://dx.doi.org/10.5194/acp-16-9533-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6150466PMC

Spatiotemporal variability and contribution of different aerosol types to the Aerosol Optical Depth over the Eastern Mediterranean.

Atmos Chem Phys 2016 9;16(21):13853-13884. Epub 2016 Nov 9.

Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.

This study characterizes the spatiotemporal variability and relative contribution of different types of aerosols to the Aerosol Optical Depth (AOD) over the Eastern Mediterranean as derived from MODIS Terra (3/2000-12/2012) and Aqua (7/2002-12/2012) satellite instruments. For this purpose, a 0.1° × 0. Read More

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http://dx.doi.org/10.5194/acp-16-13853-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946319PMC
November 2016
1 Read

Organic nitrate chemistry and its implications for nitrogen budgets in an isoprene- and monoterpene-rich atmosphere: constraints from aircraft (SEACRS) and ground-based (SOAS) observations in the Southeast US.

Atmos Chem Phys 2016 17;16(9):5969-5991. Epub 2016 May 17.

Department of Chemistry, University of Oslo, Oslo, Norway.

Formation of organic nitrates (RONO) during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NO), but the chemistry of RONO formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO) in the GEOS-Chem global chemical transport model with ∼25 × 25 km resolution over North America. We evaluate the model using aircraft (SEACRS) and ground-based (SOAS) observations of NO, BVOCs, and RONO from the Southeast US in summer 2013. Read More

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http://dx.doi.org/10.5194/acp-16-5969-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5906813PMC

Formaldehyde production from isoprene oxidation across NO regimes.

Atmos Chem Phys 2016 2;16(4):2597-2610. Epub 2016 Mar 2.

Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA.

The chemical link between isoprene and formaldehyde (HCHO) is a strong, non-linear function of NO (= NO + NO). This relationship is a linchpin for top-down isoprene emission inventory verification from orbital HCHO column observations. It is also a benchmark for overall photochemical mechanism performance with regard to VOC oxidation. Read More

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http://dx.doi.org/10.5194/acp-16-2597-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5879783PMC
March 2016
6 Reads

Why do Models Overestimate Surface Ozone in the Southeastern United States?

Atmos Chem Phys 2016 1;16(21):13561-13577. Epub 2016 Nov 1.

Department of Environmental Health and Toxicology, School of Public Health, State University of New York at Albany, Albany, New York, USA.

Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NO ≡ NO + NO) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEACRS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0. Read More

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http://dx.doi.org/10.5194/acp-16-13561-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880041PMC
November 2016
7 Reads

Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEACRS aircraft observations over the Southeast US.

Atmos Chem Phys 2016 1;16(21):13477-13490. Epub 2016 Nov 1.

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA.

Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs) but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEACRS campaign over the Southeast US in August-September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. Read More

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http://dx.doi.org/10.5194/acp-16-13477-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880299PMC
November 2016
17 Reads

The effect of future ambient air pollution on human premature mortality to 2100 using output from the ACCMIP model ensemble.

Atmos Chem Phys 2016 5;16(15):9847-9862. Epub 2016 Aug 5.

National Institute of Water and Atmospheric Research, Lauder, New Zealand.

Ambient air pollution from ground-level ozone and fine particulate matter (PM) is associated with premature mortality. Future concentrations of these air pollutants will be driven by natural and anthropogenic emissions and by climate change. Using anthropogenic and biomass burning emissions projected in the four Representative Concentration Pathway scenarios (RCPs), the ACCMIP ensemble of chemistry-climate models simulated future concentrations of ozone and PM at selected decades between 2000 and 2100. Read More

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http://dx.doi.org/10.5194/acp-16-9847-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5730074PMC
August 2016
12 Reads

Exploring the Uncertainty Associated with Satellite-Based Estimates of Premature Mortality due to Exposure to Fine Particulate Matter.

Atmos Chem Phys 2016 17;16(5):3499-3523. Epub 2016 Mar 17.

Department of Civil and Environmental Engineering and Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA, USA.

The negative impacts of fine particulate matter (PM) exposure on human health are a primary motivator for air quality research. However, estimates of the air pollution health burden vary considerably and strongly depend on the datasets and methodology. Satellite observations of aerosol optical depth (AOD) have been widely used to overcome limited coverage from surface monitoring and to assess the global population exposure to PM and the associated premature mortality. Read More

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http://dx.doi.org/10.5194/acp-16-3499-2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5482289PMC
March 2016
1 Read

On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert.

