Aerosol optical properties at a coastal site in Hong Kong, South China: temporal features, size dependencies and source analysis

NASA Astrophysics Data System (ADS)

Wang, Jiaping; Ding, Aijun; Virkkula, Aki; Lee, Shuncheng; Shen, Yicheng; Chi, Xuguang; Xu, Zheng

2016-04-01

Hong Kong is a typical coastal city adjacent to the Pearl River Delta (PRD) region in southern China, which is one of the regions suffering from severe air pollution. Atmospheric aerosols can affect the earth's radiative balance by scattering and absorbing incoming solar radiation. Black Carbon (BC) aerosol is a particularly emphasized component due to its strong light absorption. Aerosol transported from different source areas consists of distinct size distributions, leading to different optical properties. As the byproducts of the incomplete oxidation, BC and CO both have relatively long life time, their relationship is a good indicator for distinguishing different pollutant sources. In this study, temporal variations of aerosol optical properties and concentrations of BC and CO at a coastal background station in Hong Kong were investigated. Transport characteristics and origins of aerosol were elucidated by analyzing backward Lagrangian particle dispersion modeling (LPDM) results, together with related parameters including the relationships between optical properties and particle size, BC-CO correlations, ship location data and meteorological variables. From February 2012 to September 2013 and March 2014 to February 2015, continuous in-situ measurements of light scattering and absorption coefficients, particle size distribution and concentrations of BC and CO were conducted at Hok Tsui (HT), a coastal background station on the southeast tip of Hong Kong Island (22.22°N, 114.25°E, 60 m above the sea level) with few local anthropogenic activities. Affected by the Asian monsoon, this region is dominated by continental outflow in winter and by marine inflow from the South China Sea in summer, which is an ideal station for identifying the transport characteristics of aerosol and their effects on optical properties from different anthropogenic emission sources. 7-day backward Lagrangian particle dispersion modeling was performed for source identification. Three types of cases dominantly influenced by the PRD regional emission, long-range transport and marine exhaust were compared and discussed in detail.

High-field FT-ICR-MS and aromaticity equivalent approach for structural identification of water soluble organic compounds (WSOC)

NASA Astrophysics Data System (ADS)

Harir, Mourad; Yassine, Mahmoud M.; Dabek-Zlotorzynska, Ewa; Hertkorn, Norbert; Schmitt-Kopplin, Philippe

2015-04-01

Organic aerosol (OA) makes up a large and often dominant fraction, (20 to 90%) of the submicron atmospheric particulate mass, and its effects are becoming increasingly important in determining climatic and health effects of atmospheric aerosols. Despite the abundance of OA, our understanding of the sources, formation processes and atmospheric properties of OA is limited. Atmospheric OA has both primary (directly emitted) and secondary (formed in the atmosphere from precursor gases) sources, which can be natural (e.g. vegetation) and/or anthropogenic (e.g. fossil-based vehicle exhaust or biomass burning). A significant fraction of OA contains as much as 20-70% of water soluble organic compounds (WSOC). The WSOC fraction is a very complex mixture of low volatility, polyfunctional aliphatic and aromatic compounds containing carboxyl, alcohol, carbonyl, sulfo, nitro, and other functionalities. This high degree of chemical complexity of atmospheric organics has inspired a number of sophisticated approaches that are capable of identifying and detecting a variety of different analytes in OA. Accordingly, one of the most challenging areas of atmospheric particulate matter (PM) analysis is to comprehend the molecular complexity of the OA, especially WSOC fraction, a significant component of atmospheric fine PM (PM2.5). The sources of WSOC are not well understood, especially the relative contributions of primary vs. secondary organic aerosol. Therefore, the molecular characterization of WSOC is important because it allows gaining insight into aerosol sources and underlying mechanisms of secondary organic aerosols (SOA) formation and transformation. In this abstract, molecular characterization of WSOC was achieved using high-field mass spectrometry FT-ICR-MS and aromaticity equivalent approach. Aromaticity equivalent (Xc), defined recently as a new parameter calculated from the assigned molecular formulas (complementary to the aromaticity index [1]), is introduced to improve identification and characterization of aromatic and condensed aromatic compounds in WSOC [2]. We proposed threshold values of Xc≥ 2.5000 and Xc≥ 2.7143 as ambiguous minimum criteria for the presence of aromatic structure and condensed aromatic compounds, respectively. The advantage of employing this parameter is that Xc would have a constant value for each proposed core structure regardless the degree of alkylation, and thus visual representation and structural interpretations of the spectra become advantageous for characterizing and comparing complex samples. Diesel particulate matter (DPM) and two atmospheric aerosols collected in the industrial area affected by biomass burning events were used to study the applicability of the proposed criteria for the improved identification of aromatic and condensed aromatic structures in complex mixtures in the FT-ICR mass spectra. References [1] Koch.BP, Dittmar.T. From mass to structure: an aromaticity index for high-resolution mass data of natural organic matter. Rapid Commun. Mass Spectrom. 2006, 20, 926-932 [2] Yassine.MM, Harir.M, Dabek-Zlotorzynska.E, Schmitt-Kopplin.Ph. Structural characterization of organic aerosol using Fourier transform ion cyclotron resonance mass spectrometry: Aromaticity equivalent approach. Rapid Commun. Mass Spectrom. 2014. 28. 2445-2454

A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

DOE PAGES

Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; ...

2016-11-25

Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arrangedmore » into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on other bulk aerosol components commonly observed by the AMS.« less

A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

NASA Astrophysics Data System (ADS)

Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

2016-11-01

We present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography-mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on other bulk aerosol components commonly observed by the AMS.

Direct measurements of near-highway emissions in a high diesel environment

NASA Astrophysics Data System (ADS)

DeWitt, H. L.; Hellebust, S.; Temime-Roussel, B.; Ravier, S.; Polo, L.; Jacob, V.; Buisson, C.; Charron, A.; André, M.; Pasquier, A.; Besombes, J. L.; Jaffrezo, J. L.; Wortham, H.; Marchand, N.

2014-10-01

Diesel-powered passenger cars currently outnumber gasoline-powered cars in many countries, particularly in Europe. In France, diesel cars represented 61% of Light Duty Vehicles in 2011 and this percentage is still increasing (French Environment and Energy Management Agency, ADEME). As part of the September~2011 joint PM-DRIVE (Particulate Matter- DiRect and Indirect on-road Vehicular Emissions) and MOCOPO (Measuring and mOdeling traffic COngestion and POllution) field campaign, the concentration and high-resolution chemical composition of aerosols and volatile organic carbon (VOC) species were measured adjacent to a major urban highway south of Grenoble, France. Alongside these atmospheric measurements, detailed traffic data were collected from nearby traffic cameras and loop detectors, which allowed the identification of vehicle type and characteristics, traffic concentration, and traffic speed to be quantified and compared to measured aerosol and VOCs. Six aerosol age and source profiles were resolved using the positive matrix factorization (PMF) model on real-time high-resolution aerosol mass spectra. These six aerosol source/age categories included a hydrocarbon-like organic aerosol (HOA) commonly associated with primary vehicular emissions, a nitrogen containing aerosol (NOA) with a diurnal pattern similar to that of HOA, oxidized organic aerosol (OOA), and biomass burning aerosol (BBOA). While quantitatively separating the influence of diesel vs. gasoline proved impossible, a low HOA : black carbon ratio, similar to that measured in other high-diesel environments, and high levels of NOx, also indicative of diesel emissions, were observed. A comparison between these high-diesel environment measurements and measurements taken in low-diesel (North American) environments was examined and the potential feedback between vehicular emissions and SOA formation was probed. Although the measurement site was located next to a large source of primary emissions, which are typically found to have low oxygen incorporation, OOA was found to comprise the majority of the measured organic aerosol, and the measured OOA contained mainly modern carbon, not fossil-derived carbon. Thus, even in this heavily vehicular-emission impacted environment, photochemical processes, biogenic emissions, and aerosol oxidation dominated the overall organic aerosol mass measured during most of the campaign.

Aerosols in Alaska

NASA Astrophysics Data System (ADS)

Shaw, G. E.; Quinn, P. K.

2008-12-01

We are measuring the latitudinal gradient and time variation of aerosol chemical composition across Alaska looking for drifts that might be attributable to alteration in sources and chemical signatures that might allow the identification of sources. Alaska is a very clean region in the sense that the state has a low population density with little polluting emission sources. However it "receives" anthropogenic chemical signals from areas upstream in the westerly's, such as from China, and impacts of Arctic Haze. The region also generates sometime copious amounts of aerosol from wildfire in its boreal forests and condensed compounds from gases emitted by its surrounding oceans. The time series of aerosol composition from this small network goes back about a decade and shows clearly the spring peaking of anthropogenic signal known as Arctic Haze. This signal peaks year after year in spring months at all stations, but is most concentrated at north most stations. On the other hand, a signal indicative of products from the ocean, mainly sulfate with large fractional amounts of MSA peaks, year after year, in the summer and is strongest at the lower latitudes. We have identified not only chemical signatures associated with wildfire smoke from wildfires in Alaska, but the changed signatures from wildfires in far away regions, from Mongolia for example.

Water-soluble Organic Components in Aerosols Associated with Savanna Fires in Southern Africa: Identification, Evolution and Distribution

NASA Technical Reports Server (NTRS)

Gao, Song; Hegg, Dean A.; Hobbs, Peter V.; Kirchstetter, Thomas W.; Magi, Brian I.; Sadilek, Martin

2003-01-01

During the SAFARI 2000 field campaign, both smoke aerosols from savanna fires and haze aerosols in the boundary layer and in the free troposphere were collected from an aircraft in southern Africa. These aerosol samples were analyzed for their water-soluble chemical components, particularly the organic species. A novel technique, electrospray ionization-ion trap mass spectrometry, was used concurrently with an ion chromatography system to analyze for carbohydrate species. Seven carbohydrates, seven organic acids, five metallic elements, and three inorganic anions were identified and quantified. On the average, these 22 species comprised 36% and 27% of the total aerosol mass in haze and smoke aerosols, respectively. For the smoke aerosols, levoglucosan was the most abundant carbohydrate species, while gluconic acid was tentatively identified as the most abundant organic acid. The mass abundance and possible source of each class of identified species are discussed, along with their possible formation pathways. The combustion phase of a fire had an impact on the chemical composition of the emitted aerosols. Secondary formation of sulfate, nitrate, levoglucosan, and several organic acids occurred during the initial aging of smoke aerosols. It is likely that under certain conditions, some carbohydrate species in smoke aerosols, such as levoglucosan, were converted to organic acids during upward transport.

Molecular Diversity of Brown Carbon Chromophores in Biomass Burning Aerosol

NASA Astrophysics Data System (ADS)

Lin, P.; Laskin, A.; Laskin, J.; Fleming, L.; Nizkorodov, S.

2017-12-01

Brown carbon (BrC) is ubiquitous in the atmosphere and significant contributor to climate forcing. Understanding the environmental effects of BrC, its sources, formation, and atmospheric transformation mechanisms requires identification of BrC chromophores and characterization of their light-absorption properties. In this study, we investigate the chemical composition, molecular identity and optical properties of BrC chromophores associated with biomass burning aerosols emitted from burns of different biofuels during the NOAA FIREX/FireLab experiment. The results show that BrC in the biomass burning smoke contains organic compounds of various molecular structures, polarities, and volatilities. The relative contributions to light absorption from different classes of chromophores such as nitro-phenols, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and heterocyclic PAHs are quantified and are shown to be diverse among aerosol samples from different biofuel sources. Despite complexity of BrC, grouping its chromophores according to their polarity and volatility may simplify the parameters for modelling input.

IDENTIFICATION OF SOURCES AND ESTIMATION OF EMISSION PROFILES FROM HIGHLY TIME-RESOLVED POLLUTANT MEASUREMENTS IN TAMPA, FL

EPA Science Inventory

Aerosol slurry samples were collected at 30-min intervals for sequential 1-month periods at each of two sites (Sydney and "Dairy") in the Tampa Bay area during the 2002 Bay Regional Atmospheric Chemistry Experiment using the University of Maryland Semicontinuous Elements in Aeros...

Discrimination of Biomass Burning Smoke and Clouds in MAIAC Algorithm

NASA Technical Reports Server (NTRS)

Lyapustin, A.; Korkin, S.; Wang, Y.; Quayle, B.; Laszlo, I.

2012-01-01

The multi-angle implementation of atmospheric correction (MAIAC) algorithm makes aerosol retrievals from MODIS data at 1 km resolution providing information about the fine scale aerosol variability. This information is required in different applications such as urban air quality analysis, aerosol source identification etc. The quality of high resolution aerosol data is directly linked to the quality of cloud mask, in particular detection of small (sub-pixel) and low clouds. This work continues research in this direction, describing a technique to detect small clouds and introducing the smoke test to discriminate the biomass burning smoke from the clouds. The smoke test relies on a relative increase of aerosol absorption at MODIS wavelength 0.412 micrometers as compared to 0.47-0.67 micrometers due to multiple scattering and enhanced absorption by organic carbon released during combustion. This general principle has been successfully used in the OMI detection of absorbing aerosols based on UV measurements. This paper provides the algorithm detail and illustrates its performance on two examples of wildfires in US Pacific North-West and in Georgia/Florida of 2007.

Aerosol mass spectrometric features of biogenic SOA: observations from a plant chamber and in rural atmospheric environments.

PubMed

Kiendler-Scharr, Astrid; Zhang, Qi; Hohaus, Thorsten; Kleist, Einhard; Mensah, Amewu; Mentel, Thomas F; Spindler, Christian; Uerlings, Ricarda; Tillmann, Ralf; Wildt, Jürgen

2009-11-01

Secondary organic aerosol (SOA) is known to form from a variety of anthropogenic and biogenic precursors. Current estimates of global SOA production vary over 2 orders of magnitude. Since no direct measurement technique for SOA exists, quantifying SOA remains a challenge for atmospheric studies. The identification of biogenic SOA (BSOA) based on mass spectral signatures offers the possibility to derive source information of organic aerosol (OA) with high time resolution. Here we present data from simulation experiments. The BSOA from tree emissions was characterized with an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Collection efficiencies were close to 1, and effective densities of the BSOA were found to be 1.3 +/- 0.1 g/cm(3). The mass spectra of SOA from different trees were found to be highly similar. The average BSOA mass spectrum from tree emissions is compared to a BSOA component spectrum extracted from field data. It is shown that overall the spectra agree well and that the mass spectral features of BSOA are distinctively different from those of OA components related to fresh fossil fuel and biomass combustions. The simulation chamber mass spectrum may potentially be useful for the identification and interpretation of biogenic SOA components in ambient data sets.

Source identification of PM10, collected at a heavy-traffic roadside, by analyzing individual particles using synchrotron radiation.

PubMed

Yue, Weisheng; Li, Yan; Li, Xiaolin; Yu, Xiaohan; Deng, Biao; Liu, Jiangfeng; Wan, Tianmin; Zhang, Guilin; Huang, Yuying; He, Wei; Hua, Wei

2004-09-01

Synchrotron radiation microbeam X-ray fluorescence (micro-SXRF) was used to analyze individual aerosol particles collected at a height of 2 m above a heavy-traffic roadside in a heavy-industrial area of Shanghai. A pattern recognition technique, which took micro-SXRF spectra of single aerosol particles as its fingerprint, was used to identify the origins of the particles. The particles collected from the environmental monitoring site are mainly from metallurgic industry (26%), unleaded gasoline automobile exhaust (15%), coal combustion (10%), cement dust (10%) and motorcycle exhaust (8%).

Physicochemical variations in atmospheric aerosols recorded at sea onboard the Atlantic-Mediterranean 2008 Scholar Ship cruise (Part II): Natural versus anthropogenic influences revealed by PM 10 trace element geochemistry

NASA Astrophysics Data System (ADS)

Moreno, Teresa; Pérez, Noemi; Querol, Xavier; Amato, Fulvio; Alastuey, Andrés; Bhatia, Ravinder; Spiro, Baruch; Hanvey, Melanie; Gibbons, Wes

2010-07-01

The geochemistry of PM 10 filter samples collected at sea during the Scholar Ship Atlantic-Mediterranean 2008 research cruise reveals a constantly changing compositional mix of pollutants into the marine atmosphere. Source apportionment modelling using Positive Matrix Factorization identifies North African desert dust, sea spray, secondary inorganic aerosols, metalliferous carbon, and V-Ni-bearing combustion particles as the main PM 10 factors/sources. The least contaminated samples show an upper continental crust composition (UCC)-normalised geochemistry influenced by seawater chemistry, with marked depletions in Rb, Th and the lighter lanthanoid elements, whereas the arrival of desert dust intrusions imposes a more upper crustal signature enriched in "geological" elements such as Si, Al, Ti, Rb, Li and Sc. Superimposed on these natural background aerosol loadings are anthropogenic metal aerosols (e.g. Cu, Zn, Pb, V, and Mn) which allow identification of pollution sources such as fossil fuel combustion, biomass burning, metalliferous industries, and urban-industrial ports. A particularly sensitive tracer is La/Ce, which rises in response to contamination from coastal FCC oil refineries. The Scholar Ship database allows us to recognise seaborne pollution sourced from NW Africa, the Cape Verde and Canary islands, and European cities and industrial complexes, plumes which in extreme cases can produce a downwind deterioration in marine air quality comparable to that seen in many cities, and can persist hundreds of kilometres from land.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.

Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arrangedmore » into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on other bulk aerosol components commonly observed by the AMS.« less

Optical, microphysical and radiative properties of aerosols over a tropical rural site in Kenya, East Africa: Source identification, modification and aerosol type discrimination

NASA Astrophysics Data System (ADS)

Boiyo, Richard; Kumar, K. Raghavendra; Zhao, Tianliang

2018-03-01

A better understanding of aerosol optical, microphysical and radiative properties is a crucial challenge for climate change studies. In the present study, column-integrated aerosol optical and radiative properties observed at a rural site, Mbita (0.42°S, 34.20 °E, and 1125 m above sea level) located in Kenya, East Africa (EA) are investigated using ground-based Aerosol Robotic Network (AERONET) data retrieved during January, 2007 to December, 2015. The annual mean aerosol optical depth (AOD500 nm), Ångström exponent (AE440-870 nm), fine mode fraction of AOD500 nm (FMF500 nm), and columnar water vapor (CWV, cm) were found to be 0.23 ± 0.08, 1.01 ± 0.16, 0.60 ± 0.07, and 2.72 ± 0.20, respectively. The aerosol optical properties exhibited a unimodal distribution with substantial seasonal heterogeneity in their peak values being low (high) during the local wet (dry) seasons. The observed data showed that Mbita and its environs are significantly influenced by various types of aerosols, with biomass burning and/or urban-industrial (BUI), mixed (MXD), and desert dust (DDT) aerosol types contributing to 37.72%, 32.81%, and 1.40%, respectively during the local dry season (JJA). The aerosol volume size distribution (VSD) exhibited bimodal lognormal structure with a geometric mean radius of 0.15 μm and 3.86-5.06 μm for fine- and coarse-mode aerosols, respectively. Further, analysis of single scattering albedo (SSA), asymmetry parameter (ASY) and refractive index (RI) revealed dominance of fine-mode absorbing aerosols during JJA. The averaged aerosol direct radiative forcing (ARF) retrieved from the AERONET showed a strong cooling effect at the bottom of the atmosphere (BOA) and significant warming within the atmosphere (ATM), representing the important role of aerosols played in this rural site of Kenya. Finally, the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model revealed that aerosols from distinct sources resulted in enhanced loading during JJA.

Identification of dust source regions and dust emission trends across North Africa and the Middle East using MISR satellite observations

NASA Astrophysics Data System (ADS)

Yu, Y.; Kalashnikova, O. V.; Garay, M. J.; Notaro, M.

2017-12-01

Global arid and semi-arid regions supply 1100 to 5000 Tg of Aeolian dust to the atmosphere each year, primarily from North Africa and secondarily from the Middle East. Previous dust source identification methods, based on either remotely-sensed aerosol optical depth (AOD) or dust activity, yield distinct dust source maps, largely due to the limitations in each method and remote-sensing product. Here we apply a novel motion-based method for dust source identification. Dust plume thickness and motion vectors from Multi-angle Imaging SpectroRadiometer (MISR) Cloud Motion Vector Product (CMVP) are examined to identify the regions with high frequency of fast moving-dust plumes, by season. According to MISR CMVP, Bodele depression is the most important dust source across North Africa, consistent with previous studies. Seasonal variability of dust emission across the North Africa is largely driven by climatology of wind and precipitation, featuring the influence of Sharav Cyclone and western African monsoon. In the Middle East, Iraq, Kuwait, and eastern Saudi Arabia are identified as dust source regions, especially during summer months, when the Middle Eastern Shamal wind is active. Furthermore, dust emission trend at each dust source are diagnosed from the motion-based dust source dataset. Increase in dust emission from the Fertile Crescent, Sahel, and eastern African dust sources are identified from MISR CMVP, implying potential contribution from these dust sources to the upward trend in AOD and dust AOD over the Middle East in the 21st century. By comparing with various dust source identification studies, we conclude that the motion-based identification of dust sources is an encouraging alternative and compliment to the AOD-only source identification method.

Chemical Composition and Source Apportionment of high temporal resolution PM1 data for January-August 2017 in Delhi, India

NASA Astrophysics Data System (ADS)

Bhandari, S.; Wang, D. S.; Gani, S.; Seraj, S.; Arub, Z.; Habib, G.; Apte, J.; Hildebrandt Ruiz, L.

2017-12-01

Exposure to fine particulate matter (PM) poses significant health risks, especially to residents in heavily populated areas. The current understanding of the sources and dynamics of PM pollution in developing countries like India is limited. Delhi, India is the second most populated city in the world that has extremely high winter PM concentrations and frequent severe pollution episodes. This study reports on composition measurements of submicron aerosol at 1 minute time resolution from January to August of 2017, collected at the Indian Institute of Technology Delhi using an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and black carbon (BC) measurements using an Aethalometer. Source apportionment was conducted on organic and inorganic mass spectra measured by the ACSM and black carbon data measured using Positive Matrix Factorization (PMF). High concentrations of particulate matter were observed with total PM1 at times exceeding 200 µg m-3 in winter. A significant drop in PM1 concentrations was observed in the winter-spring transition. As observed elsewhere, organic species dominated the submicron mass, contributing 60% of the total mass over the duration of the campaign. However, this fractional contribution varied substantially over the day: from 48% early in the morning to 73% late at night. Along with diurnal variation in total PM1 mass loadings, particulate chloride levels also exhibited a strong diurnal cycle, with concentrations as high as 50 µg m-3 observed in the early mornings of January 2017. Literature review on identification of winter chloride sources in Delhi points to local and regional sources such as biomass/open-waste burning and coal combustion. PMF receptor modeling identified several factors with distinct diurnal patterns. While hydrocarbon-like organic aerosol (HOA) factor has the largest mass fraction contribution, PMF results consistently suggest chloride presence as attributable to ammonium chloride. Interestingly, aerosol neutralization characterization shows an apparent acidity of aerosols. These results point to substantial differences in aerosol composition in Indian cities in comparison to cities around the world, especially with regards to the abundance of particulate chloride, and provide insights into the sources of PM1 measured in Delhi.

Identification of the sources of primary organic aerosols at urban schools: a molecular marker approach.

PubMed

Crilley, Leigh R; Qadir, Raeed M; Ayoko, Godwin A; Schnelle-Kreis, Jürgen; Abbaszade, Gülcin; Orasche, Jürgen; Zimmermann, Ralf; Morawska, Lidia

2014-08-01

Children are particularly susceptible to air pollution and schools are examples of urban microenvironments that can account for a large portion of children's exposure to airborne particles. Thus this paper aimed to determine the sources of primary airborne particles that children are exposed to at school by analyzing selected organic molecular markers at 11 urban schools in Brisbane, Australia. Positive matrix factorization analysis identified four sources at the schools: vehicle emissions, biomass burning, meat cooking and plant wax emissions accounting for 45%, 29%, 16% and 7%, of the organic carbon respectively. Biomass burning peaked in winter due to prescribed burning of bushland around Brisbane. Overall, the results indicated that both local (traffic) and regional (biomass burning) sources of primary organic aerosols influence the levels of ambient particles that children are exposed at the schools. These results have implications for potential control strategies for mitigating exposure at schools. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical composition of size-segregated aerosol collected all year-round at Concordia Station (Dome C, Antarctica). Transport processes and climatic implications.

NASA Astrophysics Data System (ADS)

Udisti, Roberto; Becagli, Silvia; Frosini, Daniele; Galli, Gaia; Ghedini, Costanza; Rugi, Francesco; Severi, Mirko; Traversi, Rita

2010-05-01

Ice-core stratigraphies of chemical components of atmospheric gases and aerosols trapped in the snow layers by scavenging processes are a powerful tool in understanding past climatic and environmental changes. The deep ice core drilled at Dome C in the framework of the EPICA project allowed reconstructing the last 8 glacial-interglacial cycles and highlightened the complex relationships between climatic forcings and environmental feedback processes. In interpreting ice core records as a function of past climatic variations, some difficulties arise from uncertainties in considering selected chemical species as reliable markers of climatic and environmental processes and in attributing the different load and composition of aerosols over Antarctica to changes in source intensity (such as aridity, wind strength, emersion of continental platform by sea-level lowering etc..) and/or to variations in atmospheric processes (such as meridional and zonal atmospheric circulation, polar vortex intensity, scavenging efficiency, transport pathways etc..). Besides, two new aspects are actually under discussions: the possible use of Na as sea-ice cover marker (via frost flower formation on the sea-ice surface during the pack-ice formation) and the identification of continental source areas for mineral dust reaching internal regions of Antarctica during glacial and interglacial periods. In order to better address such controversial issues, since 2005 a continuous, high temporal resolution size-segregated aerosol and surface snow sampling has been performed at Dome C (central East Antarctic Plateau, 75° 06' S, 123° 23' E), in the framework of "Station Concordia" Project (a Italian PNRA- French IPEV joint program). The chemical analysis of size-segregated aerosol and daily superficial snow samples, collected all year-round for more than 4 years, can contribute to clarify some of the above mentioned topics. In particular: the possible seasonal pattern of sea spray aerosol could be related to sea-ice formation timing and/or to changes in zonal wind intensity and atmospheric pathway; the mineralogical analysis of insoluble dust particles can allow the identification of continental sources, by comparison with soils collected in the potential source areas (PSAs); finally, the seasonal pattern of biogenic markers (such as methanesulphonic acid and non-sea-salt sulphate) can be linked to sea surface temperature, sea-ice cover and southern-hemisphere circulation modes (e.g., SOI, AAO or SAM and ACW). As regard as depositional and post-depositional processes, the analysis of chemical markers in aerosol, superficial snow and hoar crystals, sampled contemporaneously, will allow understanding the key factors (e.g., snow acidity, solar irradiation) affecting the preservation of components reversibly fixed in the snow layers (such as, for instance, methanesulphonic acid, nitrate and chloride). A summary of the major results from the chemical analysis of aerosol and snow collected at Dome C is here presented.

Identification of aerosol composition from multi-wavelength lidar measurements

NASA Technical Reports Server (NTRS)

Wood, S. A.

1984-01-01

This paper seeks to develop the potential of lidar for the identification of the chemical composition of atmospheric aerosols. Available numerical computations suggest that aerosols can be identified by the wavelength dependence of aerosol optical properties. Since lidar can derive the volume backscatter coefficient as a function of wavelength, a multi-wavelength lidar system may be able to provide valuable information on the composition of aerosols. This research theoretically investigates the volume backscatter coefficients for the aerosol classes, sea-salts, and sulfates, as a function of wavelength. The results show that these aerosol compositions can be characterized and identified by their backscatter wavelength dependence. A method to utilize multi-wavelength lidar measurements to discriminate between compositionally different thin aerosol layers is discussed.

Identification and chemical characterization of particulate matter from wave soldering processes at a printed circuit board manufacturing company.

PubMed

Szoboszlai, Z; Kertész, Zs; Szikszai, Z; Angyal, A; Furu, E; Török, Zs; Daróczi, L; Kiss, A Z

2012-02-15

In this case study, the elemental composition and mass size distribution of indoor aerosol particles were determined in a working environment where soldering of printed circuit boards (PCB) took place. Single particle analysis using ion and electron microscopy was carried out to obtain more detailed and reliable data about the origin of these particles. As a result, outdoor and indoor aerosol sources such as wave soldering, fluxing processes, workers' activity, mineral dust, biomass burning, fertilizing and other anthropogenic sources could be separated. With the help of scanning electron microscopy, characteristic particle types were identified. On the basis of the mass size distribution data, a stochastic lung deposition model was used to calculate the total and regional deposition efficiencies of the different types of particles within the human respiratory system. The information presented in this study aims to give insights into the detailed characteristics and the health impact of aerosol particles in a working environment where different kinds of soldering activity take place. Copyright © 2011 Elsevier B.V. All rights reserved.

Pollutants identification of ambient aerosols by two types of aerosol mass spectrometers over southeast coastal area, China.

PubMed

Yan, Jinpei; Chen, Liqi; Lin, Qi; Zhao, Shuhui; Li, Lei

2018-02-01

Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer (AMS) and Single Particle Aerosol Mass Spectrometer (SPAMS) were deployed to identify the aerosol pollutants over Xiamen, representing the coastal urban area. Five obvious processes were classified during the whole observation period. Organics and sulfate were the dominant components in ambient aerosols over Xiamen. Most of the particles were in the size range of 0.2-1.0μm, accounting for over 97% of the total particles measured by both instruments. Organics, as well as sulfate, measured by AMS were in good correlation with measured by SPAMS. However, high concentration of NH 4 + was obtained by AMS, while extremely low value of NH 4 + was detected by SPAMS. Contrarily, high particle number counts of NO 3 - and Cl - were given by SPAMS while low concentrations of NO 3 - and Cl - were measured by AMS. The variations of POA and SOA obtained from SPAMS during event 1 and event 2 were in accordance with the analysis of HOA and OOA given by AMS, suggesting that both of AMS and SPAMS can well identify the organic clusters of aerosol particles. Overestimate or underestimate of the aerosol sources and acidity would be present in some circumstances when the measurement results were used to analyze the aerosol properties, because of the detection loss of some species for both instruments. Copyright © 2017. Published by Elsevier B.V.

Contributions and source identification of biogenic and anthropogenic hydrocarbons to secondary organic aerosols at Mt. Tai in 2014.

PubMed

Zhu, Yanhong; Yang, Lingxiao; Kawamura, Kimitaka; Chen, Jianmin; Ono, Kaori; Wang, Xinfeng; Xue, Likun; Wang, Wenxing

2017-01-01

Ambient fine particulate matter (PM 2.5 ) and volatile organic compounds (VOCs) collected at Mt. Tai in summer 2014 were analysed and the data were used to identify the contribution of biogenic and anthropogenic hydrocarbons to secondary organic aerosols (SOA) and their sources and potential source areas in high mountain regions. Compared with those in 2006, the 2014 anthropogenic SOA tracers in PM 2.5 aerosols and VOC species related to vehicular emissions exhibited higher concentrations, whereas the levels of biogenic SOA tracers were lower, possibly due to decreased biomass burning. Using the SOA tracer and parameterisation method, we estimated the contributions from biogenic and anthropogenic VOCs, respectively. The results showed that the average concentration of biogenic SOA was 1.08 ± 0.51 μg m -3 , among which isoprene SOA tracers were dominant. The anthropogenic VOC-derived SOA were 7.03 ± 1.21 μg m -3 and 1.92 ± 1.34 μg m -3 under low- and high-NO x conditions, respectively, and aromatics made the greatest contribution. However, the sum of biogenic and anthropogenic SOA only contributed 18.1-49.1% of the total SOA. Source apportionment by positive matrix factorisation (PMF) revealed that secondary oxidation and biomass burning were the major sources of biogenic SOA tracers. Anthropogenic aromatics mainly came from solvent use, fuel and plastics combustion and vehicular emissions. However, for > C6 alkanes and cycloalkanes, vehicular emissions and fuel and plastics combustion were the most important contributors. The potential source contribution function (PSCF) identified the Bohai Sea Region (BSR) as the major source area for organic aerosol compounds and VOC species at Mt. Tai. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of biomass burning from olive grove areas: A major source of organic aerosol in PM10 of Southwest Europe

NASA Astrophysics Data System (ADS)

Sánchez de la Campa, Ana M.; Salvador, Pedro; Fernández-Camacho, Rocío; Artiñano, Begoña; Coz, Esther; Márquez, Gonzalo; Sánchez-Rodas, Daniel; de la Rosa, Jesús

2018-01-01

The inorganic and organic geochemistry of aerosol particulate matter (APM) was studied in a major olive grove area from Southwest Europe (Baena, Spain). The biomass consists of olive tree branches and the solid waste resulting of the olive oil production. Moreover, high PM10 levels were obtained (31.5 μg m- 3), with two days of exceedance of the daily limit of 50 μg m- 3 (2008/50/CE; EU, 2008) during the experimental period. A high mean levoglucosan concentration was obtained representing up 95% of the total mass of the isomers analysed (280 ng m- 3), while galactosan and mannosan mean concentrations were lower (8.64 ng m- 3 and 7.86 ng m- 3, respectively). The contribution of wood smoke in Baena was estimated, representing 19% of OC and 17% of OM total mass. Positive matrix factor (PMF) was applied to the organic and inorganic aerosols data, which has permitted the identification of five source categories: biomass burning, traffic, mineral dust, marine aerosol and SIC (secondary inorganic compounds). The biomass burning category reached the highest mean contribution to the PM10 mass (41%, 17.6 μg m- 3). In light of these results, the use of biomass resulting from the olive oil production for residential heating and industry must be considered the most important aerosol source during the winter months. The results of this paper can be extrapolated to other olive oil producing areas in the Mediterranean basin. Therefore, a fuller understanding of this type of biomass combustion is required in order to be able to establish appropriate polices and reduce the environmental impact on the population.

Molecular identification of organic compounds in atmospheric complex mixtures and relationship to atmospheric chemistry and sources.

PubMed

Mazurek, Monica A

2002-12-01

This article describes a chemical characterization approach for complex organic compound mixtures associated with fine atmospheric particles of diameters less than 2.5 m (PM2.5). It relates molecular- and bulk-level chemical characteristics of the complex mixture to atmospheric chemistry and to emission sources. Overall, the analytical approach describes the organic complex mixtures in terms of a chemical mass balance (CMB). Here, the complex mixture is related to a bulk elemental measurement (total carbon) and is broken down systematically into functional groups and molecular compositions. The CMB and molecular-level information can be used to understand the sources of the atmospheric fine particles through conversion of chromatographic data and by incorporation into receptor-based CMB models. Once described and quantified within a mass balance framework, the chemical profiles for aerosol organic matter can be applied to existing air quality issues. Examples include understanding health effects of PM2.5 and defining and controlling key sources of anthropogenic fine particles. Overall, the organic aerosol compositional data provide chemical information needed for effective PM2.5 management.

Direct Aerosol Forcing Uncertainty

DOE Data Explorer

Mccomiskey, Allison

2008-01-15

Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

Source Apportionment of Atmospheric Particles by Electron Probe X-Ray Microanalysis and Receptor Models.

NASA Astrophysics Data System (ADS)

van Borm, Werner August

Electron probe X-ray microanalysis (EPXMA) in combination with an automation system and an energy-dispersive X-ray detection system was used to analyse thousands of microscopical particles, originating from the ambient atmosphere. The huge amount of data was processed by a newly developed X-ray correction method and a number of data reduction procedures. A standardless ZAF procedure for EPXMA was developed for quick semi-quantitative analysis of particles starting from simple corrections, valid for bulk samples and modified taking into account the particle finit diameter, assuming a spherical shape. Tested on a limited database of bulk and particulate samples, the compromise between calculation speed and accuracy yielded for elements with Z > 14 accuracies on concentrations less than 10% while absolute deviations remained below 4 weight%, thus being only important for low concentrations. Next, the possibilities for the use of supervised and unsupervised multivariate particle classification were investigated for source apportionment of individual particles. In a detailed study of the unsupervised cluster analysis technique several aspects were considered, that have a severe influence on the final cluster analysis results, i.e. data acquisition, X-ray peak identification, data normalization, scaling, variable selection, similarity measure, cluster strategy, cluster significance and error propagation. A supervised approach was developed using an expert system-like approach in which identification rules are builded to describe the particle classes in a unique manner. Applications are presented for particles sampled (1) near a zinc smelter (Vieille-Montagne, Balen, Belgium), analyzed for heavy metals, (2) in an urban aerosol (Antwerp, Belgium), analyzed for over 20 elements and (3) in a rural aerosol originating from a swiss mountain area (Bern). Thus is was possible to pinpoint a number of known and unknown sources and characterize their emissions in terms of particles abundance and particle composition. Alternatively, the bulk analysis of filters (total, fine and coarse mode) using Particle Induced X -Ray Emission (PIXE) and the application of a receptor modeling approach provided for complementary information on a macroscopical level. A computer program was developed incorporating an absolute factor analysis based receptor modeling procedure. Source profiles and contributions are described by elemental concentrations and an atmospheric mass balance is put forward. The latter method was applied in a two year study of the Antwerp urban aerosol and for the swiss aerosol, revealing a number of previously known and unknown sources. Both methods were successfully combined to increase the source resolution.

Remote Sensing and Problems of the Hydrosphere

NASA Technical Reports Server (NTRS)

Goldberg, E. D. (Editor)

1979-01-01

A discussion of freshwater and marine systems is presented including areas of the classification of lakes, identification and quantification of major functional groups of phytoplankton, sources and sinks of biochemical factors, and temporal and regional variability of surface features. Atmospheric processes linked to hydrospheric process through the transfer of matter via aerosols and gases are discussed. Particle fluxes to the aquatic environment and global geochemical problems are examined.

Long-term chemical analysis and organic aerosol source apportionment at nine sites in central Europe: source identification and uncertainty assessment

NASA Astrophysics Data System (ADS)

Daellenbach, Kaspar R.; Stefenelli, Giulia; Bozzetti, Carlo; Vlachou, Athanasia; Fermo, Paola; Gonzalez, Raquel; Piazzalunga, Andrea; Colombi, Cristina; Canonaco, Francesco; Hueglin, Christoph; Kasper-Giebl, Anne; Jaffrezo, Jean-Luc; Bianchi, Federico; Slowik, Jay G.; Baltensperger, Urs; El-Haddad, Imad; Prévôt, André S. H.

2017-11-01

Long-term monitoring of organic aerosol is important for epidemiological studies, validation of atmospheric models, and air quality management. In this study, we apply a recently developed filter-based offline methodology using an aerosol mass spectrometer (AMS) to investigate the regional and seasonal differences of contributing organic aerosol sources. We present offline AMS measurements for particulate matter smaller than 10 µm at nine stations in central Europe with different exposure characteristics for the entire year of 2013 (819 samples). The focus of this study is a detailed source apportionment analysis (using positive matrix factorization, PMF) including in-depth assessment of the related uncertainties. Primary organic aerosol (POA) is separated in three components: hydrocarbon-like OA related to traffic emissions (HOA), cooking OA (COA), and biomass burning OA (BBOA). We observe enhanced production of secondary organic aerosol (SOA) in summer, following the increase in biogenic emissions with temperature (summer oxygenated OA, SOOA). In addition, a SOA component was extracted that correlated with an anthropogenic secondary inorganic species that is dominant in winter (winter oxygenated OA, WOOA). A factor (sulfur-containing organic, SC-OA) explaining sulfur-containing fragments (CH3SO2+), which has an event-driven temporal behaviour, was also identified. The relative yearly average factor contributions range from 4 to 14 % for HOA, from 3 to 11 % for COA, from 11 to 59 % for BBOA, from 5 to 23 % for SC-OA, from 14 to 27 % for WOOA, and from 15 to 38 % for SOOA. The uncertainty of the relative average factor contribution lies between 2 and 12 % of OA. At the sites north of the alpine crest, the sum of HOA, COA, and BBOA (POA) contributes less to OA (POA / OA = 0.3) than at the southern alpine valley sites (0.6). BBOA is the main contributor to POA with 87 % in alpine valleys and 42 % north of the alpine crest. Furthermore, the influence of primary biological particles (PBOAs), not resolved by PMF, is estimated and could contribute significantly to OA in PM10.

Simultaneous analysis of heparosan oligosaccharides by isocratic liquid chromatography with charged aerosol detection/mass spectrometry.

PubMed

Ji, Xiaohu; Hu, Guixin; Zhang, Qiongyan; Wang, Fengshan; Liu, Chunhui

2016-11-05

Uncovering the biological roles of heparosan oligosaccharides requires a simple and robust method for their separation and identification. We reported on systematic investigations of the retention behaviors of synthetic heparosan oligosaccharides on porous graphitic carbon (PGC) column by HPLC with charged aerosol detection. Oligosaccharides were strongly retained by PGC material in water-acetonitrile mobile phase, and eluted by trifluoroacetic acid occurring as narrow peaks. Addition of small fraction of methanol led to better selectivity of PGC to oligosaccharides than acetonitrile modifier alone, presumably, resulting from displacement of methanol to give different chemical environment at the PGC surface. Van't-Hoff plots demonstrated that retention behaviors highly depended on the column temperature and oligosaccharide moieties. By implementing the optimal MeOH content and temperature, a novel isocratic elution method was successfully developed for baseline resolution and identification of seven heparosan oligosaccharides using PGC-HPLC-CAD/MS. This approach allows for rapid analysis of heparosan oligosaccharides from various sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aerosol Study over the Gulf of Guinea Region during DACCIWA Using a Mini Lidar onboard the French Aircraft ATR42

NASA Astrophysics Data System (ADS)

Shang, X.; Chazette, P.; Flamant, C.; Totems, J.; Denjean, C.; Meynadier, R.; Perrin, T.; Laurens, M.

2016-12-01

The EU-funded project DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) aims to investigate the relationship between weather, climate and air pollution in southern West Africa. As part of this campaign, three research aircraft based in Lomé (Togo) flew targeted missions over West Africa from 27 June to 16 July 2016. In this area aerosols, having a mixing of natural and anthropogenic sources, exert an important influence on the local weather and climate, mainly due to the aerosol-cloud interactions. A mini backscattered lidar system onboard one research aircraft (the French aircraft ATR42) performed aerosols measurements over the Gulf of Guinea region. The main objective was to study aerosol properties in different chemical landscapes: from the background state over the Gulf of Guinea (marine aerosols or mix between marine aerosols and biomass burning aerosols) to ship/flaring emissions to the coastal strip of polluted megacities to the agricultural areas and forest areas further north, and eventually dust from Sahel/Sahara. Different aerosol origins were identified by using the coupling between the lidar cross-polarized channels and a set of back trajectories analyses. The aircraft conducted flights at low ( 1 km above the mean sea level -amsl) and high altitudes ( 5 km amsl), allowing the coupling of in situ and remote sensing data to assess the properties of the aerosol layers. During several flights, depolarizing aerosol layers from the northeast were observed between 2.5 and 4 km amsl, which highlight the significant contribution of dust-like particles to the aerosol load in the coastal region. The air masses originating from the southeast were loaded with biomass burning aerosols from Central Africa, which seem to be mixed with other aerosol types. The flight sampling strategy and related lidar investigations will be presented. The retrieved aerosol distributions and properties, and the aerosol type identification will be discussed.

Towards a true aerosol-and-cloud retrieval scheme

NASA Astrophysics Data System (ADS)

Thomas, Gareth; Poulsen, Caroline; Povey, Adam; McGarragh, Greg; Jerg, Matthias; Siddans, Richard; Grainger, Don

2014-05-01

The Optimal Retrieval of Aerosol and Cloud (ORAC) - formally the Oxford-RAL Aerosol and Cloud retrieval - offers a framework that can provide consistent and well characterised properties of both aerosols and clouds from a range of imaging satellite instruments. Several practical issues stand in the way of achieving the potential of this combined scheme however; in particular the sometimes conflicting priorities and requirements of aerosol and cloud retrieval problems, and the question of the unambiguous identification of aerosol and cloud pixels. This presentation will present recent developments made to the ORAC scheme for both aerosol and cloud, and detail how these are being integrated into a single retrieval framework. The implementation of a probabilistic method for pixel identification will also be presented, for both cloud detection and aerosol/cloud type selection. The method is based on Bayesian methods applied the optimal estimation retrieval output of ORAC and is particularly aimed at providing additional information in the so-called "twilight zone", where pixels can't be unambiguously identified as either aerosol or cloud and traditional cloud or aerosol products do not provide results.

Regional and Global Aspects of Aerosols in Western Africa: From Air Quality to Climate

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Kucsera, Tom; Spinhime, Jim; Palm, Stephen; Holben, Brent; Ginoux, Paul

2006-01-01

Western Africa is one of the most important aerosol source regions in the world. Major aerosol sources include dust from the world's largest desert Sahara, biomass burning from the Sahel, pollution aerosols from local sources and long-range transport from Europe, and biogenic sources from vegetation. Because these sources have large seasonal variations, the aerosol composition over the western Africa changes significantly with time. These aerosols exert large influences on local air quality and regional climate. In this study, we use the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model to analyze satellite lidar data from the GLAS instrument on the ICESat and the sunphotometer data from the ground-based network AERONET taken in both the wet (September - October 2003) and dry (February - March 2004) seasons over western Africa. We will quantify the seasonal variations of aerosol sources and compositions and aerosol spatial (horizontal and vertical) distributions over western Africa. We will also assess the climate impact of western African aerosols. Such studies will be applied to support the international project, Africa Monsoon Multidisciplinary Analysis (AMMA) and to analyze the AMMA data.

Review on recent progress in observations, source identifications and countermeasures of PM2.5.

PubMed

Liang, Chun-Sheng; Duan, Feng-Kui; He, Ke-Bin; Ma, Yong-Liang

2016-01-01

Recently, PM2.5 (atmospheric fine particulate matter with aerodynamic diameter ≤ 2.5 μm) have received so much attention that the observations, source appointment and countermeasures of it have been widely studied due to its harmful impacts on visibility, mood (mental health), physical health, traffic safety, construction, economy and nature, as well as its complex interaction with climate. A review on the PM2.5 related research is necessary. We start with summary of chemical composition and characteristics of PM2.5 that contains both macro and micro observation results and analysis, wherein the temporal variability of concentrations of PM2.5 and major components in many recent reports is embraced. This is closely followed by an overview of source appointment, including the composition and sources of PM2.5 in different countries in the six inhabitable continents based on the best available results. Besides summarizing PM2.5 pollution countermeasures by policy, planning, technology and ideology, the World Air Day is proposed to be established to inspire and promote the crucial social action in energy-saving and emission-reduction. Some updated knowledge of the important topics (such as formation and evolution mechanisms of hazes, secondary aerosols, aerosol mass spectrometer, organic tracers, radiocarbon, emissions, solutions for air pollution problems, etc.) is also included in the present review by logically synthesizing the studies. In addition, the key research challenges and future directions are put forward. Despite our efforts, our understanding of the recent reported observations, source identifications and countermeasures of PM2.5 is limited, and subsequent efforts both of the authors and readers are needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Typical Types and Formation Mechanisms of Haze in an Eastern Asia Megacity, Shanghai

NASA Technical Reports Server (NTRS)

Huang, K.; Zhuang, G.; Lin, Y.; Fu, J. S.; Wang, Q.; Liu, T.; Zhang, R.; Jiang, Y.; Deng, C.; Fu, Q.;

Detection of a gas flaring signature in the AERONET optical properties of aerosols at a tropical station in West Africa

NASA Astrophysics Data System (ADS)

Fawole, Olusegun G.; Cai, Xiaoming; Levine, James G.; Pinker, Rachel T.; MacKenzie, A. R.

2016-12-01

The West African region, with its peculiar climate and atmospheric dynamics, is a prominent source of aerosols. Reliable and long-term in situ measurements of aerosol properties are not readily available across the region. In this study, Version 2 Level 1.5 Aerosol Robotic Network (AERONET) data were used to study the absorption and size distribution properties of aerosols from dominant sources identified by trajectory analysis. The trajectory analysis was used to define four sources of aerosols over a 10 year period. Sorting the AERONET aerosol retrievals by these putative sources, the hypothesis that there exists an optically distinct gas flaring signal was tested. Dominance of each source cluster varies with season: desert-dust (DD) and biomass burning (BB) aerosols are dominant in months prior to the West African Monsoon (WAM); urban (UB) and gas flaring (GF) aerosol are dominant during the WAM months. BB aerosol, with single scattering albedo (SSA) at 675 nm value of 0.86 ± 0.03 and GF aerosol with SSA (675 nm) value of 0.9 ± 0.07, is the most absorbing of the aerosol categories. The range of Absorption Angstr&öm Exponent (AAE) for DD, BB, UB and GF classes are 1.99 ± 0.35, 1.45 ± 0.26, 1.21 ± 0.38 and 0.98 ± 0.25, respectively, indicating different aerosol composition for each source. The AAE (440-870 nm) and Angstr&öm Exponent (AE) (440-870 nm) relationships further show the spread and overlap of the variation of these optical and microphysical properties, presumably due in part to similarity in the sources of aerosols and in part, due to mixing of air parcels from different sources en route to the measurement site.

Historical evolution of sources identification by means of Receptor Modeling in the Metropolitan Area of São Paulo, Brazil.

NASA Astrophysics Data System (ADS)

Miranda, R. M.; Andrade, M. D. F.; Marien, Y., Sr.

2017-12-01

The atmospheric aerosols sources have been identified in Sao Paulo since the 80´s with the use of receptor models. The Metropolitan Area of São Paulo (MASP) is a megacity with a population of 21 million, corresponding to more than 11% of the total population of Brazil. The first results for the identification of sources of particles were obtained with the application of Absolute Principal Component Analysis, Factor Analysis and Chemical Mass Balance. More recently the Positive Matrix Factorization has been used in combination with the other receptor models. With the improvement of the aerosol composition analytical determination (more elements and better resolution) the source identification has became more accurate. But, in spite of that, the main sources are the same for fine particles: vehicular emission, secondary formation and biomass burning. The large amount of biofuels used in the MASP makes this region an important example of the atmospheric chemistry of fossil fuel and biofuel emissions. The 7 million vehicles can run on gasohol, ethanol (95% ethanol + 5% gasoline) and biodiesel (mostly for trucks and buses). We have considered the Black Carbon as the tracer for diesel engines and biomass burning, being this last source associated not only with burning of sugar cane plantation and forest fires, but also with wood and charcoal used in restaurant and domestic cooking and residues burning. The responsibility of the vehicular emission to the fine particles has been maintained in approximately 50% of the mass. The soil resuspension was associated with 8% of the fine particles origin. We are presenting the data obtained from experiments performed from 1983 to 2014, not continuously and mainly performed in the winter time. It is a long period of data that is going to be considered. The previous results obtained with the application of PCA were compared to that obtained with PMF applied to the historical data collected at MASP, showing the evolution of the participation of mobile and biomass burning.

Predicting the Mineral Composition of Dust Aerosols. Part 2; Model Evaluation and Identification of Key Processes with Observations

NASA Technical Reports Server (NTRS)

Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

2015-01-01

A global compilation of nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match the fractions of the soil. The MMT is based upon soil measurements after wet sieving, a process that destroys aggregates of soil particles that would have been emitted from the original, undisturbed soil. The second method approximately reconstructs the emitted aggregates. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observations. Only the AMF method exhibits phyllosilicate mass at silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in better agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at distinct clay and silt particle sizes are shown to be more useful for evaluation of the models, in contrast to the sum over all particles sizes that is susceptible to compensating errors, as illustrated by the SMF experiment. Model errors suggest that allocation of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining source of uncertainty. Evaluation of both models and the MMT is hindered by the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. The importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.

Aerosol Transport Over Equatorial Africa

NASA Technical Reports Server (NTRS)

Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

1999-01-01

Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El Nino.

Predicting the mineral composition of dust aerosols – Part 2: Model evaluation and identification of key processes with observations

DOE PAGES

Perlwitz, J. P.; Perez Garcia-Pando, C.; Miller, R. L.

2015-10-21

A global compilation of nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match the fractions of the soil. The MMT is based upon soil measurements after wet sieving, a process that destroys aggregates of soil particles that would have been emitted from the original, undisturbed soil. The second methodmore » approximately reconstructs the emitted aggregates. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observations. Only the AMF method exhibits phyllosilicate mass at silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in better agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at distinct clay and silt particle sizes are shown to be more useful for evaluation of the models, in contrast to the sum over all particles sizes that is susceptible to compensating errors, as illustrated by the SMF experiment. Model errors suggest that allocation of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining source of uncertainty. Evaluation of both models and the MMT is hindered by the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. In conclusion, the importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.« less

New insights on aerosol sources and properties of Organics in the west Mediterranean basin

NASA Astrophysics Data System (ADS)

Nicolas, José B.; Sciare, Jean; Petit, Jean-Eudes; Bonnaire, Nicolas; Féron, Anais; Dulac, François; Hamonou, Eric; Gros, Valérie; Mallet, Marc; Lambert, Dominique; Sauvage, Stéphane; Léonardis, Thierry; Tison, Emmanuel; Colomb, Aurélie; Fresney, Evelyn; Pichon, Jean-Marc; Bouvier, Laetitia; Bourrianne, Thierry; Roberts, Gregory

2013-04-01

The Mediterranean basin exhibits high PM concentrations for a marine area, in particular during the dry season (summer), associated with high photochemistry. The large population of the basin is impacted by both natural and anthropogenic aerosols of various sources from Europe and North Africa. Simulations predict significant climate changes in that area, with less precipitation and hotter temperatures, reinforced by an increasing anthropogenic pressure, which will be linked by higher emissions of pollutants and also by higher impacts on the health. Nevertheless the aerosol models in that area currently suffer from large uncertainties, due to a lack of knowledge in organic aerosol (OA) sources and processes. As part of the French program ChArMEx (The Chemistry-Aerosol Mediterranean Experiment, http://charmex.lsce.ipsl.fr), a 5-week intensive campaign has been performed in June - July 2012 at the new Cape Corsica station (see Dulac et al. in that session), and aiming at a better characterization of anthropogenic versus biogenic aerosols, long range transport versus local influence, with a focus on fine OA. A complete instrumental strategy was deployed thanks to the contribution of a large French community: PM1 concentration every 6 min with a TEOM-FDMS 1405 (Thermo), major aerosol components in PM1 every 30 min (Organics, SO4, NO3, NH4) by Aerosol Chemical Speciation Monitor (Aerodyne), Equivalent Black Carbon every 5 min with a 7-? aethalometer AE31 (Magee Scientific), on-line major anions and cations (incl. light organics like oxalate & MSA) every 10 min with Particle-Into-Liquid Sampler (PILS, Metrohm) coupled with Ion Chromatographs (Dionex), on-line water-soluble organic carbon (WSOC) every 4 min with a PILS (Applikon) coupled with a Total Organic Carbon instrument (Ionics). Filter sampling in PM2.5 and PM10 was also performed every 12h for quality purposes (PM, EC/OC, ions) and for complementary measurements (metals by ICP-MS and organic tracers by LC-MS). Additional measurements of reactive gases (CO, O3 and VOCs), and of aerosol optical/physical properties (scattering, extinction, size distribution) were used for a better identification of air masses origin and optical/number closure studies. Backtrajectories issued from Hysplit 4.9 revealed the predominance of air masses from North-West to South, with some dust events from North Africa (Morocco, Algeria) and a few anthropogenic events from Italy and from South-East of France. Two intense heat waves, associated with low wind speed, gave the highest levels of OA observed during the campaign, suggesting a possible local biogenic origin. The comparison of these heat waves showed contrasted levels of WSOC, oxalate, OM-to-OC ratio suggesting various sources and/or processes.

40 CFR 52.719 - Identification of plan-Conditional approval.

Code of Federal Regulations, 2012 CFR

2012-07-01

... limits listed for aerosol- and non aerosol-based antiperspirants and deodorants. 35 IAC 233.205(a)(6)(A) erroneously provides two high-volatility VOC limits for aerosol-based antiperspirants when there should be... provides two medium-volatility VOC limits for non aerosol-based antiperspirants when there should be both a...

Influence of source distribution and geochemical composition of aerosols on children exposure in the large polymetallic mining region of the Bolivian Altiplano.

PubMed

Goix, Sylvaine; Point, David; Oliva, Priscia; Polve, Mireille; Duprey, Jean Louis; Mazurek, Hubert; Guislain, Ludivine; Huayta, Carlos; Barbieri, Flavia L; Gardon, Jacques

2011-12-15

The Bolivian Altiplano (Highlands) region is subject to intense mining, tailing and smelting activities since centuries because of the presence of large and unique polymetallic ore deposits (Ag, Au, Cu, Pb, Sn, Sb, Zn). A large scale PM(10), PM(2.5) aerosol monitoring survey was conducted during the dry season in one of the largest mining cities of this region (Oruro, 200,000 inhabitants). Aerosol fractions, source distribution and transport were investigated for 23 elements at approximately 1 km(2) scale resolution, and compared to children exposure data obtained within the same geographical space. As, Cd, Pb, Sb, W and Zn in aerosols are present at relatively high concentrations when compared to studies from other mining regions. Arsenic exceeds the European council PM(10) guide value (6 ng/m(3)) for 90% of the samples, topping 200 ng/m(3). Ag, As, Cd, Cu, Pb and Sb are present at significantly higher levels in the district located in the vicinity of the smelter zone. At the city level, principal component analysis combined with the mapping of factor scores allowed the identification and deconvolution of four individual sources: i) a natural magmatic source (Co, Cs, Fe, K, Mn, Na, Rb and U) originating from soil dust, resuspended by the traffic activity; ii) a natural sedimentary source (Mg, Ca, Sr, Ba and Th) resulting from the suspension of evaporative salt deposits located South; iii) an anthropogenic source specifically enriched in mined elements (As, Cd, Cu, Pb, Sb and Zn) mainly in the smelting district of the city; and iv) a Ni-Cr source homogenously distributed between the different city districts. Enrichment factors for As, Cd and Sb clearly show the impact of smelting activities, particularly in the finest PM(2.5) fraction. Comparison to children's hair metal contents collected in five schools from different districts shows a direct exposure to smelting activity fingerprinted by a unique trace elements pattern (Ag, As, Cu, Pb, Sb). Copyright © 2011 Elsevier B.V. All rights reserved.

Source apportionment of airborne particulates through receptor modeling: Indian scenario

NASA Astrophysics Data System (ADS)

Banerjee, Tirthankar; Murari, Vishnu; Kumar, Manish; Raju, M. P.

2015-10-01

Airborne particulate chemistry mostly governed by associated sources and apportionment of specific sources is extremely essential to delineate explicit control strategies. The present submission initially deals with the publications (1980s-2010s) of Indian origin which report regional heterogeneities of particulate concentrations with reference to associated species. Such meta-analyses clearly indicate the presence of reservoir of both primary and secondary aerosols in different geographical regions. Further, identification of specific signatory molecules for individual source category was also evaluated in terms of their scientific merit and repeatability. Source signatures mostly resemble international profile while, in selected cases lack appropriateness. In India, source apportionment (SA) of airborne particulates was initiated way back in 1985 through factor analysis, however, principal component analysis (PCA) shares a major proportion of applications (34%) followed by enrichment factor (EF, 27%), chemical mass balance (CMB, 15%) and positive matrix factorization (PMF, 9%). Mainstream SA analyses identify earth crust and road dust resuspensions (traced by Al, Ca, Fe, Na and Mg) as a principal source (6-73%) followed by vehicular emissions (traced by Fe, Cu, Pb, Cr, Ni, Mn, Ba and Zn; 5-65%), industrial emissions (traced by Co, Cr, Zn, V, Ni, Mn, Cd; 0-60%), fuel combustion (traced by K, NH4+, SO4-, As, Te, S, Mn; 4-42%), marine aerosols (traced by Na, Mg, K; 0-15%) and biomass/refuse burning (traced by Cd, V, K, Cr, As, TC, Na, K, NH4+, NO3-, OC; 1-42%). In most of the cases, temporal variations of individual source contribution for a specific geographic region exhibit radical heterogeneity possibly due to unscientific orientation of individual tracers for specific source and well exaggerated by methodological weakness, inappropriate sample size, implications of secondary aerosols and inadequate emission inventories. Conclusively, a number of challenging issues and specific recommendations have been included which need to be considered for a scientific apportionment of particulate sources in different geographical regions of India.

Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan

NASA Astrophysics Data System (ADS)

Kundu, S.; Quraishi, T. A.; Yu, G.; Suarez, C.; Keutsch, F. N.; Stone, E. A.

2013-05-01

Organosulfates are important components of atmospheric organic aerosols, yet their structures, abundances, sources and formation processes are not adequately understood. This study presents the identification and quantitation of benzyl sulfate in atmospheric aerosols, which is the first confirmed atmospheric organosulfate with aromatic carbon backbone. Benzyl sulfate was identified and quantified in fine particulate matter (PM2.5) collected in Lahore, Pakistan, during 2007-2008. An authentic standard of benzyl sulfate was synthesized, standardized, and identified in atmospheric aerosols with quadrupole time-of-flight (Q-ToF) mass spectrometry (MS). Benzyl sulfate was quantified in aerosol samples using ultra performance liquid chromatography (UPLC) coupled to negative electrospray ionization triple quadrupole (TQ) MS. The highest benzyl sulfate concentrations were recorded in November and January 2007 (0.50 ± 0.11 ng m-3) whereas the lowest concentration was observed in July (0.05 ± 0.02 ng m-3). To evaluate matrix effects, benzyl sulfate concentrations were determined using external calibration and the method of standard addition; comparable concentrations were detected by the two methods, which ruled out significant matrix effects in benzyl sulfate quantitation. Three additional organosulfates with m/z 187, 201 and 215 were qualitatively identified as aromatic organosulfates with additional methyl substituents by high-resolution mass measurements and tandem MS. The observed aromatic organosulfates form a homologous series analogous to toluene, xylene, and trimethylbenzene, which are abundant anthropogenic volatile organic compounds (VOC), suggesting that aromatic organosulfates may be formed by secondary reactions. However, stronger statistical correlations of benzyl sulfate with combustion tracers (EC and levoglucosan) than with secondary tracers (SO42- and α-pinene-derived nitrooxy organosulfates) suggest that aromatic organosulfates may be emitted from the combustion sources or their subsequent atmospheric processing. Further studies are needed to elucidate the sources and formation pathways of aromatic organosulfates in the atmosphere.