Atmos Chem Phys 2015 Feb;15:6943-6958

Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA ; Department of Atmospheric Sciences, University of Arizona, Tucson, AZ, USA ; Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USA.

A 2-year data set of measured CCN (cloud condensation nuclei) concentrations at 0.2 % supersaturation is combined with aerosol size distribution and aerosol composition data to probe the effects of aerosol number concentrations, size distribution and composition on CCN patterns. Data were collected over a period of 2 years (2012-2014) in central Tucson, Arizona: a significant urban area surrounded by a sparsely populated desert. Read More

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http://dx.doi.org/10.5194/acp-15-6943-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548966PMC
February 2015

An overview of regional and local characteristics of aerosols in South Africa using satellite, ground, and modeling data.

Atmos Chem Phys 2015;15:4259-4278

Department of Environmental Sciences and Management, North-West University, Potchefstroom, South Africa.

We present a comprehensive overview of particulate air quality across the five major metropolitan areas of South Africa (Cape Town, Bloemfontein, Johannesburg and Tshwane (Gauteng Province), the Industrial Highveld Air Quality Priority Area (HVAPA), and Durban), based on a decadal (1 January 2000 to 31 December 2009) aerosol climatology from multiple satellite platforms and detailed analysis of ground-based data from 19 sites throughout Gauteng Province. Satellite analysis was based on aerosol optical depth (AOD) from MODIS Aqua and Terra (550 nm) and MISR (555 nm) platforms, Ångström Exponent () from MODIS Aqua (550/865 nm) and Terra (470/660 nm), ultraviolet aerosol index (UVAI) from TOMS, and results from the Goddard Ozone Chemistry Aerosol Radiation and Transport (GOCART) model. At continentally influenced sites, AOD, , and UVAI reach maxima (0. Read More

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http://dx.doi.org/10.5194/acp-15-4259-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547400PMC
January 2015

An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements.

Atmos Chem Phys 2015 Jan;15(2):2577-2613

Belgian Institute for Space Aeronomy, Brussels, Belgium.

Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Read More

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http://dx.doi.org/10.5194/acpd-15-2577-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4430827PMC
January 2015
2 Reads

Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities.

Atmos Chem Phys 2015;15:4225-4239. Epub 2015 Apr 24.

Atmospheric Science Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA.

Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. Read More

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http://dx.doi.org/10.5194/acp-15-4225-2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4874526PMC

Aerosol and precipitation chemistry in the southwestern United States: spatiotemporal trends and interrelationships.

Atmos Chem Phys 2013 Aug;13(15):7361-7379

Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona, USA.

This study characterizes the spatial and temporal patterns of aerosol and precipitation composition at six sites across the United States Southwest between 1995 and 2010. Precipitation accumulation occurs mostly during the wintertime (December-February) and during the monsoon season (July-September). Rain and snow pH levels are usually between 5-6, with crustal-derived species playing a major role in acid neutralization. Read More

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http://dx.doi.org/10.5194/acp-13-7361-2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890361PMC

10-year spatial and temporal trends of PM concentrations in the southeastern US estimated using high-resolution satellite data.

Atmos Chem Phys 2014 25;14(12):6301-6314. Epub 2014 Jun 25.

Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA.

Long-term PM exposure has been associated with various adverse health outcomes. However, most ground monitors are located in urban areas, leading to a potentially biased representation of true regional PM levels. To facilitate epidemiological studies, accurate estimates of the spatiotemporally continuous distribution of PM concentrations are important. Read More

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http://dx.doi.org/10.5194/acp-14-6301-2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5619667PMC
June 2014
1 Read

Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley.

Atmos Chem Phys 2014;14:6075-6088. Epub 2014 Jun 20.

University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.

The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5 % of particle mass for particles with > 0. Read More

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http://dx.doi.org/10.5194/acp-14-6075-2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4961092PMC

Efficient determination of vehicle emission factors by fuel use category using on-road measurements: downward trends on Los Angeles freight corridor I-710.

Atmos Chem Phys 2013 Jan;13(1)

Department of Preventive Medicine, Environmental Health Sciences, University of Southern California, Los Angeles, CA 90089, USA.

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Read More

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http://dx.doi.org/10.5194/acp-13-347-2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826660PMC
January 2013

On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals.

Atmos Chem Phys 2012 May;12(5):11317-11350

Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA ; Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA.

The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. Read More

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http://dx.doi.org/10.5194/acpd-12-11317-2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564657PMC