Microbial Transformation of Dicarboxylic Acids by Airborne Bacteria

NASA Astrophysics Data System (ADS)

Cote, V.; Ariya, P.

2004-05-01

Organic aerosols are assumed to be key players in driving climatic changes and can cause health problems for human. Dicarboxylic acids (DCA) include a large fraction of identified important class of organic aerosols. In addition to direct sources, DCA are partly formed as the result of ozonolysis of terpenes and cyclic alkenes. Previous works in our laboratory show that airborne fungi collected from urban and suburban air play an important role in the transformation of severals organic aerosols such as DCA. Our present study focuses on understanding the potential chemical transformation induced by airborne bacteria and on identification of the transformation products. Airborne bacteria have been collected using a biosampler and cultivated on a solid media. Each bacterial colony is being tested by HPLC for their ability to transform DCA in liquid cultures. Also, GC-MS, SPME and NMR are being used to identify the metabolites generated from the transformation. We will present our preliminary results and we will discuss the application of bacterial activities on the chemical transformation of organics in atmosphere.

Aerosol Sources, Absorption, and Intercontinental Transport: Synergies among Models, Remote Sensing, and Atmospheric Measurements

NASA Technical Reports Server (NTRS)

Chin, Mian; Ginoux, Paul; Dubovik, Oleg; Holben, Brent; Kaufman, Yoram; chu, Allen; Anderson, Tad; Quinn, Patricia

2003-01-01

Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

Aerosol Sources, Absorption, and Intercontinental Transport: Synergies Among Models, Remote Sensing, and Atmospheric Measurements

NASA Technical Reports Server (NTRS)

Chin, Mian; Chu, Allen; Levy, Robert; Remer, Lorraine; Kaufman, Yoram; Dubovik, Oleg; Holben, Brent; Eck, Tom; Anderson, Tad; Quinn, Patricia

2004-01-01

Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, .biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERON" at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosols

NASA Technical Reports Server (NTRS)

Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

2000-01-01

Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the first two years of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this two-year grant consisted in the development and deployment of a new in-situ capability for measuring aerosol 180' backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Measurements were made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with targeted in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator and radiative transfer modeling by the University of Lille, France.

Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosol

NASA Technical Reports Server (NTRS)

Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

2000-01-01

Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the third year of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this one-year grant consisted in analysis and publication of field studies using a new in-situ capability for measuring aerosol 180 deg backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Analyzed data consisted of measurements made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with target in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator.

Size-segregated aerosol in a hot-spot pollution urban area: Chemical composition and three-way source apportionment.

PubMed

Bernardoni, V; Elser, M; Valli, G; Valentini, S; Bigi, A; Fermo, P; Piazzalunga, A; Vecchi, R

2017-12-01

In this work, a comprehensive characterisation and source apportionment of size-segregated aerosol collected using a multistage cascade impactor was performed. The samples were collected during wintertime in Milan (Italy), which is located in the Po Valley, one of the main pollution hot-spot areas in Europe. For every sampling, size-segregated mass concentration, elemental and ionic composition, and levoglucosan concentration were determined. Size-segregated data were inverted using the program MICRON to identify and quantify modal contributions of all the measured components. The detailed chemical characterisation allowed the application of a three-way (3-D) receptor model (implemented using Multilinear Engine) for size-segregated source apportionment and chemical profiles identification. It is noteworthy that - as far as we know - this is the first time that three-way source apportionment is attempted using data of aerosol collected by traditional cascade impactors. Seven factors were identified: wood burning, industry, resuspended dust, regional aerosol, construction works, traffic 1, and traffic 2. Further insights into size-segregated factor profiles suggested that the traffic 1 factor can be associated to diesel vehicles and traffic 2 to gasoline vehicles. The regional aerosol factor resulted to be the main contributor (nearly 50%) to the droplet mode (accumulation sub-mode with modal diameter in the range 0.5-1 μm), whereas the overall contribution from the two factors related to traffic was the most important one in the other size modes (34-41%). The results showed that applying a 3-D receptor model to size-segregated samples allows identifying factors of local and regional origin while receptor modelling on integrated PM fractions usually singles out factors characterised by primary (e.g. industry, traffic, soil dust) and secondary (e.g. ammonium sulphate and nitrate) origin. Furthermore, the results suggested that the information on size-segregated chemical composition in different size classes was exploited by the model to relate primary emissions to rapidly-formed secondary compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective Collection of Airborne Particulate Matter

DOE PAGES

Cheng, Meng -Dawn

2018-01-01

Here, airborne particulate matter (PM) or aerosol particles or simply aerosol are ubiquitous in the environment. They originate from natural processes such as wind erosion, road dust, forest fire, ocean spray and volcanic eruption, and man-made sources consuming fossil fuels resulting from utility power generation and transportation, and numerous industrial processes. Aerosols affect our daily life in many ways; PM reduces visibility in many polluted metropolitan areas, adversely impact human health and local air quality around the world. Aerosol alters cloud cycles and change atmospheric radiation balance. Changes in daily mortality associated with particulate air pollution were typically estimated atmore » approximately 0.5–1.5% per 10 µg m –3 increase in PM10 concentrations. Laden et al. (2006) found “an increase in overall mortality associated with each 10 µg m –3 increase in PM2.5 concentration either as the overall mean (rate ratio [RR], 1.16; 95% confidence interval [CI], 1.07–1.26) or as exposure in the year of death (RR, 1.14; 95% CI, 1.06–1.22). PM2.5 exposure was associated with lung cancer (RR, 1.27; 95% CI, 0.96–1.69) and cardiovascular deaths (RR, 1.28; 95% CI, 1.13–1.44). Improved overall mortality was associated with decreased mean PM 2.5 (10 µg m –3) between periods (RR, 0.73; 95% CI, 0.57–0.95)”. Aerosol particles also play an important role in source identification and apportionment. Since the PM problem is associated with many facets of societal issues such as energy production and economic development, making progress on reducing the effects of PM will require integrated strategies that bring together scientists, engineers and decision makers from different disciplines to consider tradeoffs.« less

Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe

NASA Astrophysics Data System (ADS)

Ulevicius, V.; Byčenkienė, S.; Bozzetti, C.; Vlachou, A.; Plauškaitė, K.; Mordas, G.; Dudoitis, V.; Abbaszade, G.; Remeikis, V.; Garbaras, A.; Masalaite, A.; Blees, J.; Fröhlich, R.; Dällenbach, K. R.; Canonaco, F.; Slowik, J. G.; Dommen, J.; Zimmermann, R.; Schnelle-Kreis, J.; Salazar, G. A.; Agrios, K.; Szidat, S.; El Haddad, I.; Prévôt, A. S. H.

2015-09-01

In early spring the Baltic region is frequently affected by high pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m-3 and black carbon (BC) up to 17 μg m-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26-44 % and 13-23 % to the TC, respectively. 5-8 % of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCf) was 4-13 %. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13-24 % and 7-12 %, respectively. Isotope ratio of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe

NASA Astrophysics Data System (ADS)

Ulevicius, Vidmantas; Byčenkienė, Steigvilė; Bozzetti, Carlo; Vlachou, Athanasia; Plauškaitė, Kristina; Mordas, Genrik; Dudoitis, Vadimas; Abbaszade, Gülcin; Remeikis, Vidmantas; Garbaras, Andrius; Masalaite, Agne; Blees, Jan; Fröhlich, Roman; Dällenbach, Kaspar R.; Canonaco, Francesco; Slowik, Jay G.; Dommen, Josef; Zimmermann, Ralf; Schnelle-Kreis, Jürgen; Salazar, Gary A.; Agrios, Konstantinos; Szidat, Sönke; El Haddad, Imad; Prévôt, André S. H.

2016-05-01

In early spring the Baltic region is frequently affected by high-pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m-3 and black carbon (BC) up to 17 µg m-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26-44 % and 13-23 % to the total carbon (TC), respectively. 5-8 % of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCf) was 4-13 %. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13-24 and 7-13 %, respectively. Isotope ratios of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.

Speciated Chemical Composition of Biomass Burning Aerosol from Various Fuels during FIREX

NASA Astrophysics Data System (ADS)

Jen, C.; Hatch, L. E.; Kreisberg, N. M.; Selimovic, V.; Yokelson, R. J.; Barsanti, K.; Goldstein, A. H.

2017-12-01

Biomass burning is the largest global source of atmospheric primary carbonaceous aerosols and the second largest global source of non-methane organic compounds, including volatile and semi-volatile organic compounds that are now understood to be major contributors to secondary particle formation in the atmosphere. As wildfires in forested regions such as the western United States become larger and more frequent, understanding the chemical composition of biomass burning organic aerosol is needed to better predict their increasing impact on human health, air quality, and climate. This study presents emission profiles of chemically speciated intermediate and semi-volatile organic compounds present in biomass burning aerosol particles ≤1.0 μm. Biomass burning organic aerosol (BBOA) samples from a variety of fuel types and burning conditions were collected during the FIREX campaign at the USDA Fire Lab (Missoula, MT). Fuels were primarily selected from vegetation commonly found in the western United States, such as ponderosa pine, lodgepole pine, ceanothus, and chaparral. Collected BBOA was thermally desorbed from the filters and analyzed using online derivatization and 2-dimensional gas chromatography with an electron impact (70 eV) and vacuum ultra violet light (10.5 eV) high resolution time of flight mass spectrometer for compound identification. Emission profiles for specific compounds (e.g., levoglucosan) and families of compounds (e.g., sugars and methoxyphenols) show distinct variations between different fuel types, with major differences between fresh and partially decomposed fuels. Results also illustrate the variability in chemical species between burns conducted under similar conditions. Furthermore, chemical fingerprints, representing ratios of normalized emissions for key chemical compounds, were measured for specific fuels/conditions and could be used in future field studies to help identify contributions of various vegetation to total BBOA and in models to estimate the chemical composition of BBOA emissions.

Selective Collection of Airborne Particulate Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Meng -Dawn

Here, airborne particulate matter (PM) or aerosol particles or simply aerosol are ubiquitous in the environment. They originate from natural processes such as wind erosion, road dust, forest fire, ocean spray and volcanic eruption, and man-made sources consuming fossil fuels resulting from utility power generation and transportation, and numerous industrial processes. Aerosols affect our daily life in many ways; PM reduces visibility in many polluted metropolitan areas, adversely impact human health and local air quality around the world. Aerosol alters cloud cycles and change atmospheric radiation balance. Changes in daily mortality associated with particulate air pollution were typically estimated atmore » approximately 0.5–1.5% per 10 µg m –3 increase in PM10 concentrations. Laden et al. (2006) found “an increase in overall mortality associated with each 10 µg m –3 increase in PM2.5 concentration either as the overall mean (rate ratio [RR], 1.16; 95% confidence interval [CI], 1.07–1.26) or as exposure in the year of death (RR, 1.14; 95% CI, 1.06–1.22). PM2.5 exposure was associated with lung cancer (RR, 1.27; 95% CI, 0.96–1.69) and cardiovascular deaths (RR, 1.28; 95% CI, 1.13–1.44). Improved overall mortality was associated with decreased mean PM 2.5 (10 µg m –3) between periods (RR, 0.73; 95% CI, 0.57–0.95)”. Aerosol particles also play an important role in source identification and apportionment. Since the PM problem is associated with many facets of societal issues such as energy production and economic development, making progress on reducing the effects of PM will require integrated strategies that bring together scientists, engineers and decision makers from different disciplines to consider tradeoffs.« less

Linking trace gas measurements and molecular tracers of organic matter in aerosols for identification of ecosystem sources and types of wildfires in Central Siberia

NASA Astrophysics Data System (ADS)

Panov, A. V.; Prokushkin, A. S.; Korets, M. A.; Bryukhanov, A. V.; Myers-Pigg, A. N.; Louchouarn, P.; Sidenko, N. V.; Amon, R.; Andreae, M. O.; Heimann, M.

2016-11-01

Summer 2012 was one of the extreme wildfire years in Siberia. At the surface air monitoring station “ZOTTO” (60°48'N, 89°21'E, 114 m a.s.l.) in Central Siberia we observed biomass burning (BB) influence on the ongoing atmospheric measurements within more than 50 % of the time in June-July 2012 that indicates a 30 times greater wildfire signal compared to previously reported ordinary biomass burning signature for the study area. While previous studies thoroughly estimated a relative input of BB into aerosol composition (i.e. size distribution, physical and optical parameters etc.) at ZOTTO, in this paper we characterize the source apportionment of the smoke aerosols with molecular tracer techniques from large-scale wildfires occurred in 2012 in the two prevailing types of Central Siberian ecosystems: complexes of pine forests and bogs and dark coniferous forests. Wildfires in the selected ecosystems are highly differed by their combustion phase (flaming/smoldering), the type of fire (crown/ground), biomass fuel, and nature of soil that greatly determines the smoke particle composition. Anhydrosugars (levoglucosan and its isomers) and lignin phenols taken as indicators of the sources and the state of particulate matter (PM) inputs in the specific fire plumes were used as powerful tools to compare wildfires in different environmental conditions and follow the role and contribution of different sources of terrestrial organic matter in the transport of BB pollutants into the pristine atmosphere of boreal zone in Central Siberia.

Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars.

PubMed

Shaheen, R; Abramian, A; Horn, J; Dominguez, G; Sullivan, R; Thiemens, Mark H

2010-11-23

The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess (17)O (0.4-3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O(3) reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth.

Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

PubMed Central

Shaheen, R.; Abramian, A.; Horn, J.; Dominguez, G.; Sullivan, R.; Thiemens, Mark H.

2010-01-01

The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess 17O (0.4–3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O3 reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

Geochemical, Sulfur Isotopic Characteristics and Source Contributions of Size-Aggregated Aerosols Collected in Baring Head, New Zealand.

NASA Astrophysics Data System (ADS)

Li, J.; Michalski, G. M.; Davy, P.; Harvey, M.; Wilkins, B. P.; Katzman, T. L.

2017-12-01

Sulfate aerosols are critical to the climate, human health, and the hydrological cycle in the atmosphere, yet the sources of sulfate in aerosols are not completely understood. In this work, we evaluated the sources of sulfate in size-aggregated aerosols from the Southern Pacific Ocean and the land of New Zealand using geochemical and isotopic analyses. Aerosols were collected at Baring Head, New Zealand between 6/30/15 to 8/4/16 using two collectors, one only collects Southern Pacific Ocean derived aerosols (open-ocean collector), the other collects aerosols from both the ocean and the land (all-direction collector). Each collector is equipped with two filters to sample size-aggregated aerosols (fine aerosols: <0.5 um and coarse aerosols: 0.5-10 um). Our results show that fine and coarse aerosols show distinctive sulfate sources: sulfate in fine aerosols is a mixture of sea-salt sulfate ( 30%) and Non-Sea-Salt sulfate (NSS-SO42-, 70%), while coarse aerosols are dominated by sea-salt sulfate. However, some NSS-SO42- was also observed in coarse aerosols collected in summer, suggesting the presence of accumulation mode NSS-SO42- aerosols, which is possibly due to high summer biogenic DMS flux. The sources of sulfur in NSS-SO42- could be further determined by their d34S values. DMS emission is likely the sole sulfur source in the open-ocean collector as it shows constant DMS-like d34S signatures (15-18‰) throughout the year. Meanwhile, the d34S of NSS-SO42- in the all-direction collector display a seasonal trend: summer time d34S values are higher and DMS-like (15-18‰), indicating DMS emission is the dominant sulfur source; winter time d34S values are lower ( 6-12‰), therefore the sulfur is likely sourced from both DMS emission and terrestrial S input with low d34S values, such as volcanic activities, fossil fuel and wood burning.

Identification of keto- and hydroxy-dicarboxylic acids in remote marine aerosols from the western North Pacific: GC and GC/TOF-MS measurements

NASA Astrophysics Data System (ADS)

Vani, D.; Kawamura, K.; Tachibana, E.; Boreddy, S. K. R.

2015-12-01

Dicarboxylic acids (diacids) are dominant components of organic aerosols in the atmosphere. They contribute significantly to the total aerosol mass and have a serious impacts on global climate changes. However, studies on keto- and hydroxy-diacids in marine aerosols are limited. Compare to diacids, keto- and hydroxy-diacids are more hygroscopic due to the additional polar groups (OH and CO) and, hence, acts as cloud condensation nuclei (CCN). Molecular characterization of these compounds provides insight into organic aerosols sources and transformation pathways. We collected marine aerosols from remote Chichijima Island in the western North Pacific from December 2010 to November 2011 and studied for water-soluble keto- and hydroxy-diacids. Carboxyl groups were derivatized to dibutyl esters with 14% boron trifluoride/n-butanol, whereas hydroxyl groups were derivatized to trimethylsilyl ethers using N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA). After two-step derivatization, samples were injected to GC, GC/MS and GC/TOF-MS. In the GC chromatogram, we detected several new peaks after BSTFA derivatization of dibutyl ester fraction. Based on mass spectral interpretation, we found these peaks as homologues series of hydroxy-diacids and keto-diacids. Some of these hydroxy-diacids have been individually reported in literature in the laboratory photo-oxidation experiments and forest environments samples. But, there are no evidences to prove their sources and formation mechanism in the atmosphere. Here, we report for the first time homologous series of hydroxy-diacids (hC3di-hC6di) and keto-diacid (oxaloacetic acid, enol and keto forms) in remote marine atmosphere. Molecular distributions of hydroxy-diacids generally showed the predominance of malic acid followed by tartronic acid. Both hydroxy- and keto-diacids show significant positive correlation with oxalic acid and SO42-, suggesting that they are generated in the atmosphere and play an important role in the formation of smaller diacids through aqueous phase photo-oxidation.

Source identification analysis for the airborne bacteria and fungi using a biomarker approach

NASA Astrophysics Data System (ADS)

Lee, Alex K. Y.; Lau, Arthur P. S.; Cheng, Jessica Y. W.; Fang, Ming; Chan, Chak K.

Our recent studies have reported the feasibility of employing the 3-hydoxy fatty acids (3-OH FAs) and ergosterol as biomarkers to determine the loading of the airborne endotoxin from the Gram-negative bacteria and fungal biomass in atmospheric aerosols, respectively [Lee, A.K.Y., Chan, C.K., Fang, K., Lau, A.P.S., 2004. The 3-hydroxy fatty acids as biomarkers for quantification and characterization of endotoxins and Gram-negative bacteria in atmospheric aerosols in Hong Kong. Atmospheric Environment 38, 6807-6317; Lau, A.P.S., Lee, A.K.Y., Chan, C.K., Fang, K., 2006. Ergosterol as a biomarker for the quantification of the fungal biomass in atmospheric aerosols. Atmospheric Environment 40, 249-259]. These quantified biomarkers do not, however, provide information on their sources. In this study, the year-long dataset of the endotoxin and ergosterol measured in Hong Kong was integrated with the common water-soluble inorganic ions for source identification through the principal component analysis (PCA) and backward air mass trajectory analysis. In the coarse particles (PM 2.5-10), the bacterial endotoxin is loaded in the same factor group with Ca 2+ and accounted for about 20% of the total variance of the PCA. This implies the crustal origin for the airborne bacterial assemblage. The fungal ergosterol in the coarse particles (PM 2.5-10) had by itself loaded in a factor group of 10.8% of the total variance in one of the sampling sites with large area of natural vegetative coverage. This suggests the single entity nature of the fungal spores and their independent emission to the ambient air upon maturation of their vegetative growth. In the fine particles (2.0) in the fine particles of the continental air masses imply the microbial source from activities related to biomass burning and industries from the north. The low K +/Na + ratios (1.2-1.4) in the fine particles of the mixed air masses suggest microbial sources from the local and regional indoor environment through kitchen emissions and the re-suspension of the road dust due to vehicular exhausts.

Novel measurement technologies for ambient and combustion source aerosols

EPA Science Inventory

Thie presentaiton examines the chemical properties of atmospheric and combustion source aerosols. It describes the aerosol chemical fractions and the specific chemical constituents in these aerosols. The presentation will cover (i) the limitatins and benefits of hyphenated chroma...

Meeting Review: Airborne Aerosol Inlet Workshop

NASA Technical Reports Server (NTRS)

Baumgardner, Darrel; Huebert, Barry; Wilson, Chuck

1991-01-01

Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies.

pH of Aerosols in a Polluted Atmosphere: Source Contributions to Highly Acidic Aerosol.

PubMed

Shi, Guoliang; Xu, Jiao; Peng, Xing; Xiao, Zhimei; Chen, Kui; Tian, Yingze; Guan, Xinbei; Feng, Yinchang; Yu, Haofei; Nenes, Athanasios; Russell, Armistead G

2017-04-18

Acidity (pH) plays a key role in the physical and chemical behavior of PM 2.5 . However, understanding of how specific PM sources impact aerosol pH is rarely considered. Performing source apportionment of PM 2.5 allows a unique link of sources pH of aerosol from the polluted city. Hourly water-soluble (WS) ions of PM 2.5 were measured online from December 25th, 2014 to June 19th, 2015 in a northern city in China. Five sources were resolved including secondary nitrate (41%), secondary sulfate (26%), coal combustion (14%), mineral dust (11%), and vehicle exhaust (9%). The influence of source contributions to pH was estimated by ISORROPIA-II. The lowest aerosol pH levels were found at low WS-ion levels and then increased with increasing total ion levels, until high ion levels occur, at which point the aerosol becomes more acidic as both sulfate and nitrate increase. Ammonium levels increased nearly linearly with sulfate and nitrate until approximately 20 μg m -3 , supporting that the ammonium in the aerosol was more limited by thermodynamics than source limitations, and aerosol pH responded more to the contributions of sources such as dust than levels of sulfate. Commonly used pH indicator ratios were not indicative of the pH estimated using the thermodynamic model.

Source apportionment of PM10 by positive matrix factorization in urban area of Mumbai, India.

PubMed

Gupta, Indrani; Salunkhe, Abhaysinh; Kumar, Rakesh

2012-01-01

Particulate Matter (PM(10)) has been one of the main air pollutants exceeding the ambient standards in most of the major cities in India. During last few years, receptor models such as Chemical Mass Balance, Positive Matrix Factorization (PMF), PCA-APCS and UNMIX have been used to provide solutions to the source identification and contributions which are accepted for developing effective and efficient air quality management plans. Each site poses different complexities while resolving PM(10) contributions. This paper reports the variability of four sites within Mumbai city using PMF. Industrial area of Mahul showed sources such as residual oil combustion and paved road dust (27%), traffic (20%), coal fired boiler (17%), nitrate (15%). Residential area of Khar showed sources such as residual oil combustion and construction (25%), motor vehicles (23%), marine aerosol and nitrate (19%), paved road dust (18%) compared to construction and natural dust (27%), motor vehicles and smelting work (25%), nitrate (16%) and biomass burning and paved road dust (15%) in Dharavi, a low income slum residential area. The major contributors of PM(10) at Colaba were marine aerosol, wood burning and ammonium sulphate (24%), motor vehicles and smelting work (22%), Natural soil (19%), nitrate and oil burning (18%).

Apportionment of urban aerosol sources in Chongqing (China) using synergistic on-line techniques

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo

2016-04-01

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Chongqing (southwestern China) have been determined. Aerosol chemical composition analyses were performed using multiple on-line techniques, such as single particle aerosol mass spectrometer (SPAMS) for single particle chemical composition, on-line elemental carbon-organic carbon analyzer (on-line OC-EC), on-line X-ray fluorescence (XRF) for elements, and in-situ Gas and Aerosol Compositions monitor (IGAC) for water-soluble ions in PM2.5. All the datasets from these techniques have been adjusted to a 1-h time resolution for receptor model input. Positive matrix factorization (PMF) has been used for resolving aerosol sources. At least six sources, including domestic coal burning, biomass burning, dust, traffic, industrial and secondary/aged factors have been resolved and interpreted. The synergistic on-line techniques were helpful for identifying aerosol sources more clearly than when only employing the results from the individual techniques. This results are useful for better understanding of aerosol sources and atmospheric processes.

Sources and Removal of Springtime Arctic Aerosol

NASA Astrophysics Data System (ADS)

Willis, M. D.; Burkart, J.; Bozem, H.; Kunkel, D.; Schulz, H.; Hanna, S.; Aliabadi, A. A.; Bertram, A. K.; Hoor, P. M.; Herber, A. B.; Leaitch, R.; Abbatt, J.

2017-12-01

The sources and removal mechanisms of pollution transported to Arctic regions are key factors in controlling the impact of short-lived climate forcing agents on Arctic climate. We lack a predictive understanding of pollution transport to Arctic regions largely due to poor understanding of removal mechanisms and aerosol chemical and physical processing both within the Arctic and during transport. We present vertically resolved observations of aerosol physical and chemical properties in High Arctic springtime. While much previous work has focused on characterizing episodic events of high pollutant concentrations transported to Arctic regions, here we focus on measurements made under conditions consistent with chronic Arctic Haze, which is more representative of the pollution seasonal maximum observed at long term monitoring stations. On six flights based at Alert and Eureka, Nunavut, Canada, we observe evidence for vertical variations in both aerosol sources and removal mechanisms. With support from model calculations, we show evidence for sources of partially neutralized aerosol with higher organic aerosol (OA) and black carbon content in the middle troposphere, compared to lower tropospheric aerosol with higher amounts of acidic sulfate. Further, we show evidence for aerosol depletion relative to carbon monoxide, both in the mid-to-upper troposphere and within the Arctic Boundary Layer (ABL). Dry deposition, with relatively low removal efficiency, was responsible for aerosol removal in the ABL while ice or liquid-phase scavenging was responsible for aerosol removal at higher altitudes during transport. Overall, we find that vertical variations in both regional and remote aerosol sources, and removal mechanisms, combine with long aerosol residence times to drive the properties of springtime Arctic aerosol.

Characteristics and Source Apportionment of Marine Aerosols over East China Sea Using a Source-oriented Chemical Transport Model

NASA Astrophysics Data System (ADS)

Kang, M.; Zhang, H.; Fu, P.

2017-12-01

Marine aerosols exert a strong influence on global climate change and biogeochemical cycling, as oceans cover beyond 70% of the Earth's surface. However, investigations on marine aerosols are relatively limited at present due to the difficulty and inconvenience in sampling marine aerosols as well as their diverse sources. East China Sea (ECS), lying over the broad shelf of the western North Pacific, is adjacent to the Asian mainland, where continental-scale air pollution could impose a heavy load on the marine atmosphere through long-range atmospheric transport. Thus, contributions of major sources to marine aerosols need to be identified for policy makers to develop cost effective control strategies. In this work, a source-oriented version of the Community Multiscale Air Quality (CMAQ) model, which can directly track the contributions from multiple emission sources to marine aerosols, is used to investigate the contributions from power, industry, transportation, residential, biogenic and biomass burning to marine aerosols over the ECS in May and June 2014. The model simulations indicate significant spatial and temporal variations of concentrations as well as the source contributions. This study demonstrates that the Asian continent can greatly affect the marine atmosphere through long-range transport.

Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a central European mountain site during HCCT-2010

NASA Astrophysics Data System (ADS)

Roth, A.; Schneider, J.; Klimach, T.; Mertes, S.; van Pinxteren, D.; Herrmann, H.; Borrmann, S.

2016-01-01

Cloud residues and out-of-cloud aerosol particles with diameters between 150 and 900 nm were analysed by online single particle aerosol mass spectrometry during the 6-week study Hill Cap Cloud Thuringia (HCCT)-2010 in September-October 2010. The measurement location was the mountain Schmücke (937 m a.s.l.) in central Germany. More than 160 000 bipolar mass spectra from out-of-cloud aerosol particles and more than 13 000 bipolar mass spectra from cloud residual particles were obtained and were classified using a fuzzy c-means clustering algorithm. Analysis of the uncertainty of the sorting algorithm was conducted on a subset of the data by comparing the clustering output with particle-by-particle inspection and classification by the operator. This analysis yielded a false classification probability between 13 and 48 %. Additionally, particle types were identified by specific marker ions. The results from the ambient aerosol analysis show that 63 % of the analysed particles belong to clusters having a diurnal variation, suggesting that local or regional sources dominate the aerosol, especially for particles containing soot and biomass burning particles. In the cloud residues, the relative percentage of large soot-containing particles and particles containing amines was found to be increased compared to the out-of-cloud aerosol, while, in general, organic particles were less abundant in the cloud residues. In the case of amines, this can be explained by the high solubility of the amines, while the large soot-containing particles were found to be internally mixed with inorganics, which explains their activation as cloud condensation nuclei. Furthermore, the results show that during cloud processing, both sulfate and nitrate are added to the residual particles, thereby changing the mixing state and increasing the fraction of particles with nitrate and/or sulfate. This is expected to lead to higher hygroscopicity after cloud evaporation, and therefore to an increase of the particles' ability to act as cloud condensation nuclei after their cloud passage.

40 CFR 52.719 - Identification of plan-Conditional approval.

Code of Federal Regulations, 2013 CFR

2013-07-01

... aerosol-based antiperspirants and deodorants. 35 IAC 233.205(a)(6)(A) erroneously provides two high-volatility VOC limits for aerosol-based antiperspirants when there should be both a high- and medium... limits for non aerosol-based antiperspirants when there should be both a high- and medium-volatility...

Combining MODIS, MISR, CALIOP, OMI, AERONET, and Models to Identify the Spatial and Temporal Distribution, Characterization, and Magnitude of Missing Urban and Wildfire Emissions Sources throughout Asia.

NASA Astrophysics Data System (ADS)

Cohen, J. B.

2016-12-01

Due to intense and changing levels of emissions as well as highly non-linear chemical processing, the concentrations of aerosols and thus their impacts are not well known. Urban areas consist of the majority of the emissions of these species and their precursors over large periods of time, while wildfires contribute very large spikes, concentrated in space and over a period of weeks to months. Yet due to urban and economic expansion, as well as clouds amd low intensity burning, the spatial and temporal profiles of these species are changing, with both new sources appearing and old sources decreasing. New work incorporates measurements at different spatial andboptical resolutions from MODIS, MISR, and OMI, coupled with new sampling approaches with CALIOP and AERONET to search for, characterize, and spatially and temporally constrain aerosols. An advanced modeling system including aerosol chemistry, physics, optics, and transport, using a multi-modal and both externally mixed and core-shell mixing is used to quantify the magnitudes of these missing sources. Comparisons between the model and additional dozens of ground stations show extreme improvement when these new sources are included. This new approach is shown to identify new source regions of emissions, many of which were previously non-urbanized or were not found to contain any fire hotspots. In addition, the use of new models run under conditions including both missing local sources from regions such as the expanded urban areas in Southeast and East Asia and advanced chemical and aerosol routines, allow for a comprehensive analysis to be performed. The impacts of insitu chemistry, horizontal, and vertical transport of species, both on the Regional and Continental scale are also included. It is shown that for proper identification, especially on intra-annual and inter-annual variations, this approach is a large improvement throughout Asia, ranging from India, to Indonesia, to China and Japan. Results specific to Southern China and Southeast East Asia demonstrate the additional importance of the climate, as additional variations are identified. Such knowledge can allow us to better understand the consequences and impacts of the rapid ongoing changes occurring in these regions.

Substantial large-scale feedbacks between natural aerosols and climate

NASA Astrophysics Data System (ADS)

Scott, C. E.; Arnold, S. R.; Monks, S. A.; Asmi, A.; Paasonen, P.; Spracklen, D. V.

2018-01-01

The terrestrial biosphere is an important source of natural aerosol. Natural aerosol sources alter climate, but are also strongly controlled by climate, leading to the potential for natural aerosol-climate feedbacks. Here we use a global aerosol model to make an assessment of terrestrial natural aerosol-climate feedbacks, constrained by observations of aerosol number. We find that warmer-than-average temperatures are associated with higher-than-average number concentrations of large (>100 nm diameter) particles, particularly during the summer. This relationship is well reproduced by the model and is driven by both meteorological variability and variability in natural aerosol from biogenic and landscape fire sources. We find that the calculated extratropical annual mean aerosol radiative effect (both direct and indirect) is negatively related to the observed global temperature anomaly, and is driven by a positive relationship between temperature and the emission of natural aerosol. The extratropical aerosol-climate feedback is estimated to be -0.14 W m-2 K-1 for landscape fire aerosol, greater than the -0.03 W m-2 K-1 estimated for biogenic secondary organic aerosol. These feedbacks are comparable in magnitude to other biogeochemical feedbacks, highlighting the need for natural aerosol feedbacks to be included in climate simulations.

An Investigation of the Radiative Effects and Climate Feedbacks of Sea Ice Sources of Sea Salt Aerosol

NASA Astrophysics Data System (ADS)

Horowitz, H. M.; Alexander, B.; Bitz, C. M.; Jaegle, L.; Burrows, S. M.

2017-12-01

In polar regions, sea ice is a major source of sea salt aerosol through lofting of saline frost flowers or blowing saline snow from the sea ice surface. Under continued climate warming, an ice-free Arctic in summer with only first-year, more saline sea ice in winter is likely. Previous work has focused on climate impacts in summer from increasing open ocean sea salt aerosol emissions following complete sea ice loss in the Arctic, with conflicting results suggesting no net radiative effect or a negative climate feedback resulting from a strong first aerosol indirect effect. However, the radiative forcing from changes to the sea ice sources of sea salt aerosol in a future, warmer climate has not previously been explored. Understanding how sea ice loss affects the Arctic climate system requires investigating both open-ocean and sea ice sources of sea-salt aerosol and their potential interactions. Here, we implement a blowing snow source of sea salt aerosol into the Community Earth System Model (CESM) dynamically coupled to the latest version of the Los Alamos sea ice model (CICE5). Snow salinity is a key parameter affecting blowing snow sea salt emissions and previous work has assumed constant regional snow salinity over sea ice. We develop a parameterization for dynamic snow salinity in the sea ice model and examine how its spatial and temporal variability impacts the production of sea salt from blowing snow. We evaluate and constrain the snow salinity parameterization using available observations. Present-day coupled CESM-CICE5 simulations of sea salt aerosol concentrations including sea ice sources are evaluated against in situ and satellite (CALIOP) observations in polar regions. We then quantify the present-day radiative forcing from the addition of blowing snow sea salt aerosol with respect to aerosol-radiation and aerosol-cloud interactions. The relative contributions of sea ice vs. open ocean sources of sea salt aerosol to radiative forcing in polar regions is discussed.

Source identification of PM2.5 at a port and an adjacent urban site in a coastal city of China: Impact of ship emissions and port activities.

PubMed

Xu, Lingling; Jiao, Ling; Hong, Zhenyu; Zhang, Yanru; Du, Wenjiao; Wu, Xin; Chen, Yanting; Deng, Junjun; Hong, Youwei; Chen, Jinsheng

2018-09-01

Daily PM 2.5 samples were collected simultaneously at an urban site (UB) and a nearby port-industrial site (PI) on the coast of southeastern China from April 2015 to January 2016. The PM 2.5 mass concentration at the PI (51.9μgm -3 ) was significantly higher than that at the UB. The V concentration at the PI was also significantly higher and well-correlated to the urban value, which suggests that shipping emissions had a significant impact on the PI and, to a lesser extent, on the urban area. A positive matrix factorization (PMF) analysis showed that secondary aerosols were the dominant contribution of PM 2.5 at both sites (36.4% at the PI and 27.2% at the UB), while the contribution of industry and ship emissions identified by V, Mn, and Ba at the PI (26.1%) were double those at the UB. The difference in each source contribution among the trajectory clusters that included significant differences and insignificant differences from the UB to the PI provided insight into the role of local impacts. With regards to the UB, local potential sources play important roles in industry and ship emissions, traffic emissions, fugitive dust, and in their contributions to secondary aerosols. A conditional probability function further revealed that the ship emissions and port activities distributed in the NE, E, and SSE wind sectors were responsible for the source contributions of industry and ship emissions and secondary aerosols at the UB. This study provides an example of investigating the impact of ship emissions and port activities on the surrounding air environment using land-based measurements. Copyright © 2018 Elsevier B.V. All rights reserved.

Apportionment of urban aerosol sources in Cork (Ireland) by synergistic measurement techniques.

PubMed

Dall'Osto, Manuel; Hellebust, Stig; Healy, Robert M; O'Connor, Ian P; Kourtchev, Ivan; Sodeau, John R; Ovadnevaite, Jurgita; Ceburnis, Darius; O'Dowd, Colin D; Wenger, John C

2014-09-15

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Cork city (Ireland) have been determined. Aerosol chemical analyses were performed by multiple techniques including on-line high resolution aerosol time-of-flight mass spectrometry (Aerodyne HR-ToF-AMS), on-line single particle aerosol time-of-flight mass spectrometry (TSI ATOFMS), on-line elemental carbon-organic carbon analysis (Sunset_EC-OC), and off-line gas chromatography/mass spectrometry and ion chromatography analysis of filter samples collected at 6-h resolution. Positive matrix factorization (PMF) has been carried out to better elucidate aerosol sources not clearly identified when analyzing results from individual aerosol techniques on their own. Two datasets have been considered: on-line measurements averaged over 2-h periods, and both on-line and off-line measurements averaged over 6-h periods. Five aerosol sources were identified by PMF in both datasets, with excellent agreement between the two solutions: (1) regional domestic solid fuel burning--"DSF_Regional," 24-27%; (2) local urban domestic solid fuel burning--"DSF_Urban," 22-23%; (3) road vehicle emissions--"Traffic," 15-20%; (4) secondary aerosols from regional anthropogenic sources--"SA_Regional" 9-13%; and (5) secondary aged/processed aerosols related to urban anthropogenic sources--"SA_Urban," 21-26%. The results indicate that, despite regulations for restricting the use of smoky fuels, solid fuel burning is the major source (46-50%) of PM2.5 in wintertime in Cork, and also likely other areas of Ireland. Whilst wood combustion is strongly associated with OC and EC, it was found that peat and coal combustion is linked mainly with OC and the aerosol from these latter sources appears to be more volatile than that produced by wood combustion. Ship emissions from the nearby port were found to be mixed with the SA_Regional factor. The PMF analysis allowed us to link the AMS cooking organic aerosol factor (AMS_PMF_COA) to oxidized organic aerosol, chloride and locally produced nitrate, indicating that AMS_PMF_COA cannot be attributed to primary cooking emissions only. Overall, there are clear benefits from factor analysis applied to results obtained from multiple techniques, which allows better association of aerosols with sources and atmospheric processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Apportionment of Primary and Secondary Organic Aerosols in Southern California During the 2005 Study of Organic Aerosols in Riverside (SOAR-1)

EPA Science Inventory

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionment techniques.

PM 10 metal concentrations and source identification using positive matrix factorization and wind sectoring in a French industrial zone

NASA Astrophysics Data System (ADS)

Alleman, Laurent Y.; Lamaison, Laure; Perdrix, Esperanza; Robache, Antoine; Galloo, Jean-Claude

2010-06-01

The elemental composition data of ambient aerosols collected upon selected wind sectors in the highly industrialised harbour of Dunkirk (France) were interpreted using pollution roses, elemental ratios, Enrichment Factors (EF), Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) receptor model. The objective was to identify the possible sources of PM10 aerosols, their respective chemical tracers and to determine their relative contribution at the sampling site. PM10 particles samples were collected from June 2003 to March 2005 in order to analyse up to 35 elements (Ag, Al, As, Ba, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Eu, Fe, K, La, Mg, Mn, Mo, Na, Ni, Pb, Rb, S, Sb, Sc, Si, Sm, Sr, Th, Ti, U, V, Zn and Zr) using Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES) and ICP-Mass Spectrometry (MS). A significant effort has been made on estimating the total uncertainty of each result by regularly analysing blanks, quality controls and SRM NIST standards. Based on this procedure, a selected set of 24 "robust" elements was compared to the 35-element matrix in order to evaluate the sturdiness of our PMF statistical treatment. Eight source factors were resolved by PCA for all the wind sectors explaining 90% of the total data variance. The PMF results confirmed that eight physically interpretable factors contributed to the ambient particulate pollution at the sampling site: crustal dust (11%), marine aerosols (12%), petrochemistry activities (9.2%), metallurgical sintering plant (8.6%), metallurgical coke plant (12.6%), ferromanganese plant (6.6%), road transport (15%) and a less clearly interpretable profile probably associated to dust resuspension (13%). These weighted contributions against wind direction frequencies demonstrate that industrial sources are the most important contributors to this site (37%) followed by the natural sources (detrital and marine sources) (23%) and the road transport (15%).

Air Quality Monitoring and Forecasting Applications of Suomi NPP VIIRS Aerosol Products

NASA Astrophysics Data System (ADS)

Kondragunta, Shobha

The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched on October 28, 2011. It provides Aerosol Optical Thickness (AOT) at two different spatial resolutions: a pixel level (~750 m at nadir) product called the Intermediate Product (IP) and an aggregated (~6 km at nadir) product called the Environmental Data Record (EDR), and a Suspended Matter (SM) EDR that provides aerosol type (dust, smoke, sea salt, and volcanic ash) information. An extensive validation of VIIRS best quality aerosol products with ground based L1.5 Aerosol Robotic NETwork (AERONET) data shows that the AOT EDR product has an accuracy/precision of -0.01/0.11 and 0.01/0.08 over land and ocean respectively. Globally, VIIRS mean AOT EDR (0.20) is similar to Aqua MODIS (0.16) with some important regional and seasonal differences. The accuracy of the SM product, however, is found to be very low (20 percent) when compared to Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and AERONET. Several algorithm updates which include a better approach to retrieve surface reflectance have been developed for AOT retrieval. For dust aerosol type retrieval, a new approach that takes advantage of spectral dependence of Rayleigh scattering, surface reflectance, dust absorption in the deep blue (412 nm), blue (440 nm), and mid-IR (2.2 um) has been developed that detects dust with an accuracy of ~80 percent. For smoke plume identification, a source apportionment algorithm that combines fire hot spots with AOT imagery has been developed that provides smoke plume extent with an accuracy of ~70 percent. The VIIRS aerosol products will provide continuity to the current operational use of aerosol products from Aqua and Terra MODIS. These include aerosol data assimilation in Naval Research Laboratory (NRL) global aerosol model, verification of National Weather Service (NWS) dust and smoke forecasts, exceptional events monitoring by different states, air quality warnings by Environmental Protection Agency (EPA). This talk will provide an overview of VIIRS algorithms, aerosol product validation, and examples of various applications with a discussion on the relevance of product accuracy.

Operational remote sensing of tropospheric aerosol over land from EOS moderate resolution imaging spectroradiometer

NASA Astrophysics Data System (ADS)

Kaufman, Y. J.; Tanré, D.; Remer, L. A.; Vermote, E. F.; Chu, A.; Holben, B. N.

1997-07-01

Daily distribution of the aerosol optical thickness and columnar mass concentration will be derived over the continents, from the EOS moderate resolution imaging spectroradiometer (MODIS) using dark land targets. Dark land covers are mainly vegetated areas and dark soils observed in the red and blue channels; therefore the method will be limited to the moist parts of the continents (excluding water and ice cover). After the launch of MODIS the distribution of elevated aerosol concentrations, for example, biomass burning in the tropics or urban industrial aerosol in the midlatitudes, will be continuously monitored. The algorithm takes advantage of the MODIS wide spectral range and high spatial resolution and the strong spectral dependence of the aerosol opacity for most aerosol types that result in low optical thickness in the mid-IR (2.1 and 3.8 μm). The main steps of the algorithm are (1) identification of dark pixels in the mid-IR; (2) estimation of their reflectance at 0.47 and 0.66 μm; and (3) derivation of the optical thickness and mass concentration of the accumulation mode from the detected radiance. To differentiate between dust and aerosol dominated by accumulation mode particles, for example, smoke or sulfates, ratios of the aerosol path radiance at 0.47 and 0.66 μm are used. New dynamic aerosol models for biomass burning aerosol, dust and aerosol from industrial/urban origin, are used to determine the aerosol optical properties used in the algorithm. The error in the retrieved aerosol optical thicknesses, τa is expected to be Δτa = 0.05±0.2τa. Daily values are stored on a resolution of 10×10 pixels (1 km nadir resolution). Weighted and gridded 8-day and monthly composites of the optical thickness, the aerosol mass concentration and spectral radiative forcing are generated for selected scattering angles to increase the accuracy. The daily aerosol information over land and oceans [Tanré et al., this issue], combined with continuous aerosol remote sensing from the ground, will be used to study aerosol climatology, to monitor the sources and sinks of specific aerosol types, and to study the interaction of aerosol with water vapor and clouds and their radiative forcing of climate. The aerosol information will also be used for atmospheric corrections of remotely sensed surface reflectance. In this paper, examples of applications and validations are provided.

Tracking Intercontinental Dust Transport With Radiogenic Isotopes: Hefei, China to California, Spring 2002

NASA Astrophysics Data System (ADS)

Christensen, J. N.; Cliff, S. S.; Vancuren, R. A.; Perry, K. D.; Depaolo, D. J.

2006-12-01

Research over the past decade has highlighted the importance of intercontinental transport and exchange of atmospheric aerosols, including soil-derived dust and industrial pollutants. Far-traveled aerosols can affect air quality, atmospheric radiative forcing and cloud formation and can be an important component in soils. Principal component analysis of elemental data for aerosols collected over California has identified a persistent Asian soil dust component that peaks with Asian dust storm events [1]. Isotopic fingerprinting can provide an additional and potentially more discriminating tool for tracing sources of dust. For example, the naturally variable isotopic compositions of Sr and Nd reflect both the geochemistry of the dust source and its pre- weathering geologic history. Sr and Nd isotopic data and chemical data have been collected for a time series of PM2.5 filter samples from Hefei, China taken from eraly April into early May, 2002. This period encompassed a series of dust storms. The sampling time frame overlapped with the 2002 Intercontinental Transport and Chemical Transformation (ITCT-2K2) experiment along the Pacific coast of North America and inland California. Highs in 87Sr/86Sr in the Hefei time series coincide with peaks in Ca and Si representing peaks in mineral particulate loading resulting from passing dust storms. Mixing diagrams combining isotopic data with chemical data identify several components; a high 87Sr/86Sr component that we identify with mineral dust (loess), and two different low 87Sr/86Sr components (local sources and marine aerosol). Using our measured isotopic composition of the "loess" standard CJ-1 [2] as representative of the pure high 87Sr/86Sr component, we calculate 24 hour average loess particulate concentrations in air which range up to 35 micrograms per cubic meter. Marine aerosol was a major component on at least one of the sampled days. The results for the Hefei samples provide a basis for our isotopic study of California mineral aerosols, including the identification and apportionment of local and far-traveled Asian dust components and their variation in time. [1]VanCuren R.A., Cliff, S.S., Perry, K.D. and Jimenez-Cruz, M. (2005) J. Geophys. Res., 110, D09S90, doi: 10.1029/2004JD004973 [2]Nishikawa, M., Hao, Q. and Morita, M. (2000) Global Environ. Res. 4, 1:103-113.

Using lanthanoid elements as tracers for anthropogenic contamination of atmospheric aerosols

NASA Astrophysics Data System (ADS)

Moreno, T.; Querol, X.; Alastuey, A.; Gibbons, W.

2009-04-01

Lanthanoid elements are present in atmospheric particulate matter both within natural mineral particles and as anthropogenic aerosols emitted from industrial and traffic pollution sources. Whereas the total lanthanoid (ΣLoid) content of atmospheric PM is controlled primarily by the amount of coarse crustal mineral material present, ratios between different lanthanoid elements (e.g. La/Ce and La/Sm) can be influenced by industrial processes such as the use of La-enriched fluid catalytic converters (FCC) in oil refineries, the combustion of refinery La-contaminated oils in power stations, or the abrasive loss of Ce-bearing PM from road vehicle catalytic converters. Use of lanthanoid ratios as tracers are especially useful in allowing the identification of specific La anomalies (La>Ce) when FCC refinery emissions are prominent. Increasing contamination of urban/industrial atmospheric PM samples away from crustal compositions may be tracked using a LaCeSm triangular plot, but this does not differentiate between FCC refinery and oil combustion emissions. Comparing lanthanoid and V concentrations does aid such differentiation, although given the likelihood of multiple PM sources in industrial locations, we recommend use of a LaCeV plot rather than simply La/V ratios. Lanthanoid geochemistry can be applied in this way to demonstrate for example how atmospheric PM in many urban areas is polluted more by V-bearing fuel oil combustion (e.g. Mexico City), whereas other cities are more influenced by different aerosol sources such as oil refineries (e.g. Houston) or coal burning (e.g. Beijing). This work was funded by the Spanish Ministry of Science and Innovation (GRACCIE-SCD2007-00067).

Heating Rate of Light Absorbing Aerosols: Time-Resolved Measurements, the Role of Clouds, and Source Identification.

PubMed

Ferrero, Luca; Močnik, Griša; Cogliati, Sergio; Gregorič, Asta; Colombo, Roberto; Bolzacchini, Ezio

2018-03-20

Light absorbing aerosols (LAA) absorb sunlight and heat the atmosphere. This work presents a novel methodology to experimentally quantify the heating rate (HR) induced by LAA into an atmospheric layer. Multiwavelength aerosol absorption measurements were coupled with spectral measurements of the direct, diffuse and surface reflected radiation to obtain highly time-resolved measurements of HR apportioned in the context of LAA species (black carbon, BC; brown carbon, BrC; dust), sources (fossil fuel, FF; biomass burning, BB), and as a function of cloudiness. One year of continuous and time-resolved measurements (5 min) of HR were performed in the Po Valley. We experimentally determined (1) the seasonal behavior of HR (winter 1.83 ± 0.02 K day -1 ; summer 1.04 ± 0.01 K day -1 ); (2) the daily cycle of HR (asymmetric, with higher values in the morning than in the afternoon); (3) the HR in different sky conditions (from 1.75 ± 0.03 K day -1 in clear sky to 0.43 ± 0.01 K day -1 in complete overcast); (4) the apportionment to different sources: HR FF (0.74 ± 0.01 K day -1 ) and HR BB (0.46 ± 0.01 K day -1 ); and (4) the HR of BrC (HR BrC : 0.15 ± 0.01 K day -1 , 12.5 ± 0.6% of the total) and that of BC (HR BC : 1.05 ± 0.02 K day -1 ; 87.5 ± 0.6% of the total).

Global View of Aerosol Vertical Distributions from CALIPSO Lidar Measurements and GOCART Simulations: Regional and Seasonal Variations

NASA Technical Reports Server (NTRS)

Yu, Hongbin; Chin, Mian; Winker, David M.; Omar, Ali H.; Liu, Zhaoyan; Kittaka, Chieko; Diehl, Thomas

2010-01-01

This study examines seasonal variations of the vertical distribution of aerosols through a statistical analysis of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar observations from June 2006 to November 2007. A data-screening scheme is developed to attain good quality data in cloud-free conditions, and the polarization measurement is used to separate dust from non-dust aerosol. The CALIPSO aerosol observations are compared with aerosol simulations from the Goddard Chemistry Aerosol Radiation Transport (GOCART) model and aerosol optical depth (AOD) measurements from the MODerate resolution Imaging Spectroradiometer (MODIS). The CALIPSO observations of geographical patterns and seasonal variations of AOD are generally consistent with GOCART simulations and MODIS retrievals especially near source regions, while the magnitude of AOD shows large discrepancies in most regions. Both the CALIPSO observation and GOCART model show that the aerosol extinction scale heights in major dust and smoke source regions are generally higher than that in industrial pollution source regions. The CALIPSO aerosol lidar ratio also generally agrees with GOCART model within 30% on regional scales. Major differences between satellite observations and GOCART model are identified, including (1) an underestimate of aerosol extinction by GOCART over the Indian sub-continent, (2) much larger aerosol extinction calculated by GOCART than observed by CALIPSO in dust source regions, (3) much weaker in magnitude and more concentrated aerosol in the lower atmosphere in CALIPSO observation than GOCART model over transported areas in midlatitudes, and (4) consistently lower aerosol scale height by CALIPSO observation than GOCART model. Possible factors contributing to these differences are discussed.

An inter-comparison of PM10 source apportionment using PCA and PMF receptor models in three European sites.

PubMed

Cesari, Daniela; Amato, F; Pandolfi, M; Alastuey, A; Querol, X; Contini, D

2016-08-01

Source apportionment of aerosol is an important approach to investigate aerosol formation and transformation processes as well as to assess appropriate mitigation strategies and to investigate causes of non-compliance with air quality standards (Directive 2008/50/CE). Receptor models (RMs) based on chemical composition of aerosol measured at specific sites are a useful, and widely used, tool to perform source apportionment. However, an analysis of available studies in the scientific literature reveals heterogeneities in the approaches used, in terms of "working variables" such as the number of samples in the dataset and the number of chemical species used as well as in the modeling tools used. In this work, an inter-comparison of PM10 source apportionment results obtained at three European measurement sites is presented, using two receptor models: principal component analysis coupled with multi-linear regression analysis (PCA-MLRA) and positive matrix factorization (PMF). The inter-comparison focuses on source identification, quantification of source contribution to PM10, robustness of the results, and how these are influenced by the number of chemical species available in the datasets. Results show very similar component/factor profiles identified by PCA and PMF, with some discrepancies in the number of factors. The PMF model appears to be more suitable to separate secondary sulfate and secondary nitrate with respect to PCA at least in the datasets analyzed. Further, some difficulties have been observed with PCA in separating industrial and heavy oil combustion contributions. Commonly at all sites, the crustal contributions found with PCA were larger than those found with PMF, and the secondary inorganic aerosol contributions found by PCA were lower than those found by PMF. Site-dependent differences were also observed for traffic and marine contributions. The inter-comparison of source apportionment performed on complete datasets (using the full range of available chemical species) and incomplete datasets (with reduced number of chemical species) allowed to investigate the sensitivity of source apportionment (SA) results to the working variables used in the RMs. Results show that, at both sites, the profiles and the contributions of the different sources calculated with PMF are comparable within the estimated uncertainties indicating a good stability and robustness of PMF results. In contrast, PCA outputs are more sensitive to the chemical species present in the datasets. In PCA, the crustal contributions are higher in the incomplete datasets and the traffic contributions are significantly lower for incomplete datasets.

Landscape fires dominate terrestrial natural aerosol - climate feedbacks

NASA Astrophysics Data System (ADS)

Scott, C.; Arnold, S.; Monks, S. A.; Asmi, A.; Paasonen, P.; Spracklen, D. V.

2017-12-01

The terrestrial biosphere is an important source of natural aerosol including landscape fire emissions and secondary organic aerosol (SOA) formed from biogenic volatile organic compounds (BVOCs). Atmospheric aerosol alters the Earth's climate by absorbing and scattering radiation (direct radiative effect; DRE) and by perturbing the properties of clouds (aerosol indirect effect; AIE). Natural aerosol sources are strongly controlled by, and can influence, climate; giving rise to potential natural aerosol-climate feedbacks. Earth System Models (ESMs) include a description of some of these natural aerosol-climate feedbacks, predicting substantial changes in natural aerosol over the coming century with associated radiative perturbations. Despite this, the sensitivity of natural aerosols simulated by ESMs to changes in climate or emissions has not been robustly tested against observations. Here we combine long-term observations of aerosol number and a global aerosol microphysics model to assess terrestrial natural aerosol-climate feedbacks. We find a strong positive relationship between the summertime anomaly in observed concentration of particles greater than 100 nm diameter and the anomaly in local air temperature. This relationship is reproduced by the model and driven by variability in dynamics and meteorology, as well as natural sources of aerosol. We use an offline radiative transfer model to determine radiative effects due to changes in two natural aerosol sources: landscape fire and biogenic SOA. We find that interannual variability in the simulated global natural aerosol radiative effect (RE) is negatively related to the global temperature anomaly. The magnitude of global aerosol-climate feedback (sum of DRE and AIE) is estimated to be -0.15 Wm-2 K-1 for landscape fire aerosol and -0.06 Wm-2 K-1 for biogenic SOA. These feedbacks are comparable in magnitude, but opposite in sign to the snow albedo feedback, highlighting the need for natural aerosol feedbacks to be included in climate simulations.

The application of chemical and isotopic tracers to characterize aerosol sources and processing in marine air

NASA Astrophysics Data System (ADS)

Turekian, Vaughan Charles

2000-12-01

Aerosol production, transport, chemical and physical evolution and deposition impact the environment by influencing radiation budgets, altering the composition of the atmosphere, and delivering nutrients to marine and terrestrial ecosystems. The objective of this research was to combine high-resolution chemical measurements with stable isotopic analysis in order to characterize the sources and processing of carbon, nitrogen and sulfur bearing compounds, associated with sized aerosols on Bermuda, during spring. Chemical tracers combined with forward and backward trajectories demonstrated the transport of biomass burning products from North America to Bermuda. The size distributions of NH4+ from 1998 differed from those during spring, 1997, a year without the large-scale burning. These results suggest that transport of biomass burning products altered the pH of the aerosols. Marine and continentally derived carbon was associated with all aerosol size fractions. Supermicron radius sea- salt aerosol was enriched in marine derived carbon by 2 orders of magnitude compared to bulk surface seawater. Enrichments of oxalate relative to methanesulfonic acid (MSA) in supermicron radius aerosol suggested in situ formation of oxalate within the sea-salt solution, or direct injection from the organic rich surface microlayer. Compound specific isotope analysis of oxalic acid, indicated a marine source for all aerosol size fractions, indicating formation from in the gas phase for the submicron radius aerosol. Stable sulfur isotopes indicated that the biogenic non- sea-salt (nss) SO42-/MSA ratio varied with aerosol size indicating that MSA may not be a conservative tracer of biogenic nss SO4 2- in bulk aerosol sampling. The calculated biogenic nss SO 42-/MSA based on stable isotopes and sized aerosol sampling, was 3 times lower than previous estimates for Bermuda. Stable nitrogen isotope values for submicron and supermicron aerosol where significantly different, consistent with their different chemical compositions. Results suggested that HNO3 incorporation into supermicron aerosol was essentially unidirectional whereas submicron aerosol was both a source and a sink for NH3(g). Variable aerosol liquid water content over the relatively longer atmospheric lifetimes of submicron aerosol may lead to multiple NH3 phase changes. This study was the first to combine sized aerosol sampling, high-resolution chemical analysis and multiple stable isotopes to characterize both the sources and the processing of aerosols in marine air. The results of this study, therefore, provide crucial information for source apportionment of environmentally important atmospheric species in continentally impacted, marine air.

Aerosol Optical Properties Measured Onboard the Ronald H. Brown During ACE Asia as a Function of Aerosol Chemical Composition and Source Region

NASA Technical Reports Server (NTRS)

Quinn, P. K.; Coffman, D. J.; Bates, T. S.; Welton, E. J.; Covert, D. S.; Miller, T. L.; Johnson, J. E.; Maria, S.; Russell, L.; Arimoto, R.

2004-01-01

During the ACE Asia intensive field campaign conducted in the spring of 2001 aerosol properties were measured onboard the R/V Ronald H. Brown to study the effects of the Asian aerosol on atmospheric chemistry and climate in downwind regions. Aerosol properties measured in the marine boundary layer included chemical composition; number size distribution; and light scattering, hemispheric backscattering, and absorption coefficients. In addition, optical depth and vertical profiles of aerosol 180 deg backscatter were measured. Aerosol within the ACE Asia study region was found to be a complex mixture resulting from marine, pollution, volcanic, and dust sources. Presented here as a function of air mass source region are the mass fractions of the dominant aerosol chemical components, the fraction of the scattering measured at the surface due to each component, mass scattering efficiencies of the individual components, aerosol scattering and absorption coefficients, single scattering albedo, Angstrom exponents, optical depth, and vertical profiles of aerosol extinction. All results except aerosol optical depth and the vertical profiles of aerosol extinction are reported at a relative humidity of 55 +/- 5%. An over-determined data set was collected so that measured and calculated aerosol properties could be compared, internal consistency in the data set could be assessed, and sources of uncertainty could be identified. By taking into account non-sphericity of the dust aerosol, calculated and measured aerosol mass and scattering coefficients agreed within overall experimental uncertainties. Differences between measured and calculated aerosol absorption coefficients were not within reasonable uncertainty limits, however, and may indicate the inability of Mie theory and the assumption of internally mixed homogeneous spheres to predict absorption by the ACE Asia aerosol. Mass scattering efficiencies of non-sea salt sulfate aerosol, sea salt, submicron particulate organic matter, and dust found for the ACE Asia aerosol are comparable to values estimated for ACE 1, Aerosols99, and INDOEX. Unique to the ACE Asia aerosol was the large mass fractions of dust, the dominance of dust in controlling the aerosol optical properties, and the interaction of dust with soot aerosol.

Single Particle Analysis by Combined Chemical Imaging to Study Episodic Air Pollution Events in Vienna

NASA Astrophysics Data System (ADS)

Ofner, Johannes; Eitenberger, Elisabeth; Friedbacher, Gernot; Brenner, Florian; Hutter, Herbert; Schauer, Gerhard; Kistler, Magdalena; Greilinger, Marion; Lohninger, Hans; Lendl, Bernhard; Kasper-Giebl, Anne

2017-04-01

The aerosol composition of a city like Vienna is characterized by a complex interaction of local emissions and atmospheric input on a regional and continental scale. The identification of major aerosol constituents for basic source appointment and air quality issues needs a high analytical effort. Exceptional episodic air pollution events strongly change the typical aerosol composition of a city like Vienna on a time-scale of few hours to several days. Analyzing the chemistry of particulate matter from these events is often hampered by the sampling time and related sample amount necessary to apply the full range of bulk analytical methods needed for chemical characterization. Additionally, morphological and single particle features are hardly accessible. Chemical Imaging evolved to a powerful tool for image-based chemical analysis of complex samples. As a complementary technique to bulk analytical methods, chemical imaging can address a new access to study air pollution events by obtaining major aerosol constituents with single particle features at high temporal resolutions and small sample volumes. The analysis of the chemical imaging datasets is assisted by multivariate statistics with the benefit of image-based chemical structure determination for direct aerosol source appointment. A novel approach in chemical imaging is combined chemical imaging or so-called multisensor hyperspectral imaging, involving elemental imaging (electron microscopy-based energy dispersive X-ray imaging), vibrational imaging (Raman micro-spectroscopy) and mass spectrometric imaging (Time-of-Flight Secondary Ion Mass Spectrometry) with subsequent combined multivariate analytics. Combined chemical imaging of precipitated aerosol particles will be demonstrated by the following examples of air pollution events in Vienna: Exceptional episodic events like the transformation of Saharan dust by the impact of the city of Vienna will be discussed and compared to samples obtained at a high alpine background site (Sonnblick Observatory, Saharan Dust Event from April 2016). Further, chemical imaging of biological aerosol constituents of an autumnal pollen breakout in Vienna, with background samples from nearby locations from November 2016 will demonstrate the advantages of the chemical imaging approach. Additionally, the chemical fingerprint of an exceptional air pollution event from a local emission source, caused by the pull down process of a building in Vienna will unravel the needs for multisensor imaging, especially the combinational access. Obtained chemical images will be correlated to bulk analytical results. Benefits of the overall methodical access by combining bulk analytics and combined chemical imaging of exceptional episodic air pollution events will be discussed.

Identifying Metals as Marker for Waste Burning Aerosol Particles in New Delhi

NASA Astrophysics Data System (ADS)

Kumar, Sudhanshu

2012-07-01

{Identifying Metals as Marker for Waste Burning Aerosol Particles in New Delhi } Tracing of aerosol sources is an important task helpful for making control strategy, and for climate change study. However, it is a difficult job as aerosols have several sources, involve in complex atmospheric processing, degradation and removal processes. Several approaches have been used for this task, e.g., models, which are based on the input of chemical species; stable- and radio-isotope compositions of certain species; chemical markers in which trace metals are the better options because they persist in atmosphere until the life of a particle. For example, K and Hg are used for biomass and coal burning tracings, respectively. Open waste burning has recently been believed to be a considerable source of aerosols in several mega cities in India and China. To better understand this source contribution in New Delhi aerosols, we have conducted aerosol sampling at a landfill site (Okhla), and in proximity (within 1 km distance) of this site. Aerosol filter samples were acid digested in microwave digestion system and analyzed using inductively coupled plasma -- high resolution mass spectrometry (ICP-HRMS) for getting metal signatures in particles. The metals, e.g., Sn, Sb and As those are found almost negligible in remote aerosols, are maximized in these waste burning aerosols. Sample collected in other location of New Delhi also shows the considerable presence of these metals in particles. Preliminary studies of isotopic ratios of these metals suggested that these metals, especially Sn can be used as marker for tracing the open waste burning sources of aerosols in New Delhi.

Modelling absorbing aerosol with ECHAM-HAM: Insights from regional studies

NASA Astrophysics Data System (ADS)

Tegen, Ina; Heinold, Bernd; Schepanski, Kerstin; Banks, Jamie; Kubin, Anne; Schacht, Jacob

2017-04-01

Quantifying distributions and properties of absorbing aerosol is a basis for investigations of interactions of aerosol particles with radiation and climate. While evaluations of aerosol models by field measurements can be particularly successful at the regional scale, such results need to be put into a global context for climate studies. We present an overview over studies performed at the Leibniz Institute for Tropospheric Research aiming at constraining the properties of mineral dust and soot aerosol in the global aerosol model ECHAM6-HAM2 based on different regional studies. An example is the impact of different sources for dust transported to central Asia, which is influenced, by far-range transport of dust from Arabia and the Sahara together with dust from local sources. Dust types from these different source regions were investigated in the context of the CADEX project and are expected to have different optical properties. For Saharan dust, satellite retrievals from MSG SEVIRI are used to constrain Saharan dust sources and optical properties. In the Arctic region, on one hand dust aerosol is simulated in the framework of the PalMod project. On the other hand aerosol measurements that will be taken during the DFG-funded (AC)3 field campaigns will be used to evaluate the simulated transport pathways of soot aerosol from European, North American and Asian sources, as well as the parameterization of soot ageing processes in ECHAM6-HAM2. Ultimately, results from these studies will improve the representation of aerosol absorption in the global model.

A51F-0123: Model Analysis of Tropospheric Aerosol Variability and Sources over the North Atlantic During NAAMES 2015-2016

NASA Technical Reports Server (NTRS)

Liu, Hongyu; Moore, Richard; Hostetler, Chris A.; Ferrare, Richard Anthony; Fairlie, Thomas Duncan; Hu, Youngxiang; Chen, Gao; Hair, Johnathan W.; Johnson, Matthew S.

2016-01-01

The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is a five-year Earth-Venture Suborbital-2 Mission to characterize the plankton ecosystems and their influences on remote marine aerosols, boundary layer clouds, and their implications for climate in the North Atlantic. While marine-sourced aerosols have been shown to make important contributions to surface aerosol loading, cloud condensation nuclei and ice nuclei concentrations over remote marine and coastal regions, it is still a challenge to differentiate the marine biogenic aerosol signal from the strong influence of continental pollution outflow. We examine here the spatiotemporal variability and quantify the sources of tropospheric aerosols over the North Atlantic during the first two phases (November 2015 and May-June 2016) of NAAMES using a state-of-the-art chemical transport model (GEOS-Chem). The model is driven by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) from the NASA Global Modeling and Assimilation Office (GMAO). It includes sulfate-nitrate-ammonium aerosol thermodynamics coupled to ozone-NOx-hydrocarbon-aerosol chemistry, mineral dust, sea salt, elemental and organic carbon aerosols, and especially a recently implemented parameterization for the marine primary organic aerosol emission. The simulated aerosols over the North Atlantic are evaluated with available satellite (e.g., MODIS) observations of aerosol optical depths (AOD), and aircraft and ship aerosol measurements. We diagnose transport pathways for continental pollution outflow over the North Atlantic using carbon monoxide, an excellent tracer for anthropogenic pollution transport. We also conduct model perturbation experiments to quantify the relative contributions of terrestrial and oceanic sources to the aerosol loading, AOD, and their variability over the North Atlantic.

Cloud-Aerosol Interaction and Its Impact on the Onset of the East Asian Summer Monsoon

NASA Technical Reports Server (NTRS)

Kim, Kyu-Myong; Lau, William K.-M.; Hsu, N. Christina; Tsay, Si-Chee

2004-01-01

Effect of aerosols from biomass burning on the early development of East Asian monsoon is investigated using various satellites and in situ observations including TOMS Aerosol Index (AI). GPCP precipitation, ISCCP cloud cover, and GISS surface air temperature. Based on TRMM fire produce and mean winds fields at 85Omb. we identified the source and interaction regions of aerosols and investigated aerosol-cloud-precipitation characteristics in those regions. During March-April, northern Thailand, Myanmar. and Laos are major source of smoke from the combustion of agricultural waste. Excessive smoke. represented by high AI, is observed especially during dry and cloud-free year. On the other hand. there is no ground source of smoke in the interaction region. The most of aerosols in this area are believed to be transported from the source region. AI is appeared to be correlated with more clouds and less precipitation in interaction region. It suggests that the aerosol-cloud interaction can alter the distribution of cloud and the characteristics of regional hydrology. Aerosol-induced changes in atmospheric stability and associated circulation turns out to be very important to pre-monsoon rainfall pattern in southern China. Prolonged biomass burning is especially effective in changing rainfall pattern during April and May. Results suggest that excessive aerosol transported from source region may intensify pre-monsoon rain band over central China in May and lead to early monsoon onset.

Supercritical Fluid Extraction of Biogenic SOA in Northern Michigan

NASA Astrophysics Data System (ADS)

Flores, R. M.; Doskey, P. V.; Perlinger, J. A.

2010-12-01

Secondary organic aerosols (SOA) are formed by photooxidation of volatile organic compounds (VOCs) and nucleation and condensation of the oxygenated products. On a global scale, monoaromatic hydrocarbons of anthropogenic origin are estimated to be the source of 12% of the SOA while biogenic emissions of isoprene (C5H8), monoterpenes (C10H16), and sesquiterpenes (C15H24) are estimated to be the source of 46, 29 and 7% of SOA, respectively. The functional groups of organic substances comprising SOA (i.e., hydroxyl, carbonyl, carboxylic acid, sulfate, and nitrate) complicate sample processing, analysis, and identification of the characteristic aerosol products of VOC oxidation pathways. Only a very small fraction of the organic molecular species in SOA have been identified due to the complexity of precursor oxidation reactions and the need for (1) methodologies that are less labor intensive and suitable for thermally labile compounds and (2) analytic instrumentation that provides more complete resolution of complex mixtures for sensitive detection of molecular species. Extraction techniques commonly used include solvent extraction, which requires large amounts of solvent and is labor intensive and thermal desorption, which evolves organic substances from aerosol at temperatures not suitable for thermally labile compounds. A promising technique that does not involve sample processing with solvents or high temperatures is supercritical fluid extraction (SFE). In this work, the composition of biogenic SOA was studied in Northern Michigan. Aerosol samples were collected on quartz fiber filters with a high-volume air sampler and extracted with supercritical CO2. Carboxylic and hydroxyl compounds were derivatized during static extraction conditions and identified by comprehensive two dimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC-TOFMS). The overall goal of the research is to couple the post-collection analytic scheme developed here with a rapid sampling technique to evaluate SOA produced from a variety of biogenic and anthropogenic sources of precursors in the Midwestern United States.

Aqueous aerosol SOA formation: impact on aerosol physical properties.

PubMed

Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

2013-01-01

Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.

Development and characterization of an aircraft aerosol time-of-flight mass spectrometer.

PubMed

Pratt, Kerri A; Mayer, Joseph E; Holecek, John C; Moffet, Ryan C; Sanchez, Rene O; Rebotier, Thomas P; Furutani, Hiroshi; Gonin, Marc; Fuhrer, Katrin; Su, Yongxuan; Guazzotti, Sergio; Prather, Kimberly A

2009-03-01

Vertical and horizontal profiles of atmospheric aerosols are necessary for understanding the impact of air pollution on regional and global climate. To gain further insight into the size-resolved chemistry of individual atmospheric particles, a smaller aerosol time-of-flight mass spectrometer (ATOFMS) with increased data acquisition capabilities was developed for aircraft-based studies. Compared to previous ATOFMS systems, the new instrument has a faster data acquisition rate with improved ion transmission and mass resolution, as well as reduced physical size and power consumption, all required advances for use in aircraft studies. In addition, real-time source apportionment software allows the immediate identification and classification of individual particles to guide sampling decisions while in the field. The aircraft (A)-ATOFMS was field-tested on the ground during the Study of Organic Aerosols in Riverside, CA (SOAR) and aboard an aircraft during the Ice in Clouds Experiment-Layer Clouds (ICE-L). Initial results from ICE-L represent the first reported aircraft-based single-particle dual-polarity mass spectrometry measurements and provide an increased understanding of particle mixing state as a function of altitude. Improved ion transmission allows for the first single-particle detection of species out to approximately m/z 2000, an important mass range for the detection of biological aerosols and oligomeric species. In addition, high time resolution measurements of single-particle mixing state are demonstrated and shown to be important for airborne studies where particle concentrations and chemistry vary rapidly.

Three years of operational experience from Schauinsland CTBT monitoring station.

PubMed

Zähringer, M; Bieringer, J; Schlosser, C

2008-04-01

Data from three years of operation of a low-level aerosol sampler and analyzer (RASA) at Schauinsland monitoring station are reported. The system is part of the International Monitoring System (IMS) for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The fully automatic system is capable to measure aerosol borne gamma emitters with high sensitivity and routinely quantifies 7Be and 212Pb. The system had a high level of data availability of 90% within the reporting period. A daily screening process rendered 66 tentative identifications of verification relevant radionuclides since the system entered IMS operation in February 2004. Two of these were real events and associated to a plausible source. The remaining 64 cases can consistently be explained by detector background and statistical phenomena. Inter-comparison with data from a weekly sampler operated at the same station shows instabilities of the calibration during the test phase and a good agreement since certification of the system.

Nitrate radical oxidation of γ-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields

NASA Astrophysics Data System (ADS)

Slade, Jonathan H.; de Perre, Chloé; Lee, Linda; Shepson, Paul B.

2017-07-01

Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO3), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO3. Under dry conditions, the hydroxy nitrate yield = 4(+1/-3) %, total ON yield = 14(+3/-2) %, and SOA yield ≤ 10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO3. Using a chemical box model, we show that the measured concentrations of NO2 and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO3 chemistry. This suggests that NO3 addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography-mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.

Chemical Components, Variation, and Source Identification of PM1 during the Heavy Air Pollution Episodes in Beijing in December 2016

NASA Astrophysics Data System (ADS)

Zhang, Yangmei; Wang, Yaqiang; Zhang, Xiaoye; Shen, Xiaojing; Sun, Junying; Wu, Lingyan; Zhang, Zhouxiang; Che, Haochi

2018-02-01

Air pollution is a current global concern. The heavy air pollution episodes (HPEs) in Beijing in December 2016 severely influenced visibility and public health. This study aims to survey the chemical compositions, sources, and formation processes of the HPEs. An aerodyne quadruple aerosol mass spectrometer (Q-AMS) was utilized to measure the non-refractory PM1 (NR-PM1) mass concentration and size distributions of the main chemical components including organics, sulfate, nitrate, ammonium, and chloride in situ during 15-23 December 2016. The NR-PM1 mass concentration was found to increase from 6 to 188 μg m-3 within 5 days. During the most serious polluted episode, the PM1 mass concentration was about 2.6 times that during the first pollution stage and even 40 times that of the clean days. The formation rates of PM2.5 in the five pollution stages were 26, 22, 22, 32, and 67 μg m-3 h-1, respectively. Organics and nitrate occupied the largest proportion in the polluted episodes, whereas organics and sulfate dominated the submicron aerosol during the clean days. The size distribution of organics is always broader than those of other species, especially in the clean episodes. The peak sizes of the interested species grew gradually during different HPEs. Aqueous reaction might be important in forming sulfate and chloride, and nitrate was formed via oxidization and condensation processes. PMF (positive matrix factorization) analysis on AMS mass spectra was employed to separate the organics into different subtypes. Two types of secondary organic aerosol with different degrees of oxidation consisted of 43% of total organics. By contrast, primary organics from cooking, coal combustion, and traffic emissions comprised 57% of the organic aerosols during the HPEs.

Coarse and fine aerosol source apportionment in Rio de Janeiro, Brazil

NASA Astrophysics Data System (ADS)

Godoy, Maria Luiza D. P.; Godoy, José Marcus; Roldão, Luiz Alfredo; Soluri, Daniela S.; Donagemma, Raquel A.

The metropolitan area of Rio de Janeiro is one of the twenty biggest urban agglomerations in the world, with 11 million inhabitants in the metropolitan area, and has a high population density, with 1700 hab. km -2. For this aerosol source apportionment study, the atmospheric aerosol sampling was performed at ten sites distributed in different locations of the metropolitan area from September/2003 to December/2005, with sampling during 24 h on a weekly basis. Stacked filter units (SFU) were used to collect fine and coarse aerosol particles with a flow rate of 17 L min -1. In both size fractions trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as well as water-soluble species by Ion-Chromatography (IC). Also gravimetric analysis and reflectance measurements provided aerosol mass and black carbon concentrations. Very good detection limits for up to 42 species were obtained. Mean annual PM 10 mass concentration ranged from 20 to 37 μg m -3, values that are within the Brazilian air quality standards. Receptor models such as principal factor analysis, cluster analysis and absolute principal factor analysis were applied in order to identify and quantify the aerosol sources. For fine and coarse modes, circa of 100% of the measured mass was quantitatively apportioned to relatively few identified aerosol sources. A very similar and consistent source apportionment was obtained for both fine and coarse modes for all 10 sampling sites. Soil dust is an important component, accounting for 22-72% and for 25-48% of the coarse and fine mass respectively. On the other hand, anthropogenic sources as vehicle traffic and oil combustion represent a relatively high contribution (52-75%) of the fine aerosol mass. The joint use of ICP-MS and IC analysis of species in aerosols has proven to be reliable and feasible for the analysis of large amount of samples, and the coupling with receptor models provided an excellent method for quantitative aerosol source apportionment in large urban areas.

Aerosol source apportionment based on multi-wavelength photoacoustic light absorption measurements: a simulation method for system's optimisation

NASA Astrophysics Data System (ADS)

Simon, Károly; Ajtai, Tibor; Kiss-Albert, Gergely; Utry, Noémi; Pintér, Máté; Szabó, Gábor; Bozóki, Zoltán

2017-04-01

Aerosol source apportionment is currently one of the outstanding challenges for environmental monitoring. In most cases atmospheric aerosol is a heterogeneous mixture as it typically originates from various sources. Consequently, each aerosol type has distinct chemical and physical properties. Contrary to chemical properties, optical absorption and size distribution of airborne particles can be measured in real time with high time resolution i.e. their measurement facilitates real time source apportionment (Favez et al (2009), Ajtai et al (2011), Favez et al (2010)). The wavelength dependency of the optical absorption coefficient (OAC) is usually characterised by the Absorption Angström Exponent (AAE). So far, the selection of light sources (lasers) into a photoacoustic aerosol measuring system was based on rule of thumb type estimations only. Recently, we proposed a simulation method that can be used to estimate the accuracy of aerosol source apportionment in case of a dual wavelength photoacoustic system (Simon et al., (2017)). This simulation is based on the assumption that the atmospheric aerosol load is dominated by two distinct sources and each of them is strongly light absorbing with specific AAE values. This is a typical scenario e.g. for urban measurements under wintry conditions when dominating aerosol sources are fossil fuel and wood burning with characteristic AAE 1 and 2, respectively. The wavelength pair of 405 and 1064 nm was found to be optimal for source apportionment in this case. In the presented study we investigated the situation when there are aerosol components with only slightly different AAE values and searched for a photoacoustic system which is optimal for distinguishing these components. Ajtai, T.; Filep, Á.; Utry, N.; Schnaiter, M.; Linke, C.; Bozóki, Z.; Szabó, G. and Leisner T. (2011) Journal of Aerosol Science 42, 859-866. Favez, O.; Cachier, H.; Sciare, J.; Sarda-Estève, R. and Martinon, L. (2009) Atmospheric Environment 43, 3640-3644. Favez, O.; El Haddad, I.; Piot, C.; Boréave, A.; Abidi, E.; Marchand, N.; Jaffrezo, J. L.; Besombes, J. L.; Personnaz, M. B.; Sciare, J.; Wortham, H.; George, C. and D'Anna, B. (2010), Atmos. Chem. Phys. 10, 5295-5314. Simon, K.A.; Ajtai, T; Gulyas, G; Utry, N; Pinter, M; Szabo, G. and Bozoki, Bozoki, Z. (2017), Journal of Aerosol Science 104, 10-15.

Aerosol and CCN over the Southern Ocean: Sources, Sinks and Processes

NASA Astrophysics Data System (ADS)

Clarke, A. D.; Freitag, S.; Howell, S. G.; Snider, J. R.; Kazil, J.; Feingold, G.; McNaughton, C. S.; Brekhovskikh, V.; Kapustin, V.; Campos, T. L.; Shank, L.

2013-12-01

Aerosol able to activate as cloud condensation nuclei (CCN) in marine stratus play an important role in cloud properties and processes. The 2008 VOCALS experiment (http://www.eol.ucar.edu/projects/vocals/) explored the aerosol cloud system over the South East Pacific (SEP). There, marine boundary layer (MBL) air from the Southern Ocean is directed north parallel to the South American coast and exposed to continental emissions. During this transport the initial clean MBL aerosol is modified in response to production, processing, entrainment, mixing, and removal. Here we discuss how the aerosol, the CCN and the clouds over the SEP are coupled by these processes. VOCALS data along 20S indicated cleanest air offshore and west of about 78W. However, some of the cleanest air (lowest CO concentrations) over the SEP were present in pockets of open cells (POC's). This suggests POC's are favored in places where remnants of Southern Ocean MBL air experienced the least mixing with higher CO sources during transport, either coastal or via entrainment of free troposphere air. Entrainment from the free troposphere (FT) was found to be an important source of marine boundary layer (MBL) aerosol in both near-shore and off-shore regions while direct advection of continental aerosol tended to influence aerosol and CCN closer to the coast. Entrainment from the FT included diverse sources from South America as well as long range transport from the western Pacific. Entrainment of FT aerosol can resupply the MBL with CCN and this process appears greatly enhanced when patchy 'rivers' of pollution lie directly above the inversion. This process was evident both offshore and near the coast. Production of CCN from sea spray aerosol (SSA) were found to increase with wind speed but atmospheric concentrations did not generally increase in the higher wind offshore regions because these regions had greater drizzle removal that compensated for increased production. Generally SSA larger than 60 nm were effective as marine cloud CCN but were only about 20% of the total. Elevated organic aerosol was usually associated with biomass burning sources and a natural marine organic aerosol source was weak. Although nucleation in clean scavenged air layers near the top of the boundary layer were observed under certain conditions, the resulting small aerosol sizes did not appear to provide an effective source of CCN sizes compared to other processes.

Aerosols in the Atmosphere: Sources, Transport, and Multi-decadal Trends

NASA Technical Reports Server (NTRS)

Chin, M.; Diehl, T.; Bian, H.; Kucsera, T.

2016-01-01

We present our recent studies with global modeling and analysis of atmospheric aerosols. We have used the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and satellite and in situ data to investigate (1) long-term variations of aerosols over polluted and dust source regions and downwind ocean areas in the past three decades and the cause of the changes and (2) anthropogenic and volcanic contributions to the sulfate aerosol in the upper tropospherelower stratosphere.

A study of photochemical againg of ambient air using Potential Aerosol Mass (PAM) chamber under the different sources and types of emissions

NASA Astrophysics Data System (ADS)

Lee, T.; Son, J.; Kim, J.; Kim, S.; Sung, K.; Park, G.; Link, M.; Park, T.; Kim, K.; Kang, S.; Ban, J.; Kim, D. S.

2016-12-01

Recent research proposed that Secondary Aerosol (SA) is important class of predicting future climate change scenarios, health effect, and a general air quality. However, there has been lack of studies to investigate SA formation all over the world. This study tried to focus on understanding potential secondary aerosol formation and its local impact by the photochemical aging of inorganic and organic aerosols in the ambient air using the Potential Aerosol Mass (PAM) chamber under the different sources and types of emissions. PAM chamber manufactured by Aerodyne make an oxidizing environment that simulates oxidation processes on timescales of 12-15 hrs in the atmosphere. Chemical compositions of ambient aerosol and aerosol that was aged in the PAM chamber were alternately measured every 2-minutes using the High Resolution-Time of Flight-Aerosol Mass Spectrometer (HR-ToF-AMS). HR-ToF-AMS provides non-refractory aerosol mass concentrations including nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol in real time. This study includes a residence area of mixture of sources, a forest site of dominant source of biogenic VOCs, an underground parking lot of dominant vehicle emission, and laboratory experiment of vehicle emissions under different fuels and speeds using the chassis dynamometer. As a result, it was revealed that gasoline and LPG vehicle relatively made more potential SA than diesel vehicle.

Potential origin of organic CNN observed at a marine site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrews, E.; Kreidenweis, S.M.; Penner, J.E.

1995-12-31

Observations by Novakov and Penner (1993) suggest that organic aerosol particles may make up a significant portion of cloud condensation nuclei (CCN) comparable, perhaps, to the sulfate aerosol contribution to CCN. Because organic CCN would influence the albedo and radiative properties of clouds and play a role in climate change, it is important to identify the sources of these aerosols. In their research Novakov and Penner assumed that particles larger than 0.05 {mu}m could act as CCN. Therefore the origins of nucleation mode aerosol (0.03 < dp < 0.1 {mu}m) are the focus of our research. In our research, wemore » apply a dynamic aerosol model (MAEROS) to explore potential sources of the nucleation mode organic aerosol observed at a marine site in Puerto Rico. Novakov and Penner measured the size segregated mass and composition of the atmospheric aerosol at this site and found that organic aerosol mass dominated the sulfate mass in the nucleation size range. The presence of organics in this size range suggests that these organic aerosol particles were generated by nucleation of a gas phase organic followed by condensational processes, i.e., identifying sources of the gas phase precursors is important to determining the organic CCN origins. Back trajectory analysis shows that the air mass was without continental contact for 12 days prior to being sampled. This implicates two possible sources for the gas phase organic: biogenic emissions from the Puerto Rican forest and emissions from the ocean surface. In this research we explore both the forest and ocean source scenarios, showing that the forest is more likely to be the ultimate source of the observed organic aerosol particles. Using MAEROS (modified to include nucleation) and reasonable input parameters taken from the literature we were able to show that an organic vapor flux very similar to the measured biogenic fluxes reported by Zimmerman et al. generated size distributions similar to the observed aerosol.« less

ISS Ambient Air Quality: Updated Inventory of Known Aerosol Sources

NASA Technical Reports Server (NTRS)

Meyer, Marit

2014-01-01

Spacecraft cabin air quality is of fundamental importance to crew health, with concerns encompassing both gaseous contaminants and particulate matter. Little opportunity exists for direct measurement of aerosol concentrations on the International Space Station (ISS), however, an aerosol source model was developed for the purpose of filtration and ventilation systems design. This model has successfully been applied, however, since the initial effort, an increase in the number of crewmembers from 3 to 6 and new processes on board the ISS necessitate an updated aerosol inventory to accurately reflect the current ambient aerosol conditions. Results from recent analyses of dust samples from ISS, combined with a literature review provide new predicted aerosol emission rates in terms of size-segregated mass and number concentration. Some new aerosol sources have been considered and added to the existing array of materials. The goal of this work is to provide updated filtration model inputs which can verify that the current ISS filtration system is adequate and filter lifetime targets are met. This inventory of aerosol sources is applicable to other spacecraft, and becomes more important as NASA considers future long term exploration missions, which will preclude the opportunity for resupply of filtration products.

Use of stable carbon and nitrogen isotope ratios in size segregated aerosol particles for the O/I penetration evaluation

NASA Astrophysics Data System (ADS)

Garbaras, Andrius; Garbariene, Inga; Masalaite, Agne; Ceburnis, Darius; Krugly, Edvinas; Kvietkus, Kestutis; Remeikis, Vidmantas; Martuzevicius, Dainius

2015-04-01

Stable carbon and nitrogen isotope ratio are successfully used in the atmospheric aerosol particle source identification [1, 2], transformation, pollution [3] research. The main purpose of this study was to evaluate the penetration of atmospheric aerosol particles from outdoor to indoor using stable carbon and nitrogen isotope ratios. Six houses in Kaunas (Lithuania) were investigated during February and March 2013. Electrical low pressure impactor was used to measure in real time concentration and size distribution of outdoor aerosol particles. ELPI+ includes 15 channels covering the size range from 0.017 to 10.0 µm. The 25 mm diameter aluminium foils were used to collect aerosol particles. Gravimetric analysis of samples was made using microbalance. In parallel, indoor aerosol samples were collected with a micro-orifice uniform deposition impactor (MOUDI model 110), where the aerosol particles were separated with the nominal D50 cut-off sizes of 0.056, 0.1, 0.18,0.32,0.56, 1.0, 1.8, 3.2, 5.6, 10, 18 μm for impactor stages 1-11, respectively. The impactor was run at a flow rate of 30 L/min. Air quality meters were used to record meteorological conditions (temperature, relative humidity) during the investigated period. All aerosol samples were analyzed for total carbon (TC) and total nitrogen (TN) contents and their isotopic compositions using elemental analyzer (EA) connected to the stable isotope ratio mass spectrometer (IRMS). TC concentration in indoors ranged from 1.5 to 247.5 µg/m3. During the sampling period outdoors TN levels ranged from 0.1 to 10.9 µg/m3. The obtained outdoor δ13C(PM2.5) values varied from -24.21 to -26.3‰, while the δ15N values varied from 2.4 to 11.1 ‰ (average 7.2±2.5 ‰). Indoors carbonaceous aerosol particles were depleted in 13C compared to outdoors in all sampling sites. This depletion in δ13C varied from 0.1 to 3.2 ‰. We think that this depletion occurs due ongoing chemical reactions (oxidation) when aerosol particles penetrates from outside to inside. Observed isotope ratio depletion indicates that information about aerosol sources can be lost if measurements are performed only inside house. Using carbon and nitrogen isotope ratios data set, we were able to identify and distinguish main aerosol sources (traffic, heating activities) and penetration of aerosol particles from outdoor to indoor. Acknowledgment This work was supported by Research Council of Lithuania under grant "Pollution Control in Biomass Combustion: from Pollutant Formation to Human Exposure" (BioMassPoll), Project no. ATE05/2012. EPA Ireland is acknowledged for the fellowship grant of D. Ceburnis 1. Garbaras, A. Masalaite, I. Garbariene, D. Ceburnis, E. Krugly V. Remeikis, E. Puida K. Kvietkus, D. Martuzevicius, Stable carbon fractionation in size-segregated aerosol particles produced by controlled biomass burning, Journal of Aerosol Science, Vol. 79, p. 86-96 (2015); 2. D. Ceburnis, A. Garbaras, S. Szidat, M. Rinaldi, S. Fahrni, N. Perron, L. Wacker, S. Leinert, V. Remeikis, M. C. Facchini, A. S. H. Prevot, S. G. Jennings, and C. D. O'Dowd, Quantification of the carbonaceous matter origin in submicron marine aerosol particles by dual carbon isotope analysis, Atmospheric Chemistry and Physics, Vol 11, pp. 8593-8606 (2011); 3. V. Ulevicius, S. Bycenkiene, V. Remeikis, A. Garbaras, S. Kecorius, J. Andriejauskiene, D. Jasineviciene, G. Mocnik, Characterization of pollution events in the East Baltic region affected by regional biomass fire emissions, Atmospheric Research, Vol. 98 (2-4), pp. 190-200 (2010).

Assessment of diverse algorithms applied on MODIS Aqua and Terra data over land surfaces in Europe

NASA Astrophysics Data System (ADS)

Glantz, P.; Tesche, M.

2012-04-01

Beside an increase of greenhouse gases (e.g., carbon dioxide, methane and nitrous oxide) human activities (for instance fossil fuel and biomass burning) have lead to perturbation of the atmospheric content of aerosol particles. Aerosols exhibits high spatial and temporal variability in the atmosphere. Therefore, aerosol investigation for climate research and environmental control require the identification of source regions, their strength and aerosol type, which can be retrieved based on space-borne observations. The aim of the present study is to validate and evaluate AOT (aerosol optical thickness) and Ångström exponent, obtained with the SAER (Satellite AErosol Retrieval) algorithm for MODIS (MODerate resolution Imaging Spectroradiometer) Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground), against AERONET (AErosol RObotic NETwork) observations and MODIS Collection 5 (c005) standard product retrievals (10 km), respectively, over land surfaces in Europe for the seasons; early spring (period 1), mid spring (period 2) and summer (period 3). For several of the cases analyzed here the Aqua and Terra satellites passed the investigation area twice during a day. Thus, beside a variation in the sun elevation the satellite aerosol retrievals have also on a daily basis been performed with a significant variation in the satellite-viewing geometry. An inter-comparison of the two algorithms has also been performed. The validation with AERONET shows that the MODIS c005 retrieved AOT is, for the wavelengths 0.469 and 0.500 nm, on the whole within the expected uncertainty for one standard deviation of the MODIS retrievals over Europe (Δτ = ±0.05 ± 0.15τ). The SAER estimated AOT for the wavelength 0.443 nm also agree reasonable well with AERONET. Thus, the majority of the SAER AOT values are within the MODIS expected uncertainty range, although somewhat larger RMSD (root mean square deviation) occurs compared to the results obtained with the MODIS c005 algorithm. The discrepancy between SAERand AERONET AOT is, however, substantially larger for the wavelength 488 nm, which means that several of the AOT values are without the MODIS expected uncertainty range. Both algorithms are unable to estimate Ångström exponent accurately, although the MODIS c005 algorithm performs a better job. Based on the inter-comparison of the SAER and MODIS c005 algorithms it was found here that the former estimation of AOT is for values up to 1on the whole within the expected uncertainties for one standard deviation of the MODIS retrievals, considering both Aqua and Terra and periods 1 and 3. The latter also occurs for Aqua and period 2, while then for AOT values lower than 0.5. The present algorithms were, beside aerosols emitted from clean sources and continental sources in Europe, also applied with favor on aerosol particles transported from agricultural fires in Russia and Ukraine. The latter events were associated with high aerosol loadings, although probably with similar single scattering albedo as the days classified as clean. We also present observations performed with space borne and ground-based lidars in the area investigated. From the latter platforms the vertical distribution of aerosol extinction in the atmosphere can be measured. This study suggests that the present satellite retrievals of AOT, particularly obtained with the MODIS c005 algorithm, will, in combination with the lidar measurements, be very useful in validation of regional and climate models over Europe.

Investigating Source Contributions of Size-Aggregated Aerosols Collected in Southern Ocean and Baring Head, New Zealand Using Sulfur Isotopes

NASA Astrophysics Data System (ADS)

Li, Jianghanyang; Michalski, Greg; Davy, Perry; Harvey, Mike; Katzman, Tanya; Wilkins, Benjamin

2018-04-01

Marine sulfate aerosols in the Southern Ocean are critical to the global radiation balance, yet the sources of sulfate and their seasonal variations are unclear. We separately sampled marine and ambient aerosols at Baring Head, New Zealand for 1 year using two collectors and evaluated the sources of sulfate in coarse (1-10 μm) and fine (0.05-1 μm) aerosols using sulfur isotopes (δ34S). In both collectors, sea-salt sulfate (SO42-SS) mainly existed in coarse aerosols and nonsea-salt sulfate (SO42-NSS) dominated the sulfate in fine aerosols, although some summer SO42-NSS appeared in coarse particles due to aerosol coagulation. SO42-NSS in the marine aerosols was mainly (88-100%) from marine biogenic dimethylsulfide (DMS) emission, while the SO42-NSS in the ambient aerosols was a combination of DMS (73-79%) and SO2 emissions from shipping activities ( 21-27%). The seasonal variations of SO42-NSS concentrations inferred from the δ34S values in both collectors were mainly controlled by the DMS flux.

Multi-Decadal Variation of Aerosols: Sources, Transport, and Climate Effects

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Bian, Huisheng; Streets, David

2008-01-01

We present a global model study of multi-decadal changes of atmospheric aerosols and their climate effects using a global chemistry transport model along with the near-term to longterm data records. We focus on a 27-year time period of satellite era from 1980 to 2006, during which a suite of aerosol data from satellite observations, ground-based measurements, and intensive field experiments have become available. We will use the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which involves a time-varying, comprehensive global emission dataset that we put together in our previous investigations and will be improved/extended in this project. This global emission dataset includes emissions of aerosols and their precursors from fuel combustion, biomass burning, volcanic eruptions, and other sources from 1980 to the present. Using the model and satellite data, we will analyze (1) the long-term global and regional aerosol trends and their relationship to the changes of aerosol and precursor emissions from anthropogenic and natural sources, (2) the intercontinental source-receptor relationships controlled by emission, transport pathway, and climate variability.

Remote sensing observation of annual dust cycles and possible causality of Kawasaki disease outbreaks in Japan

PubMed Central

LaHaye, Nick; Linstead, Erik; Sprigg, William A.; Yacoub, Magdi

Kawasaki disease (KD) is a rare vascular disease that, if left untreated, can result in irreparable cardiac damage in children. While the symptoms of KD are well-known, as are best practices for treatment, the etiology of the disease and the factors contributing to KD outbreaks remain puzzling to both medical practitioners and scientists alike. Recently, a fungus known as Candida, originating in the farmlands of China, has been blamed for outbreaks in China and Japan, with the hypothesis that it can be transported over long ranges via different wind mechanisms. This paper provides evidence to understand the transport mechanisms of dust at different geographic locations and the cause of the annual spike of KD in Japan. Candida is carried along with many other dusts, particles or aerosols, of various sizes in major seasonal wind currents. The evidence is based upon particle categorization using the Moderate Resolution Imaging Spectrometer (MODIS) Aerosol Optical Depth (AOD), Fine Mode Fraction (FMF) and Ångström Exponent (AE), the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) attenuated backscatter and aerosol subtype, and the Aerosol Robotic Network’s (AERONET) derived volume concentration. We found that seasonality associated with aerosol size distribution at different geographic locations plays a role in identifying dominant abundance at each location. Knowing the typical size of the Candida fungus, and analyzing aerosol characteristics using AERONET data reveals possible particle transport association with KD events at different locations. Thus, understanding transport mechanisms and accurate identification of aerosol sources is important in order to understand possible triggers to outbreaks of KD. This work provides future opportunities to leverage machine learning, including state-of-the-art deep architectures, to build predictive models of KD outbreaks, with the ultimate goal of early forecasting and intervention within a nascent global health early-warning system. PMID:29564343

Towards mechanistic representations of SOA from BVOC + NO3 reactions

EPA Science Inventory

Monoterpene reaction with nitrate radicals is a significant source of organic aerosol in the southeast United States. This source of organic aerosol represents an anthropogenic control on biogenic organic aerosol since nitrate radicals result from NOx emissions and are generally ...

Identification of aerosol types over an urban site based on air-mass trajectory classification

NASA Astrophysics Data System (ADS)

Pawar, G. V.; Devara, P. C. S.; Aher, G. R.

2015-10-01

Columnar aerosol properties retrieved from MICROTOPS II Sun Photometer measurements during 2010-2013 over Pune (18°32‧N; 73°49‧E, 559 m amsl), a tropical urban station in India, are analyzed to identify aerosol types in the atmospheric column. Identification/classification is carried out on the basis of dominant airflow patterns, and the method of discrimination of aerosol types on the basis of relation between aerosol optical depth (AOD500 nm) and Ångström exponent (AE, α). Five potential advection pathways viz., NW/N, SW/S, N, SE/E and L have been identified over the observing site by employing the NOAA-HYSPLIT air mass back trajectory analysis. Based on AE against AOD500 nm scatter plot and advection pathways followed five major aerosol types viz., continental average (CA), marine continental average (MCA), urban/industrial and biomass burning (UB), desert dust (DD) and indeterminate or mixed type (MT) have been identified. In winter, sector SE/E, a representative of air masses traversed over Bay of Bengal and Eastern continental Indian region has relatively small AOD (τpλ = 0.43 ± 0.13) and high AE (α = 1.19 ± 0.15). These values imply the presence of accumulation/sub-micron size anthropogenic aerosols. During pre-monsoon, aerosols from the NW/N sector have high AOD (τpλ = 0.61 ± 0.21), and low AE (α = 0.54 ± 0.14) indicating an increase in the loading of coarse-mode particles over Pune. Dominance of UB type in winter season for all the years (i.e. 2010-2013) may be attributed to both local/transported aerosols. During pre-monsoon seasons, MT is the dominant aerosol type followed by UB and DD, while the background aerosols are insignificant.

Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazurek, M.A.; Hildemann, L.M.; Cass, G.R.

1990-04-01

Extractable organic compounds having between 6 to 40 carbon atoms comprise an important mass fraction of the fine particulate matter samples from major urban emission sources. Depending on the emission source type, this solvent-soluble fraction accounts for <20% to 100% of the total organic aerosol mass, as measured by quantitative high-resolution has chromatography (HRGC) with flame ionization detection. In addition to total extract quantitation, HRGC can be applied to further analyses of the mass distributions of elutable organics present in the complex aerosol extract mixtures, thus generating profiles that serve as fingerprints'' for the sources of interest. This HRGC analyticalmore » method is applied to emission source samples that contain between 7 to 12,000 {mu}g/filter organic carbon. It is shown to be a sensitive technique for analysis of carbonaceous aerosol extract mixtures having diverse mass loadings and species distributions. This study describes the analytical chemical methods that have been applied to: the construction of chemical mass balances based on the mass of fine organic aerosol emitted for major urban sources of particulate carbon; and the generation of discrete emission source chemical profiles derived from chromatographic characteristics of the organic aerosol components. 21 refs., 1 fig., 2 tabs.« less

Long-range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the western Mediterranean basin

NASA Astrophysics Data System (ADS)

Ancellet, Gerard; Pelon, Jacques; Totems, Julien; Chazette, Patrick; Bazureau, Ariane; Sicard, Michaël; Di Iorio, Tatiana; Dulac, Francois; Mallet, Marc

2016-04-01

Long-range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground-based and airborne lidar measurements were deployed in the western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three-dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Minorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agrees very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (i) pure BB layer, (ii) weakly dusty BB, (iii) significant mixture of BB and dust transported from the trade wind region, and (iv) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at an altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS aerosol optical depth horizontal distribution during this episode over the western Mediterranean Sea shows that the Canadian fire contributions were as large as the direct northward dust outflow from Sahara.

“A significant source of isoprene aerosol controlled by acidity”

EPA Science Inventory

“A significant source of isoprene aerosol controlled by acidity” by Pye et al.Abstract: Isoprene is a significant contributor to organic aerosol in the southeastern United States where biogenic hydrocarbons mix with anthropogenic emissions. In this work, CMAQ provides explicit p...

Aeronet-based Microphysical and Optical Properties of Smoke-dominated Aerosol near Source Regions and Transported over Oceans, and Implications for Satellite Retrievals of Aerosol Optical Depth

NASA Technical Reports Server (NTRS)

Sayer, A. M.; Hsu, N. C.; Eck, T. F.; Smirnov, A.; Holben, B. N.

2013-01-01

Smoke aerosols from biomass burning are an important component of the global aerosol cycle. Analysis of Aerosol Robotic Network (AERONET) retrievals of size distribution and refractive index reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke transported to coastal/island AERONET sites also mostly lie within the range of variability at near-source sites. Two broad families of aerosol properties are found, corresponding to sites dominated by boreal forest burning (larger, broader fine mode, with midvisible SSA 0.95), and those influenced by grass, shrub, or crop burning with additional forest contributions (smaller, narrower particles with SSA 0.88-0.9 in the midvisible). The strongest absorption is seen in southern African savanna at Mongu (Zambia), with average SSA 0.85 in the midvisible. These can serve as candidate sets of aerosol microphysicaloptical properties for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean are often insufficiently absorbing to represent these biomass burning aerosols. A corollary of this is an underestimate of AOD in smoke outflow regions, which has important consequences for applications of these satellite datasets.

Modern dust aerosol availability in northwestern China.

PubMed

Wang, Xunming; Cheng, Hong; Che, Huizheng; Sun, Jimin; Lu, Huayu; Qiang, Mingrui; Hua, Ting; Zhu, Bingqi; Li, Hui; Ma, Wenyong; Lang, Lili; Jiao, Linlin; Li, Danfeng

2017-08-18

The sources of modern dust aerosols and their emission magnitudes are fundamental for linking dust with climate and environment. Using field sample data, wind tunnel experiments and statistical analysis, we determined the contributions of wadis, gobi (stony desert), lakebeds, riverbeds, and interdunes to modern dust aerosol availability in the three important potential dust sources including the Tarim Basin, Qaidam Basin, and Ala Shan Plateau of China. The results show that riverbeds are the dominant landscape for modern dust aerosol availabilities in the Qaidam Basin, while wadis, gobi, and interdunes are the main landscapes over the Ala Shan Plateau and Tarim Basin. The Ala Shan Plateau and Tarim Basin are potential dust sources in northwestern China, while the Qaidam Basin is not a major source of the modern dust aerosols nowadays, and it is not acting in a significant way to the Loess Plateau presently. Moreover, most of modern dust aerosol emissions from China originated from aeolian processes with low intensities rather than from major dust events.

Chemical characterization and source identification of PM2.5 at multiple sites in the Beijing-Tianjin-Hebei region, China

NASA Astrophysics Data System (ADS)

Huang, Xiaojuan; Liu, Zirui; Liu, Jingyun; Hu, Bo; Wen, Tianxue; Tang, Guiqian; Zhang, Junke; Wu, Fangkun; Ji, Dongsheng; Wang, Lili; Wang, Yuesi

2017-11-01

The simultaneous observation and analysis of atmospheric fine particles (PM2.5) on a regional scale is an important approach to develop control strategies for haze pollution. In this study, samples of filtered PM2.5 were collected simultaneously at three urban sites (Beijing, Tianjin, and Shijiazhuang) and at a regional background site (Xinglong) in the Beijing-Tianjin-Hebei (BTH) region from June 2014 to April 2015. The PM2.5 at the four sites was mainly comprised of organic matter, secondary inorganic ions, and mineral dust. Positive matrix factorization (PMF) demonstrated that, on an annual basis, secondary inorganic aerosol was the largest PM2.5 source in this region, accounting for 29.2-40.5 % of the PM2.5 mass at the urban sites; the second-largest PM2.5 source was motor vehicle exhaust, particularly in Beijing (24.9 %), whereas coal combustion was also a large source in Tianjin (12.4 %) and Shijiazhuang (15.5 %), with particular dominance in winter. Secondary inorganic aerosol plays a vital role in the haze process, with the exception of the spring haze in Shijiazhuang and Tianjin, for which the dust source was crucial. In addition to secondary transformations, local direct emissions (coal combustion and motor vehicle exhaust) significantly contribute to the winter haze at the urban sites. Moreover, with the aggravation of haze pollution, the OC / EC mass ratio of PM2.5 decreased considerably and the nitrate-rich secondary aerosol increased during all four seasons in Beijing, both of which indicate that local motor vehicle emissions significantly contribute to the severe haze episodes in Beijing. To assess the impacts of regional transport on haze pollution, the PMF results were further processed with backward-trajectory cluster analysis, revealing that haze pollution usually occurred when air masses originating from polluted industrial regions in the south prevailed and is characterized by high PM2.5 loadings with considerable contributions from secondary aerosols. This study suggests that control strategies to mitigate haze pollution in the BTH region should focus on the reduction of gaseous precursor emissions from fossil fuel combustion (motor vehicle emissions in Beijing and coal combustion in Tianjin, Hebei, and nearby provinces).

Single particle characterization, source apportionment, and aging effects of ambient aerosols in Southern California

NASA Astrophysics Data System (ADS)

Shields, Laura Grace

Composed of a mixture of chemical species and phases and existing in a variety of shapes and sizes, atmospheric aerosols are complex and can have serious influence on human health, the environment, and climate. In order to better understand the impact of aerosols on local to global scales, detailed measurements on the physical and chemical properties of ambient particles are essential. In addition, knowing the origin or the source of the aerosols is important for policymakers to implement targeted regulations and effective control strategies to reduce air pollution in their region. One of the most ground breaking techniques in aerosol instrumentation is single particle mass spectrometry (SPMS), which can provide online chemical composition and size information on the individual particle level. The primary focus of this work is to further improve the ability of one specific SPMS technique, aerosol time-of-flight mass spectrometry (ATOFMS), for the use of identifying the specific origin of ambient aerosols, which is known as source apportionment. The ATOFMS source apportionment method utilizes a library of distinct source mass spectral signatures to match the chemical information of the single ambient particles. The unique signatures are obtained in controlled source characterization studies, such as with the exhaust emissions of heavy duty diesel vehicles (HDDV) operating on a dynamometer. The apportionment of ambient aerosols is complicated by the chemical and physical processes an individual particle can undergo as it spends time in the atmosphere, which is referred to as "aging" of the aerosol. Therefore, the performance of the source signature library technique was investigated on the ambient dataset of the highly aged environment of Riverside, California. Additionally, two specific subsets of the Riverside dataset (ultrafine particles and particles containing trace metals), which are known to cause adverse health effects, were probed in greater detail. Finally, the impact of large wildfires on the ambient levels of particulate matter in Southern California is discussed. The results of this work provide insight into single particles impacting the Southern California region, the relative source contributions to this region, and finally an examination of how atmospheric aging influences the ability to perform source apportionment.

Climate response of the South Asian monsoon system to anthropogenic aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganguly, Dilip; Rasch, Philip J.; Wang, Hailong

2012-07-13

The equilibrium climate response to the total effects (direct, indirect and semi-direct effects) of aerosols arising from anthropogenic and biomass burning emissions on the South Asian summer monsoon system is studied using a coupled atmosphere-slab ocean model. Our results suggest that anthropogenic and biomass burning aerosols generally induce a reduction in mean summer monsoon precipitation over most parts of the Indian subcontinent, strongest along the western coastline of the Indian peninsula and eastern Nepal region, but modest increases also occur over the north western part of the subcontinent. While most of the noted reduction in precipitation is triggered by increasedmore » emissions of aerosols from anthropogenic activities, modest increases in the north west are mostly associated with decreases in local emissions of aerosols from forest fire and grass fire sources. Anthropogenic aerosols from outside Asia also contribute to the overall reduction in precipitation but the dominant contribution comes from aerosol sources within Asia. Local emissions play a more important role in the total rainfall response to anthropogenic aerosol sources during the early monsoon period, whereas both local as well as remote emissions of aerosols play almost equally important roles during the later part of the monsoon period. While precipitation responses are primarily driven by local aerosol forcing, regional surface temperature changes over the region are strongly influenced by anthropogenic aerosols from sources further away (non-local changes). Changes in local anthropogenic organic and black carbon emissions by as much as a factor of two (preserving their ratio) produce the same basic signatures in the model's summer monsoon temperature and precipitation responses.« less

Sensitive Detection and Identification of Isovanillin Aerosol Particles at the pg/cm3 Mass Concentration Level using Raman Spectroscopy

DTIC Science & Technology

2017-04-24

Spectroscopy * R. L. Aggarwal1, S. Di Cecca, L. W. Farrar, Shabshelowitz, A...Public Release A compact Raman spectroscopy system with high sensitivity to chemical aerosols has been developed. This system has been used to...this represents the lowest chemical aerosol concentration and signal integration period product ever reported for a Raman spectroscopy system.

Source identification of ambient PM 2.5 during summer inhalation exposure studies in Detroit, MI

NASA Astrophysics Data System (ADS)

Morishita, Masako; Keeler, Gerald J.; Wagner, James G.; Harkema, Jack R.

Particulate air pollution is associated with cardiopulmonary morbidity and mortality in heavily populated urban centers of the United States. Because ambient fine particulate matter (aerodynamic diameter ⩽2.5 μm; PM 2.5) is a complex mixture resulting from multiple sources and variable atmospheric conditions, it is difficult to identify specific components of PM 2.5 that are responsible for adverse health effects. During four consecutive summers from 2000 to 2003 we characterized the ambient gaseous and PM 2.5 air quality in an urban southwest Detroit community where childhood asthma hospitalization rates are more than twice the statewide average. Both integrated and continuous PM measurements together with gaseous air pollution measurements were performed using a mobile air research facility, AirCARE1, in which concurrent toxicological studies were being conducted. Chemical and physical characterizations of PM 2.5 as well as receptor modeling using positive matrix factorization (PMF) were completed. Results from PMF indicated that six major sources contributed to the observed ambient PM 2.5 mass during the summer months. Primary sources included (1) coal combustion/secondary sulfate aerosol, (2) motor vehicle/urban road dust, (3) municipal waste incinerators, (4) oil combustion/refineries, (5) sewage sludge incinerators, and (6) iron/steel manufacturing. Although the contribution of the coal/secondary sulfate aerosol source was greater than other factors, increased levels of urban PM 2.5 from local combustion sources were also observed. In addition to characterization of ambient PM 2.5 and their sources in southwest Detroit, this paper discusses possible associations of ambient PM 2.5 from local combustion sources, specifically incinerator and refinery emissions and the observed adverse health effects during the inhalation exposure campaigns.

A scoping review on bio-aerosols in healthcare and the dental environment.

PubMed

Zemouri, Charifa; de Soet, Hans; Crielaard, Wim; Laheij, Alexa

2017-01-01

Bio-aerosols originate from different sources and their potentially pathogenic nature may form a hazard to healthcare workers and patients. So far no extensive review on existing evidence regarding bio-aerosols is available. This study aimed to review evidence on bio-aerosols in healthcare and the dental setting. The objectives were 1) What are the sources that generate bio-aerosols?; 2) What is the microbial load and composition of bio-aerosols and how were they measured?; and 3) What is the hazard posed by pathogenic micro-organisms transported via the aerosol route of transmission? Systematic scoping review design. Searched in PubMed and EMBASE from inception to 09-03-2016. References were screened and selected based on abstract and full text according to eligibility criteria. Full text articles were assessed for inclusion and summarized. The results are presented in three separate objectives and summarized for an overview of evidence. The search yielded 5,823 studies, of which 62 were included. Dental hand pieces were found to generate aerosols in the dental settings. Another 30 sources from human activities, interventions and daily cleaning performances in the hospital also generate aerosols. Fifty-five bacterial species, 45 fungi genera and ten viruses were identified in a hospital setting and 16 bacterial and 23 fungal species in the dental environment. Patients with certain risk factors had a higher chance to acquire Legionella in hospitals. Such infections can lead to irreversible septic shock and death. Only a few studies found that bio-aerosol generating procedures resulted in transmission of infectious diseases or allergic reactions. Bio-aerosols are generated via multiple sources such as different interventions, instruments and human activity. Bio-aerosols compositions reported are heterogeneous in their microbiological composition dependent on the setting and methodology. Legionella species were found to be a bio-aerosol dependent hazard to elderly and patients with respiratory complaints. But all aerosols can be can be hazardous to both patients and healthcare workers.

Aerosol Source Attributions and Source-Receptor Relationships Across the Northern Hemisphere

NASA Technical Reports Server (NTRS)

Bian, Huisheng; Chin, Mian; Kucsera, Tom; Pan, Xiaohua; Darmenov, Anton; Colarco, Peter; Torres, Omar; Shults, Michael

2014-01-01

Emissions and long-range transport of air pollution pose major concerns on air quality and climate change. To better assess the impact of intercontinental transport of air pollution on regional and global air quality, ecosystems, and near-term climate change, the UN Task Force on Hemispheric Transport of Air Pollution (HTAP) is organizing a phase II activity (HTAP2) that includes global and regional model experiments and data analysis, focusing on ozone and aerosols. This study presents the initial results of HTAP2 global aerosol modeling experiments. We will (a) evaluate the model results with surface and aircraft measurements, (b) examine the relative contributions of regional emission and extra-regional source on surface PM concentrations and column aerosol optical depth (AOD) over several NH pollution and dust source regions and the Arctic, and (c) quantify the source-receptor relationships in the pollution regions that reflect the sensitivity of regional aerosol amount to the regional and extra-regional emission reductions.

Synthesizing Scientific Progress: Outcomes from US EPA’s Carbonaceous Aerosols and Source Apportionment STAR Grants

EPA Science Inventory

ABSTRACTA number of studies in the past decade have transformed the way we think about atmospheric aerosols. The advances include, but are not limited to, source apportionment of organics using aerosol mass spectrometer data, the volatility basis set approach, quantifying isopre...

Time resolved aerosol monitoring in the urban centre of Soweto

NASA Astrophysics Data System (ADS)

Formenti, P.; Annegarn, H. J.; Piketh, S. J.

1998-03-01

A programme of aerosol sampling was conducted from 1982 to 1984 in the urban area of Soweto, Johannesburg, South Africa. The particulate matter (aerodynamic diameter <15 μm) was collected using a two hours time resolution single stage streaker sampler and elemental concentrations were resolved via Particle Induced X-ray Emission (PIXE) analysis. Samples have been selected for analysis from an aerosol sample archive to establish base-line atmospheric conditions that existed in Soweto prior to large scale electrification, and to establish source apportionment of crustal elements between coal smoke and traffic induced road dust, based on chemical elemental measurements. A novel technique is demonstrated for processing PIXE-derived time sequence elemental concentration vectors. Slowly varying background components have been extracted from sulphur and crustal aerosol components, using alternatively two digital filters: a moving minimum, and a moving average. The residuals of the crustal elements, assigned to locally generated aerosol components, were modelled using surrogate tracers: sulphur as a surrogate for coal smoke; and Pb as a surrogate for traffic activity. Results from this source apportionment revealed coal emissions contributed between 40% and 50% of the aerosol mineral matter, while 18-22% originated from road dust. Background aerosol, characteristic of the regional winter aerosol burden over the South African Highveld, was between 12% and 21%. Minor contributors identified included a manganese smelter, located 30 km from the sampling site, and informal trash burning, as the source of intermittent heavy metals (Cu, Zn). Elemental source profiles derived for these various sources are presented.

Urban emission, Santa Ana wind, and fire sources of aerosol nitrogen in Southern California

NASA Astrophysics Data System (ADS)

Mackey, K. R.; Stragier, S.; Robledo, L.; Cat, L. A.; Czimczik, C. I.

2017-12-01

Southern California is a highly urbanized region surrounded by extensive areas of agriculture and wilderness. While emissions from fossil fuel combustion are a large source of aerosol NOx in urban areas, fires contribute considerable aerosol NOx and ammonium in undeveloped regions. Southern California also has frequent wildfires, particularly during dry Santa Ana wind events that occur periodically throughout the winter. To explore the relative contributions of these sources to aerosol nitrogen content, we collected aerosol samples over two years in Irvine, a city in Southern California approximately 6 km from the Pacific coast. Samples were analyzed for total nitrogen and carbon content and isotopic composition (δ15N and δ13C), and nitrate and ammonium content. Carbon content was higher and δ13C values were lower in the winter than the summer. The C/N ratios of two samples collected during a Santa Ana wind event in January of 2012 were particularly elevated (C/N of 22 and 30) relative to other samples (C/N 3-6). We found that ammonium comprised 35% of total aerosol N across samples (R2=0.65), and that the δ15N of aerosol nitrogen decreased logarithmically as the proportion of nitrate in the sample increased (R2=0.60). Aerosol deposition of bioavailable nitrate and ammonium from these sources may support primary productivity in Southern California's coastal waters, particularly during the winter months and El Nino periods when upwelled nutrient sources are limited.

A Campaign Study of Sea Spray Aerosol Properties in the Bay of Aarhus

NASA Astrophysics Data System (ADS)

Nguyen, Quynh; Rasmussen, Berit; Kristensen, Kasper; Sloth Nielsen, Lærke; Bilde, Merete

2016-04-01

The oceans of the world are a dominant source of atmospheric aerosol. Together with mineral dust, sea spray aerosols (SSA) constitute the largest mass flux of particulate matter in the atmosphere (Andreae and Rosenfeld, 2008). Due to their effects on the global radiative budget - both directly as scatterers and absorbers of solar and terrestrial radiation, and indirectly as cloud condensation nuclei (CCN), SSA are considered an important component of the climate system. The sea-surface microlayer (SML) is an ultra-thin boundary layer between the ocean and the atmosphere. The high concentration of surface-active organic compounds in the SML, compared to that of the underlying water column, creates rigid film-like layer over the surface of the ocean. The SML is believed to play an important role in the formation and composition of SSA. However, current knowledge on the SML and its impacts on SSA remain limited. To characterize the SML of natural seawater and examine its impacts on aerosol properties, a field campaign was conducted in the bay of Aarhus, Denmark, during spring 2015. Bulk seawater was collected 1-2 times every week along with selective sampling of the SML. Characterization of the sea water and SML included a wide range of measurements, including surface tension, water activity, dissolved organic matter, and chemical composition analysis by liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS). SSA was generated from sampled sea water by diffusion of air bubbles through a 10L seawater sample situated in a sea spray tank. Particle number concentration and CCN measurements were conducted along with measurements of the organic share in the aerosol phase as indicated by volatility measurements. To investigate the effect of the SML, spiking of the seawater samples with additional SML was performed and measurements repeated for comparison. Preliminary results show that the SML samples only displayed slightly lower surface tension compared to subsurface seawater. A number of overlapping masses were observed in dissolved organic matter extracted from SML and slick samples, which requires further identification. Spiking bulk seawater with SML seems to lead to a small increase in organic share in the aerosol phase as indicated by volatility measurements, while the trend is unclear in CCN measurements. Andreae, M. O., and Rosenfeld, D.: Aerosol-cloud-precipitation interactions. Part 1. The nature and sources of cloud-active aerosols, Earth-Sci Rev, 89, 13-41, 2008.

Long range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the Western Mediterranean basin

NASA Astrophysics Data System (ADS)

Ancellet, G.; Pelon, J.; Totems, J.; Chazette, P.; Bazureau, A.; Sicard, M.; Di Iorio, T.; Dulac, F.; Mallet, M.

2015-11-01

Long range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground based and airborne lidar measurements were deployed in the Western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Menorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agree very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from Western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the Westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (I) pure BB layer, (II) weakly dusty BB, (III) significant mixture of BB and dust transported from the trade wind region (IV) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at altitude above 5 km. The mixing corresponds to a 20-30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS AOD horizontal distribution during this episode over the Western Mediterranean sea shows that the Canadian fires contribution were as large as the direct northward dust outflow from Sahara.

Antarctic new particle formation from continental biogenic precursors

NASA Astrophysics Data System (ADS)

Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

2012-12-01

Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in the continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time when freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

Antarctic new particle formation from continental biogenic precursors

NASA Astrophysics Data System (ADS)

Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

2013-04-01

Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

IN SILLICO LOBAR MODELS OF HUMAN LUNGS FOR TARGETED DELIVERY OF AEROSOLIZED PHARMACEUTICALS

EPA Science Inventory

The identification of factors affecting the deposition patterns of aerosolized pharmaceuticals has important implications to medicine (e.g., inhalation therapy regimens) and toxicology (e.g., drug testing protocols). Airway morphology is a critical element of the process, influen...

Chemistry of Titan's Aerosols : Correlation of The C/n &C/h Ratios To Pressure and Temperature

NASA Astrophysics Data System (ADS)

Bernard, J.-M.; Coll, P.; Raulin, F.

The gas present in Titan's atmosphere are forming organics aerosols under action of the solar radiations and of electrons from Saturn's magnetosphere. Many experimental simulations are been realised by irradiating N2/CH4 gas mixtures with different en- ergy sources in order to reproduce the chemistry of gas and particulate phases (Thomp- son et al, 1991; Mc Donald et al, 1994; de Vanssay et al, 1995; McKay, 1996; Coll et al, 1997, 1998a,b; and Refs. included). Until very recently, only one organics re- mains detected in Titan but not in laboratory simulation : C4N2. A full program of experimental research has been developed at LISA, which was able to provide a com- plete identification of a wide range of compounds, proposed to be present in Titan's atmosphere, including C4N2. The composition of aerosol on Titan is not known, due to its complexity. Especially its building molecules are difficult to identify. Only functional groups of analogues have been determined using spectroscopy and pyrolysis. However this chemical composi- tion is a key parameter for Cassini-Huygens experiments and atmospheric modeling : even the optical properties of aerosols are related to C/N and C/H ratios. We will present the results of the variation of C/N and C/H ratios according to the temperature and the pressure in Titan's atmosphere simulations. This data will allow to constraint photochemical models, in order for them to be more realistic. Then the comprehension of the mechanism of aerosols formation on Titan as function of altitude will be easier.

Physical and Chemical Properties of Anthropogenic Aerosols: An overview

EPA Science Inventory

A wide variety of anthropogenic sources emit fine aerosols to the atmosphere. The physical and chemical properties of these aerosols are of interest due to their influence on climate, human health, and visibility. Aerosol chemical composition is complex. Combustion aerosols can c...

Day-night differences in the composition and sources of carbonaceous aerosol at a polluted regional background site in the Netherlands

NASA Astrophysics Data System (ADS)

Dusek, Ulrike; Broekema, Elise; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro

2017-04-01

The origin of carbonaceous aerosol differs during day- and night-time, because emissions from major sources such as traffic, biomass combustion, and secondary organic aerosol formation show a distinct diurnal pattern. Moreover, photochemical processing and evaporation of semi-volatile organic compounds are enhanced during day-time, due to the availability of sunlight and higher temperatures. Assessing day-night differences in sources and chemical composition can give an indication of the importance of local/regional carbon sources and processing, since day-night differences should be averaged out during long-range transport. If local sources dominate, one could expect a strong diurnal variation in the source profile, but if long-range transport dominates the diurnal variation would be much weaker. In this study we measure the isotopic (14C and 13C) and detailed chemical composition of the organic fraction of the aerosol on high volume PM2.5 filter samples that were collected separately during day and night time. Radiocarbon (14C) measurements are used to estimate three main aerosol sources of organic and elemental carbon (OC and EC): Fossil fuel combustion (ff), biomass combustion (bb), and biogenic sources (bio). The detailed chemical and stable isotopic composition are measured at different desorption temperatures from the filter, which separates the more and less refractory organic compounds. The composition of the organic aerosol is measured using an thermal-desporption Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) method (Holzinger et al, 2010) and the stable isotopic composition is measured using a thermal desorption IRMS method (Dusek et al., 2013). Source apportionment results using 14C show that the contribution of fossil fuel combustion to EC and OC is higher during day-time than during night-time. This is valid for all seasons. During night-time biomass combustion plays a bigger role as a source of carbonaceous aerosol. Even in the summer, when biomass combustion is a small source, its relative contribution increases between 19:00 and 07:00. However, the diurnal changes in source contributions are relatively moderate (e.g., the biomass burning contribution to TC increased from 31% to 43% for the winter sample with the most distinct day-night difference.) This highlights the importance of long-range transport as a source of the carbonaceous aerosol in this region. First results from chemical composition measurements on four of the samples show that the concentration of less refractory organic carbon (desorption temperature up to 200 °C) increases at night-time much more strongly than the concentration of the more refractory carbon. Similarly, the concentration of small organic compounds with m/z < 100 also increases more strongly than heavier compounds. This indicates partitioning of semi-volatile OC as a possible additional night-time source. The chemical composition will be studied in more detail, focusing on diurnal changes in O/C ratios, individual compounds and compound classes, such as hydrocarbons or organic acids. Dusek, U., Meusinger, C., Oyama, B., Ramon, W., de Wilde, P., Holzinger, R., and Röckmann, T.: A thermal desorption system for measuring δ 13 C ratios on organic aerosol, Journal of aerosol science, 66, 72-82, 2013. Holzinger, R., Williams, J., Herrmann, F., Lelieveld, J., Donahue, N., Röckmann, T., 2010. Aerosol analysis using a Thermal-Desorption Proton-Transfer-Reaction Mass Spectrometer (TD-PTR-MS): a new approach to study processing of organic aerosols. Atmospheric chemistry and physics 10, 2257-2267.

A Water Mass Tracer Detected in Aerosols Demonstrates Ocean-Atmosphere Mass Transfer and Links Sea Spray Aerosol to Source Waters

NASA Astrophysics Data System (ADS)

Pendergraft, M.; Grimes, D. J.; Giddings, S. N.; Feddersen, F.; Prather, K. A.; Santander, M.; Lee, C.; Beall, C.

2016-12-01

During September and October of 2015 the Cross Surfzone/Inner-shelf Dye Exchange (CSIDE) project released rhodamine WT dye to study nearshore water movement and exchange offshore along a Southern California sandy beach. We utilized this opportunity to investigate ocean-atmosphere mass transfer via sea spray aerosol and linkage to source waters. Aerosol-concentrating sampling equipment was deployed at beachside and inland locations during three dye releases. Concentrated aerosol samples were analyzed for dye content using fluorescence spectroscopy. Here we present the ocean and atmosphere conditions associated with the presence and absence of dye in aerosol samples. Dye was identified in aerosol samples collected 0.1-0.3 km from the shoreline for 6 hs during the first and third dye releases of the CSIDE project. During these releases the dye persisted in the waters upwind of the sampling equipment. Dye was not detected in aerosol samples collected during the second release during which dye was moved away from waters upwind of the sampling equipment. Recovery of a chemical tracer in sea spray aerosol allows direct linkage to a known source area in the ocean that is independent of, but supported by, wind data. Our observations demonstrate: a tight ocean-atmosphere spatial coupling; a short residence time of coastal marine constituents before transfer to the atmosphere; that the ocean is both a sink for and a source of atmospheric and terrestrial material; and that human inputs to the ocean can return to us in sea spray aerosol.

Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Dreyfus, Matthew A.

Analytical methods developed to sample and characterize ambient organic aerosols often face the trade-off between long sampling times and the loss of detailed information regarding specific chemical species present. The soft, universal ionization scheme of the Photoionization Aerosol Mass Spectrometer (PIAMS) allows for identification of various chemical compounds by a signature ion, often the molecular ion. The goal of this thesis work is to apply PIAMS to both laboratory and field experiments to answer questions regarding the formation, composition, and behavior of organic aerosols. To achieve this goal, a variety of hardware and software upgrades were administered to PIAMS to optimize the instrument. Data collection and processing software were either refined or built from the ground up to simplify difficult or monotonous tasks. Additional components were added to PIAMS with the intent to automate the instrument, enhance the results, and make the instrument more rugged and user-friendly. These changes, combined with the application of an external particle concentration system (mini-Versatile Aerosol Concentration Enrichment System, m-VACES), allowed PIAMS to be suitable for field measurements of organic aerosols. Two such field campaigns were completed, both at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware: a one week period in June, 2006, and an 18 day period in October and November of 2007. A sampling method developed was capable of collecting sufficient ambient organic aerosol and analyzing it with a time resolution of 3.5 minutes. Because of this method, short term concentration changes of individual species can be tracked. Combined with meteorological data, the behavior of these species can be analyzed as a function of time or wind direction. Many compounds are found at enhanced levels during the evening/night-time hours; potentially due to the combined effects of temperature inversion, and fresh emissions in a cooler environment. The high-time resolution data shows that rapid concentration changes of a common individual species can be lost with traditional bulk sampling, and a time resolution of 30 minutes is suggested to accurately represent these changes. Using the mass spectra collected from the extended sampling campaign, source apportionment was performed with positive matrix factorization (PMF). The resulting model features six factors either correlated to specific sources (meat cooking, car emissions/road dust, diesel exhaust) or types of compounds (phthalates, alkanes/alkanoic acids, PAHs). The high-time resolution data allowed for the observation of specific trends in each factor's behavior as a function of time and wind direction relative to the receptor site. Elemental carbon/organic carbon (EC/OC) data is used to calculate the percentages of primary and secondary organic aerosol. Primary organic aerosol (POA) constituted the vast majority of the total carbon at 91% (an average of 2.8 +/- 1.1mug/m 3); 30% of which came from combustion, and 70% from non-combustion sources. These results can be explained by the PIAMS data: the diesel factor contributes to the combustion-related POA; the car/road dust, meat cooking, and alkane/alkanoic acid factors contribute the majority of non-combustion POA. The remaining factors represent <5% of the remaining OC. Considering the compatibility of data from the EC/OC and PIAMS, the ability of PIAMS to yield molecular species information to further define the primary and secondary organic aerosol factions is a distinct advantage in describing the behavior of the Wilmington organic aerosol. PIAMS was also applied to laboratory experiments. These experiments simulated complex environmental processes in order to focus on answering a central question. By mixing cholesterol aerosol with ozone in a smog chamber, and monitoring the concentration of cholesterol with PIAMS, the rate of reaction was determined. This rate indicates that cholesterol aerosol, which is a suggested source tracer, will remain in the ambient air for a few days under normal conditions. PIAMS was also used to assist in identifying products from the ozonolysis of various monoterpenes. The product ion peaks observed indicates that both the stabilized Criegee intermediate pathway and the hydroperoxide channel are both active pathways in yielding dimers and high-order oligomer.

Primary Emission and the Potential of Secondary Aerosol Formation from Chinese Gasoline Engine Exhaust

NASA Astrophysics Data System (ADS)

Hu, Min; Peng, Jianfei; Qin, Yanhong; Du, Zhuofei; Li, Mengjin; Zheng, Rong; Zheng, Jing; Shang, Dongjie; Lu, Sihua; Wu, Yusheng; Zeng, Limin; Guo, Song; Shao, Min; Wang, Yinhui; Shuai, Shijin

2017-04-01

Along with the urbanization and economic growth, vehicle population in China reached 269 million, ranked the second in the world in 2015. Gasoline vehicle is identified to be the main source for urban PM2.5 in China, accounting for 15%-31%. In this study the impact of fuel components on PM2.5 and volatile organic compounds (VOCs) emissions from a gasoline port fuel injection (PFI) engine and a gasoline direct injection (GDI) engine are discussed. Results show that, higher proportion of aromatics, alkenes or sulfur in gasoline fuel will lead to higher PM emissions. The PM from the PFI engine mainly consists of OC and a small amount of EC and inorganic ions, while the PM discharge from the GDI engine mainly consists of EC, OM and a small amount of inorganic ions. Since the GDI engines can reduce fuel consumption and CO2 emissions, and it would become more and more popular in the near future. The characteristics of POM component, emission factors and source profile were investigated from GDI engine, particularly focused on the effect of engine speed, load and the catalyst, which will be very much helpful for source identification as source indicators. Chamber experiments were conducted to quantify the potential of secondary aerosol formation from exhaust of a PFI gasoline engine and China V gasoline fuel. During 4-5 h simulation, equivalent to10 days of atmospheric photo-oxidation in Beijing, the extreme SOA production was 426 ± 85 mg/kg fuel, with high precursors and OH exposure. 14% of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatility organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reduction of emissions of aerosol precursor gases from vehicles is essential to mediate pollution in China.

Aerosol Enhancements in the Upper Troposphere Over The Amazon Forest: Do Amazonian Clouds Produce Aerosols?

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Afchine, A.; Albrecht, R. I.; Artaxo, P.; Borrmann, S.; Cecchini, M. A.; Costa, A.; Dollner, M.; Fütterer, D.; Järvinen, E.; Klimach, T.; Konemann, T.; Kraemer, M.; Krüger, M. L.; Machado, L.; Mertes, S.; Pöhlker, C.; Poeschl, U.; Sauer, D. N.; Schnaiter, M.; Schneider, J.; Schulz, C.; Spanu, A.; Walser, A.; Weinzierl, B.; Wendisch, M.

2015-12-01

The German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) on the German research aircraft HALO took place over the Amazon Basin in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with trace gases, aerosol particles, and atmospheric radiation. The aircraft was equipped with about 30 remote sensing and in-situ instruments for meteorological, trace gas, aerosol, cloud, precipitation, and solar radiation measurements. Fourteen research flights were conducted during this campaign. Observations during ACRIDICON-CHUVA showed high aerosol concentrations in the upper troposphere (UT) over the Amazon Basin, with concentrations after normalization to standard conditions often exceeding those in the boundary layer (BL). This behavior was consistent between several aerosol metrics, including condensation nuclei (CN), cloud condensation nuclei (CCN), and chemical species mass concentrations. These UT aerosols were different in their composition and size distribution from the aerosol in the BL, making convective transport of particles unlikely as a source. The regions in the immediate outflow of deep convective clouds were found to be depleted in aerosol particles, whereas enhanced aerosol number and mass concentrations were found in UT regions that had experienced outflow from deep convection in the preceding 24-48 hours. This suggests that aerosol production takes place in the UT based on volatile and condensable material brought up by deep convection. Subsequently, downward mixing and transport of upper tropospheric aerosol may be a source of particles to the BL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of aerosol particles in the Amazonian BL, where aerosol nucleation and new particle formation has not been observed.

Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis

EPA Science Inventory

Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of...

Intercontinental Transport of Aerosols: Implication for Regional Air Quality

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Ginoux, Paul

2006-01-01

Aerosol particles, also known as PM2.5 (particle diameter less than 2.5 microns) and PM10 (particle diameter less than 10 microns), is one of the key atmospheric components that determine ambient air quality. Current US air quality standards for PM10 (particles with diameter < 10 microns) and PM2.5 (particles with diameter 2.5 microns) are 50 pg/cu m and 15 pg/cu m, respectively. While local and regional emission sources are the main cause of air pollution problems, aerosols can be transported on a hemispheric or global scale. In this study, we use the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model to quantify contributions of long-range transport vs. local/regional pollution sources and from natural vs. anthropogenic sources to PM concentrations different regions. In particular, we estimate the hemispheric impact of anthropogenic sulfate aerosols and dust from major source areas on other regions in the world. The GOCART model results are compared with satellite remote sensing and ground-based network measurements of aerosol optical depth and concentrations.

An Accuracy Assessment of the CALIOP/CALIPSO Version 2/Version 3 Daytime Aerosol Extinction Product Based on a Detailed Multi-Sensor, Multi-Platform Case Study

NASA Technical Reports Server (NTRS)

Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

2011-01-01

The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP s level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. spaceborne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth s Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP s low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth s surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP s extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case study seems to partially fix factor (i) although the aerosol retrieved by CALIOP is still somewhat lower than the profile measured by HSRL; the cloud contamination (ii) appears to be corrected; no particular change is apparent in the observation-based CALIOP Sa value (iii). Our case study also showed very little difference in version 2 and version 3 CALIOP attenuated backscatter coefficient profiles, illustrating a minor change in the calibration scheme (iv).

Monitoring the industrial sources of aerosol in Cubatao, Brazil, using a scanning elastic lidar and a lidar doppler

NASA Astrophysics Data System (ADS)

da Costa, Renata F.; Marques, Marcia T. A.; M Macedo, Fernanda de; Andrade, Izabel da Silva; Araujo, Elaine Cristina; Correa, Thais; de Andrade Salani, Maria Helena Goncalves; Lopes, Daniel Silveira; Goncalves Guardani, Maria Lucia; Landulfo, Eduardo; Guardani, Roberto

2018-04-01

Field campaigns with a scanning multiwavelength elastic lidar coupled with a Doppler system to monitor industrial atmospheric aerosol emissions were carried out, with the objective of monitoring aerosol emission sources and plume dispersion. Since the technique provides information on the spatial and temporal distribution of aerosol concentration, the implementation of a systematic monitoring procedure is proposed as a valuable tool in air quality monitoring applied to regions of interest.

Determination of mixing state and sources of wintertime organic aerosol in Paris using single particle mass spectrometry

NASA Astrophysics Data System (ADS)

Healy, R. M.; Sciare, J.; Poulain, L.; Wiedensohler, A.; Jeong, C.; McGuire, M.; Evans, G. J.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J.

2012-12-01

The size-resolved chemical composition of single particles at an urban background site in Paris, France, was determined using an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) as part of the MEGAPOLI winter campaign in January/February 2010. A variety of mixing states were identified for organic aerosol by mass spectral clustering and apportioned to both fossil fuel and biomass burning sources. The ATOFMS data were scaled in order to produce mass concentration estimates for each organic aerosol particle type identified. Potassium-containing organic aerosol internally mixed with nitrate, associated with local wood burning, was observed to dominate during periods characterised by marine air masses. Sulfate-rich potassium-containing organic aerosol, associated with transboundary transport of biomass burning emissions, dominated during periods influenced by continental air masses. The scaled total mass concentration for potassium-containing particles was well correlated (R2 = 0.79) with concurrent measurements of potassium mass concentration measured with a Particle-Into-Liquid-Sampler (PILS). Another organic particle type, also containing potassium but rich in trimethylamine and sulfate, was detected exclusively during continental air mass events. These particles are postulated to have accumulated gas phase trimethylamine through heterogeneous reaction before arriving at the sampling site. Potential source regions for transboundary organic aerosols have been investigated using the potential source contribution function (PSCF). Comparison with aerosol mass spectrometer (AMS) measurements will also be discussed.

The assessment of source attribution of soil pollution in a typical e-waste recycling town and its surrounding regions using the combined organic and inorganic dataset.

PubMed

Luo, Jie; Qi, Shihua; Xie, Xianming; Gu, X W Sophie; Wang, Jinji

2017-01-01

Guiyu is a well-known electronic waste dismantling and recycling town in south China. Concentrations and distribution of the 21 mineral elements and 16 polycyclic aromatic hydrocarbons (PAHs) collected there were evaluated. Principal component analyses (PCA) applied to the data matrix of PAHs in the soil extracted three major factors explaining 85.7% of the total variability identified as traffic emission, coal combustion, and an unidentified source. By using metallic or metalloid element concentrations as variables, five principal components (PCs) were identified and accounted for 70.4% of the information included in the initial data matrix, which can be denoted as e-waste dismantling-related contamination, two different geological origins, anthropogenic influenced source, and marine aerosols. Combining the 21 metallic and metalloid element datasets with the 16 PAH concentrations can narrow down the coarse source and decrease the unidentified contribution to soil in the present study and therefore effectively assists the source identification process.

The Impact of Aerosol Sources and Aging on CCN Formation in the Houston-Galveston-Gulf of Mexico Region

NASA Astrophysics Data System (ADS)

Quinn, P.; Bates, T.; Coffman, D.; Covert, D.

2007-12-01

The impact of anthropogenic aerosol on cloud properties, cloud lifetime, and precipitation processes is one of the largest uncertainties in our current understanding of climate change. Aerosols affect cloud properties by serving as cloud condensation nuclei (CCN) thereby leading to the formation of cloud droplets. The process of cloud drop activation is a function of both the size and chemistry of the aerosol particles which, in turn, depend on the source of the aerosol and transformations that occur downwind. In situ field measurements that can lead to an improved understanding of the process of cloud drop formation and simplifying parameterizations for improving the accuracy of climate models are highly desirable. During the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the NOAA RV Ronald H. Brown encountered a wide variety of aerosol types ranging from marine near the Florida panhandle to urban and industrial in the Houston-Galveston area. These varied sources provided an opportunity to investigate the role of aerosol sources, aging, chemistry, and size in the activation of particles to form cloud droplets. Here, we use the correlation between variability in critical diameter for activation (determined empirically from measured CCN concentrations and the number size distribution) and aerosol composition to quantify the impact of composition on particle activation. Variability in aerosol composition is parameterized by the mass fraction of Hydrocarbon-like Organic Aerosol (HOA) for particle diameters less than 200 nm (vacuum aerodynamic). The HOA mass fraction in this size range is lowest for marine aerosol and higher for aerosol impacted by anthropogenic emissions. Combining all data collected at 0.44 percent supersaturation (SS) reveals that composition (defined in this way) explains 40 percent of the variance in the critical diameter. As expected, the dependence of activation on composition is strongest at lower SS. At the same time, correlations between HOA mass fraction and aerosol mean diameter show that these two parameters are essentially independent of one another for this data set. We conclude that, based on the variability of the HOA mass fraction observed during GoMACCS, composition plays a dominant role in determining the fraction of particles that are activated to form cloud droplets. Using Kohler theory, we estimate the error that results in calculated CCN concentrations if the organic fraction of the aerosol is neglected (i.e., a fully soluble composition of ammonium sulfate is assumed) for the range of organic mass fractions and mean diameters observed during GoMACCS. We then relate this error to the source and age of the aerosol. At 0.22 and 0.44 percent SS, the error is considerable for anthropogenic aerosol sampled near the source region as this aerosol has, on average, a high POM mass fraction and smaller particle mean diameter. The error is lower for more aged aerosol as it has a lower POM mass fraction and larger mean particle diameter. Hence, the percent error in calculated CCN concentration is expected to be larger for younger, organic- rich aerosol and smaller for aged, sulfate rich aerosol and for marine aerosol. We extend this analysis to continental and marine data sets recently reported by Dusek et al. [Science, 312, 1375, 2006] and Hudson [Geophys. Res., Lett., 34, L08801, 2007].

SOURCE APPORTIONMENT OF PHOENIX PM2.5 AEROSOL WITH THE UNMIX RECEPTOR MODEL

EPA Science Inventory

The multivariate receptor model Unmix has been used to analyze a 3-yr PM2.5 ambient aerosol data set collected in Phoenix, AZ, beginning in 1995. The analysis generated source profiles and overall percentage source contribution estimates (SCE) for five source categories: ga...

Advanced source apportionment of carbonaceous aerosols by coupling offline AMS and radiocarbon size-segregated measurements over a nearly 2-year period

NASA Astrophysics Data System (ADS)

Vlachou, Athanasia; Daellenbach, Kaspar R.; Bozzetti, Carlo; Chazeau, Benjamin; Salazar, Gary A.; Szidat, Soenke; Jaffrezo, Jean-Luc; Hueglin, Christoph; Baltensperger, Urs; El Haddad, Imad; Prévôt, André S. H.

2018-05-01

Carbonaceous aerosols are related to adverse human health effects. Therefore, identification of their sources and analysis of their chemical composition is important. The offline AMS (aerosol mass spectrometer) technique offers quantitative separation of organic aerosol (OA) factors which can be related to major OA sources, either primary or secondary. While primary OA can be more clearly separated into sources, secondary (SOA) source apportionment is more challenging because different sources - anthropogenic or natural, fossil or non-fossil - can yield similar highly oxygenated mass spectra. Radiocarbon measurements provide unequivocal separation between fossil and non-fossil sources of carbon. Here we coupled these two offline methods and analysed the OA and organic carbon (OC) of different size fractions (particulate matter below 10 and 2.5 µm - PM10 and PM2.5, respectively) from the Alpine valley of Magadino (Switzerland) during the years 2013 and 2014 (219 samples). The combination of the techniques gave further insight into the characteristics of secondary OC (SOC) which was rather based on the type of SOC precursor and not on the volatility or the oxidation state of OC, as typically considered. Out of the primary sources separated in this study, biomass burning OC was the dominant one in winter, with average concentrations of 5.36 ± 2.64 µg m-3 for PM10 and 3.83 ± 1.81 µg m-3 for PM2.5, indicating that wood combustion particles were predominantly generated in the fine mode. The additional information from the size-segregated measurements revealed a primary sulfur-containing factor, mainly fossil, detected in the coarse size fraction and related to non-exhaust traffic emissions with a yearly average PM10 (PM2.5) concentration of 0.20 ± 0.24 µg m-3 (0.05 ± 0.04 µg m-3). A primary biological OC (PBOC) was also detected in the coarse mode peaking in spring and summer with a yearly average PM10 (PM2.5) concentration of 0.79 ± 0.31 µg m-3 (0.24 ± 0.20 µg m-3). The secondary OC was separated into two oxygenated, non-fossil OC factors which were identified based on their seasonal variability (i.e. summer and winter oxygenated organic carbon, OOC) and a third anthropogenic OOC factor which correlated with fossil OC mainly peaking in winter and spring, contributing on average 13 % ± 7 % (10 % ± 9 %) to the total OC in PM10 (PM2.5). The winter OOC was also connected to anthropogenic sources, contributing on average 13 % ± 13 % (6 % ± 6 %) to the total OC in PM10 (PM2.5). The summer OOC (SOOC), stemming from oxidation of biogenic emissions, was more pronounced in the fine mode, contributing on average 43 % ± 12 % (75 % ± 44 %) to the total OC in PM10 (PM2.5). In total the non-fossil OC significantly dominated the fossil OC throughout all seasons, by contributing on average 75 % ± 24 % to the total OC. The results also suggested that during the cold period the prevailing source was residential biomass burning while during the warm period primary biological sources and secondary organic aerosol from the oxidation of biogenic emissions became important. However, SOC was also formed by aged fossil fuel combustion emissions not only in summer but also during the rest of the year.

Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign.

PubMed

Collier, Sonya; Zhou, Shan; Onasch, Timothy B; Jaffe, Daniel A; Kleinman, Lawrence; Sedlacek, Arthur J; Briggs, Nicole L; Hee, Jonathan; Fortner, Edward; Shilling, John E; Worsnop, Douglas; Yokelson, Robert J; Parworth, Caroline; Ge, Xinlei; Xu, Jianzhong; Butterfield, Zachary; Chand, Duli; Dubey, Manvendra K; Pekour, Mikhail S; Springston, Stephen; Zhang, Qi

2016-08-16

Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (∼2700 m a.s.l.) as well as near their sources using an aircraft. The regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), an index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (∼1 h old) and emissions sampled after atmospheric transport (6-45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.

Can Biomass Burning Explain Isotopically Light Fe in Marine Aerosols?

NASA Astrophysics Data System (ADS)

Sherry, A. M.; Anbar, A. D.; Herckes, P.; Romaniello, S. J.

2016-02-01

Iron (Fe) is an important micronutrient that limits primary productivity in large parts of the ocean. In these regions, atmospheric aerosol deposition is an important source of Fe to the surface ocean and thus has a critical impact on ocean biogeochemistry. Fe-bearing aerosols originate from many sources with potentially distinct Fe isotopic compositions. Consequently, Fe isotopes may provide a new tool to trace the sources of aerosol Fe to the oceans. Mead et al. (2013) first discovered that Fe in the fine fraction of Bermuda aerosols is often isotopically lighter than Fe from known anthropogenic and crustal sources. 1 These authors suggested that this light isotopic signature was likely the result of biomass burning, since Fe in plants is the only known source of isotopically light Fe. More recently, Conway et al. found that Fe in the soluble fraction of aerosols collected during 2010-2011 North Atlantic GEOTRACES cruises also showed light isotope values, which they likewise attributed to biomass burning.2 These studies are further supported by new modeling work which suggests that biomass burning aerosols should contribute significant amounts of soluble Fe to tropical and southern oceans.3To test if biomass burning releases aerosols with a light Fe isotope composition, we are conducting lab-scale biomass burning experiments using natural samples of vegetation and leaf litter. Burn aerosols were collected on cellulose filters, then digested and analyzed for trace metal concentrations using inductively-coupled mass spectrometry (ICP-MS). Fe isotopes were determined by using multiple collector ICP-MS following separation and purification of Fe using anion exchange chromatography. We will discuss metal concentration and isotope data from these experiments with implications for the interpretation of Fe isotope signals in aerosol samples. 1Mead, C et al. GRL, 2013, 40, 5722-5727. 2 Conway, T et al. Goldschmidt Abs 2015 593. 3Ito, A. ES&T Lett, 2015, 2, 70-75.

Submicron organic aerosol in Tijuana, Mexico, from local and Southern California sources during the CalMex campaign

NASA Astrophysics Data System (ADS)

Takahama, S.; Johnson, A.; Guzman Morales, J.; Russell, L. M.; Duran, R.; Rodriguez, G.; Zheng, J.; Zhang, R.; Toom-Sauntry, D.; Leaitch, W. R.

2013-05-01

The CalMex campaign was conducted from May 15 to June 30 of 2010 to study the properties and sources of air pollution in Tijuana, Mexico. In this study, submicron organic aerosol mass (OM) composition measured by Fourier Transform Infrared Spectroscopy (FTIR), Aerosol Chemical Speciation Monitor (ACSM), and X-ray spectromicroscopy are combined with statistical analysis and measurements of other atmospheric constituents. The average (±one standard deviation) OM concentration was 3.3 ± 1.7 μg m-3. A large source of submicron aerosol mass at this location was determined to be vehicular sources, which contributed approximately 40% to the submicron OM; largely during weekday mornings. The O/C ratio estimated from ACSM measurements was 0.64 ± 0.19; diurnal variations in this value and the more oxygenated fraction of OM as determined from Positive Matrix Factorization and classification analyses suggest the high degree of oxygenation originates from aged OM, rather than locally-produced secondary organic aerosol. A large contribution of this oxygenated aerosol to Tijuana from various source classes was observed; some fraction of this aerosol mass may be associated with non-refractory components, such as dust or BC. Backtrajectory simulations using the HYSPLIT model suggest that the mean wind vector consistently originated from the northwest region, over the Pacific Ocean and near the Southern California coast, which suggests that the origin of much of the oxygenated organic aerosol observed in Tijuana (as much as 60% of OM) may have been the Southern California Air Basin. The marine aerosol contribution to OM during the period was on average 23 ± 24%, though its contribution varied over synoptic rather than diurnal timescales. BB aerosol contributed 20 ± 20% of the OM during the campaign period, with notable BB events occurring during several weekend evenings.

Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collier, Sonya; Zhou, Shan; Onasch, Timothy B.

Abstract Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, wildfire emissions in the Pacific Northwest region of the United States were characterized using real-time measurements near their sources using an aircraft, and farther downwind from a fixed ground site located at the Mt. Bachelor Observatory (~ 2700 m a.s.l.). The characteristics of aerosol emissions were found to depend strongly on the modified combustion efficiency (MCE), a qualitative index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereasmore » the carbon oxidation state of organic aerosol increased with MCE. The relationships between the aerosol properties and MCE were consistent between fresher emissions (~1 hour old) and emissions sampled after atmospheric transport (6 - 45 hours), suggesting that organic aerosol mass loading and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of regionally transported wildfire emissions and their impacts on regional air quality and global climate.« less

Measurements of aerosol chemical composition in boreal forest summer conditions

NASA Astrophysics Data System (ADS)

ńijälä, M.; Junninen, H.; Ehn, M.; Petäjä, T.; Vogel, A.; Hoffmann, T.; Corrigan, A.; Russell, L.; Makkonen, U.; Virkkula, A.; Mäntykenttä, J.; Kulmala, M.; Worsnop, D.

2012-04-01

Boreal forests are an important biome, covering vast areas of the northern hemisphere and affecting the global climate change via various feedbacks [1]. Despite having relatively few anthropogenic primary aerosol sources, they always contain a non-negligible aerosol population [2]. This study describes aerosol chemical composition measurements using Aerodyne Aerosol Mass Spectrometer (C-ToF AMS, [3]), carried out at a boreal forest area in Hyytiälä, Southern Finland. The site, Helsinki University SMEAR II measurement station [4], is situated at a homogeneous Scots pine (Pinus sylvestris) forest stand. In addition to the station's permanent aerosol, gas phase and meteorological instruments, during the HUMPPA (Hyytiälä United Measurements of Photochemistry and Particles in Air) campaign in July 2010, a very comprehensive set of atmospheric chemistry measurement instrumentation was provided by the Max Planck Institute for chemistry, Johannes Gutenberg-University, University of California and the Finnish Meteorological institute. In this study aerosol chemical composition measurements from the campaign are presented. The dominant aerosol chemical species during the campaign were the organics, although periods with elevated amounts of particulate sulfates were also seen. The overall AMS measured particle mass concentrations varied from near zero to 27 μg/m observed during a forest fire smoke episode. The AMS measured aerosol mass loadings were found to agree well with DMPS derived mass concentrations (r2=0.998). The AMS data was also compared with three other aerosol instruments. The Marga instrument [5] was used to provide a quantitative semi-online measurement of inorganic chemical compounds in particle phase. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed on daily filter samples, enabling the identification and quantification of organic aerosol subspecies. Finally an Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometer (APCI-IT-MS, [6]) was measuring gas and particle phase aerosol composition, offering additional information on molecular compositions. Overall, the availability of a variety of aerosol chemical characterization instruments provided a good opportunity for a comparison of the results obtained by these four very different measurement approaches. Overall the results were found to agree. The inorganic particulate masses measured with the AMS and Marga were found to correlate especially well for sulphates (r2=0.92) and ammonia compounds (r2=0.82). The organic mass seen by the AMS was correlated with the FTIR filter analysis (r2=0.87) and the APCI-IT-MS (r2=0.88).

Characteristics of regional aerosols: Southern Arizona and eastern Pacific Ocean

NASA Astrophysics Data System (ADS)

Prabhakar, Gouri

Atmospheric aerosols impact the quality of our life in many direct and indirect ways. Inhalation of aerosols can have harmful effects on human health. Aerosols also have climatic impacts by absorbing or scattering solar radiation, or more indirectly through their interactions with clouds. Despite a better understanding of several relevant aerosol properties and processes in the past years, they remain the largest uncertainty in the estimate of global radiative forcing. The uncertainties arise because although aerosols are ubiquitous in the Earth's atmosphere they are highly variable in space, time and their physicochemical properties. This makes in-situ measurements of aerosols vital in our effort towards reducing uncertainties in the estimate of global radiative forcing due to aerosols. This study is an effort to characterize atmospheric aerosols at a regional scale, in southern Arizona and eastern Pacific Ocean, based on ground and airborne observations of aerosols. Metals and metalloids in particles with aerodynamic diameter (Dp) smaller than 2.5 μm are found to be ubiquitous in southern Arizona. The major sources of the elements considered in the study are identified to be crustal dust, smelting/mining activities and fuel combustion. The spatial and temporal variability in the mass concentrations of these elements depend both on the source strength and meteorological conditions. Aircraft measurements of aerosol and cloud properties collected during various field campaigns over the eastern Pacific Ocean are used to study the sources of nitrate in stratocumulus cloud water and the relevant processes. The major sources of nitrate in cloud water in the region are emissions from ships and wildfires. Different pathways for nitrate to enter cloud water and the role of meteorology in these processes are examined. Observations of microphysical properties of ambient aerosols in ship plumes are examined. The study shows that there is an enhancement in the number concentration of giant cloud condensation nuclei (Dp > 2 microm) in ship plumes relative to the unperturbed background regions over the ocean.

Atmospheric aerosol composition and source apportionments to aerosol in southern Taiwan

NASA Astrophysics Data System (ADS)

Tsai, Ying I.; Chen, Chien-Lung

In this study, the chemical characteristics of winter aerosol at four sites in southern Taiwan were determined and the Gaussian Trajectory transfer coefficient model (GTx) was then used to identify the major air pollutant sources affecting the study sites. Aerosols were found to be acidic at all four sites. The most important constituents of the particulate matter (PM) by mass were SO 42-, organic carbon (OC), NO 3-, elemental carbon (EC) and NH 4+, with SO 42-, NO 3-, and NH 4+ together constituting 86.0-87.9% of the total PM 2.5 soluble inorganic salts and 68.9-78.3% of the total PM 2.5-10 soluble inorganic salts, showing that secondary photochemical solution components such as these were the major contributors to the aerosol water-soluble ions. The coastal site, Linyuan (LY), had the highest PM mass percentage of sea salts, higher in the coarse fraction, and higher sea salts during daytime than during nighttime, indicating that the prevailing daytime sea breeze brought with it more sea-salt aerosol. Other than sea salts, crustal matter, and EC in PM 2.5 at Jenwu (JW) and in PM 2.5-10 at LY, all aerosol components were higher during nighttime, due to relatively low nighttime mixing heights limiting vertical and horizontal dispersion. At JW, a site with heavy traffic loadings, the OC/EC ratio in the nighttime fine and coarse fractions of approximately 2.2 was higher than during daytime, indicating that in addition to primary organic aerosol (POA), secondary organic aerosol (SOA) also contributed to the nighttime PM 2.5. This was also true of the nighttime coarse fraction at LY. The GTx produced correlation coefficients ( r) for simulated and observed daily concentrations of PM 10 at the four sites (receptors) in the range 0.45-0.59 and biases from -6% to -20%. Source apportionment indicated that point sources were the largest PM 10 source at JW, LY and Daliao (DL), while at Meinung (MN), a suburban site with less local PM 10, SO x and NO x emissions, upwind boundary concentration was the major PM 10 source, followed by point sources and top boundary concentration.

Exploring the Contribution of Primary Marine Organic Matter to the Arctic Boundary Layer

NASA Astrophysics Data System (ADS)

Collins, D. B.; Chang, R. Y. W.; Boyer, M.; Abbatt, J.

2016-12-01

The ocean is a significant source of aerosol to the atmosphere, and contributes significantly to the aerosol population especially in remote locations. Both primary and secondary processes connect the ocean to ambient aerosol loadings, but the extent to which the ocean is a source of organic material to the atmosphere is a current topic of scientific debate. The contribution of primary marine aerosol to atmospheric organic matter may have an influence on the water uptake properties and chemical reactivity of primary marine aerosol particles, influencing their climate-relevant properties. In this study, we characterize the contribution of primary marine aerosol to the arctic marine boundary layer using coincident quantitative measurements of freshly-produced sea spray aerosol and ambient marine aerosol to the arctic boundary layer during an expedition aboard the CCGS Amundsen. Sea spray production experiments were conducted during the cruise using a tank fitted with a plunging waterfall apparatus, a technique which has been recently shown to closely mimic the aerosol production behavior of controlled breaking waves. Comparison of the chemical composition of sea spray particles generated from water samples in various locations throughout the Canadian Archipelago will be presented. A tracer analysis of specific compounds known to be important contributors to primary marine organic material are tracked using GC/MS, along with those known to be tracers of biological aerosol and other organic matter sources. Size-segregated trends in tracer concentrations and ratios with inorganic components will be discussed in the context of understanding the contribution of primary organics to the Arctic atmosphere and in comparison with other sources of organic material observed during the ship-board campaign.

Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Kawamura, K.; Umarji, G. S.; Tachibana, E.; Patil, R. S.; Gupta, P. K.

2012-08-01

To better understand the sources of PM10 samples from Mumbai, India, aerosol chemical compositions, i.e. total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied together with specific markers such as methanesulfonate (MSA), oxalic acid (C2), azelaic acid (C9), and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (δ15N) composition of aerosol total nitrogen, which ranged from 18.1 to 25.4‰, also suggest that biofuel/biomass burning is the dominant source in both summer and winter seasons. Aerosol mass concentrations of major species increased 3-4 times in winter compared to summer, indicating an enhanced emission from these sources in winter season. Photochemical production tracers, C2 diacid and nssSO42- do not show diurnal changes. Concentrations of C2 diacid and WSOC show a strong correlation (r2 = 0.95). In addition, WSOC to OC (or TC) ratios remain almost constant for day- (0.37 ± 0.06 (0.28 ± 0.04)) and nighttime (0.38 ± 0.07 (0.28 ± 0.06)), suggesting that mixing of fresh secondary organic aerosols is not significant rather the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C9 diacid present a positive correlation (r2 = 0.75), indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (δ13C) of TC ranged from -27.0 to -25.4‰ with slightly lower average (-26.5 ± 0.3‰) in summer than in winter (-25.9 ± 0.3‰). Positive correlation between WSOC/TC ratios and δ13C values suggested that the increment in δ13C of wintertime TC may be caused by prolonged photochemical processing of organic aerosols in this season. This study suggests that in winter, the tropical aerosols are more aged due to longer residence time in the atmosphere than in the summer aerosols.

Estimation of the contributions of long range transported aerosol in East Asia to carbonaceous aerosol and PM concentrations in Seoul, Korea using highly time resolved measurements: a PSCF model approach.

PubMed

Jeong, Ukkyo; Kim, Jhoon; Lee, Hanlim; Jung, Jinsang; Kim, Young J; Song, Chul H; Koo, Ja-Ho

2011-07-01

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.

Variability of adjacency effects in sky reflectance measurements.

PubMed

Groetsch, Philipp M M; Gege, Peter; Simis, Stefan G H; Eleveld, Marieke A; Peters, Steef W M

2017-09-01

Sky reflectance R sky (λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in R sky (λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous R sky (λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to R sky (λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4±6.3% for adjacency effects and 21.0±19.8% for Rayleigh- and aerosol-scattered R sky (λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

Bioaerosols in the Earth system: Climate, health, and ecosystem interactions

NASA Astrophysics Data System (ADS)

Fröhlich-Nowoisky, Janine; Kampf, Christopher J.; Weber, Bettina; Huffman, J. Alex; Pöhlker, Christopher; Andreae, Meinrat O.; Lang-Yona, Naama; Burrows, Susannah M.; Gunthe, Sachin S.; Elbert, Wolfgang; Su, Hang; Hoor, Peter; Thines, Eckhard; Hoffmann, Thorsten; Després, Viviane R.; Pöschl, Ulrich

2016-12-01

Aerosols of biological origin play a vital role in the Earth system, particularly in the interactions between atmosphere, biosphere, climate, and public health. Airborne bacteria, fungal spores, pollen, and other bioparticles are essential for the reproduction and spread of organisms across various ecosystems, and they can cause or enhance human, animal, and plant diseases. Moreover, they can serve as nuclei for cloud droplets, ice crystals, and precipitation, thus influencing the hydrological cycle and climate. The sources, abundance, composition, and effects of biological aerosols and the atmospheric microbiome are, however, not yet well characterized and constitute a large gap in the scientific understanding of the interaction and co-evolution of life and climate in the Earth system. This review presents an overview of the state of bioaerosol research, highlights recent advances, and outlines future perspectives in terms of bioaerosol identification, characterization, transport, and transformation processes, as well as their interactions with climate, health, and ecosystems, focusing on the role bioaerosols play in the Earth system.

Aerosol composition and source apportionment in Santiago de Chile

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Oyola, Pedro; Martinez, Roberto

1999-04-01

Santiago de Chile, São Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in Santiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown sampling sites in Santiago. The aerosol monitoring stations were operated in Gotuzo and Las Condes during July and August 1996. The study employed stacked filter units (SFU) for aerosol sampling, collecting fine mode aerosol (dp<2 μm) and coarse mode aerosol (2

Urban increments of gaseous and aerosol pollutants and their sources using mobile aerosol mass spectrometry measurements

NASA Astrophysics Data System (ADS)

Elser, Miriam; Bozzetti, Carlo; El-Haddad, Imad; Maasikmets, Marek; Teinemaa, Erik; Richter, Rene; Wolf, Robert; Slowik, Jay G.; Baltensperger, Urs; Prévôt, André S. H.

2016-06-01

Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero ≤ 2.5 µm) in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR)-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC) and several trace gases including carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA) constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF): hydrocarbon-like OA (HOA, from traffic emissions), biomass burning OA (BBOA, from biomass combustion), residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning), and oxygenated OA (OOA, related to secondary aerosol formation). OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded regional background levels (urban increments). HOA, eBC, CO2, and CO showed stronger enhancements on busy roads during the morning and evening traffic rush hours; BBOA had its maximum enhancement in the residential areas during the evening hours and RIOA was enhanced in both the city center (emissions from restaurants) and in the residential areas (emissions from residential cooking). In contrast, secondary components (OOA, sulfate (SO4), nitrate (NO3), ammonium (NH4), and chloride (Cl)) had very homogeneous distributions in time and space. We were able to determine a total PM2.5 urban increment in Tartu of 6.0 µg m-3 over a regional background concentration of 4.0 µg m-3 (i.e., a factor of 2.5 increase). Traffic exhaust emissions were identified as the most important source of this increase, with eBC and HOA explaining on average 53.3 and 20.5 % of the total increment, respectively.

The physico-chemical evolution of atmospheric aerosols and the gas-particle partitioning of inorganic aerosol during KORUS-AQ

NASA Astrophysics Data System (ADS)

Lee, T.; Park, T.; Lee, J. B.; Lim, Y. J.; Ahn, J.; Park, J. S.; Soo, C. J.; Desyaterik, Y.; Collett, J. L., Jr.

2017-12-01

Aerosols influence climate change directly by scattering and absorption and indirectly by acting as cloud condensation nuclei and some of the effects of aerosols are reduction in visibility, deterioration of human health, and deposition of pollutants to ecosystems. Urban area is large source of aerosols and aerosol precursors. Aerosol sources are both local and from long-range transport. Long-range transport processed aerosol are often dominant sources of aerosol pollution in Korea. To improve our knowledge of aerosol chemistry, Korea and U.S-Air Quality (KORUS-AQ) of Aircraft-based aerosol measurement took place in and around Seoul, Korea during May and June 2016. KORUS-AQ campaigns were conducted to study the chemical characterization and processes of pollutants in the Seoul Metropolitan area to regional scales of Korean peninsula. Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed on aircraft platforms on-board DC-8 (NASA) aircraft. We characterized aerosol chemical properties and mass concentrations of sulfate, nitrate, ammonium and organics in polluted air plumes and investigate the spatial and vertical distribution of the species. The results of studies show that organics is predominant in Aerosol and a significant fraction of the organics is oxygenated organic aerosol (OOA) at the high altitude. Both Nitrate and sulfate can partition between the gas and particle phases. The ratios for HNO3/(N(V) (=gaseous HNO3 + particulate Nitrate) and SO2/(SO2+Sulfate) were found to exhibit quite different distributions between the particles and gas phase for the locations during KORUS-AQ campaign, representing potential for formation of additional particulate nitrate and sulfate. The results of those studies can provide highly resolved temporal and spatial air pollutant, which are valuable for air quality model input parameters for aerosol behaviour.

Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene.

PubMed

Schüpbach, S; Fischer, H; Bigler, M; Erhardt, T; Gfeller, G; Leuenberger, D; Mini, O; Mulvaney, R; Abram, N J; Fleet, L; Frey, M M; Thomas, E; Svensson, A; Dahl-Jensen, D; Kettner, E; Kjaer, H; Seierstad, I; Steffensen, J P; Rasmussen, S O; Vallelonga, P; Winstrup, M; Wegner, A; Twarloh, B; Wolff, K; Schmidt, K; Goto-Azuma, K; Kuramoto, T; Hirabayashi, M; Uetake, J; Zheng, J; Bourgeois, J; Fisher, D; Zhiheng, D; Xiao, C; Legrand, M; Spolaor, A; Gabrieli, J; Barbante, C; Kang, J-H; Hur, S D; Hong, S B; Hwang, H J; Hong, S; Hansson, M; Iizuka, Y; Oyabu, I; Muscheler, R; Adolphi, F; Maselli, O; McConnell, J; Wolff, E W

2018-04-16

The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.

Atmospheric Teleconnection over Eurasia Induced by Aerosol Radiative Forcing During Boreal Spring

NASA Technical Reports Server (NTRS)

Kim, Maeng-Ki; Lau, K. M.; Chin, Mian; Kim, Kyu-Myong; Sud, Y. C.; Walker, Greg K.

2005-01-01

The direct effects of aerosols on global and regional climate during boreal spring are investigated based on simulations using the NASA Global Modeling and Assimilation Office (GMAO) finite-volume general circulation model (fvGCM) with Microphyics of clouds in Relaxed Arakawa Schubert Scheme (McRAS). The aerosol loading are prescribed from three-dimensional monthly distribution of tropospheric aerosols viz., sulfate, black carbon, organic carbon, soil dust, and sea salt from output of the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART). The aerosol extinction coefficient, single scattering albedo, and asymmetric factor are computed as wavelength-dependent radiative forcing in the radiative transfer scheme of the fvGCM, and as a function of the aerosol loading and ambient relative humidity. We find that anomalous atmospheric heat sources induced by absorbing aerosols (dust and black carbon) excites a planetary scale teleconnection pattern in sea level pressure, temperature and geopotential height spanning North Africa through Eurasia to the North Pacific. Surface cooling due to direct effects of aerosols is found in the vicinity and downstream of the aerosol source regions, i.e., South Asia, East Asia, and northern and western Africa. Additionally, atmospheric heating is found in regions with large loading of dust (over Northern Africa, and Middle East), and black carbon (over South-East Asia). Paradoxically, the most pronounced feature in aerosol-induced surface temperature is an east-west dipole anomaly with strong cooling over the Caspian Sea, and warming over central and northeastern Asia, where aerosol concentration are low. Analyses of circulation anomalies show that the dipole anomaly is a part of an atmospheric teleconnection driven by atmospheric heating anomalies induced by absorbing aerosols in the source regions, but the influence was conveyed globally through barotropic energy dispersion and sustained by feedback processes associated with the regional circulations.

SOURCES OF ORGANIC AEROSOL: SEMIVOLATILE EMISSIONS AND PHOTOCHEMICAL AGING

EPA Science Inventory

The proposed research integrates emissions testing, smog chamber experiments, and regional chemical transport models (CTMs) to investigate the sources of organic aerosol in urban and regional environments.

Biomarkers as indicators of fungal biomass in the atmosphere of São Paulo, Brazil.

PubMed

Emygdio, Ana Paula Mendes; Andrade, Maria de Fátima; Gonçalves, Fabio Luiz Teixeira; Engling, Guenter; Zanetti, Rafael Henrique de Souza; Kumar, Prashant

2018-01-15

The biogenic aerosol contribution to atmospheric particulate matter (PM) mass concentration is usually neglected due to the difficulty in identifying its components, although it can be significant. In the Metropolitan Area of São Paulo (MASP)-Brazil, several studies have been performed to identify sources for PM, revealing vehicular emissions and soil re-suspension as the main identified sources. The organic fraction has been related primarily to biomass burning (BB) and fuel combustion, although there is significant presence of green areas in the city which render biogenic emissions as an additional source of organic carbon (OC). The objectives of this work are to (i) characterise the composition of the PM 10 (ii) estimate the relative mass contribution of fungal spores to PM concentrations with sizes smaller than 10μm (PM 10 ) in MASP and (iii) assess the main sources of PM 10 . To achieve these objectives, we measured markers of biogenic sources and BB, during the fall-winter transition, which along with other constituents, such as ions, organic/elemental carbon, elemental composition and fungal spore concentrations, help assess the PM 10 sources. We used receptor models to identify distinct source-related PM 10 fractions and conversion factors to convert biomarker concentrations to fungal mass. Our results show the mean contributions of fungal aerosol to PM 10 and OC mass were 2% and 8%, respectively, indicating the importance of fungal spores to the aerosol burden in the urban atmosphere. Using specific rotation factor analysis, we identified the following factors contributing to PM: soil re-suspension, biogenic aerosol, secondary inorganic aerosol, vehicular emissions and BB/isoprene-related secondary organic aerosol (I-SOA). BB/I-SOA was the main source representing 28% of the PM 10 mass, while biogenic aerosol explained a significant (11%) fraction of the PM 10 mass as well. Our findings suggest that primary biogenic aerosol is an important fraction of PM 10 mass, yet not considered in most studies. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaffney, Jeffrey

This is the final technical report. The project description is as follows: to determine the role of aerosol radiative forcing on climate, the processes that control their atmospheric concentrations must be understood, and aerosol sources need to be determined for mitigation. Measurements of naturally occurring radionuclides and stable isotopic signatures allow the sources, removal and transport processes, as well as atmospheric lifetimes of fine carbonaceous aerosols, to be evaluated.

Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

PubMed

Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

2007-08-15

Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs.

Identifying Aerosol Type/Mixture from Aerosol Absorption Properties Using AERONET

NASA Technical Reports Server (NTRS)

Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.;

Chemical Properties of Combustion Aerosols: An Overview

EPA Science Inventory

A wide variety of pyrogenic and anthropogenic sources emit fine aerosols to the atmosphere. The physical and chemical properties of these aerosols are of interest due to their influence on climate, human health, and visibility. Aerosol chemical composition is remarkably complex. ...

Contributions of Organic Sources to Atmospheric Aerosol Particle Concentrations and Growth

NASA Astrophysics Data System (ADS)

Russell, L. M.

2017-12-01

Organic molecules are important contributors to aerosol particle mass and number concentrations through primary emissions as well as secondary growth in the atmosphere. New techniques for measuring organic aerosol components in atmospheric particles have improved measurements of this contribution in the last 20 years, including Scanning Transmission X-ray Microscopy Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS), Fourier Transform Infrared spectroscopy (FTIR), and High-Resolution Aerosol Mass Spectrometry (AMS). STXM-NEXAFS individual aerosol particle composition illustrated the variety of morphology of organic components in marine aerosols, the inherent relationships between organic composition and shape, and the links between atmospheric aerosol composition and particles produced in smog chambers. This type of single particle microscopy has also added to size distribution measurements by providing evidence of how surface-controlled and bulk-controlled processes contribute to the growth of particles in the atmosphere. FTIR analysis of organic functional groups are sufficient to distinguish combustion, marine, and terrestrial organic particle sources and to show that each of those types of sources has a surprisingly similar organic functional group composition over four different oceans and four different continents. Augmenting the limited sampling of these off-line techniques with side-by-side inter-comparisons to online AMS provides complementary composition information and consistent quantitative attribution to sources (despite some clear method differences). Single-particle AMS techniques using light scattering and event trigger modes have now also characterized the types of particles found in urban, marine, and ship emission aerosols. Most recently, by combining with off-line techniques, single particle composition measurements have separated and quantified the contributions of organic, sulfate and salt components from ocean biogenic and sea spray emissions to particles, addressing the persistent question of the sources of cloud condensation nuclei in clean marine conditions.

A reference aerosol for a radon reference chamber

NASA Astrophysics Data System (ADS)

Paul, Annette; Keyser, Uwe

1996-02-01

The measurement of radon and radon progenies and the calibration of their detection systems require the production and measurement of aerosols well-defined in size and concentration. In the German radon reference chamber, because of its unique chemical and physical properties, carnauba wax is used to produce standard aerosols. The aerosol size spectra are measured on-line by an aerosol measurement system in the range of 10 nm to 1 μm aerodynamic diameter. The experimental set-ups for the study of adsorption of radioactive ions on aerosols as function of their size and concentration will be described, the results presented and further adaptations for an aerosol jet introduced (for example, for the measurement of short-lived neutron-rich isotopes). Data on the dependence of aerosol radius, ion concentration and element selectivity is collected by using a 252Cf-sf source. The fission products of this source range widely in elements, isotopes and charges. Adsorption and the transport of radioactive ions on aerosols have therefore been studied for various ions for the first time, simultaneously with the aerosol size on-line spectrometry.

A climatology of fine absorbing biomass burning, urban and industrial aerosols detected from satellites

NASA Astrophysics Data System (ADS)

Kalaitzi, Nikoleta; Hatzianastassiou, Nikos; Gkikas, Antonis; Papadimas, Christos D.; Torres, Omar; Mihalopoulos, Nikos

2017-04-01

Natural biomass burning (BB) along with anthropogenic urban and industrial aerosol particles, altogether labeled here as BU aerosols, contain black and brown carbon which both absorb strongly the solar radiation. Thus, BU aerosols warm significantly the atmosphere also causing adjustments to cloud properties, which traditionally are known as cloud indirect and semi-direct effects. Given the role of the effects of BU aerosols for contemporary and future climate change, and the uncertainty associated with BU, both ascertained by the latest IPCC reports, there is an urgent need for improving our knowledge on the spatial and temporal variability of BU aerosols all over the globe. Over the last few decades, thanks to the rapid development of satellite observational techniques and retrieval algorithms it is now possible to detect BU aerosols based on satellite measurements. However, care must be taken in order to ensure the ability to distinguish BU from other aerosol types usually co-existing in the Earth's atmosphere. In the present study, an algorithm is presented, based on a synergy of different satellite measurements, aiming to identify and quantify BU aerosols over the entire globe and during multiple years. The objective is to build a satellite-based climatology of BU aerosols intended for use for various purposes. The produced regime, namely the spatial and temporal variability of BU aerosols, emphasizes the BU frequency of occurrence and their intensity, in terms of aerosol optical depth (AOD). The algorithm is using the following aerosol optical properties describing the size and atmospheric loading of BU aerosols: (i) spectral AOD, (ii) Ångström Exponent (AE), (iii) Fine Fraction (FF) and (iv) Aerosol Index (AI). The relevant data are taken from Collection 006 MODIS-Aqua, except for AI which is taken from OMI-Aura. The identification of BU aerosols by the algorithm is based on a specific thresholding technique, with AI≥1.5, AE≥1.2 and FF≥0.6 threshold values. The study spans the 11-year period 2005-2015, which enables to examine the inter-annual variability and possible changes of BU aerosols. Emphasis is given on specific world areas known to be sources of BU emissions. An effort is also made to separate with the algorithm the BB from BU aerosols, aiming to create a satellite database of biomass burning aerosols. The results of the algorithm, as to BB aerosols and the ability to separate them, are evaluated through comparisons against the global satellite databases of MODIS active fire counts as well as AIRS carbon monoxide (CO), which is a key indicator of presence of biomass burning activities. The algorithm estimates frequencies of occurrence of BU aerosols reaching up to 10 days/year and AOD values up to 1.5 or even larger. The results indicate the existence of seasonal cycles of biomass burning in south and central Africa as well as in South America (Amazonia), with highest BU frequencies during June-September, December-February and August-October, respectively, whereas they successfully reproduce features like the export of African BB aerosols into the Atlantic Ocean.

Physico-chemical characterization of Mediterranean background aerosol at the Capogranitola observatory (Sicily)

NASA Astrophysics Data System (ADS)

Rinaldi, Matteo; Gilardoni, Stefania; Paglione, Marco; Sandrini, Silvia; Decesari, Stefano; Zanca, Nicola; Marinoni, Angela; Cristofanelli, Paolo; Bonasoni, Paolo; Ielpo, Piera; Fossum, Kirsten; Gobbi, Gian Paolo; Facchini, Maria Cristina

2017-04-01

The Mediterranean basin is characterized by elevated aerosol amounts and co-existence of different aerosol types, both natural and anthropogenic, while it is one of the most climatically sensitive areas. Therefore, it offers ideal conditions for studying aerosol processes and aerosol-climate interactions. An intensive aerosol physico-chemical characterization campaign was held at the Environmental-Climatic Observatory at Capo Granitola (Sicily; 37.5753° N, 12.6595° E) during April 2016, under the framework of the project Air-Sea Lab. The Observatory is located at the coast-line, facing the Strait of Sicily, and is part of the national I-AMICA network (http://www.i-amica.it/i-amica/?lang=en). Sub-micrometer aerosol chemical composition was measured by high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS), for the first time at Capogranitola. Sea-salt concentration was estimated from AMS measurements following Ovadnevaite et al. (2012). For a complete mass closure of the submicron aerosol, black carbon (BC) concentration was derived from multiangle absorption photometer (MAAP) measurements. Positive matrix factorization was deployed to investigate organic aerosol (OA) sources at the site. Aerosol chemical composition confirms that Capogranitola is a representative background site, with generally low contribution of BC and nitrate and highly oxidized OA. In particular, aerosol sampled in the marine sector (130-310°) is less affected by local sources and it is likely representative of the central Mediterranean background. Aerosol in background conditions is dominated by sulfate and OA (37% and 31%), followed by ammonium (12%), sea-salt (10%), BC (6%) and nitrate (3%). The average reconstructed sub-micrometer aerosol mass in background conditions is 3.7±2.3 μg m-3. OA source apportionment shows a minor contribution from primary sources, with hydrocarbon-like OA (HOA), from fossil fuel combustion, contributing for 3% and biomass burning OA (BBOA) for 2%. Oxidized OA (OOA) dominates the rest of OA mass. In particular, OOA1 and OOA2 (70% in total, OM:OC ˜ 2.5) represent the result of prolonged atmospheric processing of OA, while OOA3 (25%, OM:OC ˜ 2.0) clearly represents fresher inputs of OOA from land. Investigation of HOA and BC time trends suggests that HOA in background conditions may be strongly contributed by ship traffic more than by land sources. The representativity of the background aerosol collected at Capogranitola will be discussed by comparing with measurements performed in parallel at the other I-AMICA southern Italy coastal stations and with those acquired in a subsequent cruise (May-June 2016) around the Italian Peninsula. Aerosol climate relevant properties, in relation with chemical composition, will be also presented and discussed. Ovadnevaite J. et al. (2012), J. Geophys. Res., 117, D16201.

Identification of long-range transport of aerosols over Austria using EARLINET lidar measurements

NASA Astrophysics Data System (ADS)

Camelia, Talianu

2018-04-01

The aims of the study is to identify the paths of the long-range transported aerosols over Austria and their potential origin, and to estimate their properties, using lidar measurements from EARLINET stations closest to Austria from Germany and Romania and aerosol transport models. As of now, there is no lidar station in Austria. The study is part of a project to estimate the usefulness of a lidar station located in Vienna, Austria.

Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

2012-08-01

Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban Environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter <2.5 μm) resolved Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie FP7-EU framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the unique approach used is the simultaneous PIXE measurements at two monitoring sites: urban background (UB) and a street canyon traffic road site (RS). Elements related to primary non exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (secondary sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non exhaust brake dust (Fe-Cu) - 7%), and three types industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%). The validity of the PMF solution of the PIXE data is supported by strong correlations with external single particle mass spectrometry measurements. Beside apportioning the aerosol sources, some important air quality related conclusions can be drawn about the PM2.5 fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with industrial combustion emissions) is found a to be the major (82%) source of Cl in the urban agglomerate; (4) PM2.5 traffic brake dust (Fe-Cu) is mainly primarily emitted and not resuspended, whereas PM2.5 urban crustal dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing dust concentrations in road sites, far more effective than street sweeping activities.

Resolving the Aerosol Piece of the Global Climate Picture

NASA Astrophysics Data System (ADS)

Kahn, R. A.

2017-12-01

Factors affecting our ability to calculate climate forcing and estimate model predictive skill include direct radiative effects of aerosols and their indirect effects on clouds. Several decades of Earth-observing satellite observations have produced a global aerosol column-amount (AOD) record, but an aerosol microphysical property record required for climate and many air quality applications is lacking. Surface-based photometers offer qualitative aerosol-type classification, and several space-based instruments map aerosol air-mass types under favorable conditions. However, aerosol hygroscopicity, mass extinction efficiency (MEE), and quantitative light absorption, must be obtained from in situ measurements. Completing the aerosol piece of the climate picture requires three elements: (1) continuing global AOD and qualitative type mapping from space-based, multi-angle imagers and aerosol vertical distribution from near-source stereo imaging and downwind lidar, (2) systematic, quantitative in situ observations of particle properties unobtainable from space, and (3) continuing transport modeling to connect observations to sources, and extrapolate limited sampling in space and time. At present, the biggest challenges to producing the needed aerosol data record are: filling gaps in particle property observations, maintaining global observing capabilities, and putting the pieces together. Obtaining the PDFs of key particle properties, adequately sampled, is now the leading observational deficiency. One simplifying factor is that, for a given aerosol source and season, aerosol amounts often vary, but particle properties tend to be repeatable. SAM-CAAM (Systematic Aircraft Measurements to Characterize Aerosol Air Masses), a modest aircraft payload deployed frequently could fill this gap, adding value to the entire satellite data record, improving aerosol property assumptions in retrieval algorithms, and providing MEEs to translate between remote-sensing optical constraints and aerosol mass book-kept in climate models [Kahn et al., BAMS 2017]. This will also improve connections between remote-sensing particle types and those defined in models. The third challenge, maintaining global observing capabilities, requires continued community effort and good budgetary fortune.

Spatial Variability of AERONET Aerosol Optical Properties and Satellite Data in South Korea during NASA DRAGON-Asia Campaign.

PubMed

Lee, Hyung Joo; Son, Youn-Suk

2016-04-05

We investigated spatial variability in aerosol optical properties, including aerosol optical depth (AOD), fine-mode fraction (FMF), and single scattering albedo (SSA), observed at 21 Aerosol Robotic Network (AERONET) sites and satellite remote sensing data in South Korea during the spring of 2012. These dense AERONET networks established in a National Aeronautics and Space Administration (NASA) field campaign enabled us to examine the spatially detailed aerosol size distribution and composition as well as aerosol levels. The springtime particle air quality was characterized by high background aerosol levels and high contributions of coarse-mode aerosols to total aerosols. We found that between-site correlations and coefficient of divergence for AOD and FMF strongly relied on the distance between sites, particularly in the south-north direction. Higher AOD was related to higher population density and lower distance from highways, and the aerosol size distribution and composition reflected source-specific characteristics. The ratios of satellite NO2 to AOD, which indicate the relative contributions of local combustion sources to aerosol levels, represented higher local contributions in metropolitan Seoul and Pusan. Our study demonstrates that the aerosol levels were determined by both local and regional pollution and that the relative contributions of these pollutions to aerosols generated spatial heterogeneity in the particle air quality.

Recent Progress on Deep Blue Aerosol Algorithm as Applied TO MODIS, SEA WIFS, and VIIRS, and Their Intercomparisons with Ground Based and Other Satellite Measurements

NASA Technical Reports Server (NTRS)

Hsu, N. Christina; Bettenhausen, Corey; Sawyer, Andrew; Tsay, Si-Chee

2012-01-01

The impact of natural and anthropogenic sources of aerosols has gained increasing attention from scientific communities in recent years. Indeed, tropospheric aerosols not only perturb radiative energy balance by interacting with solar and terrestrial radiation, but also by changing cloud properties and lifetime. Furthermore, these anthropogenic and natural air particles, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across oceans and continents resulting in important biogeochemical impacts on the ecosystem. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented data records, studies of the radiative and biogeochemical effects due to tropospheric aerosols are now possible. In this talk, we will demonstrate how this newly available SeaWiFS/MODIS aerosol climatology can provide an important piece of puzzles in reducing the uncertainty of estimated climatic forcing due to aerosols. We will start with the global distribution of aerosol loading and their variabilities over both land and ocean on short- and long-term temporal scales observed over the last decade. The recent progress made in Deep Blue aerosol algorithm on improving accuracy of these Sea WiFS / MODIS aerosol products in particular over land will be discussed. The impacts on quantifying physical and optical processes of aerosols over source regions of adding the Deep Blue products of aerosol properties over bright-reflecting surfaces into Sea WiFS / MODIS as well as VIIRS data suite will also be addressed. We will also show the intercomparison results of SeaWiFS/MODIS retrieved aerosol optical thickness with data from ground based AERONET sunphotometers over land and ocean as well as with other satellite measurements. The trends observed in global aerosol loadings of both natural and anthropogenic sources based upon more than a decade of combined MODIS/SeaWiFS data (1997-2011) will be discussed. We will also address the importance of various key issues such as differences in spatial-temporal sampling rates and observation time between different satellite measurements could potentially impact these intercomparisons results, especially for using the monthly mean data, and thus on estimates of long-term aerosol trends.

Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS - diurnal variations and PMF receptor modelling

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

2013-04-01

Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter < 2.5 μm) resolved aerosol samples analysed by Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie European Union framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the approach used is the simultaneous sampling at two monitoring sites in Barcelona (Spain) during September-October 2010: an urban background site (UB) and a street canyon traffic road site (RS). Elements related to primary non-exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (regional sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non-exhaust brake dust (Fe-Cu) - 7%), and three types of industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%, percentages presented are average source contributions to the total elemental mass measured). The validity of the PMF solution of the PIXE data is supported by very good correlations with external single particle mass spectrometry measurements. Some important conclusions can be drawn about the PM2.5 mass fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with combustion emissions) is found to be the major (82%) source of fine Cl in the urban agglomerate; (4) the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu) suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

A study of impact of Asian dusts and their transport pathways to Hong Kong using multiple AERONET data, trajectory, and in-situ measurements

NASA Astrophysics Data System (ADS)

Wong, Man Sing; Nichol, Janet Elizabeth; Lee, Kwon Ho

2010-10-01

Hong Kong, a commercial and financial city located in south-east China has suffered serious air pollution for the last decade due largely to rapid urban and industrial expansion of the cities of mainland China. However, the potential sources and pathways of aerosols transported to Hong Kong have not been well researched due to the lack of air quality monitoring stations in southern China. Here, an integrated method combining the AErosol RObotic NETwork (AERONET) data, trajectory and Potential Source Contribution Function (PSCF) modeling is used to identify the potential transport pathways and contribution of sources from four characteristic aerosol types. Four characteristic aerosol types were defined using a total of 730 AERONET data measurements between 2005 and 2008. They are coastal urban, polluted urban, dust (likely to be long distance desert dust), and heavy pollution. Results show that the sources of polluted urban and heavy pollution are associated with industrial emissions in southern China, whereas coastal urban aerosols have been affected both from natural marine aerosol and emissions. The PSCF map of dust shows a wide range of pathways followed by east- and south-eastwards trajectories from northwest China to Hong Kong. Although the contribution from dust sources is small compared to the anthropogenic aerosols, a serious recent dust outbreak has been observed in Hong Kong with an elevation of the Air Pollution Index to 500, compared with 50-100 on normal days. Therefore, the combined use of clustered AERONET data, trajectory and the PSCF models can help to resolve the longstanding issue about source regions and characteristics of pollutants carried to Hong Kong.

Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collier, Sonya; Zhou, Shan; Onasch, Timothy B.

Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (~2700 m a.s.l.) as well as near their sources using an aircraft. In addition, the regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), anmore » index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (~1 h old) and emissions sampled after atmospheric transport (6–45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. In conclusion, these results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.« less

Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

DOE PAGES

Collier, Sonya; Zhou, Shan; Onasch, Timothy B.; ...

2016-07-11

Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (~2700 m a.s.l.) as well as near their sources using an aircraft. In addition, the regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), anmore » index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (~1 h old) and emissions sampled after atmospheric transport (6–45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. In conclusion, these results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.« less

Integrating Cloud Processes in the Community Atmosphere Model, Version 5.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, S.; Bretherton, Christopher S.; Rasch, Philip J.

2014-09-15

This paper provides a description on the parameterizations of global cloud system in CAM5. Compared to the previous versions, CAM5 cloud parameterization has the following unique characteristics: (1) a transparent cloud macrophysical structure that has horizontally non-overlapped deep cumulus, shallow cumulus and stratus in each grid layer, each of which has own cloud fraction, mass and number concentrations of cloud liquid droplets and ice crystals, (2) stratus-radiation-turbulence interaction that allows CAM5 to simulate marine stratocumulus solely from grid-mean RH without relying on the stability-based empirical empty stratus, (3) prognostic treatment of the number concentrations of stratus liquid droplets and icemore » crystals with activated aerosols and detrained in-cumulus condensates as the main sources and evaporation-sedimentation-precipitation of stratus condensate as the main sinks, and (4) radiatively active cumulus. By imposing consistency between diagnosed stratus fraction and prognosed stratus condensate, CAM5 is free from empty or highly-dense stratus at the end of stratus macrophysics. CAM5 also prognoses mass and number concentrations of various aerosol species. Thanks to the aerosol activation and the parameterizations of the radiation and stratiform precipitation production as a function of the droplet size, CAM5 simulates various aerosol indirect effects associated with stratus as well as direct effects, i.e., aerosol controls both the radiative and hydrological budgets. Detailed analysis of various simulations revealed that CAM5 is much better than CAM3/4 in the global performance as well as the physical formulation. However, several problems were also identifed, which can be attributed to inappropriate regional tuning, inconsistency between various physics parameterizations, and incomplete model physics. Continuous efforts are going on to further improve CAM5.« less

Aerosol composition, oxidation properties, and sources in Beijing: results from the 2014 Asia-Pacific Economic Cooperation summit study

NASA Astrophysics Data System (ADS)

Xu, W. Q.; Sun, Y. L.; Chen, C.; Du, W.; Han, T. T.; Wang, Q. Q.; Fu, P. Q.; Wang, Z. F.; Zhao, X. J.; Zhou, L. B.; Ji, D. S.; Wang, P. C.; Worsnop, D. R.

2015-12-01

The mitigation of air pollution in megacities remains a great challenge because of the complex sources and formation mechanisms of aerosol particles. The 2014 Asia-Pacific Economic Cooperation (APEC) summit in Beijing serves as a unique experiment to study the impacts of emission controls on aerosol composition, size distributions, and oxidation properties. Herein, a high-resolution time-of-flight aerosol mass spectrometer was deployed in urban Beijing for real-time measurements of size-resolved non-refractory submicron aerosol (NR-PM1) species from 14 October to 12 November 2014, along with a range of collocated measurements. The average (±σ) PM1 was 41.6 (±38.9) μg m-3 during APEC, which was decreased by 53 % compared with that before APEC. The aerosol composition showed substantial changes owing to emission controls during APEC. Secondary inorganic aerosol (SIA: sulfate + nitrate + ammonium) showed significant reductions of 62-69 %, whereas organics presented much smaller decreases (35 %). The results from the positive matrix factorization of organic aerosol (OA) indicated that highly oxidized secondary organic aerosol (SOA) showed decreases similar to those of SIA during APEC. However, primary organic aerosol (POA) from cooking, traffic, and biomass-burning sources were comparable to those before APEC, indicating the presence of strong local source emissions. The oxidation properties showed corresponding changes in response to OA composition. The average oxygen-to-carbon level during APEC was 0.36 (±0.10), which is lower than the 0.43 (±0.13) measured before APEC, demonstrating a decrease in the OA oxidation degree. The changes in size distributions of primary and secondary species varied during APEC. SIA and SOA showed significant reductions in large accumulation modes with peak diameters shifting from ~ 650 to 400 nm during APEC, whereas those of POA remained relatively unchanged. The changes in aerosol composition, size distributions, and oxidation degrees during the aging processes were further illustrated in a case study of a severe haze episode. Our results elucidated a complex response of aerosol chemistry to emission controls, which has significant implications that emission controls over regional scales can substantially reduce secondary particulates. However, stricter emission controls for local source emissions are needed for further mitigating air pollution in the megacity of Beijing.

Current and future contributions of local emissions from shipping and hydrocarbon extraction flaring to short lived pollutants in the Arctic

NASA Astrophysics Data System (ADS)

Marelle, L.; Raut, J. C.; Law, K.; Thomas, J. L.; Fast, J. D.; Berg, L. K.; Shrivastava, M. B.; Easter, R. C.; Herber, A. B.

2015-12-01

The Arctic is increasingly open to human activity due to rapid Arctic warming, associated with decreased sea ice extent and snow cover. While pollution from in-Arctic sources is currently low, oil and gas extraction and marine traffic could become a significant future source of short-lived pollutants (aerosols, ozone) in the Arctic. It is currently unclear if these local sources might become significant compared to the long-range transport of anthropogenic pollution from the midlatitudes, which is currently the main source of Arctic pollution. Here, we investigate the current (2012) and future (2050) impact of emissions from shipping and oil and gas extraction on Arctic aerosols and ozone, in relation to emissions from long-range transport. These impacts are determined by performing 6-month long, quasi-hemispheric simulations over the Arctic region with the WRF-Chem model. Our regional simulations include up-to-date representations of cloud/aerosol interactions and secondary organic aerosol formation developed recently for WRF-Chem. In order to determine the impact of Arctic shipping and oil and gas extraction, we use recent emission inventories by Winther et al., 2014 for local shipping and ECLIPSEv5 for oil and gas flaring. Both inventories suggest that current and future emissions from these sources are higher than previous estimates. Simulations are evaluated using measurements at Arctic surface sites and aircraft campaigns (ACCESS, YAK) in 2012. Model results are then used to assess the impact of Arctic shipping and oil and gas flaring on modeled surface aerosol and ozone concentrations, direct aerosol and ozone radiative effects, indirect aerosol radiative effects, and aerosol deposition. Results are used to determine if these local emissions are expected to have a significant influence on these quantities at the local or the regional scale, compared to emissions transported from the midlatitudes and to other emission sources, including boreal fires.

Aerosol Profile Measurements from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

NASA Technical Reports Server (NTRS)

Obland, Michael D.; Hostetler, Chris A.; Ferrare, Richard A.; Hair, John W.; Roers, Raymond R.; Burton, Sharon P.; Cook, Anthony L.; Harper, David B.

2008-01-01

Since achieving first light in December of 2005, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) has been involved in seven field campaigns, accumulating over 450 hours of science data across more than 120 flights. Data from the instrument have been used in a variety of studies including validation and comparison with the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission, aerosol property retrievals combining passive and active instrument measurements, aerosol type identification, aerosol-cloud interactions, and cloud top and planetary boundary layer (PBL) height determinations. Measurements and lessons learned from the HSRL are leading towards next-generation HSRL instrument designs that will enable even further studies of aerosol intensive and extensive parameters and the effects of aerosols on the climate system. This paper will highlight several of the areas in which the NASA Airborne HSRL is making contributions to climate science.

Light-absorbing oligomer formation in secondary organic aerosol from reactive uptake of isoprene epoxydiols.

PubMed

Lin, Ying-Hsuan; Budisulistiorini, Sri Hapsari; Chu, Kevin; Siejack, Richard A; Zhang, Haofei; Riva, Matthieu; Zhang, Zhenfa; Gold, Avram; Kautzman, Kathryn E; Surratt, Jason D

2014-10-21

Secondary organic aerosol (SOA) produced from reactive uptake and multiphase chemistry of isoprene epoxydiols (IEPOX) has been found to contribute substantially (upward of 33%) to the fine organic aerosol mass over the Southeastern U.S. Brown carbon (BrC) in rural areas of this region has been linked to secondary sources in the summer when the influence of biomass burning is low. We demonstrate the formation of light-absorbing (290 < λ < 700 nm) SOA constituents from reactive uptake of trans-β-IEPOX onto preexisting sulfate aerosols as a potential source of secondary BrC. IEPOX-derived BrC generated in controlled chamber experiments under dry, acidic conditions has an average mass absorption coefficient of ∼ 300 cm(2) g(-1). Chemical analyses of SOA constituents using UV-visible spectroscopy and high-resolution mass spectrometry indicate the presence of highly unsaturated oligomeric species with molecular weights separated by mass units of 100 (C5H8O2) and 82 (C5H6O) coincident with the observations of enhanced light absorption, suggesting such oligomers as chromophores, and potentially explaining one source of humic-like substances (HULIS) ubiquitously present in atmospheric aerosol. Similar light-absorbing oligomers were identified in fine aerosol collected in the rural Southeastern U.S., supporting their atmospheric relevance and revealing a previously unrecognized source of oligomers derived from isoprene that contributes to ambient fine aerosol mass.

Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions

PubMed Central

Gentner, Drew R.; Isaacman, Gabriel; Worton, David R.; Chan, Arthur W. H.; Dallmann, Timothy R.; Davis, Laura; Liu, Shang; Day, Douglas A.; Russell, Lynn M.; Wilson, Kevin R.; Weber, Robin; Guha, Abhinav; Harley, Robert A.; Goldstein, Allen H.

2012-01-01

Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon and key precursors to secondary organic aerosol (SOA) in urban areas. Their relative importance for aerosol formation is a controversial issue with implications for air quality control policy and public health. We characterize the chemical composition, mass distribution, and organic aerosol formation potential of emissions from gasoline and diesel vehicles, and find diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust. However, both sources are important for air quality; depending on a region’s fuel use, diesel is responsible for 65% to 90% of vehicular-derived SOA, with substantial contributions from aromatic and aliphatic hydrocarbons. Including these insights on source characterization and SOA formation will improve regional pollution control policies, fuel regulations, and methodologies for future measurement, laboratory, and modeling studies. PMID:23091031

Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions.

PubMed

Gentner, Drew R; Isaacman, Gabriel; Worton, David R; Chan, Arthur W H; Dallmann, Timothy R; Davis, Laura; Liu, Shang; Day, Douglas A; Russell, Lynn M; Wilson, Kevin R; Weber, Robin; Guha, Abhinav; Harley, Robert A; Goldstein, Allen H

2012-11-06

Emissions from gasoline and diesel vehicles are predominant anthropogenic sources of reactive gas-phase organic carbon and key precursors to secondary organic aerosol (SOA) in urban areas. Their relative importance for aerosol formation is a controversial issue with implications for air quality control policy and public health. We characterize the chemical composition, mass distribution, and organic aerosol formation potential of emissions from gasoline and diesel vehicles, and find diesel exhaust is seven times more efficient at forming aerosol than gasoline exhaust. However, both sources are important for air quality; depending on a region's fuel use, diesel is responsible for 65% to 90% of vehicular-derived SOA, with substantial contributions from aromatic and aliphatic hydrocarbons. Including these insights on source characterization and SOA formation will improve regional pollution control policies, fuel regulations, and methodologies for future measurement, laboratory, and modeling studies.

Fine mode aerosol chemistry over a rural atmosphere near the north-east coast of Bay of Bengal in India

NASA Astrophysics Data System (ADS)

Adak, Anandamay; Chatterjee, Abhijit; Ghosh, Sanjay; Raha, Sibaji; Roy, Arindam

2016-07-01

A study was conducted on the chemical characterization of fine mode aerosol or PM2.5 over a rural atmosphere near the coast of Bay of Bengal in eastern India. Samples were collected and analyzed during March 2013 - February 2014. The concentration of PM2.5 was found span over a wide range from as low as 3 µg m-3 to as high as 180 µg m-3. The average concentration of PM2.5 was 62 µg m-3. Maximum accumulation of fine mode aerosol was observed during winter whereas minimum was observed during monsoon. Water soluble ionic species of fine mode aerosol were characterized over this rural atmosphere. In spite of being situated near the coast of Bay of Bengal, we observed significantly higher concentrations for anthropogenic species like ammonium and sulphate. The concentrations of these two species were much higher than the sea-salt aerosols. Ammonium and sulphate contributed around 30 % to the total fine mode aerosols. Even dust aerosol species like calcium also showed higher concentrations. Chloride to sodium ratio was found to be much less than that in standard sea-water indicating strong interaction between sea-salt and anthropogenic aerosols. Use of fertilizers in various crop fields and human and animal wastes significantly increased ammonium in fine mode aerosols. Dust aerosol species were accumulated in the atmosphere which could be due to transport of finer dust species from nearby metropolis or locally generated. Non-sea-sulphate and nitrate showed significant contributions in fine mode aerosols having both local and transported sources. Source apportionment shows prominent emission sources of anthropogenic aerosols from local anthropogenic activities and transported from nearby Kolkata metropolis as well.

Source identification of coarse particles in the Desert ...

EPA Pesticide Factsheets

The Desert Southwest Coarse Particulate Matter Study was undertaken to further our understanding of the spatial and temporal variability and sources of fine and coarse particulate matter (PM) in rural, arid, desert environments. Sampling was conducted between February 2009 and February 2010 in Pinal County, AZ near the town of Casa Grande where PM concentrations routinely exceed the U.S. National Ambient Air Quality Standards (NAAQS) for both PM10 and PM2.5. In this desert region, exceedances of the PM10 NAAQS are dominated by high coarse particle concentrations, a common occurrence in this region of the United States. This work expands on previously published measurements of PM mass and chemistry by examining the sources of fine and coarse particles and the relative contribution of each to ambient PM mass concentrations using the Positive Matrix Factorization receptor model (Clements et al., 2014). Highlights • Isolation of coarse particles from fine particle sources. • Unique chemical composition of coarse particles. • Role of primary biological particles on aerosol loadings.

Characterization of primary organic aerosol emissions from meat cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations.

PubMed

Mohr, Claudia; Huffman, Alex; Cubison, Michael J; Aiken, Allison C; Docherty, Kenneth S; Kimmel, Joel R; Ulbrich, Ingrid M; Hannigan, Michael; Jimenez, Jose L

2009-04-01

Organic aerosol (OA) emissions from motor vehicles, meat-cooking and trash burning are analyzed here using a high-resolution aerosol mass spectrometer (AMS). High resolution data show that aerosols emitted by combustion engines and plastic burning are dominated by hydrocarbon-like organic compounds. Meat cooking and especially paper burning emissions contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to those from ambient hydrocarbon-like OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from these sources is unlikelyto be a significant direct source of ambient OOA. There are significant differences in high-resolution tracer m/zs that may be useful for differentiating some of these sources. Unlike in most ambient spectra, all of these sources have low total m/z 44 and this signal is not dominated by the CO2+ ion. All sources have high m/z 57, which is low during high OOA ambient periods. Spectra from paper burning are similar to some types of biomass burning OA, with elevated m/z 60. Meat cooking aerosols also have slightly elevated m/z 60, whereas motor vehicle emissions have very low signal at this m/z.

Final Report for “Simulating the Arctic Winter Longwave Indirect Effects. A New Parameterization for Frost Flower Aerosol Salt Emissions” (DESC0006679) for 9/15/2011 through 9/14/2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Lynn M.; Somerville, Richard C.J.; Burrows, Susannah

Description of the Project: This project has improved the aerosol formulation in a global climate model by using innovative new field and laboratory observations to develop and implement a novel wind-driven sea ice aerosol flux parameterization. This work fills a critical gap in the understanding of clouds, aerosol, and radiation in polar regions by addressing one of the largest missing particle sources in aerosol-climate modeling. Recent measurements of Arctic organic and inorganic aerosol indicate that the largest source of natural aerosol during the Arctic winter is emitted from crystal structures, known as frost flowers, formed on a newly frozen seamore » ice surface [Shaw et al., 2010]. We have implemented the new parameterization in an updated climate model making it the first capable of investigating how polar natural aerosol-cloud indirect effects relate to this important and previously unrecognized sea ice source. The parameterization is constrained by Arctic ARM in situ cloud and radiation data. The modified climate model has been used to quantify the potential pan-Arctic radiative forcing and aerosol indirect effects due to this missing source. This research supported the work of one postdoc (Li Xu) for two years and contributed to the training and research of an undergraduate student. This research allowed us to establish a collaboration between SIO and PNNL in order to contribute the frost flower parameterization to the new ACME model. One peer-reviewed publications has already resulted from this work, and a manuscript for a second publication has been completed. Additional publications from the PNNL collaboration are expected to follow.« less

Sources of atmospheric aerosol from long-term measurements (5 years) of chemical composition in Athens, Greece.

PubMed

Paraskevopoulou, D; Liakakou, E; Gerasopoulos, E; Mihalopoulos, N

2015-09-15

To identify the sources of aerosols in Greater Athens Area (GAA), a total of 1510 daily samples of fine (PM 2.5) and coarse (PM 10-2,5) aerosols were collected at a suburban site (Penteli), during a five year period (May 2008-April 2013) corresponding to the period before and during the financial crisis. In addition, aerosol sampling was also conducted in parallel at an urban site (Thissio), during specific, short-term campaigns during all seasons. In all these samples mass and chemical composition measurements were performed, the latest only at the fine fraction. Particulate organic matter (POM) and ionic masses (IM) are the main contributors of aerosol mass, equally contributing by accounting for about 24% of the fine aerosol mass. In the IM, nss-SO4(-2) is the prevailing specie followed by NO3(-) and NH4(+) and shows a decreasing trend during the 2008-2013 period similar to that observed for PM masses. The contribution of water in fine aerosol is equally significant (21 ± 2%), while during dust transport, the contribution of dust increases from 7 ± 2% to 31 ± 9%. Source apportionment (PCA and PMF) and mass closure exercises identified the presence of six sources of fine aerosols: secondary photochemistry, primary combustion, soil, biomass burning, sea salt and traffic. Finally, from winter 2012 to winter 2013 the contribution of POM to the urban aerosol mass is increased by almost 30%, reflecting the impact of wood combustion (dominant fuel for domestic heating) to air quality in Athens, which massively started in winter 2013. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of aerosol pollution sources during sandstorms in Northwestern China using remote sensed and model simulated data

NASA Astrophysics Data System (ADS)

Filonchyk, Mikalai; Yan, Haowen; Yang, Shuwen; Lu, Xiaomin

2018-02-01

The present paper has used a comprehensive approach to study atmosphere pollution sources including the study of vertical distribution characteristics, the epicenters of occurrence and transport of atmospheric aerosol in North-West China under intensive dust storm registered in all cities of the region in April 2014. To achieve this goal, the remote sensing data using Moderate Resolution Imaging Spectroradiometer satellite (MODIS) as well as model-simulated data, were used, which facilitate tracking the sources, routes, and spatial extent of dust storms. The results of the study have shown strong territory pollution with aerosol during sandstorm. According to ground-based air quality monitoring stations data, concentrations of PM10 and PM2.5 exceeded 400 μg/m3 and 150 μg/m3, respectively, the ratio PM2.5/PM10 being within the range of 0.123-0.661. According to MODIS/Terra Collection 6 Level-2 aerosol products data and the Deep Blue algorithm data, the aerosol optical depth (AOD) at 550 nm in the pollution epicenter was within 0.75-1. The vertical distribution of aerosols indicates that the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) 532 nm total attenuates backscatter coefficient ranges from 0.01 to 0.0001 km-1 × sr-1 with the distribution of the main types of aerosols in the troposphere of the region within 0-12.5 km, where the most severe aerosol contamination is observed in the lower troposphere (at 3-6 km). According to satellite sounding and model-simulated data, the sources of pollution are the deserted regions of Northern and Northwestern China.

Sources of primary and secondary organic aerosols in Chinese versus European Cities during winter time

NASA Astrophysics Data System (ADS)

Prevot, A. S.; Slowik, J.; El-Haddad, I.; Pieber, S. M.; Yuan, B.; Stefenelli, G.; Pospisilova, V.; Lopez-Hilfiker, F.; Qi, L.; Tong, Y.; Wang, L.; Daellenbach, K.; Klein, F.; Elser, M.; Junji, C.; Huang, R. J. J.; Baltensperger, U.

2017-12-01

In the recent years, aerosol mass spectrometric (AMS) measurements were performed in Beijing (China), Zurich (Switzerland) and other Chinese and European cities indicating the importance of not only primary sources but also secondary organic aerosol (SOA) sources despite low radiation levels for photooxidation. Among the primary sources, residential burning is especially important in winter including wood and coal burning. Also for secondary organic aerosols, VOC emissions of residential burning are likely an important source in winter. An interesting question is whether daytime photooxidation and/or night-time NO3 radical chemistry are important pathways for the SOA formation. Recently we developed a new measurement technique based on exctractive electrospray ionization (EESI) that allow for the study of the organic molecules in the particulate phase without fragmentation. Combined measurements with AMS and EESI will be discussed for smogchamber experiments (simulating both nighttime and daytime chemistry) SOA formation potential, the link between VOCs and SOA and the SOA composition. In-situ and off-line measurements in Europe and China are analyzed in the light of those experiments with a focus on the importance of residential burning to both primary and secondary organic aerosols in cities during winter.

MODELING PHOTOCHEMISTRY AND AEROSOL FORMATION IN POINT SOURCE PLUMES WITH THE CMAQ PLUME-IN-GRID

EPA Science Inventory

Emissions of nitrogen oxides and sulfur oxides from the tall stacks of major point sources are important precursors of a variety of photochemical oxidants and secondary aerosol species. Plumes released from point sources exhibit rather limited dimensions and their growth is gradu...

Compound Specific Isotope Analysis of Fatty Acids in Southern African Aerosols

NASA Astrophysics Data System (ADS)

Billmark, K. A.; Macko, S. A.; Swap, R. J.

2003-12-01

This study, conducted as a part of the Southern African Regional Science Initiative (SAFARI 2000), applied compound specific isotope analysis to describe aerosols at source regions and rural locations. Stable carbon isotopic compositions of individual fatty acids were determined for aerosol samples collected at four sites throughout southern Africa. Mongu, Zambia and Skukuza, South Africa were chosen for their location within intense seasonal Miombo woodland savanna and bushveld savanna biomass burning source regions, respectively. Urban aerosols were collected at Johannesburg, South Africa and rural samples were collected at Sua Pan, Botswana. Fatty acid isotopic compositions varied temporally. Urban aerosols showed significant isotopic enrichment of selected short chain fatty acids (C < 20) compared to aerosols produced during biomass combustion. Sua Pan short chain fatty acid signatures were significantly different from the other non-urban sites, which suggests that sources other than biomass combustion products, such as organic eolian material, impact the Sua Pan aerosol profile. However, a high degree of correlation between Sua Pan and Skukuza long chain fatty acid δ 13C values confirm atmospheric linkages between the two areas and that isotopic signatures of combusted fatty acids are unaltered during atmospheric transport highlighting their potential for use as a conservative tracer.

Comparison of dust release from epoxy and paint nanocomposites and conventional products during sanding and sawing.

PubMed

Gomez, Virginia; Levin, Marcus; Saber, Anne T; Irusta, Silvia; Dal Maso, Miikka; Hanoi, Roberto; Santamaria, Jesus; Jensen, Keld A; Wallin, Håkan; Koponen, Ismo K

2014-10-01

The release of dust generated during sanding or sawing of nanocomposites was compared with conventional products without nanomaterials. Epoxy-based polymers with and without carbon nanotubes, and paints with different amounts of nano-sized titanium dioxide, were machined in a closed aerosol chamber. The temporal evolution of the aerosol concentration and size distribution were measured simultaneously. The morphology of collected dust by scanning electron microscopy was different depending on the type of nanocomposites: particles from carbon nanotubes (CNTs) nanocomposites had protrusions on their surfaces and aggregates and agglomerates are attached to the paint matrix in particles emitted from alkyd paints. We observed no significant differences in the particle size distributions when comparing sanding dust from nanofiller containing products with dust from conventional products. Neither did we observe release of free nanomaterials. Instead, the nanomaterials were enclosed or partly enclosed in the matrix. A source strength term Si (cm(-3) s(-1)) that describes particle emission rates from continuous sources was introduced. Comparison between the Si parameters derived from sanding different materials allows identification of potential effects of addition of engineered nanoparticles to a composite. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Source contributions to black carbon mass fractions in aerosol particles over the northwestern Pacific

NASA Astrophysics Data System (ADS)

Koga, Seizi; Maeda, Takahisa; Kaneyasu, Naoki

Aerosol particle number size distributions above 0.3 μm in diameter and black carbon mass concentrations in aerosols were observed on Chichi-jima of the Ogasawara Islands in the northwestern Pacific from January 2000 to December 2002. Chichi-jima is suitable to observe polluted air masses from East Asia in winter and clean air masses over the western North Pacific in summer. In winter, aerosols over Chichi-jima were strongly affected by anthropogenic emissions in East Asia. The form of energy consumption in East Asia varies in various regions. Hence, each source region is expected to be characterized by an individual black carbon mass fraction. A three-dimensional Eulerian transport model was used to estimate contribution rates to air pollutants from each source region in East Asia. Because the Miyake-jima eruption began at the end of June 2000, the influence of smokes from Miyake-jima was also considered in the model calculation. The results of model calculations represent what must be noticed about smokes from volcanoes including Miyake-jima to interpret temporal variations of sulfur compounds over the northwestern Pacific. To evaluate black carbon mass fractions in anthropogenic aerosols as a function of source region, the relationships between the volume concentration of aerosol particles and the black carbon mass concentration in the winter were classified under each source region in East Asia. Consequently, the black carbon mass fractions in aerosols from China, Japan and the Korean Peninsula, and other regions were estimated to be 9-13%, 5-7%, and 4-5%, respectively.

Spectroscopic characterization of Antarctic marine aerosol

NASA Astrophysics Data System (ADS)

Paglione, Marco; Zanca, Nicola; Rinaldi, Matteo; Dall'osto, Manuel; Simo, Rafel; Facchini, Maria Cristina; Decesari, Stefano

2017-04-01

Marine aerosol constitutes an important and not thoroughly investigated natural aerosol system. In particular, the poor knowledge of the physical-chemical properties of primary (sea-spray) and secondary particles, especially over biologically active seawaters, affects the current capability of modeling the effect of marine aerosol on climate (O'Dowd et al., 2004). In polar regions, surface seawater composition and its exchanges with the atmosphere is complicated also by the presence of sea-ice and of the variety of micro-organisms (viruses, prokaryotes and microalgae) living within it (Levasseur,2013). In the framework of the Spanish project PEGASO (Plankton-derived Emission of Gases and Aerosols in the Southern Ocean) submicron aerosol samples were collected during a 6 weeks long oceanographic cruise (2nd January 2015 - 11th February 2015) conducted in the regions of Antarctic Peninsula, South Orkney and South Georgia Islands, an area of the Southern Ocean characterized every summer by both large patches of productive waters (phytoplankton blooms) and sea-ice cover. The collected samples were analyzed by means of proton-Nuclear Magnetic Resonance (H-NMR) spectroscopy with aim of organic compounds characterization in terms of functional groups and specific molecular tracers identification (Decesari et al., 2011). H-NMR spectral features resulted quite variable among the different samples both in terms of relative abundance of main functional groups and in terms of presence of specific compounds. In all the samples were found biogenic markers, like low-molecular-weight alkyl-amines and methanesulphonate (MSA), of secondary origin (formed by the condensation of vapors onto particles). Resonance signals of other aliphatic compounds of possible primary origin, like lipids, aminoacids (e.g. alanine) and sugars (e.g. sucrose) are present in variable concentrations in the samples. A hierarchical cluster analysis applied on the NMR spectra allowed to identify similarities in the samples collected close the Weddell-Sea area, showing an enhancement of biogenic alkyl-amines (including mono-, di- and tri-methylamine) and MSA and suggesting a common source probably linked with the sea-ice cover dominating that region. As such, our results point to secondary organic aerosol (SOA) sources from precursors emitted by sea ice regions around Antarctica and call for better representation of the sea ice-ocean-atmosphere biogeochemistry in Earth system models. References: Decesari, S. et al., JGR-Atmospheres 116 (2011). Levasseur, M., Nature Geoscience, Vol. 6, September (2013). O'Dowd, C. et al., Nature 431, 676-680 (2004). Acknowledgments: The cruise was funded by the Spanish Ministry of Economy through projects PEGASO (CTM2012-37615) and Bio-Nuc (CGL2013-49020-R), and by the EU though the FP7-PEOPLE-2013-IOF program (Project number 624680, MANU - Marine Aerosol NUcleations).

Atmospheric Aerosols in a Changing World

NASA Astrophysics Data System (ADS)

Heald, C. L.

2015-12-01

Aerosols in the atmosphere impact human and environmental health, visibility, and climate. Exposure to air pollution is the leading environmental cause of premature mortality world-wide. The role of aerosols on the Earth's climate represents the single largest source of uncertainty in our understanding of global radiative forcing. Tremendous strides have been made to clean up the air in recent decades, and yet poor air quality continues to plague many regions of the world, and our understanding of how global change will feedback on to aerosol sources, formation, and impacts is limited. In this talk, I will use recent results from my research group to highlight some of the key uncertainties and research topics in global aerosol lifecycle.

Laboratory and field based evaluations of chromatography related performance of the Monitor for AeRosols and GAses in ambient Air (MARGA)

EPA Science Inventory

The semi-continuous Monitor for AeRosols and Gases in Ambient air (MARGA) was evaluated using laboratory and field data with a focus on chromatography. The performance and accuracy assessment revealed various errors and uncertainties resulting from mis-identification and mis-int...

Laboratory and field based evaluation of chromatography related performance of the Monitor for AeRosols and Gases in ambient Air (MARGA)

EPA Science Inventory

The semi-continuous Monitor for AeRosols and Gases in Ambient air (MARGA) was evaluated using laboratory and field data with a focus on chromatography. The performance and accuracy assessment revealed various errors and uncertainties resulting from mis-identification and mis-int...

IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC OR HYDROXYL GROUPS. 2. ORGANIC TRACER COMPOUNDS FROM MONOTERPENES

EPA Science Inventory

A comparison was made of polar organic compounds found in the field with those produced in secondary organic aerosol from laboratory irradiations of natural hydrocarbons and oxides of nitrogen. The field samples comprised atmospheric particulate matter (PM_2.5) collect...

Size Resolved Measurements of Springtime Aerosol Particles over the Northern South China Sea

NASA Technical Reports Server (NTRS)

Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Cliff, Stephen S.; Zhao, Yongjing; Lin, Neng-Huei; Tsay, Si-Chee; Chu, Yu-Chi; Westphal, Douglas L.

2012-01-01

Large sources of aerosol particles and their precursors are ubiquitous in East Asia. Such sources are known to impact the South China Sea (henceforth SCS), a sometimes heavily polluted region that has been suggested as particularly vulnerable to climate change. To help elucidate springtime aerosol transport into the SCS, an intensive study was performed on the remote Dongsha (aka Pratas) Islands Atoll in spring 2010. As part of this deployment, a Davis Rotating-drum Uniform size-cut Monitor (DRUM) cascade impactor was deployed to collect size-resolved aerosol samples at the surface that were analyzed by X-ray fluorescence for concentrations of selected elements. HYSPLIT backtrajectories indicated that the transport of aerosol observed at the surface at Dongsha was occurring primarily from regions generally to the north and east. This observation was consistent with the apparent persistence of pollution and dust aerosol, along with sea salt, in the ground-based dataset. In contrast to the sea-level observations, modeled aerosol transport suggested that the westerly flow aloft (w700 hPa) transported smoke-laden air toward the site from regions from the south and west. Measured aerosol optical depth at the site was highest during time periods of modeled heavy smoke loadings aloft. These periods did not coincide with elevated aerosol concentrations at the surface, although the model suggested sporadic mixing of this free-tropospheric aerosol to the surface over the SCS. A biomass burning signature was not clearly identified in the surface aerosol composition data, consistent with this aerosol type remaining primarily aloft and not mixing strongly to the surface during the study. Significant vertical wind shear in the region also supports the idea that different source regions lead to varying aerosol impacts in different vertical layers, and suggests the potential for considerable vertical inhomogeneity in the SCS aerosol environment.

Type of Aerosols Determination Over Malaysia by AERONET Data

NASA Astrophysics Data System (ADS)

Lim, H.; Tan, F.; Abdullah, K.; Holben, B. N.

2013-12-01

Aerosols are one of the most interesting studies by the researchers due to the complicated of their characteristic and are not yet well quantified. Besides that there still have huge uncertainties associated with changes in Earth's radiation budget. The previous study by other researchers shown a lot of difficulties and challenges in quantifying aerosol influences arise. As well as the heterogeneity from the aerosol loading and properties: spatial, temporal, size, and composition. In this study, we were investigated the aerosol characteristics over two regions with different environmental conditions and aerosol sources contributed. The study sites are Penang and Kuching, Malaysia where ground-based AErosol RObotic NETwork (AERONET) sun-photometer was deployed. The types of the aerosols for both study sites were identified by analyzing aerosol optical depth, angstrom parameter and spectral de-convolution algorithm product from sun-photometer. The analysis was carried out associated with the in-situ meteorological data of relative humidity, visibility and air pollution index. The major aerosol type over Penang found in this study was hydrophobic aerosols. Whereas the hydrophilic type of the aerosols was highly distributed in Kuching. The major aerosol size distributions for both regions were identified in this study. The result also shows that the aerosol optical properties were affected by the types and characteristic of aerosols. Therefore, in this study we generated an algorithm to determine the aerosols in Malaysia by considered the environmental factors. From this study we found that the source of aerosols should always being consider in to retrieve the accurate information of aerosol for air quality study.

An automatic aerosol classification for earlinet: application and results

NASA Astrophysics Data System (ADS)

Papagiannopoulos, Nikolaos; Mona, Lucia; Amiridis, Vassilis; Binietoglou, Ioannis; D'Amico, Giuseppe; Guma-Claramunt, P.; Schwarz, Anja; Alados-Arboledas, Lucas; Amodeo, Aldo; Apituley, Arnoud; Baars, Holger; Bortoli, Daniele; Comeron, Adolfo; Guerrero-Rascado, Juan Luis; Kokkalis, Panos; Nicolae, Doina; Papayannis, Alex; Pappalardo, Gelsomina; Wandinger, Ulla; Wiegner, Matthias

2018-04-01

Aerosol typing is essential for understanding the impact of the different aerosol sources on climate, weather system and air quality. An aerosol classification method for EARLINET (European Aerosol Research Lidar Network) measurements is introduced which makes use the Mahalanobis distance classifier. The performance of the automatic classification is tested against manually classified EARLINET data. Results of the application of the method to an extensive aerosol dataset will be presented.

Accumulation-mode aerosol number concentrations in the Arctic during the ARCTAS aircraft campaign: Long-range transport of polluted and clean air from the Asian continent

NASA Astrophysics Data System (ADS)

Matsui, H.; Kondo, Y.; Moteki, N.; Takegawa, N.; Sahu, L. K.; Koike, M.; Zhao, Y.; Fuelberg, H. E.; Sessions, W. R.; Diskin, G.; Anderson, B. E.; Blake, D. R.; Wisthaler, A.; Cubison, M. J.; Jimenez, J. L.

2011-10-01

We evaluate the impact of transport from midlatitudes on aerosol number concentrations in the accumulation mode (light-scattering particles (LSP) with diameters >180 nm) in the Arctic during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. We focus on transport from the Asian continent. We find marked contrasts in the number concentration (NLSP), transport efficiency (TEN_LSP, the fraction transported from sources to the Arctic), size distribution, and the chemical composition of aerosols between air parcels from anthropogenic sources in East Asia (Asian AN) and biomass burning sources in Russia and Kazakhstan (Russian BB). Asian AN air had lower NLSP and TEN_LSP (25 cm-3 and 18% in spring and 6.2 cm-3 and 3.0% in summer) than Russian BB air (280 cm-3 and 97% in spring and 36 cm-3 and 7.6% in summer) due to more efficient wet scavenging during transport from East Asia. Russian BB in this spring is the most important source of accumulation-mode aerosols over the Arctic, and BB emissions are found to be the primary source of aerosols within all the data in spring during ARCTAS. On the other hand, the contribution of Asian AN transport had a negligible effect on the accumulation-mode aerosol number concentration in the Arctic during ARCTAS. Compared with background air, NLSP was 2.3-4.7 times greater for Russian BB air but 2.4-2.6 times less for Asian AN air in both spring and summer. This result shows that the transport of Asian AN air decreases aerosol number concentrations in the Arctic, despite the large emissions of aerosols in East Asia. The very low aerosol number concentrations in Asian AN air were caused by wet removal during vertical transport in association with warm conveyor belts (WCBs). Therefore, this cleansing effect will be prominent for air transported via WCBs from other midlatitude regions and seasons. The inflow of clean midlatitude air can potentially have an important impact on accumulation-mode aerosol number concentrations in the Arctic.

Azores 2017 Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehner, Birgit; Chevallier, Karine; Weinhold, Kay

Aerosol particles play an important role for the regional and global climate. Therefore, a network of measurement sites has been established worldwide, but only a small fraction of them is capturing the marine boundary layer (MBL) while approximately 70% of the Earth’s surface is covered with water. The main focus of this project is to improve the knowledge of sources and exchange processes of aerosol particles in general (German Research Foundation [DFG] project WE 2757/2-1) and of cloud condensation nuclei in particular (DFG project HE 6770/2-1) in the MBL in the northeastern Atlantic Ocean where the influence of local anthropogenicmore » sources is negligible. The main hypothesis of the project is that long-range transport of aerosols from North America as well as new particle formation in the free troposphere (FT) and at cloud edges followed by vertical transport contribute significantly to the aerosol budget in the MBL. The knowledge of sources and sinks of aerosol particles in combination with vertical exchange between FT and MBL is a prerequisite to predict aerosol particle number concentrations in the lowest regions of the MBL and its influence on the formation of clouds. These processes are not sufficiently quantified over the ocean up to now. To verify the hypothesis stated above, vertical exchange processes and particle sources over the Azores will be quantified using data of 17 measurement flights with high spatial resolution using a helicopter-borne platform developed at the Leibniz Institute for Tropospheric Research (TROPOS). Here, aerosol particle number concentration and vertical wind speed have been measured with a temporal resolution allowing the direct estimate of the vertical turbulent flux of aerosol particles in different heights for the first time. In addition, aerosol particle number size distributions, number concentrations of cloud condensation nuclei (CCN), cloud droplet number concentration (CDNC), and particle absorption at three different wavelengths have been determined. The data analysis is ongoing and final results are not available yet. The detailed analysis of these data will be used to conclude sources and origin of the investigated aerosol particles.« less

Light absorption, optical and microphysical properties of trajectory-clustered aerosols at two AERONET sites in West Africa

NASA Astrophysics Data System (ADS)

Fawole, O. G.; Cai, X.; MacKenzie, A. R.

2015-12-01

Aerosol remote sensing techniques and back-trajectory modeling can be combined to identify aerosol types. We have clustered 7 years of AERONET aerosol signals using trajectory analysis to identify dominant aerosol sources at two AERONET sites in West Africa: Ilorin (4.34 oE, 8.32 oN) and Djougou (1.60 oE, 9.76 oN). Of particular interest are air masses that have passed through the gas flaring region in the Niger Delta area, of Nigeria, en-route the AERONET sites. 7-day back trajectories were calculated using the UK UGAMP trajectory model driven by ECMWF wind analyses data. Dominant sources identified, using literature classifications, are desert dust (DD), Biomass burning (BB) and Urban-Industrial (UI). Below, we use a combination of synoptic trajectories and aerosol optical properties to distinguish a fourth source: that due to gas flaring. Gas flaring, (GF) the disposal of gas through stack in an open-air flame, is believed to be a prominent source of black carbon (BC) and greenhouse gases. For these different aerosol source signatures, single scattering albedo (SSA), refractive index , extinction Angstrom exponent (EEA) and absorption Angstrom exponent (AAE) were used to classify the light absorption characteristics of the aerosols for λ = 440, 675, 870 and1020 nm. A total of 1625 daily averages of aerosol data were collected for the two sites. Of which 245 make up the GF cluster for both sites. For GF cluster, the range of fine-mode fraction is 0.4 - 0.7. Average values SSA(λ), for the total and GF clusters are 0.90(440), 0.93(675), 0.95(870) and 0.96(1020), and 0.93(440), 0.92(675), 0.9(870) and 0.9(1020), respectively. Values of for the GF clusters for both sites are 0.62 - 1.11, compared to 1.28 - 1.66 for the remainder of the clusters, which strongly indicates the dominance of carbonaceous particles (BC), typical of a highly industrial area. An average value of 1.58 for the real part of the refractive index at low SSA for aerosol in the GF cluster is also an indicator of high BC content. Extinction Angstrom exponent, is an indicator of the particle size. EAE values of 0.95-1.32 for aerosol in the GF cluster shows that the aerosols are mainly fine or accumulation mode while values of EAE (0.36-0.6) for the other cluster indicate coarse mode domination of the aerosol. See table 1 for a summary of result.

Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Kawamura, K.; Umarji, G. S.; Tachibana, E.; Patil, R. S.; Gupta, P. K.

2013-05-01

To better understand the sources of PM10 samples in Mumbai, India, aerosol chemical composition, i.e., total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied together with specific markers such as methanesulfonate (MSA), oxalic acid (C2), azelaic acid (C9), and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (δ15N) composition of aerosol total nitrogen, which ranged from 18.1 to 25.4‰, also suggests that biofuel/biomass burning is a predominate source in both the summer and winter seasons. Aerosol mass concentrations of major species increased 3-4 times in winter compared to summer, indicating enhanced emission from these sources in the winter season. Photochemical production tracers, C2 diacid and nssSO42-, do not show diurnal changes. Concentrations of C2 diacid and WSOC show a strong correlation (r2 = 0.95). In addition, WSOC to OC (or TC) ratios remain almost constant for daytime (0.37 ± 0.06 (0.28 ± 0.04)) and nighttime (0.38 ± 0.07 (0.28 ± 0.06)), suggesting that mixing of fresh secondary organic aerosols is not significant and the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C9 diacid present a positive correlation (r2 = 0.75), indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (δ13C) of TC ranged from -27.0 to -25.4‰, with slightly lower average (-26.5 ± 0.3‰) in summer than in winter (-25.9 ± 0.3‰). Positive correlation between WSOC/TC ratios and δ13C values suggested that the relative increment in 13C of wintertime TC may be caused by prolonged photochemical processing of organic aerosols in this season. This study suggests that in winter, the tropical aerosols are more aged due to longer residence time in the atmosphere than in summer aerosols. However, these conclusions are based on the analysis of a limited number of samples (n=25) and more information on this topic may be needed from other similar coastal sites in future.

Organic compounds in aerosols from selected European sites - Biogenic versus anthropogenic sources

NASA Astrophysics Data System (ADS)

Alves, Célia; Vicente, Ana; Pio, Casimiro; Kiss, Gyula; Hoffer, Andras; Decesari, Stefano; Prevôt, André S. H.; Minguillón, María Cruz; Querol, Xavier; Hillamo, Risto; Spindler, Gerald; Swietlicki, Erik

2012-11-01

Atmospheric aerosol samples from a boreal forest (Hyytiälä, April 2007), a rural site in Hungary (K-puszta, summer 2008), a polluted rural area in Italy (San Pietro Capofiume, Po Valley, April 2008), a moderately polluted rural site in Germany located on a meadow (Melpitz, May 2008), a natural park in Spain (Montseny, March 2009) and two urban background locations (Zurich, December 2008, and Barcelona, February/March 2009) were collected. Aliphatics, polycyclic aromatic hydrocarbons, carbonyls, sterols, n-alkanols, acids, phenolic compounds and anhydrosugars in aerosols were chemically characterised by gas chromatography-mass spectrometry, along with source attribution based on the carbon preference index (CPI), the ratios between the unresolved and the chromatographically resolved aliphatics, the contribution of wax n-alkanes, n-alkanols and n-alkanoic acids from plants, diagnostic ratios of individual target compounds and source-specific markers to organic carbon ratios. In spite of transboundary pollution episodes, Hyytiälä registered the lowest levels among all locations. CPI values close to 1 for the aliphatic fraction of the Montseny aerosol suggest that the anthropogenic input may be associated with the transport of aged air masses from the surrounding industrial/urban areas, which superimpose the locally originated hydrocarbons with biogenic origin. Aliphatic and aromatic hydrocarbons in samples from San Pietro Capofiume reveal that fossil fuel combustion is a major source influencing the diel pattern of concentrations. This source contributed to 25-45% of the ambient organic carbon (OC) at the Po Valley site. Aerosols from the German meadow presented variable contributions from both biogenic and anthropogenic sources. The highest levels of vegetation wax components and biogenic secondary organic aerosol (SOA) products were observed at K-puszta, while anthropogenic SOA compounds predominated in Barcelona. The primary vehicular emissions in the Spanish city accounted for around 25-30% of the OC in aerosols. Besides the traffic input (10% of OC), residential wood burning was found to be another dominant emission source contributing to the atmospheric aerosol (up to 38% of OC) at the Swiss urban location. It was estimated that around 10% of the OC mass in the urban sites originates from cooking emissions. Aerosols from the urban area of Zurich presented a much higher PAH content, and benzo(a)pyrene equivalent concentrations sometimes exceeding the mandatory limit.

Biomass burning source characterization requirements in air quality models with and without data assimilation: challenges and opportunities

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Zhang, J. L.; Reid, J. S.; Curtis, C. A.; Westphal, D. L.

2007-12-01

Quantitative models of the transport and evolution of atmospheric pollution have graduated from the laboratory to become a part of the operational activity of forecast centers. Scientists studying the composition and variability of the atmosphere put great efforts into developing methods for accurately specifying sources of pollution, including natural and anthropogenic biomass burning. These methods must be adapted for use in operational contexts, which impose additional strictures on input data and methods. First, only input data sources available in near real-time are suitable for use in operational applications. Second, operational applications must make use of redundant data sources whenever possible. This is a shift in philosophy: in a research context, the most accurate and complete data set will be used, whereas in an operational context, the system must be designed with maximum redundancy. The goal in an operational context is to produce, to the extent possible, consistent and timely output, given sometimes inconsistent inputs. The Naval Aerosol Analysis and Prediction System (NAAPS), a global operational aerosol analysis and forecast system, recently began incorporating assimilation of satellite-derived aerosol optical depth. Assimilation of satellite AOD retrievals has dramatically improved aerosol analyses and forecasts from this system. The use of aerosol data assimilation also changes the strategy for improving the smoke source function. The absolute magnitude of emissions events can be refined through feedback from the data assimilation system, both in real- time operations and in post-processing analysis of data assimilation results. In terms of the aerosol source functions, the largest gains in model performance are now to be gained by reducing data latency and minimizing missed detections. In this presentation, recent model development work on the Fire Locating and Monitoring of Burning Emissions (FLAMBE) system that provides smoke aerosol boundary conditions for NAAPS is described, including redundant integration of multiple satellite platforms and development of feedback loops between the data assimilation system and smoke source.

Source apportionment of airborne particulate matter using organic compounds as tracers

NASA Astrophysics Data System (ADS)

Schauer, James J.; Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

A chemical mass balance receptor model based on organic compounds has been developed that relates source contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.

Global CALIPSO Observations of Aerosol Changes Near Clouds

NASA Technical Reports Server (NTRS)

Varnai, Tamas; Marshak, Alexander

2011-01-01

Several recent studies have found that clouds are surrounded by a transition zone of rapidly changing aerosol optical properties and particle size. Characterizing this transition zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects, and also for improving satellite retrievals of aerosol properties. This letter presents a statistical analysis of a monthlong global data set of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar observations over oceans. The results show that the transition zone is ubiquitous over all oceans and extends up to 15 km away from clouds. They also show that near-cloud enhancements in backscatter and particle size are strongest at low altitudes, slightly below the top of the nearest clouds. Also, the enhancements are similar near illuminated and shadowy cloud sides, which confirms that the asymmetry of Moderate Resolution Imaging Spectroradiometer reflectances found in an earlier study comes from 3-D radiative processes and not from differences in aerosol properties. Finally, the effects of CALIPSO aerosol detection and cloud identification uncertainties are discussed. The findings underline the importance of accounting for the transition zone to avoid potential biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

Natural Aerosols Explain Seasonal and Spatial Patterns of Southern Ocean Cloud Albedo

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCoy, Daniel; Burrows, Susannah M.; Wood, R.

2015-07-17

Small particles called aerosols act as nucleation sites for cloud drop formation, affecting clouds and cloud properties – ultimately influencing the cloud dynamics, lifetime, water path and areal extent that determine the reflectivity (albedo) of clouds. The concentration Nd of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations not only affect cloud properties themselves, but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. Here, it is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more thanmore » half of the spatiotemporal variability in satellite-observed Nd. Enhanced Nd over regions of high biological activity is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35-45°S) and by organic matter in sea spray aerosol at higher latitudes (45-55°S). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m-2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere.« less

Aerosol Production and Growth in the Upper Troposphere over the Amazon Forest Observed during ACRIDICON-CHUVA

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Afchine, A.; Albrecht, R. I.; Artaxo, P.; Borrmann, S.; Cecchini, M. A.; Costa, A.; Fütterer, D.; Järvinen, E.; Klimach, T.; Konemann, T.; Kraemer, M.; Machado, L.; Mertes, S.; Pöhlker, C.; Pöhlker, M. L.; Poeschl, U.; Sauer, D. N.; Schnaiter, M.; Schneider, J.; Schulz, C.; Spanu, A.; Walser, A.; Wang, J.; Weinzierl, B.; Wendisch, M.

2016-12-01

Observations during ACRIDICON-CHUVA showed high aerosol concentrations in the upper troposphere (UT) over the Amazon Basin, with aerosol number concentrations after normalization to STP often exceeding those in the boundary layer (BL) by one or two orders of magnitude. The measurements were made during the German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) on the German research aircraft HALO. The campaign took place over the Amazon Basin in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were consistently observed on all flights, using several aerosol metrics, including condensation nuclei (CN), cloud condensation nuclei (CCN), and chemical species mass concentrations. These UT aerosols were different in their composition and size distribution from the aerosol in the BL, making convective transport of particles unlikely as a source. The regions in the immediate outflow of deep convective clouds were depleted in aerosol particles, whereas dramatically enhanced small (<90 nm diameter) aerosol number concentrations were found in UT regions that had experienced outflow from deep convection in the preceding 24-48 hours. We also found elevated concentrations of larger (>90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest that aerosol production takes place in the UT from volatile material brought up by deep convection, which is converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol may be a source of particles to the BL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of aerosol particles in the Amazonian BL, where aerosol nucleation and new particle formation has not been observed. We propose that this may have been the dominant process supplying secondary aerosols in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.

Sources and Transport of Aerosol above the Boundary Layer over the Mediterranean Basin

NASA Astrophysics Data System (ADS)

Roberts, Greg; Corrigan, Craig; Ritchie, John; Pont, Veronique; Claeys, Marine; Sciare, Jean; Mallet, Marc; Dulac, François; Mihalopoulos, Nikos

2015-04-01

The Mediterranean Region has been identified as sensitive to changes in the hydrological cycle, which could affect the water resources for millions of people by the turn of the century. However, prior to recent observations, most climate models have not accounted for the impacts of aerosol in this region. Past airborne studies have shown that aerosol sources from Europe and Africa are often transported throughout the lower troposphere; yet, because of their complex vertical distribution, it is a challenge to capture the variability and quantify the contribution of these sources to the radiative budget and precipitation processes. The PAEROS ChArMEx Mountain Experiment (PACMEx) complemented the regional activities by collecting aerosol data from atop a mountain on the island of Corsica, France in order to assess boundary layer / free troposphere atmospheric processes. In June/July 2013, PACMEx instruments were deployed at 2000 m.asl near the center of Corsica, France to complement ground-based aerosol observations at 550 m.asl on the northern peninsula, as well as airborne measurements. Comparisons between the peninsula site and the mountain site show similar general trends in aerosol properties; yet, differences in aerosol properties reveal the myriad transport mechanisms over the Mediterranean Basin. Using aerosol physicochemical data coupled with back trajectory analysis, different sources have been identified including Saharan dust transport, residual dust mixed with sea salt, anthropogenic emissions from Western Europe, and a period of biomass burning from Eastern Europe. Each period exhibits distinct signatures in the aerosol related to transport processes above and below the boundary layer. In addition, the total aerosol concentrations at the mountain site revealed a strong diurnal cycling the between the atmospheric boundary layer and the free troposphere, which is typical of mountain-top observations. PACMEx was funded by the National Science Foundation (NSF) as a cooperative collaboration with French research agencies (INSU-MISTRALS, ANR-ADRIMED, and Météo France).

Biomass Burning Dominates Brown Carbon Absorption in the Rural Southeastern U.S.

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Guo, H.; Weber, R. J. J.; Xu, L.; Ng, N. L.; Stone, E. A.; Edgerton, E. S.; Baumann, K.; Hu, W.; Palm, B. B.; Jimenez, J. L.; Fry, J.; Ayres, B. R.; Draper, D.; Allen, H.

2014-12-01

Aerosol scattering and absorption are still among the largest uncertainties in quantifying radiative forcing. Brown carbon has a wavelength-dependent absorption that increases in the UV spectral region, and its major atmospheric sources include biomass burning, anthropogenic combustion of fossil fuels, and secondary organic aerosol. The rural Southeastern U.S. is influenced by high isoprene concentrations and varying concentrations of biomass burning aerosol, making it an ideal place to compare the relative contributions of these two sources to the brown carbon absorption budget. During the Southern Oxidant and Aerosol Study in summer 2013, we deployed a new field instrument that uses cavity enhanced spectroscopy with a broadband light source to measure aerosol optical extinction as a function of wavelength. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We combine these data with direct absorption measurements of water-soluble organic carbon obtained from a novel UV/VIS-WSOC instrument, and with aerosol composition measurements. We examine these data sets to determine: 1) the optical closure between measured dry aerosol extinction and values calculated from aerosol composition and size distribution; 2) the magnitude of brown and black carbon absorption; 3) the relative contributions of biomass burning, anthropogenic, and secondary organic aerosol contributions to brown carbon absorption in the Southeast U.S. during the summer. We conclude that biomass burning is a major contributor to optical absorption by organic aerosol in the rural southeastern U.S.

Implementation of warm-cloud processes in a source-oriented WRF/Chem model to study the effect of aerosol mixing state on fog formation in the Central Valley of California

NASA Astrophysics Data System (ADS)

Lee, H.-H.; Chen, S.-H.; Kleeman, M. J.; Zhang, H.; DeNero, S. P.; Joe, D. K.

2015-11-01

The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include warm cloud processes and applied to investigate how aerosol mixing states influence fog formation and optical properties in the atmosphere. SOWC tracks a 6-dimensional chemical variable (X, Z, Y, Size Bins, Source Types, Species) through an explicit simulation of atmospheric chemistry and physics. A source-oriented cloud condensation nuclei module was implemented into the SOWC model to simulate warm clouds using the modified two-moment Purdue Lin microphysics scheme. The Goddard shortwave and longwave radiation schemes were modified to interact with source-oriented aerosols and cloud droplets so that aerosol direct and indirect effects could be studied. The enhanced SOWC model was applied to study a fog event that occurred on 17 January 2011, in the Central Valley of California. Tule fog occurred because an atmospheric river effectively advected high moisture into the Central Valley and nighttime drainage flow brought cold air from mountains into the valley. The SOWC model produced reasonable liquid water path, spatial distribution and duration of fog events. The inclusion of aerosol-radiation interaction only slightly modified simulation results since cloud optical thickness dominated the radiation budget in fog events. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into CCN at a supersaturation of 0.5 % in the Central Valley decreased from 94 % in the internal mixture model to 80 % in the source-oriented model. This increased surface energy flux by 3-5 W m-2 and surface temperature by as much as 0.25 K in the daytime.

Aerosol carbon isotope composition over Baltic Sea

NASA Astrophysics Data System (ADS)

Garbaras, Andrius; Pabedinskas, Algirdas; Masalaite, Agne; Petelski, Tomasz; Gorokhova, Elena; Sapolaite, Justina; Ezerinskis, Zilvinas; Remeikis, Vidmantas

2017-04-01

Particulate carbonaceous matter is significant contributor to ambient particulate matter originating from intervening sources which contribution is difficult to quantify due to source diversity, chemical complexity and processes during atmospheric transport. Carbon isotope analysis can be extremely useful in source apportionment of organic matter due to the unique isotopic signatures associated with anthropocentric (fossil fuel), continental (terrestrial plants) and marine sources, and is particularly effective when these sources are mixed (Ceburnis et al., 2011;Ceburnis et al., 2016). We will present the isotope ratio measurement results of aerosol collected during the cruise in the Baltic Sea. Sampling campaign of PM10 and size segregated aerosol particles was performed on the R/V "Oceania" in October 2015. Air mass back trajectories were prevailing both from the continental and marine areas during the sampling period. The total carbon concentration varied from 1 µg/m3 to 8 µg/m3. Two end members (δ13C = -25‰ and δ13C = -28 ‰ ) were established from the total stable carbon isotope analysis in PM10 fraction. δ13C analysis in size segregated aerosol particles revealed δ13C values being highest in the 1 - 2.5 µm range (δ13C = -24.9 ‰ ) during continental transport, while lowest TC δ13C values (δ13C ≈ -27 ‰ ) were detected in the size range D50 <1 µm during stormy weather when air mass trajectory prevailed from the western direction. These measurements revealed that simplified isotope mixing model can not be applied for the aerosol source apportionment (Masalaite et al., 2015) in the perturbed marine environment. Additionally, concentration of bacteria and fungi were measured in size segregated and PM10 aerosol fraction. We were able to relate aerosol source δ13C end members with the abundance of bacteria and fungi over Baltic Sea combining air mass trajectories, stable isotope data, fungi and bacteria concentrations. Ceburnis, D., Garbaras, A., Szidat, S., Rinaldi, M., Fahrni, S., Perron, N., Wacker, L., Leinert, S., Remeikis, V., and Facchini, M.: Quantification of the carbonaceous matter origin in submicron marine aerosol by 13 C and 14 C isotope analysis, Atmospheric Chemistry and Physics, 11, 8593-8606, 2011. Ceburnis, D., Masalaite, A., Ovadnevaite, J., Garbaras, A., Remeikis, V., Maenhaut, W., Claeys, M., Sciare, J., Baisnée, D., and O'Dowd, C. D.: Stable isotopes measurements reveal dual carbon pools contributing to organic matter enrichment in marine aerosol, Scientific Reports, 6, 2016. Masalaite, A., Remeikis, V., Garbaras, A., Dudoitis, V., Ulevicius, V., and Ceburnis, D.: Elucidating carbonaceous aerosol sources by the stable carbon δ13C TC ratio in size-segregated particles, Atmospheric Research, 158, 1-12, 2015.

CARBON CONTAINING COMPONENT OF THE LOS ANGELES AEROSOL: SOURCE APPORTIONMENT AND CONTRIBUTIONS TO THE VISIBILITY BUDGET

EPA Science Inventory

Source resolution of the organic component of the fine fraction of the ambient aerosol (d(sub p) < 3.5 micrometers) has been carried out by combining source information from the organic component with thermal analysis and local emission inventories. The primary and secondary carb...

A multi-satellite analysis of the direct radiative effects of absorbing aerosols above clouds

NASA Astrophysics Data System (ADS)

Chang, Y. Y.; Christopher, S. A.

2015-12-01

Radiative effects of absorbing aerosols above liquid water clouds in the southeast Atlantic as a function of fire sources are investigated using A-Train data coupled with the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (Suomi NPP). Both the VIIRS Active Fire product and the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Thermal Anomalies product (MYD14) are used to identify the biomass burning fire origin in southern Africa. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) are used to assess the aerosol type, aerosol altitude, and cloud altitude. We use back trajectory information, wind data, and the Fire Locating and Modeling of Burning Emissions (FLAMBE) product to infer the transportation of aerosols from the fire source to the CALIOP swath in the southeast Atlantic during austral winter.

Impact of Transpacific Aerosol on Air Quality over the United States: A Perspective from Aerosol-Cloud-Radiation Interactions

NASA Technical Reports Server (NTRS)

Tao, Zhining; Yu, Hongbin; Chin, Mian

2015-01-01

Observations have well established that aerosols from various sources in Asia, Europe, and Africa can travel across the Pacific and reach the contiguous United States (U.S.) at least on episodic bases throughout a year, with a maximum import in spring. The imported aerosol not only can serve as an additional source to regional air pollution (e.g., direct input), but also can influence regional air quality through the aerosol-cloud-radiation (ACR) interactions that change local and regional meteorology. This study assessed impacts of the transpacific aerosol on air quality, focusing on surface ozone and PM2.5, over the U.S. using the NASA Unified Weather Research Forecast model. Based on the results of 3- month (April to June of 2010) simulations, the impact of direct input (as an additional source) of transpacific aerosol caused an increase of surface PM2.5 concentration by approximately 1.5 micro-g/cu m over the west coast and about 0.5 micro-g/cu m over the east coast of the U.S. By influencing key meteorological processes through the ACR interactions, the transpacific aerosol exerted a significant effect on both surface PM2.5 (+/-6 micro-g/cu m3) and ozone (+/-12 ppbv) over the central and eastern U.S. This suggests that the transpacific transport of aerosol could either improve or deteriorate local air quality and complicate local effort toward the compliance with the U.S. National Ambient Air Quality Standards.

Aerosol as a player in the Arctic Amplification - an aerosol-climate model evaluation study

NASA Astrophysics Data System (ADS)

Schacht, Jacob; Heinold, Bernd; Tegen, Ina

2017-04-01

Climate warming is much more pronounced in the Arctic than in any other region on Earth - a phenomenon referred to as the "Arctic Amplification". This is closely related to a variety of specific feedback mechanisms, which relative importance, however, is not yet sufficiently understood. The local changes in the Arctic climate are far-reaching and affect for example the general atmospheric circulation and global energy transport. Aerosol particles from long-range transport and local sources play an important role in the Arctic system by modulating the energy balance (directly by interaction with solar and thermal infrared radiation and indirectly by changing cloud properties and atmospheric dynamics). The main source regions of anthropogenic aerosol are Europe and East Asia, but also local shipping and oil/gas extraction may contribute significantly. In addition, important sources are widespread, mainly natural boreal forest fires. Most of the European aerosol is transported through the lower atmospheric layers in wintertime. The Asian aerosol is transported through higher altitudes. Because of the usually pristine conditions in the Arctic even small absolute changes in aerosol concentration can have large impacts on the Arctic climate. Using global and Arctic-focused model simulations, we aim at investigating the sources and transport pathways of natural and anthropogenic aerosol to the Arctic region, as well as their impact on radiation and clouds. Here, we present first results from an aerosol-climate model evaluation study. Simulations were performed with the global aerosol-climate model ECHAM6-HAM2, using three different state-of-the-art emission inventories (ACCMIP, ACCMIP + GFAS emissions for wildfires and ECLIPSE). The runs were performed in nudged mode at T63 horizontal resolution (approximately 1.8°) with 47 vertical levels for the 10-year period 2006-2015. Black carbon (BC) and sulphate (SO4) are of particular interest. BC is highly absorbing in the solar spectrum, an effect that is enhanced by the contrast between the bright snow/ice surfaces and the dark BC. When deposited on snow and ice, BC also accelerates melting and lowers the surface albedo. SO4 however is more scattering and, therefore, cooling. The model results are compared among each other and evaluated against ground-based in-situ and remote sensing, as well as active satellite observations. The following questions are addressed in the evaluation: 1) Are the sources and transport pathways of aerosol to the Arctic region captured? 2) Is the annual cycle of aerosol conditions reproduced? 3) What are uncertainties related to the emission database? After thorough evaluation, the model results will provide a state-of-the-art estimate of the aerosol budget and the effective radiative forcing by anthropogenic aerosols in the Arctic region.

African Dust Aerosols as Atmospheric Ice Nuclei

NASA Technical Reports Server (NTRS)

DeMott, Paul J.; Brooks, Sarah D.; Prenni, Anthony J.; Kreidenweis, Sonia M.; Sassen, Kenneth; Poellot, Michael; Rogers, David C.; Baumgardner, Darrel

2003-01-01

Measurements of the ice nucleating ability of aerosol particles in air masses over Florida having sources from North Africa support the potential importance of dust aerosols for indirectly affecting cloud properties and climate. The concentrations of ice nuclei within dust layers at particle sizes below 1 pn exceeded 1/cu cm; the highest ever reported with our device at temperatures warmer than homogeneous freezing conditions. These measurements add to previous direct and indirect evidence of the ice nucleation efficiency of desert dust aerosols, but also confirm their contribution to ice nuclei populations at great distances from source regions.

Transport of Aerosols: Regional and Global Implications for Climate, Weather, and Air Quality

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Yu, Hongbin; Bian, Huisheng; Remer, Lorraine; Kahn, Ralph

2008-01-01

Long-range transport of atmospheric aerosols can have a significant impact on global climate, regional weather, and local air quality. In this study, we use a global model GOCART together with satellite data and ground-based measurements to assess the emission and transport of pollution, dust, biomass burning, and volcanic aerosols and their implications. In particular, we will show the impact of emissions and long-range transport of aerosols from major pollution and dust source regions to (1) the surface air quality, (2) the atmospheric heating rates, and (3) surface radiation change near the source and downwind regions.

Modeling the Impact of Arctic Shipping Pollution on Air Quality off the Coast of Northern Norway

NASA Astrophysics Data System (ADS)

Thomas, J. L.; Law, K.; Marelle, L.; Raut, J.; Jalkanen, J.; Johansson, L.; Roiger, A.; Schlager, H.; Kim, J.; Reiter, A.; Weinzierl, B.; Rose, M.; Fast, J. D.

2013-12-01

As the Arctic is undergoing rapid and potentially irreversible changes, such as the shrinking and thinning of sea-ice cover, the levels of atmospheric pollution are expected to rise dramatically due to the emergence of local pollution sources including shipping. Shipping routes through the Arctic (such as Russia's Northern Sea Route) are already used as an alternative to the traditional global transit shipping routes. In summer 2012, the ACCESS (Arctic Climate Change, Economy, and Society) aircraft campaign focused on studying pollution sources off the coast of northern Norway to quantify emissions from shipping and other anthropogenic pollution sources. To complement these measurements, a regional chemical transport model is used to study the impact of shipping pollution on gas and aerosol concentrations in the region. WRF-Chem (The Weather Research and Forecasting Model with Chemistry, which simulates gas and aerosols simultaneously with meteorology) is run with real time shipping emissions from STEAM (Ship Traffic Emission Assessment Model) for July 2012. The STEAM model calculates gas and aerosol emissions of marine traffic based on the ship type and location provided by the Automatic Identification System (AIS). Use of real time position, speed, and ship specific information allows for development of emissions with very high spatial (1x1 km) and temporal (30 min) resolution, which are used in the regional model runs. STEAM emissions have been specifically generated for shipping off the coast of Norway during the entire ACCESS campaign period. Simulated ship plumes from high-resolution model runs are compared to aircraft measurements. The regional impact of current summertime shipping is also examined. At present, relatively light ship traffic off the coast of northern Norway results in only a small impact of shipping pollution on regional atmospheric chemistry. The impact of increased future shipping on regional atmospheric chemistry is also assessed.

ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

NASA Astrophysics Data System (ADS)

Fröhlich, R.; Crenn, V.; Setyan, A.; Belis, C. A.; Canonaco, F.; Favez, O.; Riffault, V.; Slowik, J. G.; Aas, W.; Aijälä, M.; Alastuey, A.; Artiñano, B.; Bonnaire, N.; Bozzetti, C.; Bressi, M.; Carbone, C.; Coz, E.; Croteau, P. L.; Cubison, M. J.; Esser-Gietl, J. K.; Green, D. C.; Gros, V.; Heikkinen, L.; Herrmann, H.; Jayne, J. T.; Lunder, C. R.; Minguillón, M. C.; Močnik, G.; O'Dowd, C. D.; Ovadnevaite, J.; Petralia, E.; Poulain, L.; Priestman, M.; Ripoll, A.; Sarda-Estève, R.; Wiedensohler, A.; Baltensperger, U.; Sciare, J.; Prévôt, A. S. H.

2015-02-01

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSM) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about three weeks in November and December 2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). Individual application and optimisation of the ME-2 boundary conditions (profile constraints) are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative SD from the mean between 13.7 and 22.7% of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2%, COA: 15.0 ± 3.4%, OOA: 41.5 ± 5.7%, BBOA: 29.3 ± 5.0%). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2%.

Source appointment of fine particle number and volume concentration during severe haze pollution in Beijing in January 2013.

PubMed

Liu, Zirui; Wang, Yuesi; Hu, Bo; Ji, Dongsheng; Zhang, Junke; Wu, Fangkun; Wan, Xin; Wang, Yonghong

2016-04-01

Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012-2013, causing major environmental and health problems. To better understand these extreme events, particle number size distribution (PNSD) and particle chemical composition (PCC) data collected in an intensive winter campaign in an urban site of Beijing were used to investigate the sources of ambient fine particles. Positive matrix factorization (PMF) analysis resolved a total of eight factors: two traffic factors, combustion factors, secondary aerosol, two accumulation mode aerosol factors, road dust, and long-range transported (LRT) dust. Traffic emissions (54%) and combustion aerosol (27%) were found to be the most important sources for particle number concentration, whereas combustion aerosol (33%) and accumulation mode aerosol (37%) dominated particle volume concentrations. Chemical compositions and sources of fine particles changed dynamically in the haze episodes. An enhanced role of secondary inorganic species was observed in the formation of haze pollution. Regional transport played an important role for high particles, contribution of which was on average up to 24-49% during the haze episodes. Secondary aerosols from urban background presented the largest contributions (45%) for the rapid increase of fine particles in the severest haze episode. In addition, the invasion of LRT dust aerosols further elevated the fine particles during the extreme haze episode. Our results showed a clear impact of regional transport on the local air pollution, suggesting the importance of regional-scale emission control measures in the local air quality management of Beijing.

Investigation of air pollution and regional climate change due to anthropogenic aerosols

NASA Astrophysics Data System (ADS)

Nakata, Makiko; Sano, Itaru; Mukai, Sonoyo

2016-10-01

Increased emissions of anthropogenic aerosols associated with economic growth can lead to increased concentrations of hazardous air pollutants. In particular, large cities in East Asia have experienced numerous heavy haze episodes. Atmospheric aerosol distributions in East Asia are complex, being influenced by both natural phenomena and human activity, with urban areas in particular being dominated by fine anthropogenic aerosols released from diesel-powered vehicles and industrial activity. In Japan, air pollution levels have been reduced; nevertheless, in recent years, there is increasing concern regarding air pollution caused by fine particulate matter. The origins of air pollution were examined, focusing on the comparison between aerosol properties observed from satellites and that on the ground. Because of their short life spans, concentrations of anthropogenic aerosols are highest over the source regions, and as a result, the climatic impacts of anthropogenic aerosols are also found to be most pronounced in these regions. In this study, aerosol impacts on climate are assessed by numerical model simulations. The direct effects of aerosols include reduced solar radiation, and hence a decrease in surface temperatures. In addition to these changes in the radiation budget, aerosols have a significant potential to change cloud and precipitation fields. These climatic responses to aerosols can manifest far from their source regions with high industrial activities.

Chemical characterization and source apportionment of fine and coarse particulate matter in Lahore, Pakistan

NASA Astrophysics Data System (ADS)

Stone, Elizabeth; Schauer, James; Quraishi, Tauseef A.; Mahmood, Abid

2010-03-01

Lahore, Pakistan is an emerging megacity that is heavily polluted with high levels of particle air pollution. In this study, respirable particulate matter (PM 2.5 and PM 10) were collected every sixth day in Lahore from 12 January 2007 to 19 January 2008. Ambient aerosol was characterized using well-established chemical methods for mass, organic carbon (OC), elemental carbon (EC), ionic species (sulfate, nitrate, chloride, ammonium, sodium, calcium, and potassium), and organic species. The annual average concentration (±one standard deviation) of PM 2.5 was 194 ± 94 μg m -3 and PM 10 was 336 ± 135 μg m -3. Coarse aerosol (PM 10-2.5) was dominated by crustal sources like dust (74 ± 16%, annual average ± one standard deviation), whereas fine particles were dominated by carbonaceous aerosol (organic matter and elemental carbon, 61 ± 17%). Organic tracer species were used to identify sources of PM 2.5 OC and chemical mass balance (CMB) modeling was used to estimate relative source contributions. On an annual basis, non-catalyzed motor vehicles accounted for more than half of primary OC (53 ± 19%). Lesser sources included biomass burning (10 ± 5%) and the combined source of diesel engines and residual fuel oil combustion (6 ± 2%). Secondary organic aerosol (SOA) was an important contributor to ambient OC, particularly during the winter when secondary processing of aerosol species during fog episodes was expected. Coal combustion alone contributed a small percentage of organic aerosol (1.9 ± 0.3%), but showed strong linear correlation with unidentified sources of OC that contributed more significantly (27 ± 16%). Brick kilns, where coal and other low quality fuels are burned together, are suggested as the most probable origins of unapportioned OC. The chemical profiling of emissions from brick kilns and other sources unique to Lahore would contribute to a better understanding of OC sources in this megacity.

Source apportionment of airborne particulate matter using organic compounds as tracers

NASA Astrophysics Data System (ADS)

Schauer, James J.; Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

A chemical mass balance receptor model based on organic compounds has been developed that relates sours; contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution:; from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.

Numerical simulations of Asian dust storms using a coupled climate-aerosol microphysical model

NASA Astrophysics Data System (ADS)

Su, Lin; Toon, Owen B.

2009-07-01

We have developed a three-dimensional coupled microphysical/climate model based on the National Center for Atmospheric Research Community Atmospheres Model and the University of Colorado/NASA Community Aerosol and Radiation Model for Atmospheres. We have used the model to investigate the sources, removal processes, transport, and optical properties of Asian dust aerosol and its impact on downwind regions. The model simulations are conducted primarily during the time frame of the Aerosol Characterization Experiment-Asia field experiment (March-May 2001) since considerable in situ data are available at that time. Our dust source function follows Ginoux et al. (2001). We modified the dust source function by using the friction velocity instead of the 10-m wind based on wind erosion theory, by adding a size-dependent threshold friction velocity following Marticorena and Bergametti (1995) and by adding a soil moisture correction. A Weibull distribution is implemented to estimate the subgrid-scale wind speed variability. We use eight size bins for mineral dust ranging from 0.1 to 10 μm radius. Generally, the model reproduced the aerosol optical depth retrieved by the ground-based Aerosol Robotic Network (AERONET) Sun photometers at six study sites ranging in location from near the Asian dust sources to the Eastern Pacific region. By constraining the dust complex refractive index from AERONET retrievals near the dust source, we also find the single-scattering albedo to be consistent with AERONET retrievals. However, large regional variations are observed due to local pollution. The timing of dust events is comparable to the National Institute for Environmental Studies (NIES) lidar data in Beijing and Nagasaki. However, the simulated dust aerosols are at higher altitudes than those observed by the NIES lidar.

Large contribution of fossil fuel derived secondary organic carbon to water soluble organic aerosols in winter haze in China

NASA Astrophysics Data System (ADS)

Zhang, Yan-Lin; El-Haddad, Imad; Huang, Ru-Jin; Ho, Kin-Fai; Cao, Jun-Ji; Han, Yongming; Zotter, Peter; Bozzetti, Carlo; Daellenbach, Kaspar R.; Slowik, Jay G.; Salazar, Gary; Prévôt, André S. H.; Szidat, Sönke

2018-03-01

Water-soluble organic carbon (WSOC) is a large fraction of organic aerosols (OA) globally and has significant impacts on climate and human health. The sources of WSOC remain very uncertain in polluted regions. Here we present a quantitative source apportionment of WSOC, isolated from aerosols in China using radiocarbon (14C) and offline high-resolution time-of-flight aerosol mass spectrometer measurements. Fossil emissions on average accounted for 32-47 % of WSOC. Secondary organic carbon (SOC) dominated both the non-fossil and fossil derived WSOC, highlighting the importance of secondary formation to WSOC in severe winter haze episodes. Contributions from fossil emissions to SOC were 61 ± 4 and 50 ± 9 % in Shanghai and Beijing, respectively, significantly larger than those in Guangzhou (36 ± 9 %) and Xi'an (26 ± 9 %). The most important primary sources were biomass burning emissions, contributing 17-26 % of WSOC. The remaining primary sources such as coal combustion, cooking and traffic were generally very small but not negligible contributors, as coal combustion contribution could exceed 10 %. Taken together with earlier 14C source apportionment studies in urban, rural, semi-urban and background regions in Asia, Europe and the USA, we demonstrated a dominant contribution of non-fossil emissions (i.e., 75 ± 11 %) to WSOC aerosols in the Northern Hemisphere; however, the fossil fraction is substantially larger in aerosols from East Asia and the eastern Asian pollution outflow, especially during winter, due to increasing coal combustion. Inclusion of our findings can improve a modelling of effects of WSOC aerosols on climate, atmospheric chemistry and public health.

Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

NASA Astrophysics Data System (ADS)

Brown, S. S.; Dubé, W. P.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Warneke, C.; de Gouw, J. A.; Washenfelder, R. A.; Atlas, E.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Schwarz, J. P.; Spackman, R.; Trainer, M.; Parrish, D. D.; Fehshenfeld, F. C.; Ravishankara, A. R.

2013-11-01

Organic compounds are a large component of aerosol mass, but organic aerosol (OA) sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter category serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within the nocturnal boundary layer (NBL), which varied in depth from 100-400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2-2.7 ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1 ppbv h-1), mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Some profiles may have been influenced by biomass burning sources as well, making quantitative attribution of organic aerosol sources difficult. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m-3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m-3.

Natural and Anthropogenic Aerosols in the World's Megacities and Climate Impacts

NASA Astrophysics Data System (ADS)

Kafatos, M.; Singh, R.; El-Askary, H.; Qu, J.

2005-12-01

The world's megacities are the sites of production of a variety of aerosols and are themselves affected by natural and human-induced aerosols. In particular, sources of aerosols impacting cities include: industrial and automobile emission; sand and dust storms from, e.g., the Sahara and Gobi Deserts; as well as fire-induced aerosols. Improving the ability of various stakeholder organizations to respond effectively to high concentrations of aerosols, with special emphasis on mineral dust from dust storms; smoke from controlled burns, wild fires and agricultural burning; and anthropogenic aerosols, would be an important goal not just to understand climate forcings but also to be able to better respond to the increasing amounts of aerosols at global and regional levels. Cities and surrounding areas are affected without good estimates of the current and future conditions of the aerosols and their impact on regional and global climate. Remotely sensed (RS) NASA, NOAA and international platform data can be used to characterize the properties of aerosol clouds and special hazard events such as sand and dust storms (SDS). Aerosol analysis and prediction-model capabilities from which stakeholders can choose the tools that best match their needs and technological expertise are important. Scientists validating mesoscale and aerosol-transport models, aerosol retrievals from satellite measurements are indispensable for robust climate predictions. Here we give two examples of generic SDS cases and urban pollution and their possible impact on climate: The Sahara desert is a major source of dust aerosols dust transport is an important climatic process. The aerosols in the form of dust particles reflect the incoming solar radiation to space, thereby reducing the amount of radiation available to the ground, known as `direct' radiative forcing of aerosols. The aerosols also change the cloud albedo and microphysical properties of clouds, known as `indirect' radiative forcing of aerosols. The highest boundary layer heights are associated with regions where the sensible heat flux is greatest, and latent heat flux is smallest due to lack of vegetation. Boundary layer heights in the deserts may be systematically higher than the slightly wetter regions at the edges of deserts. Latent heat flux model runs and MODIS observations of dust storms affecting the Nile Delta and Cairo indicate strong influence on the local weather and climate forcings. In the Indo-Gangetic, during the pre-monsoon period, dust storms form. We have examined SDS transport using RS data acquired from NASA's MODIS MISR instruments and from sun photometer measurements. The aerosol optical depth and size of the dust particles are found to be significantly higher during such dust storm events. Moreover, our results clearly show that power plants in this region are the key point source of air pollutants. The detailed analysis of aerosol parameters show the existence of absorbing and non-absorbing aerosols emitted from these plants. The combined effects of urban aerosols with dust aerosols in India and Cairo not only affect megacities, they also have long-term climate impacts. We will also discuss how the assimilation of RS data into mesoscale models can improve these models and predictability of hazards and effects on megacities, such as SDS events, and forest fires, all sources of aerosols. Therefore RS data can improve the prediction of climate forcings by aerosols.

Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

NASA Astrophysics Data System (ADS)

Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilde, S.; Zhang, Y.; Dall'Osto, M.

2014-04-01

The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterized by a less dense urbanization. We present here the results obtained in San Pietro Capofiume, which is located in a sparsely inhabited sector of the Po Valley, Italy. The experiment was carried out in summer 2009 in the framework of the EUCAARI project ("European Integrated Project on Aerosol, Cloud Climate Aerosol Interaction"). For the first time in Europe, six state-of-the-art techniques were used in parallel: (1) on-line TSI aerosol time-of-flight mass spectrometer (ATOFMS), (2) on-line Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS), (3) soot particle aerosol mass spectrometer (SP-AMS), (4) on-line high resolution time-of-flight mass spectrometer-thermal desorption aerosol gas chromatograph (HR-ToFMS-TAG), (5) off-line twelve-hour resolution proton nuclear magnetic resonance (H-NMR) spectroscopy, and (6) chemical ionization mass spectrometry (CIMS) for the analysis of gas-phase precursors of secondary aerosol. Data from each aerosol spectroscopic method were analysed individually following ad-hoc tools (i.e. PMF for AMS, Art-2a for ATOFMS). The results obtained from each techniques are herein presented and compared. This allows us to clearly link the modifications in aerosol chemical composition to transitions in air mass origin and meteorological regimes. Under stagnant conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), only partly internally mixed with secondary semivolatile compounds such as ammonium nitrate and amines. Other organic components originating from anthropogenic sources at night include monocarboxylic acids which correspond to an AMS factor analogous to the "cooking" organic aerosol (COA) already identified in urban areas. In daytime, enhanced mixing in the planetary boundary layer (PBL) along with increasing temperature determined dramatic changes in aerosol composition caused by the evaporation of semivolatile components and by the entrainment of aged aerosols transported downwards from residual layers. In other words, the entrainment of aged air masses is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOAs) and also for the recycling of primary species such as black carbon. The LV-OOA concentrations were shown to correlate to the simple meteorological tracers of humid PBL air produced by daytime convection over land areas. In particular, both PMF-AMS and PMF-NMR could resolve two components of LV-OOA: one from long-range transport from Central Europe, the second from recirculated PBL air from the Po Valley. According to organic aerosol source apportionment by PMF-AMS, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in North Italy, while a substantial fraction (41%) was due to the most aged aerosols imported from transalpine areas. Overall, the deployment of six state-of-the-art spectrometric techniques provided a comprehensive picture of the nature and source contributions of aerosols and aerosol precursors at a European rural site with unprecedented level of details.

Aerosol composition and sources in the central Arctic Ocean during ASCOS

NASA Astrophysics Data System (ADS)

Chang, R. Y.-W.; Leck, C.; Graus, M.; Müller, M.; Paatero, J.; Burkhart, J. F.; Stohl, A.; Orr, L. H.; Hayden, K.; Li, S.-M.; Hansel, A.; Tjernström, M.; Leaitch, W. R.; Abbatt, J. P. D.

2011-10-01

Measurements of submicron aerosol chemical composition were made over the central Arctic Ocean from 5 August to 8 September 2008 as a part of the Arctic Summer Cloud Ocean Study (ASCOS) using an aerosol mass spectrometer (AMS). The median levels of sulphate and organics for the entire study were 0.051 and 0.055 μ g m-3, respectively. Positive matrix factorisation was performed on the entire mass spectral time series and this enabled marine biogenic and continental sources of particles to be separated. These factors accounted for 33% and 36% of the sampled ambient aerosol mass, respectively, and they were both predominantly composed of sulphate, with 47% of the sulphate apportioned to marine biogenic sources and 48% to continental sources, by mass. Within the marine biogenic factor, the ratio of methane sulphonate to sulphate was 0.25 ± 0.02, consistent with values reported in the literature. The organic component of the continental factor was more oxidised than that of the marine biogenic factor, suggesting that it had a longer photochemical lifetime than the organics in the marine biogenic factor. The remaining ambient aerosol mass was apportioned to an organic-rich factor that could have arisen from a combination of marine and continental sources. In particular, given that the factor does not correlate with common tracers of continental influence, we cannot rule out that the organic factor arises from a primary marine source.

In-situ droplet monitoring for self-tuning spectrometers

DOEpatents

Montaser, Akbar; Jorabchi, Kaveh; Kahen, Kaveh

2010-09-28

A laser scattering based imaging technique is utilized in order to visualize the aerosol droplets in an inductively coupled plasma (ICP) torch from an aerosol source to the site of analytical measurements. The resulting snapshots provide key information about the spatial distribution of the aerosol introduced by direct and indirect injection devices: 1) a direct injection high efficiency nebulizer (DIHEN); 2) a large-bore DIHEN (LB-DIHEN); and 3) a PFA microflow nebulizer with a PFA Scott-type spray chamber. Moreover, particle image velocimetry (PIV) is used to study the in-situ behavior of the aerosol before interaction with, for example, plasma, while the individual surviving droplets are explored by particle tracking velocimetry (PTV). Further, the velocity distribution of the surviving droplets demonstrates the importance of the initial droplet velocities in complete desolvation of the aerosol for optimum analytical performance in ICP spectrometries. These new observations are important in the design of the next-generation direct injection devices for lower sample consumption, higher sensitivity, lower noise levels, suppressed matrix effects, and for developing smart spectrometers. For example, a controller can be provided to control the output of the aerosol source by controlling the configuration of the source or the gas flow rate via feedback information concerning the aerosol.

Effects of Aircraft On Aerosol Abundance in the Upper Troposphere

NASA Technical Reports Server (NTRS)

Ferry, G. V.; Pueschel, R. F.; Strawa, A. W.; Howard, S. D.; Verma, S.; Mahoney, M. J.; Bui, T. P.; Hannan, J. R.; Fuelberg, H. E.; Condon, Estelle P. (Technical Monitor)

1999-01-01

A significant increase in sulfuric acid aerosol concentration was detected above 10 km pressure altitude during a cross-corridor flight out of Shannon on October 23, 1997. The source of this aerosol is ascribed to commercial aircraft operations in flight corridors above 10 km, because (1) a stable atmosphere prevented vertical air mass exchanges and thus eliminated surface sources, (2) air mass back trajectories documented the absence of remote continental sources, and (3) temperature profiler data showed the tropopause at least one kilometers above flight altitude throughout the flight. Particle volatility identified 70% H2SO4, 20% (NH4)2SO4 and 10% nonvolatile aerosol in the proximity of flight corridors, and (10-30)% H2SO4, up to 50% (NH4)2SO4, and (40-60)% nonvolatile aerosols in air that was not affected by aircraft operations below 10 km. Only a very small fraction of the nonvolatile particles (determined with a condensation nucleus counter) could be morphologically identified as soot aerosol (validated by scanning electron microscopy of wire impactor samples). The newly formed H2SO4 particles did not measurably affect surface area and volume of the background aerosol due to their small size, hence did not affect radiative transfer directly.

New Measurements of Aerosol Vertical Structure from Space Using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

NASA Technical Reports Server (NTRS)

Welton, Ellsworth J.; Ginoux, Paul; Colarco, Peter; Chin, Mian; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis; Hart, William

2003-01-01

In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GUS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output,

New Measurements of Aerosol Vertical Structure from Space using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

NASA Technical Reports Server (NTRS)

Welton, E. J.; Spinhime, J.; Palm, S.; Hlavka, D.; Hart, W.; Ginoux, P.; Chin, M.; Colarco, P.

2004-01-01

In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth,s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GLAS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output.

Evolution of aerosol vertical distribution during particulate pollution events in Shanghai

NASA Astrophysics Data System (ADS)

Zhang, Yunwei; Zhang, Qun; Leng, Chunpeng; Zhang, Deqin; Cheng, Tiantao; Tao, Jun; Zhang, Renjian; He, Qianshan

2015-06-01

A set of micro pulse lidar (MPL) systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011. Three typical particulate pollution events (e.g., haze) were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer (PBL) during these pollution episodes. The aerosol vertical extinction coefficient (VEC) at any given measured altitude was prominently larger during haze periods than that before or after the associated event. Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering, leading to different aerosol vertical distribution structures. Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions. Several peaks in aerosol VECs were found at altitudes above 1 km during the dust- and bioburning-influenced haze events. Aerosol VECs decreased with increasing altitude during the local-polluted haze event, with a single maximum in the surface atmosphere. PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events; subsequently, PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages. The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.

Interactive coupling of regional climate and sulfate aerosol models over eastern Asia

NASA Astrophysics Data System (ADS)

Qian, Yun; Giorgi, Filippo

1999-03-01

The NCAR regional climate model (RegCM) is interactively coupled to a simple radiatively active sulfate aerosol model over eastern Asia. Both direct and indirect aerosol effects are represented. The coupled model system is tested for two simulation periods, November 1994 and July 1995, with aerosol sources representative of present-day anthropogenic sulfur emissions. The model sensitivity to the intensity of the aerosol source is also studied. The main conclusions from our work are as follows: (1) The aerosol distribution and cycling processes show substantial regional spatial variability, and temporal variability varying on a range of scales, from the diurnal scale of boundary layer and cumulus cloud evolution to the 3-10 day scale of synoptic scale events and the interseasonal scale of general circulation features; (2) both direct and indirect aerosol forcings have regional effects on surface climate; (3) the regional climate response to the aerosol forcing is highly nonlinear, especially during the summer, due to the interactions with cloud and precipitation processes; (4) in our simulations the role of the aerosol indirect effects is dominant over that of direct effects; (5) aerosol-induced feedback processes can affect the aerosol burdens at the subregional scale. This work constitutes the first step in a long term research project aimed at coupling a hierarchy of chemistry/aerosol models to the RegCM over the eastern Asia region.

Identification of amines in wintertime ambient particulate material using high resolution aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Bottenus, Courtney L. H.; Massoli, Paola; Sueper, Donna; Canagaratna, Manjula R.; VanderSchelden, Graham; Jobson, B. Thomas; VanReken, Timothy M.

2018-05-01

Significant amounts of amines were detected in fine particulate matter (PM) during ambient wintertime conditions in Yakima, WA, using a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Positive matrix factorization (PMF) of the organic aerosol (OA) signal resulted in a six-factor solution that included two previously unreported amine OA factors. The contributions of the amine factors were strongly episodic, but the concentration of the combined amine factors was as high as 10-15 μg m-3 (2-min average) during those episodes. In one occasion, the Amine-II component was 45% of total OA signal. The Amine-I factor was dominated by spectral peaks at m/z 86 (C5H12N+) and m/z 100 (C6H14N+), while the Amine-II factor was dominated by spectral peaks at m/z 58 (C3H8N+ and C2H6N2+) and m/z 72 (C4H10N+ and C3H8N2+). The ions dominating each amine factor showed distinct time traces, suggesting different sources or formation processes. Investigation into the chemistry of the amine factors suggests a correlation with inorganic anions for Amine-I, but no evidence that the Amine-II was being neutralized by the same inorganic ions. We also excluded the presence of organonitrates (ON) in the OA. The presence of C2H4O2+ at m/z 60 (a levoglucosan fragment) in the Amine-I spectrum suggests some influence of biomass burning emissions (more specifically residential wood combustion) in this PMF factor, but wind direction suggested that the most likely sources of these amines were agricultural activities and feedlots to the S-SW of the site.

Chemical characteristics of soluble aerosols over the central Himalayas: insights into spatiotemporal variations and sources.

PubMed

Tripathee, Lekhendra; Kang, Shichang; Rupakheti, Dipesh; Cong, Zhiyuan; Zhang, Qianggong; Huang, Jie

2017-11-01

In order to investigate the spatial and temporal variations of aerosols and its soluble chemical compositions of the data gap zone in the central Himalayan region, aerosol samples were collected at four sites. The sampling location were characterized by four different categories, such as urban (Bode), semi-urban site in the northern Indo-Gangetic Plain (Lumbini), rural (Dhunche), and semiarid rural (Jomsom). A total of 230 aerosol samples were collected from four representative sites for a yearlong period and analyzed for water-soluble inorganic ions (WSIIs). The annual average aerosol mass concentration followed the sequence as Bode (238.24 ± 162.24 μg/m 3 )> Lumbini (161.14 ± 105.95 μg/m 3 )> Dhunche (112.40 ± 40.30 μg/m 3 )> Jomsom (78.85 ± 34.28 μg/m 3 ), suggesting heavier particulate pollution in the urban and semi-urban sites. The total soluble ions contributed to 12.61-28.19% of TSP aerosol mass. The results revealed that SO 4 2- and NO 3 - were the major anion and Ca 2+ and NH 4 + were the major cation influencing the aerosol composition over the central Himalayas. Calcium played a major role in neutralizing aerosol acidity followed by NH 4 + at all the sites. The major compound of aerosol was (NH 4 ) 2 SO 4 and NH 4 HSO 4 in the central Himalayas. Clear seasonality was observed at three observation sites, with higher concentrations during non-monsoon (dry periods) and lower during monsoon (wet period), suggesting washing out of aerosol particles by heavy precipitation during monsoon. In contrast, semiarid sites did not show the clear seasonal trend due to limited precipitation. Stationary sources were predominant over the mobile sources mostly in the remote sites. Principal component analysis confirmed that the major sources of WSIIs in the region were industrial emissions, fossil fuel and biomass burning, and crustal fugitive dusts. Nevertheless, transboundary aerosol transport over the region from polluted cities from south Asia could not be ignored as indicated by the clusters of air mass backward trajectory analysis.

Chemical and microphysical properties of the aerosol during foggy and nonfoggy episodes: a relationship between organic and inorganic content of the aerosol

NASA Astrophysics Data System (ADS)

Kaul, D. S.; Gupta, T.; Tripathi, S. N.

2012-06-01

An extensive field measurement during winter was carried out at a site located in the Indo-Gangetic Plain (IGP) which gets heavily influenced by the fog during winter almost every year. The chemical and microphysical properties of the aerosols during foggy and nonfoggy episodes and chemical composition of the fogwater are presented. Positive matrix factorization (PMF) as a tool for the source apportionment was employed to understand the sources of pollution. Four major sources viz. biomass burning, refractory, secondary and mineral dust were identified. Aerosols properties during foggy episodes were heavily influenced by almost all the sources and they caused considerable loading of almost all the organic and inorganic species during the period. The biomass generated aerosols were removed from the atmosphere by scavenging during foggy episodes. The wet removal of almost all the species by the fog droplets was observed. The K+, water soluble organic carbon (WSOC), water soluble inorganic carbon (WSIC) and NO3- were most heavily scavenged among the species and their concentrations consequently became lower than the nonfoggy episode concentrations. The production of secondary inorganic aerosol, mainly sulfate and ammonium, during foggy episodes was considerably higher than nitrate which was rather heavily scavenged and removed by the fog droplets. The fogwater analysis showed that dissolved inorganic species play a vital role in processing of organic carbon such as the formation of organo-sulfate and organo-nitrate inside the fog droplets. The formation of organo-sulfate and organo-nitrate in aerosol and the influence of acidity on the secondary organic aerosol (SOA) formation were rather found to be negligible. The study average inorganic component of the aerosol was considerably higher than the carbonaceous component during both foggy and nonfoggy episode. The secondary production of the aerosol changed the microphysical properties of aerosol which was reflected by increase in the modal diameter of the size distribution during foggy episodes and growth in the diameter of the particles upon the fog evaporation.

Aerosol composition and sources in the Central Arctic Ocean during ASCOS

NASA Astrophysics Data System (ADS)

Chang, R. Y.-W.; Leck, C.; Graus, M.; Müller, M.; Paatero, J.; Burkhart, J. F.; Stohl, A.; Orr, L. H.; Hayden, K.; Li, S.-M.; Hansel, A.; Tjernström, M.; Leaitch, W. R.; Abbatt, J. P. D.

2011-05-01

Measurements of submicron aerosol chemical composition were made in the Central Arctic Ocean from 5 August to 8 September 2008 as a part of the Arctic Summer Cloud Ocean Study (ASCOS) using an aerosol mass spectrometer (AMS). The median levels of sulphate and organics for the entire study were 0.042 and 0.046 μg m-3, respectively. Positive matrix factorisation was performed on the entire mass spectral time series and this enabled marine biogenic and continental sources of particles to be separated. These factors accounted for 33 % and 36 % of the sampled ambient aerosol mass, respectively, and they were both predominantly composed of sulphate, with 47 % of the sulphate apportioned to marine biogenic sources and 48 % to continental sources, by mass. Within the marine biogenic factor, the ratio of methane sulphonate to sulphate was 0.25 ± 0.02, consistent with values reported in the literature. The organic component of the continental factor was more oxidised than that of the marine biogenic factor, suggesting that it was more processed and had been present longer in the atmosphere than the organics in the marine biogenic factor. The remaining ambient aerosol mass was apportioned to an organic-rich factor that could have arisen from a combination of marine and continental sources.

The spectroscopic search for the trace aerosols in the planetary atmospheres - the results of numerical simulations

NASA Astrophysics Data System (ADS)

Blecka, Maria I.

2010-05-01

The passive remote spectrometric methods are important in examinations the atmospheres of planets. The radiance spectra inform us about values of thermodynamical parameters and composition of the atmospheres and surfaces. The spectral technology can be useful in detection of the trace aerosols like biological substances (if present) in the environments of the planets. We discuss here some of the aspects related to the spectroscopic search for the aerosols and dust in planetary atmospheres. Possibility of detection and identifications of biological aerosols with a passive InfraRed spectrometer in an open-air environment is discussed. We present numerically simulated, based on radiative transfer theory, spectroscopic observations of the Earth atmosphere. Laboratory measurements of transmittance of various kinds of aerosols, pollens and bacterias were used in modeling.

Metagenomic analysis of the airborne environment in urban spaces.

PubMed

Be, Nicholas A; Thissen, James B; Fofanov, Viacheslav Y; Allen, Jonathan E; Rojas, Mark; Golovko, George; Fofanov, Yuriy; Koshinsky, Heather; Jaing, Crystal J

2015-02-01

The organisms in aerosol microenvironments, especially densely populated urban areas, are relevant to maintenance of public health and detection of potential epidemic or biothreat agents. To examine aerosolized microorganisms in this environment, we performed sequencing on the material from an urban aerosol surveillance program. Whole metagenome sequencing was applied to DNA extracted from air filters obtained during periods from each of the four seasons. The composition of bacteria, plants, fungi, invertebrates, and viruses demonstrated distinct temporal shifts. Bacillus thuringiensis serovar kurstaki was detected in samples known to be exposed to aerosolized spores, illustrating the potential utility of this approach for identification of intentionally introduced microbial agents. Together, these data demonstrate the temporally dependent metagenomic complexity of urban aerosols and the potential of genomic analytical techniques for biosurveillance and monitoring of threats to public health.

Satellite Remote Sensing: Aerosol Measurements

NASA Technical Reports Server (NTRS)

Kahn, Ralph A.

2013-01-01

Aerosols are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional aerosol science, the term "aerosol" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many aerosol sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based aerosol remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale aerosol studies.

ORGANIC MOLECULAR MARKER ANALYSIS OF LOW VOLUME RESIDENTIAL SAMPLES FOR SOURCE APPORTIONMENT IN THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

EPA Science Inventory

This abstract describes a poster on results for organic speciation analysis for Detroit Exposure and Aerosol Research Study (DEARS) to be presented at the 2006 International Aerosol Conference sponsored by the American Association for Aerosol Research in St. Paul, Minnesota on Se...

Aerosol Vacuum-Assisted Plasma Ionization (Aero-VaPI) Coupled to Ion Mobility-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Blair, Sandra L.; Ng, Nga L.; Zambrzycki, Stephen C.; Li, Anyin; Fernández, Facundo M.

2018-02-01

In this communication, we report on the real-time analysis of organic aerosol particles by Vacuum-assisted Plasma Ionization-Mass Spectrometry (Aero-VaPI-MS) using a home-built VaPI ion source coupled to a Synapt G2-S HDMS ion mobility-mass spectrometry (IM-MS) system. Standards of organic molecules of interest in prebiotic chemistry were used to generate aerosols. Monocaprin and decanoic acid aerosol particles were successfully detected in both the positive and negative ion modes, respectively. A complex aerosol mixture of different sizes of polymers of L-malic acid was also examined through ion mobility (IM) separations, resulting in the detection of polymers of up to eight monomeric units. This noncommercial plasma ion source is proposed as a low cost alternative to other plasma ionization platforms used for aerosol analysis, and a higher-performance alternative to more traditional aerosol mass spectrometers. VaPI provides robust online ionization of organics in aerosols without extensive ion activation, with the coupling to IM-MS providing higher peak capacity and excellent mass accuracy. [Figure not available: see fulltext.

Marine Emissions and Atmospheric Processing Influence Aerosol Mixing States in the Bering Strait and Chukchi Sea

NASA Astrophysics Data System (ADS)

Kirpes, R.; Rodriguez, B.; Kim, S.; Park, K.; China, S.; Laskin, A.; Pratt, K.

2017-12-01

The Arctic region is rapidly changing due to sea ice loss and increasing oil/gas development and shipping activity. These changes influence aerosol sources and composition, resulting in complex aerosol-cloud-climate feedbacks. Atmospheric particles were collected aboard the R/V Araon in July-August 2016 in the Alaskan Arctic along the Bering Strait and Chukchi Sea. Offline analysis of individual particles by microscopic and spectroscopic techniques provided information on particle size, morphology, and chemical composition. Sea spray aerosol (SSA) and organic aerosol (OA) particles were the most commonly observed particle types, and sulfate was internally mixed with both SSA and OA. Evidence of multiphase sea spray aerosol reactions was observed, with varying degrees of chlorine depletion observed along the cruise. Notably, atmospherically processed SSA, completely depleted in chlorine, and internally mixed organic and sulfate particles, were observed in samples influenced by the central Arctic Ocean. Changes in particle composition due to fog processing were also investigated. Due to the changing aerosol sources and atmospheric processes in the Arctic region, it is crucial to understand aerosol composition in order to predict climate impacts.

Aerosol patterns and aerosol-cloud-interactions off the West African Coast based on the A-train formation

NASA Astrophysics Data System (ADS)

Fuchs, Julia; Bendix, Jörg; Cermak, Jan

2013-04-01

In this study, spatial and temporal aerosol patterns off the Western African coast are characterized and related to cloud properties, based on satellite data Atmospheric aerosols play a key role in atmospheric processes and influence our environmental system in a complex way. Their identification, characterization, transport patterns as well as their interactions with clouds pose major challenges. Especially the last aspect reveals major uncertainties in terms of the Earth's radiation budget as reported in the IPCC's Fourth Assessment Report (IPCC, 2007). Western and Southern Africa are dominated by two well-known source types of atmospheric aerosols. First, the Saharan Desert is the world's largest aeolian dust emitting source region. Second, biomass burning aerosol is commonly transported off-shore further south (Kaufman et al., 2005). Both aerosol types influence Earth's climate in different manners and can be detected by the MODIS (MODerate resolution Imaging Spectrometer) sensor onboard the EOS platforms as they propagate to the Central and Southern Atlantic. The motivation of this study was to reveal the seasonal pattern of the Saharan dust transport based on an observation period of 11 years and trying to explain the meteorological mechanisms. North African dust plumes are transported along a latitude of 19°N in July and 6°N in January. The seasonally fluctuating intensities adapt to the annual cycle of wind and precipitation regimes. A strong relationship is found between the spatial shift of the Azores High and the Saharan dust load over the middle Atlantic Ocean. Monthly Aerosol Optical Thickness products of Terra MODIS and NCEP-DOE (National Centers for Environmental Predictions) Reanalysis II data are used for this purpose. The relationship between aerosol and cloud droplet parameters is blurred by high sensitivities to aerosol size and composition (Feingold, 2003; McFiggans et al., 2006) as well as meteorological context (Ackerman et al., 2004). Satellite data from the A-train formation, including the Aqua, CloudSat and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) are used to analyze aerosol-cloud-interactions in detail, along with re-analysis data to constrain by meteorological conditions. Information about the vertical and geographical distribution of different aerosol types and cloud parameters will lead to a process-oriented understanding of these issues on a regional scale. Ackerman, A., Kirkpatrick, M., Stevens, D., & Toon, O. (2004). The impact of humidity above stratiform clouds on indirect aerosol climate forcing. Nature, 432(December), 1014-1017. doi:10.1038/nature03137.1. Feingold, G. (2003). First measurements of the Twomey indirect effect using ground-based remote sensors. Geophysical Research Letters, 30(6), 1287. doi:10.1029/2002GL016633 IPCC. (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working group I to the Fourth Assessment Report of the Interfovernmental Panel on climate Change. Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kaufman, Y. J., Koren, I., Remer, L. A., Tanré, D., Ginoux, P., & Fan, S. (2005). Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean. Journal of Geophysical Research, 110(D10), 1-16. doi:10.1029/2003JD004436 McFiggans, G., Artaxo, P., Baltensperger, U., Coe, H., Facchini, M. C., Feingold, G., Fuzzi, S., et al. (2006). The effect of physical and chemical aerosol properties on warm cloud droplet activation. Atmospheric Chemistry and Physics, 6(9), 2593-2649. doi:10.5194/acp-6-2593-2006

Eddy covariance measurements of sea spray particles over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Norris, S.; Brooks, I.; de Leeuw, G.; Smith, M. H.; Moeman, M.; Lingard, J.

2007-09-01

Most estimates of sea spray aerosol source functions have used indirect means to infer the rate of production as a function of wind speed. Only recently has the technology become available to make high frequency measurements of aerosol concentration suitable for direct eddy correlation determination of the particle flux. This was accomplished in this study by combining a newly developed fast aerosol particle counter with an ultrasonic anemometer which allowed for eddy covariance measurements of size-segregated particle fluxes. The aerosol instrument is the Compact Lightweight Aerosol Spectrometer Probe (CLASP) - capable of measuring 8-channel size spectra for mean radii between 0.15 and 0.35 μm at 10 Hz. The first successful measurements were made during the WASFAB (Waves, Air Sea Fluxes, Aerosol and Bubbles) field campaign in October 2005 in Duck (NC, USA). The method and results are presented and comparisons are made with recent sea spray source functions from the literature.

The Remote Sensing of Mineral Aerosols and their Impact on Phytoplankton Productivity

NASA Technical Reports Server (NTRS)

Tindale, Neil W.

1997-01-01

The overall objective of this experiment was to test the iron hypothesis does the addition of iron to nutrient rich surface waters enhance productivity? Our specific objectives in this experiment included sampling and studying the marine aerosol size and type (which are related to chemical reactivity) during the PlumEx cruise to determine the importance of local (Galapagos Islands) versus long-range sources of atmospheric material. Detailed results of single particle analysis of our samples are being prepared for publication in two papers. We collect aerosol samples and they have been analyzed for trace metals and other elements. We are mapped aerosol distribution and the desert source areas around the Arabian Sea region. We did record a clear relationship between the aerosol radiance and synoptic weather patterns with distinct signals over the ocean northwest and southwest of Australia. While the interpretation was limited an aerosol climatology pattern was presented.

Chemical Composition and Oxidation State of Iron-Containing Aerosol Particles Over West Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Fan, S.; Yu, S.; Lai, B.; Gao, Y.

2017-12-01

Iron is a limiting micronutrient element critical for the marine ecosystem. In the extensive high-nutrient low-chlorophyll (HNLC) regions of the Southern Ocean, the activities of phytoplankton are partly controlled by iron (Fe) from different sources, including atmospheric deposition. Among important properties of atmospheric Fe are the elemental composition and Fe oxidation state of Fe-containing aerosol particles, as these properties affect aerosol Fe solubility. To explore these issues, aerosol samples were collected at Palmer Station in West Antarctic Peninsula. Samples were analyzed by submicron synchrotron-based X-ray fluorescence (XRF) and X-ray absorption near edge structure (XANES) spectroscopy for the Fe oxidation state and elemental composition of aerosol particles. The morphological information of aerosol particles was also observed by the high-resolution fluorescence microscopy, revealing possible sources and formation processes of iron-containing particles. More detailed results will be discussed in this presentation.

Sources, Transport, and Climate Impacts of Biomass Burning Aerosols

NASA Technical Reports Server (NTRS)

Chin, Mian

2010-01-01

In this presentation, I will first talk about fundamentals of modeling of biomass burning emissions of aerosols, then show the results of GOCART model simulated biomass burning aerosols. I will compare the model results with observations of satellite and ground-based network in terms of total aerosol optical depth, aerosol absorption optical depth, and vertical distributions. Finally the long-range transport of biomass burning aerosols and the climate effects will be addressed. I will also discuss the uncertainties associated with modeling and observations of biomass burning aerosols

Radiocarbon-based Source Apportionment of Organic, Elemental and Water-soluble Organic Carbon Aerosols and the Light Absorption of Water-soluble Organic Carbon Aerosols in the East Asia High-intensity Winter Campaigns in 2014

NASA Astrophysics Data System (ADS)

Fang, W.; Andersson, A.; Zheng, M.; Lee, M.; Kim, S. W.; Du, K.; Gustafsson, O.

2016-12-01

Improved understanding of anthropogenic aerosol effects on atmospheric chemistry and climate as well as efficient mitigation actions are hampered by the limited comprehension of the relative contributions of different sources of carbonaceous aerosols and of their subsequent atmospheric processing. Here, we present dual carbon isotope constrained source apportionment and optical properties of carbonaceous aerosols simultaneously both at urban and rural receptor sites, includes North China Plain (NCP, Beijing and Tianjin), Yangtze River Delta (YRD, Shanghai, Zhejiang), and Jeju Island (Korea Climate Observatory at Gosan) during January 2014 field campaigns. The radiocarbon (Δ14C) data show that fossil combustions contribute equally ˜80 ± 5% to elemental carbon (EC) aerosol in Beijing, Tianjin, and Shanghai, and 66 ± 9% to Gosan-EC aerosol, while the specific sources of the dominant fossil fuel component were dramatically different among these sites. The mean fraction coal combustion of Beijing-EC, Tianjin-EC, and Gosan-EC is double that of Shanghai-EC. The other large fraction (72―92%) of carbonaceous aerosol is organic carbon (OC) aerosol which contains water soluble and water insoluble organic carbon (WSOC and WISOC). OC, WISOC, and WSOC in Beijing and Gosan sites were still observed largely from fossil sources (53―75%). The more 13C-enriched signature of Gosan-WSOC (-22.8 ± 0.2‰) compared to Gosan-EC (-23.9 ± 0.4‰) and Beijing-WSOC (-23.5 ± 0.7‰) reflects that WSOC is likely more affected by atmospheric aging during long-rang transport than is EC. The high light absorption coefficients of PM2.5, PM1, and TSP were observed at Gosan during this study and was frequently reaching 20―60 Mm-1 by aethalometer and continuous light absorption photometer. The mass absorption cross section of WSOC (MAC365) for above sites is high (1.5 ± 0.8 m2/g), accounted for ˜14 ± 5% of the total direct absorbance relative to EC, which is significantly higher than the previous findings in S. Asia, N. America, and Europe.

RACORO aerosol data processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elisabeth Andrews

2011-10-31

The RACORO aerosol data (cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter aerosol data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured aerosol size distributions. Below we first briefly describe the measurementsmore » and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several aerosol data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-aerosol interactions and improved cloud simulations in climate models.« less

CATS Cloud-Aerosol Products and Near Real Time Capabilities

NASA Astrophysics Data System (ADS)

Nowottnick, E. P.; Yorks, J. E.; McGill, M. J.; Palm, S. P.; Hlavka, D. L.; Selmer, P. A.; Rodier, S. D.; Vaughan, M. A.

2016-12-01

The Cloud-Aerosol Transport System (CATS) is a backscatter lidar that is designed to demonstrate technologies in space for future Earth Science missions. CATS is located on the International Space Station (ISS), where it has been operating semi-continuously since February 2015. CATS provides observations of cloud and aerosol vertical profiles similar to CALIPSO, but with more comprehensive coverage of the tropics and mid-latitudes due to the ISS orbit properties. Additionally, the ISS orbit permits the study of diurnal variability of clouds and aerosols. CATS data has applications for identifying of cloud phase and aerosol types. Analysis of recent Level 2 data yield several biases in cloud and aerosol layer detection and identification, as well as retrievals of optical properties that will be improved for the next version to be released in late 2016. With data latency of less than 6 hours, CATS data is also being used for forecasting of volcanic plume transport, experimental data assimilation into aerosol transport models (GEOS-5, NAAPS), and field campaign flight planning (KORUS-AQ, ORACLES).

Summer aerosol particle mixing in different climate and source regions of the United Arab Emirates (UAE)

NASA Astrophysics Data System (ADS)

Semeniuk, T. A.; Bruintjes, R. T.; Salazar, V.; Breed, D. W.; Jensen, T. L.; Buseck, P. R.

2005-12-01

The high aerosol loadings over the UAE reflect local to regional natural and anthropogenic pollution sources. To understand the impact of the high levels of pollution on both local and global climate systems, aerosol characterization flights in summer 2002 were used to sample major source areas, and to provide information on the interaction of aerosol particles within different geographic regions of the UAE. Atmospheric information and aerosol samples were collected from the marine/oil-industry region, NW coastal industries and cities, Oman Mountain Range, and NE coastal region. Aerosol samples were collected with multi-stage impactors and were analysed later using transmission electron microscopy. All samples are dominated by mineral grains or mineral aggregates in the coarse-mode fraction, and ammonium sulfate droplets in the fine-mode fraction. Differences in the types of mineral grains (different regional desert sources), inorganic salt and soot fractions, and types of internally mixed particles occur between regions. Oil-related industry sites have an abundance of coated and internally mixed particles, including sulfate-coated mineral grains, and mineral aggregates with chloride and sulfate. Cities have slightly elevated soot fractions, and typically have metal oxides. The NE coastal area is characterized by high soot fractions (local shipping) and mixed volatile droplets (regional Asian pollution). Particle populations within the convection zone over the Oman Mountain Range comprise an external mixture of particles from NW and NE sources, with many deliquesced particles. Both land-sea breezes in the NW regions and convection systems in the mountains mix aerosol particles from different local and regional sources, resulting in the formation of abundant internally mixed particles. The interaction between desert dust and anthropogenic pollution, and in particular the formation of mineral aggregates with chloride and sulfate, enhances the coarse-mode fraction and droplet fraction in industrial and mountainous regions.

Sources and Variability of Aerosols and Aerosol-Cloud Interactions in the Arctic

NASA Astrophysics Data System (ADS)

Liu, H.; Zhang, B.; Taylor, P. C.; Moore, R.; Barahona, D.; Fairlie, T. D.; Chen, G.; Ham, S. H.; Kato, S.

2017-12-01

Arctic sea ice in recent decades has significantly declined. This requires understanding of the Arctic surface energy balance, of which clouds are a major driver. However, the mechanisms for the formation and evolution of clouds in the Arctic and the roles of aerosols therein are highly uncertain. Here we conduct data analysis and global model simulations to examine the sources and variability of aerosols and aerosol-cloud interactions in the Arctic. We use the MERRA-2 reanalysis data (2006-present) from the NASA Global Modeling and Assimilation Office (GMAO) to (1) quantify contributions of different aerosol types to the aerosol budget and aerosol optical depths in the Arctic, (2) ­examine aerosol distributions and variability and diagnose the major pathways for mid-latitude pollution transport to the Arctic, including their seasonal and interannual variability, and (3) characterize the distribution and variability of clouds (cloud optical depth, cloud fraction, cloud liquid and ice water path, cloud top height) in the Arctic. We compare MERRA-2 aerosol and cloud properties with those from C3M, a 3-D aerosol and cloud data product developed at NASA Langley Research Center and merged from multiple A-Train satellite (CERES, CloudSat, CALIPSO, and MODIS) observations. We also conduct perturbation experiments using the NASA GEOS-5 chemistry-climate model (with GOCART aerosol module coupled with two-moment cloud microphysics), and discuss the roles of various types of aerosols in the formation and evolution of clouds in the Arctic.

Influence of the Surf Zone on the Marine Aerosol Concentration in a Coastal Area

NASA Astrophysics Data System (ADS)

Tedeschi, Gilles; van Eijk, Alexander M. J.; Piazzola, Jacques; Kusmierczyk-Michulec, Jolanta T.

2017-01-01

Sea-salt aerosol concentrations in the coastal zone are assessed with the numerical aerosol-transport model MACMod that applies separate aerosol source functions for open ocean and the surf zone near the sea-land transition. Numerical simulations of the aerosol concentration as a function of offshore distance from the surf zone compare favourably with experimental data obtained during a surf-zone aerosol experiment in Duck, North Carolina in autumn 2007. Based on numerical simulations, the effect of variations in aerosol production (source strength) and transport conditions (wind speed, air-sea temperature difference), we show that the surf-zone aerosols are replaced by aerosols generated over the open ocean as the airmass advects out to sea. The contribution from the surf-generated aerosol is significant during high wind speeds and high wave events, and is significant up to 30 km away from the production zone. At low wind speeds, the oceanic component dominates, except within 1-5 km of the surf zone. Similar results are obtained for onshore flow, where no further sea-salt aerosol production occurs as the airmass advects out over land. The oceanic aerosols that are well-mixed throughout the boundary layer are then more efficiently transported inland than are the surf-generated aerosols, which are confined to the first few tens of metres above the surface, and are therefore also more susceptible to the type of surface (trees or grass) that determines the deposition velocity.

Atmospheric Teleconnection over Eurasia Induced by Aerosol Radiative Forcing during Boreal Spring

NASA Technical Reports Server (NTRS)

Kim, Maeng-Ki; Lau, William K. M.; Chin, Mian; Kim, Kyu-Myong; Sud, Y. C.; Walker, Greg K.

2006-01-01

The direct effects of aerosols on global and regional climate during boreal spring are investigated based on numerical simulations with the NASA Global Modeling and Assimilation Office finite-volume general circulation model (fvGCM) with Microphyics of Clouds with the Relaxed Arakawa Schubert Scheme (McRAS), using aerosol forcing functions derived from the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART). The authors find that anomalous atmospheric heat sources induced by absorbing aerosols (dust and black carbon) excite a planetary-scale teleconnection pattern in sea level pressure, temperature, and geopotential height spanning North Africa through Eurasia to the North Pacific. Surface cooling due to direct effects of aerosols is found in the vicinity and downstream of the aerosol source regions, that is, South Asia, East Asia, and northern and western Africa. Significant atmospheric heating is found in regions with large loading of dust (over northern Africa and the Middle East) and black carbon (over Southeast Asia). Paradoxically, the most pronounced feature in aerosol-induced surface temperature is an east west dipole anomaly with strong cooling over the Caspian Sea and warming over central and northeastern Asia, where aerosol concentrations are low. Analyses of circulation anomalies show that the dipole anomaly is a part of an atmospheric teleconnection pattern driven by atmospheric heating anomalies induced by absorbing aerosols in the source regions, but the influence was conveyed globally through barotropic energy dispersion and sustained by feedback processes associated with the regional circulations. The surface temperature signature associated with the aerosol-induced teleconnection bears striking resemblance to the spatial pattern of observed long-term trend in surface temperature over Eurasia. Additionally, the boreal spring wave train pattern is similar to that reported by Fukutomi et al. associated with the boreal summer precipitation seesaw between eastern and western Siberia. The results of this study raise the possibility that global aerosol forcing during boreal spring may play an important role in spawning atmospheric teleconnections that affect regional and global climates.

Source apportionments of aerosols and their direct radiative forcing and long-term trends over continental United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yang; Wang, Hailong; Smith, Steven J.

Due to US air pollution regulations, aerosol and precursor emissions have decreased during recent decades, while changes in emissions in other regions of the world also influence US aerosol trends through long-range transport. We examine here the relative roles of these domestic and foreign emission changes on aerosol concentrations and direct radiative forcing (DRF) at the top of the atmosphere over the continental US. Long-term (1980-2014) trends and aerosol source apportionment are quantified in this study using a global aerosol-climate model equipped with an explicit aerosol source tagging technique. Due to US emission control policies, the annual mean near-surface concentrationmore » of particles, consisting of sulfate, black carbon, and primary organic aerosol, decreases by about –1.1 (±0.1) / –1.4 (±0.1) μg m -3 in western US and –3.3 (±0.2) / –2.9 (±0.2) μg m -3 in eastern US during 2010–2014, as compared to those in 1980–1984. Meanwhile, decreases in US emissions lead to a warming of +0.48 (±0.03) / –0.46 (±0.03) W m -2 in western US and +1.41 (±0.07) /+1.32 (±0.09) W m -2 in eastern US through changes in aerosol DRF. Increases in emissions from East Asia generally have a modest impact on US air quality, but mitigated the warming effect induced by reductions in US emissions by 25% in western US and 7% in eastern US. Thus, as US domestic aerosol and precursor emissions continue to decrease, foreign emissions may become increasingly important to radiative forcing over the US.« less

Source apportionments of aerosols and their direct radiative forcing and long-term trends over continental United States

DOE PAGES

Yang, Yang; Wang, Hailong; Smith, Steven J.; ...

2018-05-23

Due to US air pollution regulations, aerosol and precursor emissions have decreased during recent decades, while changes in emissions in other regions of the world also influence US aerosol trends through long-range transport. We examine here the relative roles of these domestic and foreign emission changes on aerosol concentrations and direct radiative forcing (DRF) at the top of the atmosphere over the continental US. Long-term (1980-2014) trends and aerosol source apportionment are quantified in this study using a global aerosol-climate model equipped with an explicit aerosol source tagging technique. Due to US emission control policies, the annual mean near-surface concentrationmore » of particles, consisting of sulfate, black carbon, and primary organic aerosol, decreases by about –1.1 (±0.1) / –1.4 (±0.1) μg m -3 in western US and –3.3 (±0.2) / –2.9 (±0.2) μg m -3 in eastern US during 2010–2014, as compared to those in 1980–1984. Meanwhile, decreases in US emissions lead to a warming of +0.48 (±0.03) / –0.46 (±0.03) W m -2 in western US and +1.41 (±0.07) /+1.32 (±0.09) W m -2 in eastern US through changes in aerosol DRF. Increases in emissions from East Asia generally have a modest impact on US air quality, but mitigated the warming effect induced by reductions in US emissions by 25% in western US and 7% in eastern US. Thus, as US domestic aerosol and precursor emissions continue to decrease, foreign emissions may become increasingly important to radiative forcing over the US.« less

XBAER-derived aerosol optical thickness from OLCI/Sentinel-3 observation

NASA Astrophysics Data System (ADS)

Mei, Linlu; Rozanov, Vladimir; Vountas, Marco; Burrows, John P.; Richter, Andreas

2018-02-01

A cloud identification algorithm used for cloud masking, which is based on the spatial variability of reflectances at the top of the atmosphere in visible wavelengths, has been developed for the retrieval of aerosol properties by MODIS. It is shown that the spatial pattern of cloud reflectance, as observed from space, is very different from that of aerosols. Clouds show a high spatial variability in the scale of a hundred metres to a few kilometres, whereas aerosols in general are homogeneous. The concept of spatial variability of reflectances at the top of the atmosphere is mainly applicable over the ocean, where the surface background is sufficiently homogeneous for the separation between aerosols and clouds. Aerosol retrievals require a sufficiently accurate cloud identification to be able to mask these ground scenes. However, a conservative mask will exclude strong aerosol episodes and a less conservative mask could introduce cloud contamination that biases the retrieved aerosol optical properties (e.g. aerosol optical depth and effective radii). A detailed study on the effect of cloud contamination on aerosol retrievals has been performed and parameters are established determining the threshold value for the MODIS aerosol cloud mask (3×3-STD) over the ocean. The 3×3-STD algorithm discussed in this paper is the operational cloud mask used for MODIS aerosol retrievals over the ocean.A prolonged pollution haze event occurred in the northeast part of China during the period 16-21 December 2016. To assess the impact of such events, the amounts and distribution of aerosol particles, formed in such events, need to be quantified. The newly launched Ocean Land Colour Instrument (OLCI) onboard Sentinel-3 is the successor of the MEdium Resolution Imaging Spectrometer (MERIS). It provides measurements of the radiance and reflectance at the top of the atmosphere, which can be used to retrieve the aerosol optical thickness (AOT) from synoptic to global scales. In this study, the recently developed AOT retrieval algorithm eXtensible Bremen AErosol Retrieval (XBAER) has been applied to data from the OLCI instrument for the first time to illustrate the feasibility of applying XBAER to the data from this new instrument. The first global retrieval results show similar patterns of aerosol optical thickness, AOT, to those from MODIS and MISR aerosol products. The AOT retrieved from OLCI is validated by comparison with AERONET observations and a correlation coefficient of 0.819 and bias (root mean square) of 0.115 is obtained. The haze episode is well captured by the OLCI-derived AOT product. XBAER is shown to retrieve AOT well from the observations of MERIS and OLCI.

Aerosol typing - key information from aerosol studies

NASA Astrophysics Data System (ADS)

Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

2016-04-01

Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the classification. The harmonization of the aerosol typing procedures is a fundamental need in aerosol studies for long-term perspectives, satellite validation, and accuracy. However, the possibilities and limits in defining a common set of aerosol types for satellite missions and ground-based measurements depends on different information content among measurement techniques and for different retrieval conditions (e.g. for low aerosol content there is smaller satellite aerosol type retrieval sensitivity), as well as different historical choices. The concept of aReference database for aerosol typing (REDAT) is developed with the specific purpose of providing a dataset suitable for the comparison of typing procedures (from ground-based, and satellite measurements) and to be used as reference dataset for the modelling community. It will also allow the definition of translating rules between the different aerosol typing nomenclature, information strongly needed for the more and more increased audience of scientific data with no scientific background, as well as policy and decision makers. Acknowledgments: The research leading to these results is partially funded by ACTRIS2 Research Infrastructure Project by the European Union's Horizon 2020 research and innovation programme under the grant agreement n. 654169.

Size-resolved trace metal characterization of aerosols emitted by four important source types in Switzerland

NASA Astrophysics Data System (ADS)

Buerki, Peter R.; Gaelli, Brigitte C.; Nyffeler, Urs P.

In central Switzerland five types of emission sources are mainly responsible for airborne trace metals: traffic, industrial plants burning heavy oil, resuspension of soil particles, residential heatings and refuse incineration plants. The particulate emissions of each of these source types except refuse incineration were sampled using Berner impactors and the mass and elemental size distributions of Cd, Cu, Mn, Pb, Zn, As and Na determined. Cd, Na and Zn are not characteristic for any of these source types. As and Cu, occurring in the fine particle fractions are characteristic for heavy oil combustion, Mn for soil dust and sometimes for heavy and fuel oil combustion and Pb for traffic aerosols. The mass size distributions of aerosols originating from erosion and abrasion processes show a maximum mass fraction in the coarse particle range larger than about 1 μm aerodynamic equivalent diameters (A.E.D.). Aerosols originating from combustion processes show a second maximum mass fraction in the fine particle range below about 0.5μm A.E.D. Scanning electron microscopy combined with an EDS analyzer was used for the morphological characterization of emission and ambient aerosols.

Urban air quality in a mid-size city - PM2.5 composition, sources and identification of impact areas: From local to long range contributions

NASA Astrophysics Data System (ADS)

Squizzato, Stefania; Cazzaro, Marta; Innocente, Elena; Visin, Flavia; Hopke, Philip K.; Rampazzo, Giancarlo

2017-04-01

Urban air quality represents a major public health burden and is a long-standing concern to European citizens. Combustion processes and traffic-related emissions represent the main primary particulate matter (PM) sources in urban areas. Other sources can also affect air quality (e.g., secondary aerosol, industrial) depending on the characteristics of the study area. Thus, the identification and the apportionment of all sources is of crucial importance to make effective corrective decisions within environmental policies. The aim of this study is to evaluate the impacts of different emissions sources on PM2.5 concentrations and compositions in a mid-size city in the Po Valley (Treviso, Italy). Data have been analyzed to highlight compositional differences (elements and major inorganic ions), to determine PM2.5 sources and their contributions, and to evaluate the influence of air mass movements. Non-parametric tests, positive matrix factorization (PMF), conditional bivariate probability function (CBPF), and concentration weighted trajectory (CWT) have been used in a multi-chemometrics approach to understand the areal-scale (proximate, local, long-range) where different sources act on PM2.5 levels and composition. Results identified three levels of scale from which the pollution arose: (i) a proximate local scale (close to the sampling site) for traffic non-exhaust and resuspended dust sources; (ii) a local urban scale (including both sampling site and areas close to them) for combustion and industrial; and (iii) a regional scale characterized by ammonium nitrate and ammonium sulfate. This approach and results can help to develop and adopt better air quality policy action.

Modeling the Current and Future Roles of Particulate Organic Nitrates in the Southeastern United States.

PubMed

Pye, Havala O T; Luecken, Deborah J; Xu, Lu; Boyd, Christopher M; Ng, Nga L; Baker, Kirk R; Ayres, Benjamin R; Bash, Jesse O; Baumann, Karsten; Carter, William P L; Edgerton, Eric; Fry, Juliane L; Hutzell, William T; Schwede, Donna B; Shepson, Paul B

2015-12-15

Organic nitrates are an important aerosol constituent in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. While regional and global chemical transport models may include a representation of organic aerosol from monoterpene reactions with nitrate radicals (the primary source of particle-phase organic nitrates in the Southeast United States), secondary organic aerosol (SOA) models can underestimate yields. Furthermore, SOA parametrizations do not explicitly take into account organic nitrate compounds produced in the gas phase. In this work, we developed a coupled gas and aerosol system to describe the formation and subsequent aerosol-phase partitioning of organic nitrates from isoprene and monoterpenes with a focus on the Southeast United States. The concentrations of organic aerosol and gas-phase organic nitrates were improved when particulate organic nitrates were assumed to undergo rapid (τ = 3 h) pseudohydrolysis resulting in nitric acid and nonvolatile secondary organic aerosol. In addition, up to 60% of less oxidized-oxygenated organic aerosol (LO-OOA) could be accounted for via organic nitrate mediated chemistry during the Southern Oxidants and Aerosol Study (SOAS). A 25% reduction in nitrogen oxide (NO + NO2) emissions was predicted to cause a 9% reduction in organic aerosol for June 2013 SOAS conditions at Centreville, Alabama.

Natural aerosols explain seasonal and spatial patterns of Southern Ocean cloud albedo

PubMed Central

McCoy, Daniel T.; Burrows, Susannah M.; Wood, Robert; Grosvenor, Daniel P.; Elliott, Scott M.; Ma, Po-Lun; Rasch, Phillip J.; Hartmann, Dennis L.

2015-01-01

Atmospheric aerosols, suspended solid and liquid particles, act as nucleation sites for cloud drop formation, affecting clouds and cloud properties—ultimately influencing the cloud dynamics, lifetime, water path, and areal extent that determine the reflectivity (albedo) of clouds. The concentration Nd of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations affect not only cloud properties themselves but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. It is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more than half of the spatiotemporal variability in satellite-observed Nd. Enhanced Nd is spatially correlated with regions of high chlorophyll a, and the spatiotemporal variability in Nd is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35o to 45oS) and by organic matter in sea spray aerosol at higher latitudes (45o to 55oS). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m–2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere. PMID:26601216

Natural aerosols explain seasonal and spatial patterns of Southern Ocean cloud albedo.

PubMed

McCoy, Daniel T; Burrows, Susannah M; Wood, Robert; Grosvenor, Daniel P; Elliott, Scott M; Ma, Po-Lun; Rasch, Phillip J; Hartmann, Dennis L

2015-07-01

Atmospheric aerosols, suspended solid and liquid particles, act as nucleation sites for cloud drop formation, affecting clouds and cloud properties-ultimately influencing the cloud dynamics, lifetime, water path, and areal extent that determine the reflectivity (albedo) of clouds. The concentration N d of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations affect not only cloud properties themselves but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. It is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more than half of the spatiotemporal variability in satellite-observed N d. Enhanced N d is spatially correlated with regions of high chlorophyll a, and the spatiotemporal variability in N d is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35(o) to 45(o)S) and by organic matter in sea spray aerosol at higher latitudes (45(o) to 55(o)S). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m(-2) over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere.

Evidence of Aerosols as a Media for Rapid Daytime HONO Production over China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Zhen; Wang, Yuhang; Costabile, Francesa

Current knowledge of daytime HONO sources remains incomplete. A large missing daytime HONO source has been found in many places around the world, including polluted regions in China. Conventional understanding and recent studies attributed this missing source mainly to ground surface processes or gas-phase chemistry, while assuming aerosols to be an insignificant media for HONO production. We analyze in situ observations of HONO and its precursors at an urban site in Beijing, China, and report an apparent dependence of the missing HONO source strength on aerosol surface area and solar ultraviolet radiation. Based on extensive correlation analysis and process-modeling, wemore » propose that the rapid daytime HONO production in Beijing can be explained by enhanced hydrolytic disproportionation of NO2 on aqueous aerosol surfaces due to catalysis by dicarboxylic acid anions. The combination of high abundance of NO2, aromatic hydrocarbons, and aerosols over broad regions in China likely leads to elevated HONO levels, rapid OH production, and enhanced oxidizing capacity on a regional basis. Our findings call for attention to aerosols as a media for daytime heterogeneous HONO production in polluted regions like Beijing. This study also highlights the complex and uncertain heterogeneous chemistry in China, which merits future efforts of reconciling regional modeling and laboratory experiments, in order to understand and mitigate the regional particulate and O3 pollutions over China.« less

Do differences in future sulfate emission pathways matter for near-term climate? A case study for the Asian monsoon

NASA Astrophysics Data System (ADS)

Bartlett, Rachel E.; Bollasina, Massimo A.; Booth, Ben B. B.; Dunstone, Nick J.; Marenco, Franco; Messori, Gabriele; Bernie, Dan J.

2018-03-01

Anthropogenic aerosols could dominate over greenhouse gases in driving near-term hydroclimate change, especially in regions with high present-day aerosol loading such as Asia. Uncertainties in near-future aerosol emissions represent a potentially large, yet unexplored, source of ambiguity in climate projections for the coming decades. We investigated the near-term sensitivity of the Asian summer monsoon to aerosols by means of transient modelling experiments using HadGEM2-ES under two existing climate change mitigation scenarios selected to have similar greenhouse gas forcing, but to span a wide range of plausible global sulfur dioxide emissions. Increased sulfate aerosols, predominantly from East Asian sources, lead to large regional dimming through aerosol-radiation and aerosol-cloud interactions. This results in surface cooling and anomalous anticyclonic flow over land, while abating the western Pacific subtropical high. The East Asian monsoon circulation weakens and precipitation stagnates over Indochina, resembling the observed southern-flood-northern-drought pattern over China. Large-scale circulation adjustments drive suppression of the South Asian monsoon and a westward extension of the Maritime Continent convective region. Remote impacts across the Northern Hemisphere are also generated, including a northwestward shift of West African monsoon rainfall induced by the westward displacement of the Indian Ocean Walker cell, and temperature anomalies in northern midlatitudes linked to propagation of Rossby waves from East Asia. These results indicate that aerosol emissions are a key source of uncertainty in near-term projection of regional and global climate; a careful examination of the uncertainties associated with aerosol pathways in future climate assessments must be highly prioritised.

What We Can Say About the Roles of Natural and Anthropogenic Aerosols in Climate Change

NASA Astrophysics Data System (ADS)

Kahn, Ralph

2016-07-01

Although particles from natural sources dominate the globally averaged aerosol load, it is widely understood that human activity has added significantly to the atmospheric aerosol inventory in many regions. Anthropogenic contributions include pollution particles from industrial activity, transportation, cook-stoves, and other combustion sources, smoke from agricultural fires and those wildfires that result from land-management practices, soil and mineral dust mobilized in regions where overgrazing, severe tilling, or overuse of surface water resources have occurred, and biogenic particles from vegetation planted and maintained by the populance. The history of human influence is complex - in the 18th and 19th centuries agricultural burning tended to dominate the anthropogenic component in most places, whereas more recently, fossil fuel combustion leads the human contribution is many areas. However, identifying and quantifying the anthropogenic aerosol component on global scales is a challenging endeavor at present. Most estimates of the anthropogenic component come from aerosol transport models that are initialized with aerosol and precursor-gas source locations, emission strengths, and injection heights. The aerosol is then advected based on meteorological modeling, possibly modified chemically or physically, and removed by parameterized wet or dry deposition processes. Aerosol effects on clouds are also represented in some climate models, but with even greater uncertainty than the direct aerosol effects on Earth's radiation balance. Even for present conditions, aerosol source inventories are deduced from whatever constraints can be found, along with much creativity and many assumptions. Aerosol amount (i.e., aerosol optical depth) is routinely measured globally from space, but observational constraints on the anthropogenic component require some knowledge of the aerosol type as well, a much more difficult quantity to derive. As large-swath, multi-spectral, single-view instruments such as MODIS can provide some information about fine-mode vs. coarse-mode dominated aerosol over dark water, early efforts to constrain aerosol type assumed that some or all the fine-mode fraction is anthropogenic. However, this information is not sufficient to make the key anthropogenic vs. natural distinction in most places where the likely answer is not already known. Instruments providing more detailed measurements, such as multi-spectral, multi-angle and polarimetric imagers and multi-channel lidars, can offer tighter aerosol-type constraints in some circumstances, though generally not enough to specifically identify anthropogenic aerosols. The best we seem to be able to do with current data is to combine satellite and suborbital observations with models. And for the "pre-industrial" period, the analogy is usually made to the "natural" component of present-day aerosol, although there are ambiguities in our ability to distinguish natural from anthropogenic particles on regional-to-global scales, and the natural component itself might have changed over time. This talk will review where we stand, and what might be possible to say in the future.

Composition and oxidation state of sulfur in atmospheric particulate matter

NASA Astrophysics Data System (ADS)

Longo, Amelia F.; Vine, David J.; King, Laura E.; Oakes, Michelle; Weber, Rodney J.; Huey, Lewis Gregory; Russell, Armistead G.; Ingall, Ellery D.

2016-10-01

The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS) and X-ray fluorescence (XRF) microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm) analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

Aerosol studies during the ESCOMPTE experiment: an overview

NASA Astrophysics Data System (ADS)

Cachier, Hélène; Aulagnier, Fabien; Sarda, Roland; Gautier, François; Masclet, Pierre; Besombes, Jean-Luc; Marchand, Nicolas; Despiau, Serge; Croci, Delphine; Mallet, Marc; Laj, Paolo; Marinoni, Angela; Deveau, Pierre-Alexandre; Roger, Jean-Claude; Putaud, Jean-Philippe; Van Dingenen, Rita; Dell'Acqua, Alessandro; Viidanoja, Jyrkki; Martins-Dos Santos, Sebastiao; Liousse, Cathy; Cousin, Frédéric; Rosset, Robert; Gardrat, Eric; Galy-Lacaux, Corinne

2005-03-01

The "Expérience sur Site pour COntraindre les Modèles de Pollution atmosphérique et de Transport d'Emissions" (ESCOMPTE) experiment took place in the Southern part of France in the Marseilles/Fos-Berre region during 6 weeks in June and July 2001. One task was to document the regional sources of atmospheric particles and to gain some insight into the aerosol transformations in the atmosphere. For this purpose, seven sites were chosen and equipped with the same basic instrumentation to obtain the chemical closure of the bulk aerosol phase and size-segregated samples. Some specific additional experiments were conducted for the speciation of the organic matter and the aerosol size distribution in number. Finally, four multiwavelength sun-photometers were also deployed during the experiment. Interestingly, in this region, three intense aerosol sources (urban, industrial and biogenic) are very active, and data show consistent results, enlightening an important background of particles over the whole ESCOMPTE domain. Notable is the overwhelming importance of the carbonaceous fraction (comprising primary and secondary particles), which is always more abundant than sulphates. Particle size studies show that, on average, more than 90% of the mean regional aerosol number is found on a size range smaller than 300 nm in diameter. The most original result is the evidence of the rapid formation of secondary aerosols occurring in the whole ESCOMPTE domain. This formation is much more important than that usually observed at these latitudes since two thirds of the particulate mass collected off source zones is estimated to be generated during atmospheric transport. On the other hand, the marine source has poor influence in the region, especially during the overlapping pollution events of Intensive Observation Periods (IOP). Preliminary results from the 0D and 3D versions of the MesoNH-aerosol model show that, with optimised gas and particle sources, the model accounts satisfactorily for the measured aerosol concentrations. The formation of secondary particles in the model is currently underway; initial encouraging results show that the model accounts for the formation of secondary species, such as sulphate and organic particles. Finally, radiative calculations suggest that the role of the fine aerosol fraction is predominant mostly due to the presence of black carbon (BC) particles, which could induce a regional atmospheric heating.

Aerosol composition, oxidative properties, and sources in Beijing: results from the 2014 Asia-Pacific Economic Cooperation Summit study

NASA Astrophysics Data System (ADS)

Xu, W. Q.; Sun, Y. L.; Chen, C.; Du, W.; Han, T. T.; Wang, Q. Q.; Fu, P. Q.; Wang, Z. F.; Zhao, X. J.; Zhou, L. B.; Ji, D. S.; Wang, P. C.; Worsnop, D. R.

2015-08-01

The mitigation of air pollution in megacities remains a great challenge because of the complex sources and formation mechanisms of aerosol particles. The 2014 Asia- Pacific Economic Cooperation (APEC) summit in Beijing serves as a unique experiment to study the impacts of emission controls on aerosol composition, size distributions, and oxidative properties. Herein, a high-resolution time-of-flight aerosol mass spectrometer was deployed in urban Beijing for real-time measurements of size-resolved non-refractory submicron aerosol (NR-PM1) species from 14 October to 12 November 2014, along with a range of collocated measurements. The average (±σ) PM1 was 41.6 (±38.9) μg m-3 during APEC, which was decreased by 53 % compared with that before APEC. The aerosol composition showed substantial changes owing to emission controls during APEC. Secondary inorganic aerosols (SIA = sulfate + nitrate + ammonium) showed significant reductions of 62-69 %, whereas organics presented much smaller decreases (35 %). The results from the positive matrix factorization of organic aerosols (OA) indicated that highly oxidized secondary OA (SOA) showed decreases similar to those of SIA during APEC. However, primary OA (POA) from cooking, traffic, and biomass burning sources were comparable to those before APEC, indicating the presence of strong local source emissions. The oxidation properties showed corresponding changes in response to OA composition. The average oxygen-to-carbon level during APEC was 0.36 (±0.10), which is lower than the 0.43 (±0.13) measured before APEC, demonstrating a decrease in the OA oxidation degree. The changes in size distributions of primary and secondary species varied during APEC. SIA and SOA showed significant reductions in large accumulation modes with peak diameters shifting from ~ 650 to 400 nm during APEC, whereas those of POA remained relatively unchanged. The changes in aerosol composition, size distributions, and oxidation degrees during the aging processes were further illustrated in a case study of a severe haze episode. Our results elucidated a complex response of aerosol chemistry to emission controls, which has significant implications that emission controls over regional scales can substantially reduce secondary particulates. However, stricter emission controls for local source emissions are needed for further mitigating air pollution in the megacity of Beijing.

Characteristics and sources of submicron aerosols above the urban canopy (260 m) in Beijing, China, during the 2014 APEC summit

NASA Astrophysics Data System (ADS)

Chen, C.; Sun, Y. L.; Xu, W. Q.; Du, W.; Zhou, L. B.; Han, T. T.; Wang, Q. Q.; Fu, P. Q.; Wang, Z. F.; Gao, Z. Q.; Zhang, Q.; Worsnop, D. R.

2015-11-01

The megacity of Beijing has experienced frequent severe fine particle pollution during the last decade. Although the sources and formation mechanisms of aerosol particles have been extensively investigated on the basis of ground measurements, real-time characterization of aerosol particle composition and sources above the urban canopy in Beijing is rare. In this study, we conducted real-time measurements of non-refractory submicron aerosol (NR-PM1) composition at 260 m at the Beijing 325 m meteorological tower (BMT) from 10 October to 12 November 2014, by using an aerosol chemical speciation monitor (ACSM) along with synchronous measurements of size-resolved NR-PM1 composition near ground level using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The NR-PM1 composition above the urban canopy was dominated by organics (46 %), followed by nitrate (27 %) and sulfate (13 %). The high contribution of nitrate and high NO3- / SO42- mass ratios illustrates an important role of nitrate in particulate matter (PM) pollution during the study period. The organic aerosol (OA) was mainly composed of secondary OA (SOA), accounting for 61 % on an average. Different from that measured at the ground site, primary OA (POA) correlated moderately with SOA, likely suggesting a high contribution from regional transport above the urban canopy. The Asia-Pacific Economic Cooperation (APEC) summit with strict emission controls provides a unique opportunity to study the impacts of emission controls on aerosol chemistry. All aerosol species were shown to have significant decreases of 40-80 % during APEC from those measured before APEC, suggesting that emission controls over regional scales substantially reduced PM levels. However, the bulk aerosol composition was relatively similar before and during APEC as a result of synergetic controls of aerosol precursors. In addition to emission controls, the routine circulations of mountain-valley breezes were also found to play an important role in alleviating PM levels and achieving the "APEC blue" effect. The evolution of vertical differences between 260 m and the ground level was also investigated. Our results show complex vertical differences during the formation and evolution of severe haze episodes that are closely related to aerosol sources and boundary-layer dynamics.

Characteristics and sources of submicron aerosols above the urban canopy (260 m) in Beijing, China during 2014 APEC summit

NASA Astrophysics Data System (ADS)

Chen, C.; Sun, Y. L.; Xu, W. Q.; Du, W.; Zhou, L. B.; Han, T. T.; Wang, Q. Q.; Fu, P. Q.; Wang, Z. F.; Gao, Z. Q.; Zhang, Q.; Worsnop, D. R.

2015-08-01

The megacity of Beijing has experienced frequent severe fine particle pollution during the last decade. Although the sources and formation mechanisms of aerosol particles have been extensively investigated on the basis of ground measurements, real-time characterization of aerosol particle composition and sources above the urban canopy in Beijing is rare. In this study, we conducted real-time measurements of non-refractory submicron aerosol (NR-PM1) composition at 260 m at the 325 m Beijing Meteorological Tower (BMT) from 10 October to 12 November 2014, by using an aerosol chemical speciation monitor (ACSM) along with synchronous measurements of size-resolved NR-PM1 composition at near ground level using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS). The NR-PM1 composition above the urban canopy was dominated by organics (46 %), followed by nitrate (27 %) and sulfate (13 %). The high contribution of nitrate and high NO3-/SO42- mass ratios illustrate an important role of nitrate in particulate matter (PM) pollution during the study period. The organic aerosol (OA) was mainly composed by secondary OA (SOA), accounting for 61 % on an average. Different from that measured at the ground site, primary OA (POA) correlated moderately with SOA, likely suggesting a high contribution from regional transport above the urban canopy. The Asia-Pacific Economic Cooperation (APEC) summit with strict emission controls provides a unique opportunity to study the impacts of emission controls on aerosol chemistry. All aerosol species were shown to have significant decreases of 40-80 % during APEC from those measured before APEC, suggesting that emission controls over regional scales substantially reduced PM levels. However, the bulk aerosol composition was relatively similar before and during APEC as a result of synergetic controls of aerosol precursors such as SO2, NOx, and volatile organic compounds (VOCs). In addition to emission controls, the routine circulations of mountain-valley breezes were also found to play an important role in alleviating PM levels and achieving the "APEC blue" effect. The evolution of vertical differences between 260 m and the ground level was also investigated. Our results show complex vertical differences during the formation and evolution of severe haze episodes that are closely related to aerosol sources and boundary layer dynamics.

Ambient Aerosols in the Southern Hemisphere on Ascension Island during the LASIC Campaign: Biomass Burning Season versus Near Pristine Background Conditions

NASA Astrophysics Data System (ADS)

Aiken, A. C.; Springston, S. R.; Watson, T. B.; Sedlacek, A. J., III; Zuidema, P.; Adebiyi, A. A.; Uin, J.; Kuang, C.; Flynn, C. J.

2017-12-01

Ascension Island is located 8 degrees South of the Equator and 15 degrees West Longitude in the middle of the South Atlantic Ocean, at least 1000 miles from any major shoreline and closest to the continent of Africa. While low Southern Hemisphere background aerosol and trace gas measurements are observed most of the year, that picture changes during the South African Biomass Burning (BB) season. BB emissions are a large source of carbon to the atmosphere via particles and gas phase species and with a potential rise in drought and extreme events in the future, these numbers are expected to increase. From approximately June-October every year, the plume of South African BB emissions, the largest BB source in the world, are advected West and are known to impact both the boundary layer and free troposphere at Ascension Island (Zuidema et al., 2016). During the U.S. DOE ARM field campaign, Layered Atlantic Smoke Interactions with Clouds (LASIC), aerosol and trace gas measurements were collected continuously from June 2016 through October 2017 over a 1.5 year period. Two BB seasons are contrasted with the near pristine background conditions during the campaign from the ARM Aerosol Mobile Facility 1 (AMF1) and Mobile Aerosol Observing System (MAOS). Numerous direct in situ aerosol and trace gas measurements are presented, e.g. black carbon (BC), carbon monoxide (CO), PM1 and PM10 aerosol absorption and scattering, submicron non-refractory chemical composition (Organics, Sulfate, Nitrate, Ammonium, Chloride), etc. Aerosol and trace gas signatures are investigated along with backtrajectories to identify sources. Carbonaceous aerosols emitted with gas-phase CO are used to determine particulate emission ratios along with intrinsic and extrinsic aerosol properties. BC mass concentrations reach 1 µg m-3 during multiday plumes and exceed 25% of the total aerosol submicron mass concentration. Organic Aerosol (OA) to BC Ratios of 2.4 in the plume are much higher than previously observed BB emissions in the Northern Hemisphere from forest fires in the US and also BB sources in Brazil. The differences observed between BB emissions in the Northern versus Southern Hemispheres highlights the need to understand the different atmospheric chemistries within the context of the differing background conditions of the two hemispheres.

Characterizing the oxygen isotopic composition of phosphate sources to aquatic ecosystems

USGS Publications Warehouse

Young, M.B.; McLaughlin, K.; Kendall, C.; Stringfellow, W.; Rollog, M.; Elsbury, K.; Donald, E.; Paytan, A.

2009-01-01

The oxygen isotopic composition of dissolved inorganic phosphate (δ18Op) in many aquatic ecosystems is not in isotopic equilibrium with ambient water and, therefore, may reflect the source δ18Op. Identification of phosphate sources to water bodies is critical for designing best management practices for phosphate load reduction to control eutrophication. In order for δ18O p to be a useful tool for source tracking, the δ18Op of phosphate sources must be distinguishable from one another; however, the δ18Op of potential sources has not been well characterized. We measured the δ18O p of a variety of known phosphate sources, including fertilizers, semiprocessed phosphorite ore, particulate aerosols, detergents, leachates of vegetation, soil, animal feces, and wastewater treatment plant effluent. We found a considerable range of δ18Op values (from +8.4 to +24.9‰) for the various sources, and statistically significant differences were found between several of the source types. δ18Op measured in three different fresh water systems was generally not in equilibrium with ambient water. Although there is overlap in δ18Op values among the groups of samples, our results indicate that some sources are isotopically distinct and δ18Op can be used for identifying phosphate sources to aquatic systems.

Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

NASA Astrophysics Data System (ADS)

Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

2014-11-01

The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in residual layers but still originating in northern Italy, while a substantial fraction (41%) was due to the most aged aerosols imported from transalpine areas. The different meteorological regimes also affected the BC mixing state: in periods of enhanced stagnation and recirculation of pollutants, the number fraction of the BC-containing particles determined by ATOFMS was 75% of the total, while in the days of enhanced ventilation of the planetary boundary layer (PBL), such fraction was significantly lower (50%) because of the relative greater influence of non-BC-containing aerosol local sources in the Po Valley. Overall, a full internal mixing between BC and the non-refractory aerosol chemical components was not observed during the experiment in this environment.

New directions: Mineral dust and ozone - Heterogeneous chemistry

NASA Astrophysics Data System (ADS)

Ramachandran, S.

2015-04-01

Aerosols, the tiny solid or liquid particles suspended in air and produced from natural sources and anthropogenic activities, continue to contribute the largest uncertainty to radiative forcing (IPCC, 2013). Aerosol particles give rise to radiative forcing directly through scattering and absorption of solar and infrared radiation in the atmosphere. Aerosols also give rise to indirect radiative forcing by modifying the cloud optical properties and lifetimes. Among the aerosol species mineral dust and black carbon cause a warming (positive forcing) while sulphate and sea salt cause a cooling (negative forcing) of the Earth-atmosphere system. In tropics and sub-tropics mineral dust is a major contributor to aerosol loading and optical thickness. The global source strength of dust aerosol varies significantly on spatial and temporal scales. The source regions of dust are mainly deserts, dry lake beds, and semi-arid regions, in addition to drier regions where vegetation has been reduced or soil surfaces that are disturbed by man made activities. Anthropogenic activities mainly related to agriculture such as harvesting, ploughing, overgrazing, and cement production and transport also produce mineral dust. An estimated 2500 terragram (Tg, 1012 g) of mineral dust is emitted into the atmosphere per year, and dominates the aerosol mass over continental regions in south Asia and China accounting for ∼35% of the total aerosol mass (IPCC, 2013). In India, dust is prevalent throughout the north and western India during the year and peaks during premonsoon season.

Marine biogenic sources of organic nitrogen and water-soluble organic aerosols over the western North Pacific in summer

NASA Astrophysics Data System (ADS)

Miyazaki, Y.; Kawamura, K.; Sawano, M.

2009-12-01

Size-segregated aerosol samples of organic nitrogen (ON) as well as water-soluble organic compounds were obtained over the western North Pacific in the summer of 2008. Mass contributions of organics to the total aerosol mass were 20-40% in the supermicron mode and 45-60% in the submicron mode. ON as well as diacids and water-soluble organic carbon (WSOC) showed bimodal size distributions over the remote ocean, where high values of chlorophyll-a concentrations and depth-integrated primary production were observed. The ON concentrations increased with increasing biogenic tracer compounds such as methanesulfuric acid (MSA) and azelaic acid (C9). The average concentrations of ON and organic carbon (OC) in aerosols more influenced by marine biological activity were found to be about two times greater than those in biologically less influenced aerosols. These results provide evidence of marine biogenic sources of ON as well as OC. An average ON/OC ratio in biologically more influenced aerosols was as high as 0.49±0.11, which is higher than that in biologically less influenced aerosols (0.35±0.10). This result indicates that organic aerosol in this region is enriched in organic nitrogen, which linked to oceanic biological activity and comparable in magnitude to the marine biogenic OC source. We discuss possible processes for primary and secondary production of ON and OC in these samples, and stable nitrogen and carbon isotope ratios for total nitrogen (TN) and total carbon (TC).

On-road measurement of black carbon mass, absorption, and single-scattering albedo

EPA Science Inventory

Absorption and scattering of solar radiation by aerosols emitted from combustion sources can affect the earth’s radiative balance and may potentially affect local and regional climate. Optical properties of aerosols emitted from mobile sources have not been thoroughly characteri...

Analysis of individual biological particles by mass spectrometry

NASA Technical Reports Server (NTRS)

Sinha, M. P.; Platz, R. M.; Vilker, V. L.; Friedlander, S. K.

1984-01-01

A method is developed for the detection and identification of biological particles introduced in aerosol form into a quadrupole mass spectrometer. The bacterial aerosol is generated by nebulizing an ethanol suspension. The particles are introduced into the ion source of the mass spectrometer in the form of a beam, where they are individually volatilized on a V-type rhenium filament and ionized by electron impaction. It is shown that the average intensity of a mass peak is obtained from the pulse height distribution of about a thousand ion pulses from different particles. Pseudomonas putida, Bacillus subtilis, and Bacillus cereus are used in the studies. Differences between the relative intensities of mass peaks in the spectra from P. putida and B. subtilis are found and may provide a method for differentiation of microorganisms. The results for the two species agree reasonably well with those reported by Kistemaker et al. (1975) and Schulten et al. (1973). However, there exist some differences between the two spectra in the high mass range due to the difference in the pyrolysis conditions.

A study of remotely sensed aerosol properties from ground-based sun and sky scanning radiometers

NASA Astrophysics Data System (ADS)

Giles, David M.

Aerosol particles impact human health by degrading air quality and affect climate by heating or cooling the atmosphere. The Indo-Gangetic Plain (IGP) of Northern India, one of the most populous regions in the world, produces and is impacted by a variety of aerosols including pollution, smoke, dust, and mixtures of them. The NASA Aerosol Robotic Network (AERONET) mesoscale distribution of Sun and sky-pointing instruments in India was established to measure aerosol characteristics at sites across the IGP and around Kanpur, India, a large urban and industrial center in the IGP, during the 2008 pre-monsoon (April-June). This study focused on detecting spatial and temporal variability of aerosols, validating satellite retrievals, and classifying the dominant aerosol mixing states and origins. The Kanpur region typically experiences high aerosol loading due to pollution and smoke during the winter and high aerosol loading due to the addition of dust to the pollution and smoke mixture during the pre-monsoon. Aerosol emissions in Kanpur likely contribute up to 20% of the aerosol loading during the pre-monsoon over the IGP. Aerosol absorption also increases significantly downwind of Kanpur indicating the possibility of the black carbon emissions from aerosol sources such as coal-fired power plants and brick kilns. Aerosol retrievals from satellite show a high bias when compared to the mesoscale distributed instruments around Kanpur during the pre-monsoon with few high quality retrievals due to imperfect aerosol type and land surface characteristic assumptions. Aerosol type classification using the aerosol absorption, size, and shape properties can identify dominant aerosol mixing states of absorbing dust and black carbon particles. Using 19 long-term AERONET sites near various aerosol source regions (Dust, Mixed, Urban/Industrial, and Biomass Burning), aerosol absorption property statistics are expanded upon and show significant differences when compared to previous work. The sensitivity of absorption properties is evaluated and quantified with respect to aerosol retrieval uncertainty. Using clustering analysis, aerosol absorption and size relationships provide a simple method to classify aerosol mixing states and origins and potentially improve aerosol retrievals from ground-based and satellite-based instrumentation.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

NASA Astrophysics Data System (ADS)

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; Berkemeier, Thomas; Shiraiwa, Manabu; Zuend, Andreas; Nin Chan, Man

2017-12-01

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5) hydroxyl functionalization product (C5H8O5) and a C4 fragmentation product (C4H6O3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon-carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.

The role of anthropogenic species in Biogenic aerosol formation

EPA Science Inventory

Isoprene is a widely recognized source of organic aerosol in the southeastern United States. Models have traditionally represented isoprene-derived aerosol as semivolatile species formed from the initial isoprene + OH reaction. Recent laboratory and field studies indicate later g...

The regime of biomass burning aerosols over the Mediterranean basin based on satellite observations

NASA Astrophysics Data System (ADS)

Kalaitzi, Nikoleta; Gkikas, Antonis; Papadimas, Christos. D.; Hatzianastassiou, Nikolaos; Torres, Omar; Mihalopoulos, Nikolaos

2016-04-01

Biomass burning (BB) aerosol particles have significant effects on global and regional climate, as well as on regional air quality, visibility, cloud processes and human health.Biomass burning contributes by about 40% to the global emission of black carbonBC, and BB aerosols can exert a significant positive radiative forcing. The BB aerosols can originate from natural fires and human induced burning, such as wood or agricultural waste. However, the magnitude, but also the sign of the radiative forcing of BB aerosols is still uncertain, according to the third assessment report of IPCC (2013). Moreover, there are significant differences between different models as to their representation (inventories) of BB aerosols, more than for others, e.g. of fossil fuel origin. Therefore, it is important to better understand the spatial and temporal regime of BB aerosols. This is attempted here for the broader Mediterranean basin, which is a very interesting study area for aerosols, also being one of the most climaticallysensitive world regions. The determination of spatial and temporal regime of Mediterranean BB aerosols premises the identification of these particles at a complete spatial and long temporal coverage. Such a complete coverage is only ensured by contemporary satellite observations, which offer a challenging ability to characterize the existence of BB aerosols. This is possible thanks to the current availability of derived satellite products offering information on the size and absorption/scattering ability of aerosol particles. A synergistic use of such satellite aerosol data is made here, in conjunction with a developed algorithm, in order to identify the existence of BB aerosols over the Mediterranean basin over the 11-year period from 2005 to 2015. The algorithm operates, on a daily basis and at 1°×1°latitude-longitude resolution, setting threshold values (criteria) for specific physical and optical properties, which are representative of BB aerosols. More specifically, the algorithm examines the fulfillment of these criteria for Ångström Exponent (AE), Fine Fraction (FF) and Aerosol Index (AI). The AE and FF data, which are characteristic of the aerosol size, are derived from multispectralCollection 006 MODIS-AquaAerosol Optical Depth (AOD) data, whereas the AI data, that characterize the absorption ability of aerosols, are taken from the OMI-Aura database. The algorithm enables the identification of BB aerosols over specific geographical cells (pixels) throughout the study region, over both sea and land surfaces, during days of the 2005-2015 period. The results make possible the construction of a climatological-like database of Mediterranean BB aerosols, permitting to perceive the geographical patterns of their regime, namely the areas in which they occur, in relation to their timing, i.e. the months and seasons of their occurrence. This regime is quantified, which means that the frequency (absolute and percent) of occurrence of BB aerosols is calculated, along with the associated computed AOD values. The year by year variability of BB aerosols is also investigated over the period 2005-2015, with emphasis to inter-annual and seasonal tendencies.

Field Measurements of Trace Gases and Aerosols Emitted by Undersampled Combustion Sources Including Wood and Dung Cooking Fires, Garbage and Crop Residue Burning, and Indonesian Peat Fires

NASA Astrophysics Data System (ADS)

Stockwell, C.; Jayarathne, T. S.; Goetz, D.; Simpson, I. J.; Selimovic, V.; Bhave, P.; Blake, D. R.; Cochrane, M. A.; Ryan, K. C.; Putra, E. I.; Saharjo, B.; Stone, E. A.; DeCarlo, P. F.; Yokelson, R. J.

2017-12-01

Field measurements were conducted in Nepal and in the Indonesian province of Central Kalimantan to improve characterization of trace gases and aerosols emitted by undersampled combustion sources. The sources targeted included cooking with a variety of stoves, garbage burning, crop residue burning, and authentic peat fires. Trace gas and aerosol emissions were studied using a land-based Fourier transform infrared spectrometer, whole air sampling, photoacoustic extinctiometers (405 and 870nm), and filter samples that were analyzed off-line. These measurements were used to calculate fuel-based emission factors (EFs) for up to 90 gases, PM2.5, and PM2.5 constituents. The aerosol optical data measured included EFs for the scattering and absorption coefficients, the single scattering albedo (at 870 and 405 nm), as well as the absorption Ångström exponent. The emissions varied significantly by source, although light absorption by both brown and black carbon (BrC and BC, respectively) was important for all non-peat sources. For authentic peat combustion, the emissions of BC were negligible and absorption was dominated by organic aerosol. The field results from peat burning were in reasonable agreement with recent lab measurements of smoldering Kalimantan peat and compare well to the limited data available from other field studies. The EFs can be used with estimates of fuel consumption to improve regional emissions inventories and assessments of the climate and health impacts of these undersampled sources.

Using the Aerosol Single Scattering Albedo and Angstrom Exponent from AERONET to Determine Aerosol Origins and Mixing States over the Indo-Gangetic Plain

NASA Astrophysics Data System (ADS)

Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Slutsker, I.; Smirnov, A.; Schafer, J. S.; Dickerson, R. R.; Thompson, A. M.; Tripathi, S. N.; Singh, R. P.; Ghauri, B.

2012-12-01

Aerosol mixtures—whether dominated by dust, carbon, sulfates, nitrates, sea salt, or mixtures of them—complicate the retrieval of remotely sensed aerosol properties from satellites and possibly increase the uncertainty of the aerosol radiative impact on climate. Major aerosol source regions in South Asia include the Thar Desert as well as agricultural lands, Himalayan foothills, and large urban centers in and near the Indo-Gangetic Plain (IGP). Over India and Pakistan, seasonal changes in meteorology, including the monsoon (June-September), significantly affect the transport, lifetime, and type of aerosols. Strong monsoonal winds can promote long range transport of dust resulting in mixtures of dust and carbonaceous aerosols, while more stagnant synoptic conditions (e.g., November-January) can prolong the occurrence of urban/industrial pollution, biomass burning smoke, or mixtures of them over the IGP. Aerosol Robotic Network (AERONET) Sun/sky radiometer data are analyzed to show the aerosol optical depth (AOD) seasonality and aerosol dominant mixing states. The Single Scattering Albedo (SSA) and extinction Angstrom exponent (EAE) relationship has been shown to provide sound clustering of dominant aerosol types using long term AERONET site data near known source regions [Giles et al., 2012]. In this study, aerosol type partitioning using the SSA (440 nm) and EAE (440-870 nm) relationship is further developed to quantify the occurrence of Dust, Mixed (e.g., dust and carbonaceous aerosols), Urban/Industrial (U/I) pollution, and Biomass Burning (BB) smoke. Based on EAE thresholds derived from the cluster analysis (for AOD440nm>0.4), preliminary results (2001-2010) for Kanpur, India, show the overall contributions of each dominant particle type (rounded to the nearest 10%): 10% for Dust (EAE≤0.25), 60% for Mixed (0.251.25). In the IGP, BB aerosols may have varying sizes (e.g., corresponding to 1.2

ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

NASA Astrophysics Data System (ADS)

Fröhlich, R.; Crenn, V.; Setyan, A.; Belis, C. A.; Canonaco, F.; Favez, O.; Riffault, V.; Slowik, J. G.; Aas, W.; Aijälä, M.; Alastuey, A.; Artiñano, B.; Bonnaire, N.; Bozzetti, C.; Bressi, M.; Carbone, C.; Coz, E.; Croteau, P. L.; Cubison, M. J.; Esser-Gietl, J. K.; Green, D. C.; Gros, V.; Heikkinen, L.; Herrmann, H.; Jayne, J. T.; Lunder, C. R.; Minguillón, M. C.; Močnik, G.; O'Dowd, C. D.; Ovadnevaite, J.; Petralia, E.; Poulain, L.; Priestman, M.; Ripoll, A.; Sarda-Estève, R.; Wiedensohler, A.; Baltensperger, U.; Sciare, J.; Prévôt, A. S. H.

2015-06-01

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2 %, COA: 15.0 ± 3.4 %, OOA: 41.5 ± 5.7 %, BBOA: 29.3 ± 5.0 %). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2 %.

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

NASA Astrophysics Data System (ADS)

Cheng, Yafang; Zheng, Guangjie; Wei, Chao; Mu, Qing; Zheng, Bo; Wang, Zhibin; Gao, Meng; Zhang, Qiang; Wang, Kebin; Carmichael, Gregory; Pöschl, Ulrich; Su, Hang

2017-04-01

Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to 300 μg m-3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution. Reference: Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Science Advances, 2, 10.1126/sciadv.1601530, 2016.

Characterizing the Asian Tropopause Aerosol Layer (ATAL) Using Satellite Observations, Balloon Measurements and a Chemical Transport Model

NASA Technical Reports Server (NTRS)

Fairlie, T. D.; Vernier, J.-P.; Liu, H.; Deshler, T.; Natarajan, M.; Bedka, K.; Wegner, T.; Baker, N.; Gadhavi, H.; Ratnam, M. V.;

The Asian Tropopause Aerosol Layer: Balloon-Borne Measurements, Satellite Observations and Modeling Approaches

NASA Technical Reports Server (NTRS)

Fairlie, T. D.; Vernier, J.-P.; Natarajan, M.; Deshler, Terry; Liu, H.; Wegner, T.; Baker, N.; Gadhavi, H.; Jayaraman, A.; Pandit, A.;

Reactive Nitrogen Chemistry in Aerosol Water as a Source of Sulfate during Haze Events in China

NASA Astrophysics Data System (ADS)

Su, H.; Zheng, G.; Wei, C.; Mu, Q.; Zheng, B.; Wang, Z.; Zhang, Q.; Gao, M.; He, K.; Carmichael, G. R.; Poeschl, U.; Cheng, Y.

2017-12-01

Fine particle pollution associated with winter haze threatens the health of over 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations up to 300 μg m-3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models relying on sulfate production mechanisms that require photochemical oxidants, cannot predict these high levels due to the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content leading to faster sulfate production and more severe haze pollution. Reference: Cheng, Y., Zheng, G., Wei, C., Mu, Q., Zheng, B., Wang, Z., Gao, M., Zhang, Q., He, K., Carmichael, G., Pöschl, U., and Su, H.: Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China, Science Advances, 2, 10.1126/sciadv.1601530, 2016.

Standoff detection: classification of biological aerosols using laser induced fluorescence (LIF) technique

NASA Astrophysics Data System (ADS)

Hausmann, Anita; Duschek, Frank; Fischbach, Thomas; Pargmann, Carsten; Aleksejev, Valeri; Poryvkina, Larisa; Sobolev, Innokenti; Babichenko, Sergey; Handke, Jürgen

2014-05-01

The challenges of detecting hazardous biological materials are manifold: Such material has to be discriminated from other substances in various natural surroundings. The detection sensitivity should be extremely high. As living material may reproduce itself, already one single bacterium may represent a high risk. Of course, identification should be quite fast with a low false alarm rate. Up to now, there is no single technique to solve this problem. Point sensors may collect material and identify it, but the problems of fast identification and especially of appropriate positioning of local collectors are sophisticated. On the other hand, laser based standoff detection may instantaneously provide the information of some accidental spillage of material by detecting the generated thin cloud. LIF technique may classify but hardly identify the substance. A solution can be the use of LIF technique in a first step to collect primary data and - if necessary- followed by utilizing these data for an optimized positioning of point sensors. We perform studies on an open air laser test range at distances between 20 and 135 m applying LIF technique to detect and classify aerosols. In order to employ LIF capability, we use a laser source emitting two wavelengths alternatively, 280 and 355 nm, respectively. Moreover, the time dependence of fluorescence spectra is recorded by a gated intensified CCD camera. Signal processing is performed by dedicated software for spectral pattern recognition. The direct comparison of all results leads to a basic classification of the various compounds.

Where and What Is Pristine Marine Aerosol?

NASA Astrophysics Data System (ADS)

Russell, L. M.; Frossard, A. A.; Long, M. S.; Burrows, S. M.; Elliott, S.; Bates, T. S.; Quinn, P.

2014-12-01

The sources and composition of atmospheric marine aerosol particles have been measured by functional group composition (from Fourier transform infrared spectroscopy) to identify the organic composition of the pristine primary marine (ocean-derived) particles as 65% hydroxyl, 21% alkane, 6% amine, and 7% carboxylic acid functional groups [Frossard et al., 2014a,b]. Pristine but non-primary components from photochemical reactions (likely from biogenic marine vapor emissions) add carboxylic acid groups. Non-pristine contributions include shipping effluent in seawater and ship emissions, which add additional alkane groups (up to 70%), and coastal or continental emissions mix in alkane and carboxylic acid groups. The pristine primary marine (ocean-derived) organic aerosol composition is nearly identical to model generated primary marine aerosol particles from bubbled seawater, indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. While the seawater organic functional group composition was nearly invariant across all three ocean regions studied and the ratio of organic carbon to sodium (OC/Na+) in the generated primary marine aerosol particles remained nearly constant over a broad range of chlorophyll-a concentrations, the generated primary marine aerosol particle alkane group fraction increased with chlorophyll-a concentrations. In addition, the generated primary marine aerosol particles have a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater hydroxyl group peak location is closer to that of polysaccharides. References Cited Frossard, Amanda A., Lynn M. Russell, Paola Massoli, Timothy S. Bates, and Patricia K. Quinn, "Side-by-Side Comparison of Four Techniques Explains the Apparent Differences in the Organic Composition of Generated and Ambient Marine Aerosol Particles," Aerosol Science and Technology - Aerosol Research Letter, 48:v-x, doi10.1080/02786826.2013.879979, 2014a. Frossard, A.A., L.M. Russell, M.S. Long, S.M. Burrows, S.M. Elliot, T.S. Bates, and P.K. Quinn, "Sources and Composition of Submicron Organic Mass in Marine Aerosol Particles," Journal of Geophysical Research - Atmospheres, submitted 2014b.

An advanced technique for speciation of organic nitrogen in atmospheric aerosols

NASA Astrophysics Data System (ADS)

Samy, S.; Robinson, J.; Hays, M. D.

2011-12-01

The chemical composition of organic nitrogen (ON) in the environment is a research topic of broad significance. The topic intersects the branches of atmospheric, aquatic, and ecological science; thus, a variety of instrumentation, analytical methods, and data interpretation tools have evolved for determination of ON. Recent studies that focus on atmospheric particulate nitrogen (N) suggest a significant fraction (20-80%) of total N is bound in organic compounds. The sources, bioavailability and transport mechanisms of these N-containing compounds can differ, producing a variety of environmental consequences. Amino acids (AA) are a key class of atmospheric ON compounds that can contribute to secondary organic aerosol (SOA) formation and potentially influence water cycles, air pollutant scavenging, and the radiation balance. AA are water-soluble organic compounds (WSOC) that can significantly alter the acid-base chemistry of aerosols, and may explain the buffering capacity that impacts heterogeneous atmospheric chemistry. The chemical transformations that N-containing organic compounds (including AA) undergo can increase the light-absorbing capacity of atmospheric carbon via formation of 'brown carbon'. Suggested sources of atmospheric AA include: marine surface layer transport from bursting sea bubbles, the suspension of bacteria, fungi, algae, pollen, spores, or biomass burning. Methodology for detection of native (underivatized) amino acids (AA) in atmospheric aerosols has been developed and validated (Samy et al., 2011). This presentation describes the use of LC-MS (Q-TOF) and microwave-assisted gas phase hydrolysis for detection of free and combined amino acids in aerosols collected in a Southeastern U.S. forest environment. Accurate mass detection and the addition of isotopically labeled surrogates prior to sample preparation allows for sensitive quantitation of target AA in a complex aerosol matrix. A total of 16 native AA were detected above the reporting threshold as water-soluble free AA, with an average concentration of 22 ± 9 ng m-3 (N=13). Following microwave-assisted gas phase hydrolysis, the total AA concentration in the forest environment increased significantly (70 ± 35 ng m-3) and additional compounds (methionine, isoleucine) were detected above the reporting threshold. The ability to quantify AA in aerosol samples without derivatization reduces time consuming preparation procedures while providing the advancement of selective mass determination that eliminates potential interferences associated with traditional fluorescence detection. This step forward in precise mass determination with the use of internal standardization, improves the confidence of compound identification. With the increasing focus on WSOC (including ON) characterization in the atmospheric science community, native detection by LC-MS (Q-TOF) will play a central role in determining the most direct approach to quantify an increasing fraction of the co-extracted polar organic compounds. Method application for further characterization of atmospheric ON will be discussed. Reference: Samy, S., Robinson, J., and M.D. Hays. "An Advanced LC-MS (Q-TOF) Technique for the Detection of Amino Acids in Atmospheric Aerosols", Analytical Bioanalytical Chemistry, 2011, DOI: 10.1007/s00216-011-5238-2

Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers

USGS Publications Warehouse

Stubbins, Aron; Hood, Eran; Raymond, Peter A.; Aiken, George R.; Sleighter, Rachel L.; Hernes, Peter J.; Butman, David; Hatcher, Patrick G.; Striegl, Robert G.; Schuster, Paul F.; Abdulla, Hussain A.N.; Vermilyea, Andrew W.; Scott, Durelle T.; Spencer, Robert G.M.

2012-01-01

Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems. This finding runs counter to logical perceptions of age–reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.

Characterization of PM2.5 and identification of transported secondary and biomass burning contribution in Seoul, Korea.

PubMed

Kim, Yumi; Seo, Jihoon; Kim, Jin Young; Lee, Ji Yi; Kim, Hwajin; Kim, Bong Mann

2018-02-01

The chemical and seasonal characteristics of fine particulates in Seoul, Korea, were investigated based on 24-h integrated PM 2.5 measurements made over four 1-month periods in each season between October 2012 and September 2013. The four-season average concentration of PM 2.5 was 37 μg m -3 , and the major chemical components were secondary inorganic aerosol (SIA) species of sulfate, nitrate, and ammonium (49%), followed by organic matter (34%). The mass concentration and most of the chemical components of PM 2.5 showed clear seasonal variation, with a winter-high and summer-low pattern. The winter-to-summer sulfate ratio and the winter organic carbon (OC)-to-elemental carbon (EC) ratio were unusually high compared with those in previous studies. Strong correlations of both the sulfate level and the sulfur oxidation ratio with relative humidity, and between water-soluble OC (WSOC) and SIA in winter, suggest the importance of aqueous phase chemistry for secondary aerosols. A strong correlation between non-sea salt sulfate and Na + levels, a high Cl - /Na + ratio, and an unusual positive correlation between the nitrogen oxidation ratio and temperature during the winter indicate the influence of transported secondary emission sources from upwind urban areas and from China across the Yellow Sea. Despite the absence of local forest fires and the regulation of wood burning, a high levoglucosan concentration and its correlations with OC and WSOC indicate that Seoul was affected by biomass burning sources in the winter. The unusually high water-insoluble OC (WIOC)-to-EC ratio in winter implies additional transported combustion sources of WIOC. The strong correlation between WIOC and levoglucosan suggests the likely influence of transported biomass burning sources on the high WIOC/EC ratio during the winter.

A View of Earth's Aerosol System from Space to Your Office Chair

NASA Technical Reports Server (NTRS)

Colarco, Peter

2008-01-01

Aerosols are tiny particles and droplets suspended in the air. Each day you breathe in about 10 billion of them, about a half a million per breath. They are formed in nature by volcanoes, dust storms, sea spray, and emissions from vegetation. Humans create aerosols and alter their natural sources by burning fossil fuels and modifying land cover. Fires are another important source of aerosols; some are natural, such as wildfires started by lightning strikes, while others are from human-caused burning of vegetation for cooking, heating, and land clearing. Aerosols have complex effects on Earth's climate. In general, they cool the surface by reflecting (scattering) radiation from the sun back into space. Dust and smoke absorb solar radiation and heat the atmosphere where they are concentrated. Aerosols change the properties of clouds. Indeed, it would be very difficult to form clouds in the atmosphere without aerosols to act as 'seeds' for water to condense on. In aerosol polluted environments clouds tend to have smaller droplets than clouds formed in cleaner environments; these polluted clouds appear brighter from space because they reflect more sunlight, and they may persist longer and not rain as intensely. Aerosols also affect local air quality and visibility. Data collected by NASA satellites over the past decade have provided an unprecedented view of Earth's aerosol distribution and dramatically increased our understanding of where aerosols come from and just how far they travel in the atmosphere. In this talk I will discuss observations of aerosols from space and how they inform numerical transport models attempting to simulate the global aerosol system.

Comparative Study of Aerosol and Cloud Detected by CALIPSO and OMI

NASA Technical Reports Server (NTRS)

Chen, Zhong; Torres, Omar; McCormick, M. Patrick; Smith, William; Ahn, Changwoo

2012-01-01

The Ozone Monitoring Instrument (OMI) on the Aura Satellite detects the presence of desert dust and smoke particles (also known as aerosols) in terms of a parameter known as the UV Aerosol Index (UV AI). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission measures the vertical distribution of aerosols and clouds. Aerosols and clouds play important roles in the atmosphere and climate system. Accurately detecting their presence, altitude, and properties using satellite radiance measurements is a very important task. This paper presents a comparative analysis of the CALIPSO Version 2 Vertical Feature Mask (VFM) product with the (OMI) UV Aerosol Index (UV AI) and reflectivity datasets for a full year of 2007. The comparison is done at regional and global scales. Based on CALIPSO arid OMI observations, the vertical and horizontal extent of clouds and aerosols are determined and the effects of aerosol type selection, load, cloud fraction on aerosol identification are discussed. It was found that the spatial-temporal correlation found between CALIPSO and OMI observations, is strongly dependent on aerosol types and cloud contamination. CALIPSO is more sensitivity to cloud and often misidentifies desert dust aerosols as cloud, while some small scale aerosol layers as well as some pollution aerosols are unidentified by OMI UV AI. Large differences in aerosol distribution patterns between CALIPSO and OMI are observed, especially for the smoke and pollution aerosol dominated areas. In addition, the results found a significant correlation between CALIPSO lidar 1064 nm backscatter and the OMI UV AI over the study regions.

Implementation of warm-cloud processes in a source-oriented WRF/Chem model to study the effect of aerosol mixing state on fog formation in the Central Valley of California

NASA Astrophysics Data System (ADS)

Lee, Hsiang-He; Chen, Shu-Hua; Kleeman, Michael J.; Zhang, Hongliang; DeNero, Steven P.; Joe, David K.

2016-07-01

The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include warm cloud processes and was applied to investigate how aerosol mixing states influence fog formation and optical properties in the atmosphere. SOWC tracks a 6-D chemical variable (X, Z, Y, size bins, source types, species) through an explicit simulation of atmospheric chemistry and physics. A source-oriented cloud condensation nuclei module was implemented into the SOWC model to simulate warm clouds using the modified two-moment Purdue Lin microphysics scheme. The Goddard shortwave and long-wave radiation schemes were modified to interact with source-oriented aerosols and cloud droplets so that aerosol direct and indirect effects could be studied. The enhanced SOWC model was applied to study a fog event that occurred on 17 January 2011, in the Central Valley of California. Tule fog occurred because an atmospheric river effectively advected high moisture into the Central Valley and nighttime drainage flow brought cold air from mountains into the valley. The SOWC model produced reasonable liquid water path, spatial distribution and duration of fog events. The inclusion of aerosol-radiation interaction only slightly modified simulation results since cloud optical thickness dominated the radiation budget in fog events. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into cloud condensation nuclei (CCN) at a supersaturation of 0.5 % in the Central Valley decreased from 94 % in the internal mixture model to 80 % in the source-oriented model. This increased surface energy flux by 3-5 W m-2 and surface temperature by as much as 0.25 K in the daytime.

Global Distributions of Mineral Dust Properties from SeaWiFS and MODIS: From Sources to Sinks

NASA Technical Reports Server (NTRS)

Hsu, N. Christina; Bettenhausen, C.; Sayer, A.

2011-01-01

The impact of natural and anthropogenic sources of mineral dust has gained increasing attention from scientific communities in recent years. Indeed, these airborne dust particles, once lifted over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the oceans resulting in important biogeochemical impacts on the ecosystem. Due to the relatively short lifetime (a few hours to about a week), the distributions of these mineral dust particles vary extensively in both space and time. Consequently, satellite observations are needed over both source and sink regions for continuous temporal and spatial sampling of aerosol properties. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented satellite data records, studies of the radiative and biogeochemical effects due to dust aerosols are now possible. In this study, we will show the comparisons of satellite retrieved aerosol optical thickness using Deep Blue algorithm with data from AERONET sunphotometers over desert and semi-desert regions as well as vegetated areas. Our results indicate reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from Sea WiFS and MODIS-like instruments. The multiyear satellite measurements since 1997 from Sea WiFS will be compared with those retrieved from MODIS and MISR, and will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the dust outbreaks over the entire globe. Finally, the trends observed over the last decade based upon the SeaWiFS time series in the amounts of tropospheric aerosols due to natural and anthropogenic sources (such as changes in the frequency of dust storms) will be discussed.

Seasonal variability in size-segregated airborne bacterial particles and their characterization at different source-sites.

PubMed

Agarwal, Smita

2017-05-01

Size-segregated aerosol samplings were carried out near the potential sources of airborne biological particles i.e. at a landfill site, an agricultural field and a road side restaurant-cluster site in winter, spring and summer seasons during 2013-2015 in New Delhi. The culturable airborne bacterial (CAB) concentrations showed significant seasonal variation from higher to moderate in spring and winter seasons and lowest during summer. Highest CAB concentrations were observed at the Okhla landfill site followed by restaurant-cluster area and agriculture site. The CAB particles showed bimodal size distribution, abundant in the size ranges of 1.1-2.1, 2.1-3.3 and 4.7-5.8 μm. However, substantial concentrations were also observed in the size bins of 0.43-0.65 and <0.43 μm, which are important for cloud condensation nuclei (CCN) activity of aerosols in addition to their adverse health effects. In spring, bacterial particles were also maximized in size ranges between 5.8 and >9.0 μm. Fine mode proportions of CAB were found to be higher in winter than other two seasons. Bacterial identification was done by 16s rDNA sequencing, and most abundant identified strains were Bacillus cereus (16%), Bacillus licheniformis (11%), Bacillus thuringiensis (9%), Micrococcus sp. (7%) and Acinetobacter sp. (9%).

Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinman L. I.; Daum, P. H.; Lee, Y.-N.

2012-01-04

During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O{sub 3} and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate. Pollutant layers in the free troposphere (FT) can be a result of emissionsmore » to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 C with dry air descending from the upper atmospheric and moist air having a boundary layer (BL) contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (D{sub p} > 100 nm) gives a linear relation up to a number concentration of {approx}150 cm{sup -3}, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that {approx}25 % of aerosol with D{sub p} > 100 nm are interstitial (not activated). A direct comparison of pre-cloud and in-cloud aerosol yields a higher estimate. Artifacts in the measurement of interstitial aerosol due to droplet shatter and evaporation are discussed. Within each of 102 constant altitude cloud transects, CDNC and interstitial aerosol were anti-correlated. An examination of one cloud as a case study shows that the interstitial aerosol appears to have a background, upon which is superimposed a high frequency signal that contains the anti-correlation. The anti-correlation is a possible source of information on particle activation or evaporation.« less

AEROSOL CHEMICAL CHARACTERISTION ON BOARD THE DOE G1 AIRCRAFT USING A PARTICLE INTO LIQUID SAMPLER DURING THE TEXAQS 2000 EXPERIMENT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

LEE,Y.N.; SONG,Z.; LIU,Y.

2001-01-13

Knowledge of aerosol chemical composition is key to understanding a number of properties of ambient aerosol particles including sources, size/number distribution, chemical evolution, optical properties and human health effects. Although filter based techniques have been widely used to determine aerosol chemical constituents, they generally cannot provide sufficiently fast time resolution needed to investigate sources and chemical evolution that effect aerosol chemical, size and number changes. In order to gain an ability to describe and predict the life cycles of ambient aerosols as a basis for ambient air quality control, fast and sensitive determination of the aerosol chemical composition must bemore » made available. To help to achieve this goal, we deployed a newly developed technique, referred to as PILS (particle-into-liquid-sampler), on the DOE G1 aircraft during the 2000 Texas Air Quality Study (TexAQS 2000) to characterize the major ionic species of aerosol particles with aerodynamic size smaller than 2.5 {micro}m (PM 2.5). The results obtained are examined in the context of other simultaneously collected data for insights into the measurement capability of the PILS system.« less

Implementing Marine Organic Aerosols Into the GEOS-Chem Model

NASA Technical Reports Server (NTRS)

Johnson, Matthew S.

2015-01-01

Marine-sourced organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large under-prediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

Characterization of emissions from South Asian biofuels and application to source apportionment of carbonaceous aerosol in the Himalayas

NASA Astrophysics Data System (ADS)

Stone, Elizabeth A.; Schauer, James J.; Pradhan, Bidya Banmali; Dangol, Pradeep Man; Habib, Gazala; Venkataraman, Chandra; Ramanathan, V.

2010-03-01

This study focuses on improving source apportionment of carbonaceous aerosol in South Asia and consists of three parts: (1) development of novel molecular marker-based profiles for real-world biofuel combustion, (2) application of these profiles to a year-long data set, and (3) evaluation of profiles by an in-depth sensitivity analysis. Emissions profiles for biomass fuels were developed through source testing of a residential stove commonly used in South Asia. Wood fuels were combusted at high and low rates, which corresponded to source profiles high in organic carbon (OC) or high in elemental carbon (EC), respectively. Crop wastes common to the region, including rice straw, mustard stalk, jute stalk, soybean stalk, and animal residue burnings, were also characterized. Biofuel profiles were used in a source apportionment study of OC and EC in Godavari, Nepal. This site is located in the foothills of the Himalayas and was selected for its well-mixed and regionally impacted air masses. At Godavari, daily samples of fine particulate matter (PM2.5) were collected throughout the year of 2006, and the annual trends in particulate mass, OC, and EC followed the occurrence of a regional haze in South Asia. Maximum concentrations occurred during the dry winter season and minimum concentrations occurred during the summer monsoon season. Specific organic compounds unique to aerosol sources, molecular markers, were measured in monthly composite samples. These markers implicated motor vehicles, coal combustion, biomass burning, cow dung burning, vegetative detritus, and secondary organic aerosol as sources of carbonaceous aerosol. A molecular marker-based chemical mass balance (CMB) model provided a quantitative assessment of primary source contributions to carbonaceous aerosol. The new profiles were compared to widely used biomass burning profiles from the literature in a sensitivity analysis. This analysis indicated a high degree of stability in estimates of source contributions to OC when different biomass profiles were used. The majority of OC was unapportioned to primary sources and was estimated to be of secondary origin, while biomass combustion was the next-largest source of OC. The CMB apportionment of EC to primary sources was unstable due to the diversity of biomass burning conditions in the region. The model results suggested that biomass burning and fossil fuel were important contributors to EC, but could not reconcile their relative contributions.

Characterization of a large biogenic secondary organic aerosol event from eastern Canadian forests

NASA Astrophysics Data System (ADS)

Slowik, J. G.; Stroud, C.; Bottenheim, J. W.; Brickell, P. C.; Chang, R. Y.-W.; Liggio, J.; Makar, P. A.; Martin, R. V.; Moran, M. D.; Shantz, N. C.; Sjostedt, S. J.; van Donkelaar, A.; Vlasenko, A.; Wiebe, H. A.; Xia, A. G.; Zhang, J.; Leaitch, W. R.; Abbatt, J. P. D.

2010-03-01

Measurements of aerosol composition, volatile organic compounds, and CO are used to determine biogenic secondary organic aerosol (SOA) concentrations at a rural site 70 km north of Toronto. These biogenic SOA levels are many times higher than past observations and occur during a period of increasing temperatures and outflow from Northern Ontario and Quebec forests in early summer. A regional chemical transport model approximately predicts the event timing and accurately predicts the aerosol loading, identifying the precursors as monoterpene emissions from the coniferous forest. The agreement between the measured and modeled biogenic aerosol concentrations contrasts with model underpredictions for polluted regions. Correlations of the oxygenated organic aerosol mass with tracers such as CO support a secondary aerosol source and distinguish biogenic, pollution, and biomass burning periods during the field campaign. Using the Master Chemical Mechanism, it is shown that the levels of CO observed during the biogenic event are consistent with a photochemical source arising from monoterpene oxidation. The biogenic aerosol mass correlates with satellite measurements of regional aerosol optical depth, indicating that the event extends across the eastern Canadian forest. This regional event correlates with increased temperatures, indicating that temperature-dependent forest emissions can significantly affect climate through enhanced direct optical scattering and higher cloud condensation nuclei numbers.

Volatility Properties of Internally- and Externally-Mixed Ambient Aerosols at an Anthropogenically-influenced Forest Site in Southeastern USA

NASA Astrophysics Data System (ADS)

Khlystov, A.; Subramanian, R.

2015-12-01

Secondary organic aerosol (SOA) from biogenic sources has a significant contribution to ambient aerosol loadings in Southeastern USA and thus contributes to adverse health effects of air pollution and influences regional and global climate. Volatility properties of biogenic SOA determine its concentration, reactivity, and lifetime, but are still largely unknown. As part of a larger study to assess the effect of biogenic SOA on aerosol optical properties, a set of instruments, including scanning mobility sizers (SMPS), single particle soot photometer (SP2), and a thermodenuder, was deployed during June 2015 at a Duke Forest site near Chapel Hill, NC. The site is characterized by a significant contribution of both biogenic and urban (mostly traffic) sources. Measurements of changes in aerosol volume and optical size upon heating in the thermodenuder at different temperatures are used to derive volatility properties of the ambient aerosol. A limited set of experiments was carried out using the tandem differential mobility analysis (TDMA) approach to investigate whether the ambient aerosol at the Duke Forest site is internally mixed with respect to its volatility properties. In this presentation we will discuss equilibrium and kinetic aspects of aerosol volatility observed during this study and implications of external vs. internal mixing for derivation of bulk volatility properties of ambient aerosol.

Classification of Aerosol Retrievals from Spaceborne Polarimetry Using a Multiparameter Algorithm

NASA Technical Reports Server (NTRS)

Russell, Philip B.; Kacenelenbogen, Meloe; Livingston, John M.; Hasekamp, Otto P.; Burton, Sharon P.; Schuster, Gregory L.; Johnson, Matthew S.; Knobelspiesse, Kirk D.; Redemann, Jens; Ramachandran, S.;

Integrating multiple remote sensing and surface measurements with models, to quantify and constrain the past decade's total 4D aerosol source profile and impacts

NASA Astrophysics Data System (ADS)

Cohen, J. B.; Lan, R.; Lin, C.; Ng, D. H. L.; Lim, A.

2017-12-01

A multi-instrument, inverse modeling approach, is employed to identify and quantify large-scale global biomass urban aerosol emissions profiles. The approach uses MISR, MODIS, OMI and MOPITT, with data from 2006 to 2016, to generate spatial and temporal loads, as well as some information about composition. The method is able to identify regions impacted by stable urban sources, changing urban sources, intense fires, and linear-combinations. Subsequent quantification is a unified field, leading to a less biased profile, with the result not requiring arbitrary scaling to match long-term means. Additionally, the result reasonably reproduces inter and intra annual variation. Both meso-scale (WRF-CHEM) and global (MIT-AERO, multi-mode, multi-mixing state aerosol model) models of aerosol transport, chemistry, and physics, are used to generate resulting 4D aerosol fields. Comparisons with CALIOP, AERONET, and surface chemical and aerosol networks, provide unbiased confirmation, while column and vertical loadings provide additional feedback. There are three significant results. First, there is a reduction in sources over existing urban areas in East Asia. Second, there is an increase in sources over new urban areas in South, South East, and East Asia. Third, that there is an increase in fire sources in South and South East Asia. There are other initial findings relevant to the global tropics, which have not been as deeply investigated. The results improve the model match with both the mean and variation, which is essential if we hope to understand seasonal extremes. The results also quantify impacts of both local and long-range sources. This is of extreme urgency, in particular in developing nations, where there are considerable contributions from long-range or otherwise unknown sources, that impact hundreds of millions of people throughout Asia. It is hoped that the approach provided here can help us to make critical decisions about total sources, as well as point out the many missing scientific and analytical issues still required to address.

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and Source of Titan's Aerosols?

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Hartle, R. E.; Cooper, J. F.; Johnson, R. E.; Coates, A.; dePater, imke; Strom, Daphne; Simoes, F.; Steele, A.; Robb, F.

2007-01-01

With the recent discovery of heavy ions, positive and negative, by the Cassini Plasma Spectrometer (CAPS) instrument in Titan's ionosphere, it reveals new possibilities for aerosol formation at Titan and the introduction of free oxygen to the aerosol chemistry from Saturn's magnetosphere with Enceladus as the primary oxygen source. One can estimate whether the heavy ions in the ionosphere are of sufficient number to account for all the aerosols, under what conditions are favorable for heavy ion formation and how they are introduced as seed particles deeper in Titan's atmosphere where the aerosols form and eventually find themselves on Titan's surface where unknown chemical processes can take place. Finally, what are the possibilities with regard to their chemistry on the surface with some free oxygen present in their seed particles?

Secondary organic aerosol formation from fossil fuel sources contribute majority of summertime organic mass at Bakersfield

EPA Science Inventory

Secondary organic aerosols (SOA), known to form in the atmosphere from oxidation of volatile organic compounds (VOCs) emitted by anthropogenic and biogenic sources, are a poorly understood but substantial component of atmospheric particles. In this study, we examined the chemic...

Natural and Anthropogenically Perturbed Biogenic Aerosol over Tropical South East Asia

NASA Astrophysics Data System (ADS)

Coe, H.; Robinson, N.; Allan, J. D.; Hewitt, C. N.

2014-12-01

Tropical forested regions are of interest as sources of atmospheric aerosol since they cover very large areas of the tropics and are a source of a large amount of volatile organic compounds which act as precursors for particle formation. Natural forest regions offer the potential to study the background state of the tropics and so potentially gain some insight into the pre-perturbed atmosphere. However, over the last decade in South East Asia, a considerable fraction of the native tropical deciduous forest has been deforested and replanted with palm oil plantations. This changes the range of volatile organic compounds that are emitted and act as sources of secondary organic aerosol. A suite of intensive ground and airborne measurements were made over both tropical forest and oil palm plantations in Sabah, Malaysia as part of the "Oxidant and Particle Photochemical Processes above a South East Asian tropical rainforest (OP3) during 2008. These data will be used together with recent improvements in our understanding of aerosol formation from biogenic compounds to discuss aerosol formation in tropical regions and the influence of human influence through widespread palm oil agriculture.

Influences of upwind emission sources and atmospheric processing on aerosol chemistry and properties at a rural location in the Northeastern U.S.: URBAN INFLUENCE ON RURAL AEROSOL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Shan; Collier, Sonya; Xu, Jianzhong

2016-05-19

Continuous real-time measurements of atmospheric aerosol with an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) coupled with a fast temperature-stepping thermodenuder were carried out in summer 2011 at Brookhaven National Laboratory (BNL, 40.871°N, 72.89°W) during the DOE Aerosol Life Cycle Intensive Operational Period (ALC-IOP) campaign.

Influence of Atmospheric Processes on the Solubility and Composition of Iron in Saharan Dust

NASA Astrophysics Data System (ADS)

Ingall, E. D.; Longo, A.; Feng, Y.; Lai, B.; Landing, W. M.; Shelley, R.; Nenes, A.; Mihalopoulos, N.; Violaki, K.

2016-12-01

Iron is a key micronutrient that is vital for all organisms. The supply of bioavailable, soluble iron controls primary productivity in approximately 30% of the world's oceans. The significant contribution of atmospheric aerosols to the bioavailable iron budget in vast ocean regions, underscores the need to understand the controls and transformations of aerosol iron solubility during atmospheric transport. The Sahara Desert contains the largest and most active sources of aerosol dust globally and can be a key source of nutrients to the Mediterranean Sea, much of the North Atlantic Ocean, and even as far as the Gulf of Mexico. Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated aerosol iron in Mediterranean samples. In Atlantic samples, iron(II & III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. Atmospheric processing, including acidic reactions and photo-reduction, likely influence the form of iron minerals and the oxidation state in Saharan dust aerosols and contribute to increases in aerosol iron solubility. Overall, these findings suggest that a combination of factors affects aerosol iron solubility during long-distance atmospheric transport and emphasize the need to consider reductive mechanisms as well as proton-induced solubilization of aerosol iron in modeling studies.

Signatures of Biomass Burning Aerosols in the Plume of a Saltmarsh Wildfire in South Texas.

PubMed

Myers-Pigg, Allison N; Griffin, Robert J; Louchouarn, Patrick; Norwood, Matthew J; Sterne, Amanda; Cevik, Basak Karakurt

2016-09-06

The most conventional and abundant tracers of biomass combustion in aerosol particles include potassium and biomarkers derived from thermally altered cellulose/hemicellulose (anhydrosugars) and lignin (methoxyphenols). However, little is known of the role biomass combustion plays as a particulate source of major plant polymers to the atmosphere. Here, concentrations of solvent-extractable anhydrosugars and methoxyphenols are compared to the yields of polymeric lignin oxidation products (LOPs) during a smoke plume event in Houston, Texas. Downwind aerosol samples (PM2.5) were collected surrounding a two-day wildfire in the McFaddin National Wildlife Refuge, 125 km southeast of Houston, which was 12-16 h directly downwind during the peak of the burn. Concentrations of all organic markers, potassium, and calcium increased by a factor of 2-13 within 1-2 days of the start of the fire and dropped to prefire levels 3 days after the peak event. Source signatures of anhydrosugars and methoxyphenols during the peak of the plume were identical to those of grass charcoals collected from the site, confirming the use of charcoals as end-members for source input reconstruction during atmospheric transport. An enrichment factor of 20 in the anhydrosugar to methoxyphenol ratio of aerosols versus charcoals can be explained partially by differences in degradation rate constants between the biomarker groups. LOPs comprised 73-91% of all lignin material in the aerosols, pointing to fires as major sources of primary biogenic aerosol particles in which lignin phenols occur predominantly in polymeric form.

Aerosol-halogen interaction: Change of physico-chemical properties of SOA by naturally released halogen species

NASA Astrophysics Data System (ADS)

Ofner, J.; Balzer, N.; Buxmann, J.; Grothe, H.; Krüger, H.; Platt, U.; Schmitt-Kopplin, P.; Zetzsch, C.

2011-12-01

Reactive halogen species are released by various sources like photo-activated sea-salt aerosol or salt pans and salt lakes. These heterogeneous release mechanisms have been overlooked so far, although their potential of interaction with organic aerosols like Secondary Organic Aerosol (SOA), Biomass Burning Organic Aerosol (BBOA) or Atmospheric Humic LIke Substances (HULIS) is completely unknown. Such reactions can constitute sources of gaseous organo-halogen compounds or halogenated organic particles in the atmospheric boundary layer. To study the interaction of organic aerosols with reactive halogen species (RHS), SOA was produced from α-pinene, catechol and guaiacol using an aerosol smog-chamber. The model SOAs were characterized in detail using a variety of physico-chemical methods (Ofner et al., 2011). Those aerosols were exposed to molecular halogens in the presence of UV/VIS irradiation and to halogens, released from simulated natural halogen sources like salt pans, in order to study the complex aerosol-halogen interaction. The heterogeneous reaction of RHS with those model aerosols leads to different gaseous species like CO2, CO and small reactive/toxic molecules like phosgene (COCl2). Hydrogen containing groups on the aerosol particles are destroyed to form HCl or HBr, and a significant formation of C-Br bonds could be verified in the particle phase. Carbonyl containing functional groups of the aerosol are strongly affected by the halogenation process. While changes of functional groups and gaseous species were visible using FTIR spectroscopy, optical properties were studied using Diffuse Reflectance UV/VIS spectroscopy. Overall, the optical properties of the processed organic aerosols are significantly changed. While chlorine causes a "bleaching" of the aerosol particles, bromine shifts the maximum of UV/VIS absorption to the red end of the UV/VIS spectrum. Further physico-chemical changes were recognized according to the aerosol size-distributions or the averaged carbon oxidation state (OSc). The heterogeneous reaction of SOA with molecular halogens released from the simulated salt-pan at different simulated environmental conditions leads to changes of several physico-chemical features of the aerosol. However, the halogen release mechanisms are also affected by the presence of organic aerosols. One order of magnitude less BrO was detected by an active Differential Optical Absorption Spectroscopy (DOAS) instrument in the presence of SOA compared to experiments without SOA. This work was supported by the German Research Foundation within the HALOPROC project. Ofner, J., Krüger, H.-U., Grothe, H., Schmitt-Kopplin, P., Whitmore, K., and Zetzsch, C. (2011), Atmos. Chem. Phys., 11, 1-15.

Performance Characteristics of Compact Mobile LIFS (Laser-Induced Fluorescence Spectrum) Lidar

NASA Astrophysics Data System (ADS)

Tomida, Takayuki; Nishizawa, Naoto; Sakurai, Kosuke; Suganumata, Hikaru; Tsukada, Shodai; Song, Sung-Moo; Park, Ho-Dong; Saito, Yasunori

2016-06-01

We developed a compact but versatile laser-induced fluorescence spectrum (LIFS) lidar that has potential use for material or aerosol identification outside experimental rooms. The compactness and mobility of the LIFS lidar means observations can be more freely conducted at any place and any time. Its performance characteristics were validated by threedimensional fluorescence imaging of targets and remote detection of quasi bio/organic aerosols.

IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC AND/OR HYDROXYL GROUPS. 1. METHOD DEVELOPMENT

EPA Science Inventory

In this study, a new analytical technique was developed for the identification and quantification of multi-functional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) ...

Eddy covariance measurements of sea spray particles over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Norris, S. J.; Brooks, I. M.; de Leeuw, G.; Smith, M. H.; Moerman, M.; Lingard, J. J. N.

2008-02-01

Most estimates of sea spray aerosol source functions have used indirect means to infer the rate of production as a function of wind speed. Only recently has the technology become available to make high frequency measurements of aerosol spectra suitable for direct eddy correlation determination of the sea spray particle flux. This was accomplished in this study by combining a newly developed fast aerosol particle counter with an ultrasonic anemometer which allowed for eddy covariance measurements of size-segregated particle fluxes. The aerosol instrument is the Compact Lightweight Aerosol Spectrometer Probe (CLASP) - capable of measuring 8-channel size spectra for mean radii between 0.15 and 3.5 µm at 10 Hz. The first successful measurements were made during the Waves, Air Sea Fluxes, Aerosol and Bubbles (WASFAB) field campaign in October 2005 in Duck (NC, USA). The method and initial results are presented and comparisons are made with recent sea spray source functions from the literature.

Stratospheric Aerosol and Gas Experiment (SAGE 3)

NASA Technical Reports Server (NTRS)

Mccormick, M. P.

1993-01-01

The proposed SAGE III instrument would be the principal source of data for global changes of stratospheric aerosols, stratospheric water vapor, and ozone profiles, and a contributing source of data for upper tropospheric water vapor, aerosols, and clouds. The ability to obtain such data has been demonstrated by the predecessor instrument, SAGE II, but SAGE III will be substantially more capable, as discussed below. The capabilities for monitoring the profiles of atmospheric constituents have been verified in detail, including ground-based validations, for aerosol, ozone, and water vapor. Indeed, because of its self-calibrating characteristics, SAGE II was an essential component of the international ozone trend assessments, and SAGE II is now proving to be invaluable in tracking the aerosols from Mt. Pinatubo. Although SAGE profiles generally terminate at the height of the first tropospheric cloud layer, it has been found that the measurements extend down to 3 km altitude more than 40 percent of the time at most latitudes. Thus, useful information can also be obtained on upper tropospheric aerosols, water vapor, and ozone.

Monsoonal variations in atmospheric surfactants at different coastal areas of the Malaysian Peninsula.

PubMed

Jaafar, Shoffian Amin; Latif, Mohd Talib; Razak, Intan Suraya; Shaharudin, Muhammad Zulhilmi; Khan, Md Firoz; Wahid, Nurul Bahiyah Abd; Suratman, Suhaimi

2016-08-15

This study determined the effect of monsoonal changes on the composition of atmospheric surfactants in coastal areas. The composition of anions (SO4(2-), NO3(-), Cl(-), F(-)) and the major elements (Ca, K, Mg, Na) in aerosols were used to determine the possible sources of surfactants. Surfactant compositions were determined using a colorimetric method as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS). The anion and major element compositions of the aerosol samples were determined by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results indicated that the concentrations of surfactant in aerosols were dominated by MBAS (34-326pmolm(-3)). Monsoonal changes were found to significantly affect the concentration of surfactants. Using principal component analysis-multiple linear regressions (PCA-MLR), major possible sources for surfactants in the aerosols were motor vehicle emissions, secondary aerosol and the combustion of biomass along with marine aerosol. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Global Modeling Study on Carbonaceous Aerosol Microphysical Characteristics and Radiative Effects

NASA Technical Reports Server (NTRS)

Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

2010-01-01

Recently, attention has been drawn towards black carbon aerosols as a short-term climate warming mitigation candidate. However the global and regional impacts of the direct, indirect and semi-direct aerosol effects are highly uncertain, due to the complex nature of aerosol evolution and the way that mixed, aged aerosols interact with clouds and radiation. A detailed aerosol microphysical scheme, MATRIX, embedded within the GISS climate model is used in this study to present a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative effects. Our best estimate for net direct and indirect aerosol radiative flux change between 1750 and 2000 is -0.56 W/m2. However, the direct and indirect aerosol effects are quite sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative flux change can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Absorption of black carbon aerosols is amplified by sulfate and nitrate coatings and, even more strongly, by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative fluxeswhen sources with a large proportion of black carbon, such as diesel, are reduced; however reducing sources with a larger organic carbon component as well, such as bio-fuels, does not necessarily lead to a reduction in positive radiative flux.

Aerosol physicochemical properties in relation to meteorology: Case studies in urban, marine, and arid settings

NASA Astrophysics Data System (ADS)

Wonaschuetz, Anna

Atmospheric aerosols are a highly relevant component of the climate system affecting atmospheric radiative transfer and the hydrological cycle. As opposed to other key atmospheric constituents with climatic relevance, atmospheric aerosol particles are highly heterogeneous in time and space with respect to their size, concentration, chemical composition and physical properties. Many aspects of their life cycle are not understood, making them difficult to represent in climate models and hard to control as a pollutant. Aerosol-cloud interactions in particular are infamous as a major source of uncertainty in future climate predictions. Field measurements are an important source of information for the modeling community and can lead to a better understanding of chemical and microphysical processes. In this study, field data from urban, marine, and arid settings are analyzed and the impact of meteorological conditions on the evolution of aerosol particles while in the atmosphere is investigated. Particular attention is given to organic aerosols, which are a poorly understood component of atmospheric aerosols. Local wind characteristics, solar radiation, relative humidity and the presence or absence of clouds and fog are found to be crucial factors in the transport and chemical evolution of aerosol particles. Organic aerosols in particular are found to be heavily impacted by processes in the liquid phase (cloud droplets and aerosol water). The reported measurements serve to improve the process-level understanding of aerosol evolution in different environments and to inform the modeling community by providing realistic values for input parameters and validation of model calculations.

A global modeling study on carbonaceous aerosol microphysical characteristics and radiative effects

NASA Astrophysics Data System (ADS)

Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

2010-08-01

Recently, attention has been drawn towards black carbon aerosols as a short-term climate warming mitigation candidate. However the global and regional impacts of the direct, indirect and semi-direct aerosol effects are highly uncertain, due to the complex nature of aerosol evolution and the way that mixed, aged aerosols interact with clouds and radiation. A detailed aerosol microphysical scheme, MATRIX, embedded within the GISS climate model is used in this study to present a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative effects. Our best estimate for net direct and indirect aerosol radiative flux change between 1750 and 2000 is -0.56 W/m2. However, the direct and indirect aerosol effects are quite sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative flux change can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Absorption of black carbon aerosols is amplified by sulfate and nitrate coatings and, even more strongly, by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative fluxeswhen sources with a large proportion of black carbon, such as diesel, are reduced; however reducing sources with a larger organic carbon component as well, such as bio-fuels, does not necessarily lead to a reduction in positive radiative flux.

Current Status of Aerosol Retrievals from TOMS

NASA Technical Reports Server (NTRS)

Torres, O.; Herman, J. R.; Bhartia, P. K.; Ginoux, P.

1999-01-01

Properties of atmospheric aerosols over all land and water surfaces are retrieved from TOMS measurements of backscattered radiances. The TOMS technique, uses observations at two wavelengths. In the near ultraviolet (330-380 nm) range, where the effects of gaseous absorption are negligible. The retrieved properties are optical depth and a measure of aerosol absorptivity, generally expressed as single scattering albedo. The main sources of error of the TOMS aerosol products are sub-pixel cloud contamination and uncertainty on the height above the surface of UV-absorbing aerosol layers. The first error source is related to the large footprint (50 x 50 km at nadir) of the sensor, and the lack of detection capability of sub-pixel size clouds. The uncertainty associated with the height of the absorbing aerosol layers, on the other hand, is related to the pressure dependence of the molecular scattering process, which is the basis of the near-UV method of absorbing aerosol detection. The detection of non-absorbing aerosols is not sensitive to aerosol layer height. We will report on the ongoing work to overcome both of these difficulties. Coincident measurements of high spatial resolution thermal infrared radiances are used to address the cloud contamination issue. Mostly clear scenes for aerosol retrieval are selected by examining the spatial homogeneity of the IR radiance measurements within a TOMS pixel. The approach to reduce the uncertainty associated with the height of the aerosol layer by making use of a chemical transport model will also be discussed.

Development of a Photo-fragmentation Laser Induced Fluorescence Instrument for the Measurement of Nitrous Acid

NASA Astrophysics Data System (ADS)

Boustead, G.; Blitz, M. A.; Heard, D. E.; Ingham, T.; Stone, D. J.; Whalley, L.

2017-12-01

The hydroxyl radical (OH) is the primary oxidant in the atmosphere with its concentration determining the lifetime of many species and its reaction with volatile organic compounds (VOCs) leading to the production of secondary organic aerosols (SOA) and tropospheric ozone. Nitrous acid (HONO) is an important source of OH as it builds up overnight and is photolysed to form OH in the morning. HONO is also present during the day, with several hundred pptv observed in urban environments. Atmospheric models currently under predict the concentration of HONO observed during the day, indicating a missing source. Heterogeneous reactions on ground and aerosol surfaces are now recognised as potentially important HONO sources. To identify and quantify some of these missing heterogeneous sources, a photo-fragmentation laser induced fluorescence (PF-LIF) instrument has been developed to provide a fast and sensitive measurement of HONO. The PF-LIF instrument detects the OH fragment at 308 nm after the photolysis of HONO at 355 nm. This instrument is coupled to an aerosol flow tube and can be used to measure HONO production from aerosols under illuminated conditions. We will present an overview of the instrument and its development as well as preliminary results including the production of HONO from illuminated TiO2 aerosols.

Chemical composition, sources and secondary processes of aerosols in Baoji city of northwest China

NASA Astrophysics Data System (ADS)

Wang, Y. C.; Huang, R.-J.; Ni, H. Y.; Chen, Y.; Wang, Q. Y.; Li, G. H.; Tie, X. X.; Shen, Z. X.; Huang, Y.; Liu, S. X.; Dong, W. M.; Xue, P.; Fröhlich, R.; Canonaco, F.; Elser, M.; Daellenbach, K. R.; Bozzetti, C.; El Haddad, I.; Prévôt, A. S. H.; Canagaratna, M. R.; Worsnop, D. R.; Cao, J. J.

2017-06-01

Particulate air pollution is a severe environmental problem in China, affecting visibility, air quality, climate and human health. However, previous studies focus mainly on large cities such as Beijing, Shanghai, and Guangzhou. In this study, an Aerodyne Aerosol Chemical Speciation Monitor was deployed in Baoji, a middle size inland city in northwest China from 26 February to 27 March 2014. The non-refractory submicron aerosol (NR-PM1) was dominated by organics (55%), followed by sulfate (16%), nitrate (15%), ammonium (11%) and chloride (3%). A source apportionment of the organic aerosol (OA) was performed with the Sofi (Source Finder) interface of ME-2 (Multilinear Engine), and six main sources/factors were identified and classified as hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), coal combustion OA (CCOA), less oxidized oxygenated OA (LO-OOA) and more oxidized oxygenated OA (MO-OOA), which contributed 20%, 14%, 13%, 9%, 23% and 21% of total OA, respectively. The contribution of secondary components shows increasing trends from clean days to polluted days, indicating the importance of secondary aerosol formation processes in driving particulate air pollution. The formation of LO-OOA and MO-OOA is mainly driven by photochemical reactions, but significantly influenced by aqueous-phase chemistry during periods of low atmospheric oxidative capacity.

Characterization of Optical Properties of Desert Dust and Other Aerosols Using Postive Matrix Factorization

NASA Astrophysics Data System (ADS)

Lihavainen, H.; Alghamdi, M.; Hyvärinen, A.; Hussein, T.; Neitola, K.; Khoder, M.; Abdelmaksoud, A. S.; Al-Jeelani, H.; Shabbaj, I. I.; Almehmadi, F. M.

2017-12-01

To derive the comprehensive aerosol in situ characteristics at a rural background area in Saudi Arabia, an aerosol measurements station was established to Hada Al Sham, 60 km east from the Red Sea and the city of Jeddah. The present sturdy describes the observational data from February 2013 to February 2015 of scattering and absorption coefficients, Ångström exponents and single scattering albedo over the measurement period. As expected, the scattering coefficient was dominated by large desert dust particles with low Ångström scattering exponent. Especially from February to June the Ångström scattering exponent was clearly lower and scattering coefficients higher than total averages because of the dust outbreak season. Aerosol optical properties had clear diurnal cycle. The lowest scattering and absorption coefficients and aerosol optical depths were observed around noon. The observed diurnal variation is caused by wind direction and speed, during night time very calm easterly winds are dominating whereas during daytime the stronger westerly winds are dominating (sea breeze). Positive Matrix Factorization mathematical tool was applied to the scattering and absorption coefficients and PM2.5 and coarse mode (PM10- PM2.5) mass concentrations to characterise aerosols from different sources. Analysis revealed three clearly different types of sources, anthropogenic, BC source and desert dust. These factors have clearly different seasonal and diurnal variation. The contribution of desert dust factor was dominating from February to May, whereas the contribution of anthropogenic factor is quite steady over the whole year. We estimated the mass absorption and scattering efficiencies for the factors and they agreed well with earlier observations. Hence, this method could be used to distinguish aerosol source characteristics, at least in fairly simple cases.

Chemical signatures of urban, open burning and dust transportation in an urban environment- megacity in South Asia

NASA Astrophysics Data System (ADS)

Priyadharshini, B.; Verma, S.

2016-12-01

A sub-micron aerosol sampler (SAS) consisting of two parallel stacked filter units (SFU) was deployed at an urban location (Kolkata) to study the sub-micron aerosols (water soluble inorganic ions (WSII) and carbonaceous aerosols (elemental carbon (EC) and organic carbon (OC)) collected over a year (September 2010 to August 2011). Quantification of 10 WSII species using Ion Chromatograph (IC) indicated alkaline nature of aerosols with calcium (Ca2+) being the major neutralizing factor of acidity at the study site. In terms of WSII percentage contribution, the most abundant were crustal species (Ca2+, magnesium (Mg2+) and marine species (chloride (Cl-)), followed by the secondary species sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) . Ca2+ (fugitive and transported dust) was dominant throughout the study period with K+ concentrations exhibiting seasonality with agricultural residue burning. Further, results of carbonaceous aerosols analyzed using the OC-EC aerosol analyzer following Interagency Monitoring of Protected Visual Environment (IMPROVE) protocol exhibited pronounced seasonality in OC than EC with the overall mean concentration of OC being three folds than EC. Primary organic carbon (POC) and secondary organic carbon concentrations (SOC) estimated using EC tracer method showed 57% (43%) of POC (SOC) from various emission sources. Investigation of OC/EC ratio along with non-sea salt potassium (nss-K+) values revealed influence of season specific anthropogenic activities on both OC and EC concentrations (viz. Open burning (OB)) besides fossil fuel (FF) and biofuel (BF) usage for cooking and heating prevalent over the region. Source apportionment was discerned using positive matrix factorization (PMF) with four major factors (crustal, agricultural, anthropogenic sources and mixed source (crustal + agriculture + anthropogenic) as the primary contributors to the sub-micron aerosols at the study site.

Signatures of Biomass Burning Aerosols during a Smoke Plume Event from a Saltmarsh Wildfire in South Texas

NASA Astrophysics Data System (ADS)

Louchouarn, P.; Griffin, R. J.; Norwood, M. J.; Sterne, A. M. E.; Karakurt Cevik, B.

2014-12-01

The most conventional and abundant tracers of biomass combustion in aerosol particles include potassium and biomarkers derived from thermally altered cellulose/hemicellulose (anhydrosugars) and lignin (methoxyphenols). However, little is known of the role of biomass combustion as a particulate source of major plant polymers to the atmosphere. Here, concentrations of "free" (solvent-extractable) anhydrosugars and methoxyphenols are compared to the yields of polymeric lignin oxidation products (LOPs) during a smoke plume event in Houston, Texas. Downwind aerosol samples (PM2.5) were collected prior to, during, and following a two-day wildfire event that burned ~5,000 acres of a spartina saltmarsh ecosystem in the McFaddin National Wildlife Refuge, 125 km southeast of Houston. In addition, charcoals of the burned plants were collected within a week of the fire at the wildfire site. HYSPLIT modeling shows that Houston was directly downwind of this wildfire during the peak of the burn, with an approximate travel time from source to aerosol sampling site of 12-16 hrs. Concentrations of all organic markers, K+, and Ca2+ jumped by a factor of 2-13 within 1-2 days of the start of the fire and dropped to pre-fire levels three days after the peak event. Source signatures of anhydrosugars and free methoxyphenols during the peak of the plume were identical to those of grass charcoals collected from the site, confirming the potential use of charcoals as endmembers for source input reconstruction during atmospheric transport. An enrichment factor of 20 in the anhydrosugar to methoxyphenol ratio of aerosols vs. charcoals can partially be explained by differences in degradation rate constants between the two biomarker groups. Polymeric LOP comprised 73-91% of all lignin material in the aerosols, pointing to fires as major sources of primary biogenic aerosol particles and confirming an earlier study that lignin phenols in atmospheric particles occur predominantly in polymeric form.

Stable carbon and nitrogen isotopic compositions of ambient aerosols collected from Okinawa Island in the western North Pacific Rim, an outflow region of Asian dusts and pollutants

NASA Astrophysics Data System (ADS)

Kunwar, Bhagawati; Kawamura, Kimitaka; Zhu, Chunmao

2016-04-01

Stable carbon (δ13C) and nitrogen (δ15N) isotope ratios were measured for total carbon (TC) and nitrogen (TN), respectively, in aerosol (TSP) samples collected at Cape Hedo, Okinawa, an outflow region of Asian pollutants, during 2009-2010. The averaged δ13C and δ15N ratios are -22.2‰ and +12.5‰, respectively. The δ13C values are similar in both spring (-22.5‰) and winter (-22.5‰), suggesting the similar sources and/or source regions. We found that δ13C from Okinawa aerosols are ca. 2‰ higher than those reported from Chinese megacities probably due to photochemical aging of organic aerosols. A strong correlation (r = 0.81) was found between nss-Ca and TSP, suggesting that springtime aerosols are influenced from Asian dusts. However, carbonates in the Asian dusts were titrated with acidic species such as sulfuric acid and oxalic acid during atmospheric transport although two samples suggested the presence of remaining carbonate. No correlations were found between δ13C and tracer compounds (levoglucosan, elemental carbon, oxalic acid, and Na+). During winter and spring, coal burning is significant source in China. Based on isotopic mass balance, contribution of coal burning origin particles to total aerosol carbon was estimated as ca. 97% in winter, which is probably associated with the high emissions in China. Contribution of NO3- to TN was on average 45% whereas that of NH4+ was 18%. These results suggest that vehicular exhaust is an important source of TN in Okinawa aerosols. Concentration of water-soluble organic nitrogen (WSON) is higher in summer, suggesting that WSON is more emitted from the ocean in warmer season whereas inorganic nitrogen is more emitted in winter and spring from pollution sources in the Asian continent.

Modeling the Absorbing Aerosol Index

NASA Technical Reports Server (NTRS)

Penner, Joyce; Zhang, Sophia

2003-01-01

We propose a scheme to model the absorbing aerosol index and improve the biomass carbon inventories by optimizing the difference between TOMS aerosol index (AI) and modeled AI with an inverse model. Two absorbing aerosol types are considered, including biomass carbon and mineral dust. A priori biomass carbon source was generated by Liousse et al [1996]. Mineral dust emission is parameterized according to surface wind and soil moisture using the method developed by Ginoux [2000]. In this initial study, the coupled CCM1 and GRANTOUR model was used to determine the aerosol spatial and temporal distribution. With modeled aerosol concentrations and optical properties, we calculate the radiance at the top of the atmosphere at 340 nm and 380 nm with a radiative transfer model. The contrast of radiance at these two wavelengths will be used to calculate AI. Then we compare the modeled AI with TOMS AI. This paper reports our initial modeling for AI and its comparison with TOMS Nimbus 7 AI. For our follow-on project we will model the global AI with aerosol spatial and temporal distribution recomputed from the IMPACT model and DAO GEOS-1 meteorology fields. Then we will build an inverse model, which applies a Bayesian inverse technique to optimize the agreement of between model and observational data. The inverse model will tune the biomass burning source strength to reduce the difference between modelled AI and TOMS AI. Further simulations with a posteriori biomass carbon sources from the inverse model will be carried out. Results will be compared to available observations such as surface concentration and aerosol optical depth.

A new approach to chemically-speciated submicron aerosol fluxes over tropical and temperate forests.

NASA Astrophysics Data System (ADS)

Farmer, D. K.; Kimmel, J. R.; Nemitz, E.; Phillips, G.; Docherty, K.; Chen, Q.; Martin, S.; Cubison, M.; Jimenez, J.

2008-12-01

Aerosols play an important role in the planet's radiation balance; however, their sources and sinks remain highly uncertain. In particular, due to instrumental limitations, there are few measurements of particle fluxes over the Earth's surface. Particles are expected to deposit over forests, leading not only to an aerosol sink, but also to an ecosystem source of nutrients and acids. However, forests emit volatile organic compounds (VOCs) that are known to produce secondary organic aerosol, thus also acting as aerosol sources. We have developed a new approach to measure biosphere-atmosphere exchange of chemically-speciated aerosol using a High Resolution-Time of Flight-Aerosol Mass Spectrometer (HR-ToF-AMS; DeCarlo et al., Anal. Chem., 2006) in a new Eddy Covariance Flux mode (10 Hz). This approach allows us to directly measure fluxes of non-refractory organic, sulphate, nitrate and ammonium in submicron particles. Measurements have been carried out over two forests: a temperate ponderosa pine plantation at Blodgett Forest (BEARPEX-I campaign, 2007) and a tropical rain forest in the Brazilian Amazon during the wet season (AMAZE campaign, 2008). Data collected at these sites allows us to demonstrate that the flux mode of the HR-ToF-AMS meets the rigorous instrumental requirements of the eddy covariance approach and that fluxes of different chemical species can be quantified. Aerosol fluxes under clean and anthropogenically-impacted conditions are compared. These measurements allow us to better constrain dry deposition over forested environments and to understand the potential of flux measurements to constrain the biogenic SOA budget.

Dust in the Sky: Atmospheric Composition. Modeling of Aerosol Optical Thickness

NASA Technical Reports Server (NTRS)

Chin, Mian; Ginoux, Paul; Kinne, Stefan; Torres, Omar; Holben, Brent; Duncan, Bryan; Martin, Randall; Logan, Jennifer; Higurashi, Akiko; Nakajima, Teruyuki

2000-01-01

Aerosol is any small particle of matter that rests suspended in the atmosphere. Natural sources, such as deserts, create some aerosols; consumption of fossil fuels and industrial activity create other aerosols. All the microscopic aerosol particles add up to a large amount of material floating in the atmosphere. You can see the particles in the haze that floats over polluted cities. Beyond this visible effect, aerosols can actually lower temperatures. They do this by blocking, or scattering, a portion of the sun's energy from reaching the surface. Because of this influence, scientists study the physical properties of atmospheric aerosols. Reliable numerical models for atmospheric aerosols play an important role in research.

Follow the Carbon: Isotopic Labeling Studies of Early Earth Aerosol.

PubMed

Hicks, Raea K; Day, Douglas A; Jimenez, Jose L; Tolbert, Margaret A

2016-11-01

Despite the faint young Sun, early Earth might have been kept warm by an atmosphere containing the greenhouse gases CH 4 and CO 2 in mixing ratios higher than those found on Earth today. Laboratory and modeling studies suggest that an atmosphere containing these trace gases could lead to the formation of organic aerosol haze due to UV photochemistry. Chemical mechanisms proposed to explain haze formation rely on CH 4 as the source of carbon and treat CO 2 as a source of oxygen only, but this has not previously been verified experimentally. In the present work, we use isotopically labeled precursor gases and unit-mass resolution (UMR) and high-resolution (HR) aerosol mass spectrometry to examine the sources of carbon and oxygen to photochemical aerosol formed in a CH 4 /CO 2 /N 2 atmosphere. UMR results suggest that CH 4 contributes 70-100% of carbon in the aerosol, while HR results constrain the value from 94% to 100%. We also confirm that CO 2 contributes approximately 10% of the total mass to the aerosol as oxygen. These results have implications for the geochemical interpretations of inclusions found in Archean rocks on Earth and for the astrobiological potential of other planetary atmospheres. Key Words: Atmosphere-Early Earth-Planetary atmospheres-Carbon dioxide-Methane. Astrobiology 16, 822-830.

Diurnal and seasonal trends and source apportionment of redox-active metals in Los Angeles using a novel online metal monitor and Positive Matrix Factorization (PMF)

NASA Astrophysics Data System (ADS)

Mousavi, Amirhosein; Sowlat, Mohammad H.; Sioutas, Constantinos

2018-02-01

In the present study, we identified the sources of four redox-active metals, including Iron (Fe), Chromium (Cr), Cupper (Cu), and Manganese (Mn) and quantified the contribution of these sources to PM2.5 concentrations in central Los Angeles, California, by employing time-resolved measurements (i.e., a time resolution of 2 h) with a recently developed online metal monitor and Positive Matrix Factorization (PMF). Size distribution of ambient PM (14 nm-10 μm) was measured using the Scanning Mobility Particle Sizer (SMPS) and Optical Particle Sizer (OPS). Auxiliary variables were also collected, including elemental (EC) and organic carbon (OC), gaseous pollutants (NO2 and O3), meteorological parameters (including relative humidity (RH) and temperature), and traffic data (for heavy- (HDVs) and light-duty vehicles (LDVs)). A 4-factor solution was found to be optimum for the chemically-speciated dataset, whereas a 5-factor solution appeared to be most plausible for the size distribution data. The factors included fresh traffic, soil/road dust, urban background aerosol, secondary aerosol, and nucleation (only resolved for the size distribution data). Fresh traffic was the major contributor to Fe and Cu concentrations, whereas Cr was mostly found in the urban background aerosol (reflecting a mixture of small local sources as well as aged traffic emissions), and Mn mostly came from both soil/road dust and was to a lesser degree found in urban background aerosol. Secondary aerosol did not contribute to the concentrations of any of these metals, but was associated with very high loading of OC, as expected. Even though the urban background aerosol and secondary aerosol appeared to be characterized by "aged" particles and have a rather homogeneous spatial distribution, the reactions and processes involved in their formation are entirely different. Our results provide insights into the sources of redox-active metals in central Los Angeles. They also underscore the benefits of novel measurement techniques for PM-bound metals, which could enhance our understanding of the sources of atmospheric aerosols by providing us with measurements with finer time resolutions that otherwise would not have been possible using traditional filter-based measurement techniques.

Biomass burning dominates brown carbon absorption in the rural southeastern United States

NASA Astrophysics Data System (ADS)

Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Guo, H.; Xu, L.; Weber, R. J.; Ng, N. L.; Allen, H. M.; Ayres, B. R.; Baumann, K.; Cohen, R. C.; Draper, D. C.; Duffey, K. C.; Edgerton, E.; Fry, J. L.; Hu, W. W.; Jimenez, J. L.; Palm, B. B.; Romer, P.; Stone, E. A.; Wooldridge, P. J.; Brown, S. S.

2015-01-01

carbon aerosol consists of light-absorbing organic particulate matter with wavelength-dependent absorption. Aerosol optical extinction, absorption, size distributions, and chemical composition were measured in rural Alabama during summer 2013. The field site was well located to examine sources of brown carbon aerosol, with influence by high biogenic organic aerosol concentrations, pollution from two nearby cities, and biomass burning aerosol. We report the optical closure between measured dry aerosol extinction at 365 nm and calculated extinction from composition and size distribution, showing agreement within experiment uncertainties. We find that aerosol optical extinction is dominated by scattering, with single-scattering albedo values of 0.94 ± 0.02. Black carbon aerosol accounts for 91 ± 9% of the total carbonaceous aerosol absorption at 365 nm, while organic aerosol accounts for 9 ± 9%. The majority of brown carbon aerosol mass is associated with biomass burning, with smaller contributions from biogenically derived secondary organic aerosol.

Using radiocarbon to constrain black and organic carbon aerosol sources in Salt Lake City

NASA Astrophysics Data System (ADS)

Mouteva, Gergana O.; Randerson, James T.; Fahrni, Simon M.; Bush, Susan E.; Ehleringer, James R.; Xu, Xiaomei; Santos, Guaciara M.; Kuprov, Roman; Schichtel, Bret A.; Czimczik, Claudia I.

2017-09-01

Black carbon (BC) and organic carbon (OC) aerosols are important components of fine particulate matter (PM2.5) in polluted urban environments. Quantifying the contribution of fossil fuel and biomass combustion to BC and OC concentrations is critical for developing and validating effective air quality control measures and climate change mitigation policy. We used radiocarbon (14C) to measure fossil and contemporary biomass contributions to BC and OC at three locations in Salt Lake City, Utah, USA, during 2012-2014, including during winter inversion events. Aerosol filters were analyzed with the Swiss_4S thermal-optical protocol to isolate BC. We measured fraction modern (fM) of BC and total carbon in PM2.5 with accelerator mass spectrometry and derived the fM of OC using isotope mass balance. Combined with 14C information of end-member composition, our data set of 31 14C aerosol measurements provided a baseline of the fossil and contemporary biomass components of carbonaceous aerosol. We show that fossil fuels were the dominant source of carbonaceous aerosol during winter, contributing 88% (80-98%) of BC and 58% (48-69%) of OC. While the concentration of both BC and OC increased during inversion events, the relative source contributions did not change. The sources of BC also did not vary throughout the year, while OC had a considerably higher contemporary biomass component in summer at 62% (49-76%) and was more variable. Our results suggest that in order to reduce PM2.5 levels in Salt Lake City to meet national standards, a more stringent policy targeting mobile fossil fuel sources may be necessary.

The impact of biogenic carbon emissions on aerosol absorption inMexico City

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marley, N; Gaffney, J; Tackett, M J

2009-02-24

In order to determine the wavelength dependence of atmospheric aerosol absorption in the Mexico City area, the absorption angstrom exponents (AAEs) were calculated from aerosol absorption measurements at seven wavelengths obtained with a seven-channel aethalometer during two field campaigns, the Mexico City Metropolitan Area study in April 2003 (MCMA 2003) and the Megacity Initiative: Local and Global Research Observations in March 2006 (MILAGRO). The AAEs varied from 0.76 to 1.56 in 2003 and from 0.54 to 1.52 in 2006. The AAE values determined in the afternoon were consistently higher than the corresponding morning values, suggesting the photochemical formation of absorbingmore » secondary organic aerosols (SOA) in the afternoon. The AAE values were compared to stable and radiocarbon isotopic measurements of aerosol samples collected at the same time to determine the sources of the aerosol carbon. The fraction of modern carbon (fM) in the aerosol samples, as determined from {sup 14}C analysis, showed that 70% of the carbonaceous aerosols in Mexico City were from modern sources, indicating a significant impact from biomass burning during both field campaigns. The {sup 13}C/{sup 12}C ratios of the aerosol samples illustrate the significant impact of Yucatan forest fires (C-3 plants) in 2003 and local grass fires (C-4 plants) at site T1 in 2006. A direct comparison of the fM values, stable carbon isotope ratios, and calculated aerosol AAEs suggested that the wavelength dependence of the aerosol absorption was controlled by the biogenically derived aerosol components.« less

An aerosol climatology for a rapidly growing arid region (southern Arizona): Major aerosol species and remotely sensed aerosol properties

NASA Astrophysics Data System (ADS)

Sorooshian, Armin; Wonaschütz, Anna; Jarjour, Elias G.; Hashimoto, Bryce I.; Schichtel, Bret A.; Betterton, Eric A.

2011-10-01

This study reports a comprehensive characterization of atmospheric aerosol particle properties in relation to meteorological and back trajectory data in the southern Arizona region, which includes two of the fastest growing metropolitan areas in the United States (Phoenix and Tucson). Multiple data sets (MODIS, AERONET, OMI/TOMS, MISR, GOCART, ground-based aerosol measurements) are used to examine monthly trends in aerosol composition, aerosol optical depth (AOD), and aerosol size. Fine soil, sulfate, and organics dominate PM2.5 mass in the region. Dust strongly influences the region between March and July owing to the dry and hot meteorological conditions and back trajectory patterns. Because monsoon precipitation begins typically in July, dust levels decrease, while AOD, sulfate, and organic aerosol reach their maximum levels because of summertime photochemistry and monsoon moisture. Evidence points to biogenic volatile organic compounds being a significant source of secondary organic aerosol in this region. Biomass burning also is shown to be a major contributor to the carbonaceous aerosol budget in the region, leading to enhanced organic and elemental carbon levels aloft at a sky-island site north of Tucson (Mt. Lemmon). Phoenix exhibits different monthly trends for aerosol components in comparison with the other sites owing to the strong influence of fossil carbon and anthropogenic dust. Trend analyses between 1988 and 2009 indicate that the strongest statistically significant trends are reductions in sulfate, elemental carbon, and organic carbon, and increases in fine soil during the spring (March-May) at select sites. These results can be explained by population growth, land-use changes, and improved source controls.

Direct Radiative Effects of Aerosols Over South Asia From Observations and Modeling

NASA Technical Reports Server (NTRS)

Nair, Vijayakumar S.; Babu, S. Suresh; Manoj, M. R.; Moorthy, Krishna K.; Chin, Mian

2016-01-01

Quantitative assessment of the seasonal variations in the direct radiative effect (DRE) of composite aerosols as well as the constituent species over the Indian sub continent has been carried out using a synergy of observations from a dense network of ground based aerosol observatories and modeling based on chemical transport model simulations. Seasonal variation of aerosol constituents depict significant influence of anthropogenic aerosol sources in winter and the dominance of natural sources in spring, even though the aerosol optical depth doesn't change significantly between these two seasons. A significant increase in the surface cooling and atmospheric warming has been observed as season changes from winter DRE(sub SUR) = -28 +/- 12 W m(exp -2) and DRE(sub ATM) = +19.6 +/- 9 W m(exp -2) to spring DRE(sub SUR) = -33.7 +/- 12 W m(exp -2) and DRE(sub ATM) = +27 +/- 9 W m(exp-2). Interestingly, springtime aerosols are more absorptive in nature compared to winter and consequently the aerosol induced diabatic heating of the atmosphere goes as high as approximately 1 K day(exp -1) during spring, especially over eastern India. The atmospheric DRE due to dust aerosols (+14 +/- 7 W m(exp 2) during spring overwhelms that of black carbon DRE (+11.8 +/- 6 W m(exp -2) during winter. The DRE at the top of the atmosphere is mostly governed by the anthropogenic aerosols during all the seasons. The columnar aerosol loading, its anthropogenic fraction and radiative effects shows a steady increase with latitude across Indian mainland leading to a larger aerosol-induced atmospheric warming during spring than in winter.

Remote sensing for studying atmospheric aerosols in Malaysia

NASA Astrophysics Data System (ADS)

Kanniah, Kasturi D.; Kamarul Zaman, Nurul A. F.

2015-10-01

The aerosol system is Southeast Asia is complex and the high concentrations are due to population growth, rapid urbanization and development of SEA countries. Nevertheless, only a few studies have been carried out especially at large spatial extent and on a continuous basis to study atmospheric aerosols in Malaysia. In this review paper we report the use of remote sensing data to study atmospheric aerosols in Malaysia and document gaps and recommend further studies to bridge the gaps. Satellite data have been used to study the spatial and seasonal patterns of aerosol optical depth (AOD) in Malaysia. Satellite data combined with AERONET data were used to delineate different types and sizes of aerosols and to identify the sources of aerosols in Malaysia. Most of the aerosol studies performed in Malaysia was based on station-based PM10 data that have limited spatial coverage. Thus, satellite data have been used to extrapolate and retrieve PM10 data over large areas by correlating remotely sensed AOD with ground-based PM10. Realising the critical role of aerosols on radiative forcing numerous studies have been conducted worldwide to assess the aerosol radiative forcing (ARF). Such studies are yet to be conducted in Malaysia. Although the only source of aerosol data covering large region in Malaysia is remote sensing, satellite observations are limited by cloud cover, orbital gaps of satellite track, etc. In addition, relatively less understanding is achieved on how the atmospheric aerosol interacts with the regional climate system. These gaps can be bridged by conducting more studies using integrated approach of remote sensing, AERONET and ground based measurements.

Direct radiative effects of aerosols over South Asia from observations and modeling

NASA Astrophysics Data System (ADS)

Nair, Vijayakumar S.; Babu, S. Suresh; Manoj, M. R.; Moorthy, K. Krishna; Chin, Mian

2017-08-01

Quantitative assessment of the seasonal variations in the direct radiative effect (DRE) of composite aerosols as well as the constituent species over the Indian sub continent has been carried out using a synergy of observations from a dense network of ground based aerosol observatories and modeling based on chemical transport model simulations. Seasonal variation of aerosol constituents depict significant influence of anthropogenic aerosol sources in winter and the dominance of natural sources in spring, even though the aerosol optical depth doesn't change significantly between these two seasons. A significant increase in the surface cooling and atmospheric warming has been observed as season changes from winter (DRESUR = -28 ± 12 W m-2 and DREATM = +19.6 ± 9 W m-2) to spring (DRESUR = -33.7 ± 12 W m-2 and DREATM = +27 ± 9 W m-2). Interestingly, springtime aerosols are more absorptive in nature compared to winter and consequently the aerosol induced diabatic heating of the atmosphere goes as high as 1 K day-1 during spring, especially over eastern India. The atmospheric DRE due to dust aerosols (+14 ± 7 W m-2) during spring overwhelms that of black carbon DRE (+11.8 ± 6 W m-2) during winter. The DRE at the top of the atmosphere is mostly governed by the anthropogenic aerosols during all the seasons. The columnar aerosol loading, its anthropogenic fraction and radiative effects shows a steady increase with latitude across Indian mainland leading to a larger aerosol-induced atmospheric warming during spring than in winter.

Spatial and temporal variations of aerosols around Beijing in summer 2006: Model evaluation and source apportionment

NASA Astrophysics Data System (ADS)

Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Kita, K.; Miyazaki, Y.; Hu, M.; Chang, S.; Blake, D. R.; Fast, J. D.; Zaveri, R. A.; Streets, D. G.; Zhang, Q.; Zhu, T.

2009-12-01

Regional aerosol model calculations were made using the WRF-CMAQ and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the CAREBEIJING-2006 intensive campaign was conducted. Model calculations captured temporal variations of primary (such as elemental carbon, EC) and secondary (such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODIS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 x 1000 km2 under an anticyclonic pressure system. This airmass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synoptic-scale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 hours, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols.

Characterization of Organic Nitrate Formation in Limonene Secondary Organic Aerosol using High-Resolution Chemical Ionization Mass Spectrometry

NASA Astrophysics Data System (ADS)

Faxon, Cameron; Hammes, Julia; Peng, Jianfei; Hallquist, Mattias; Pathak, Ravi

2016-04-01

Previous work has shown that organic nitrates (RONO2) are prevalent in the boundary layer, and can contribute significantly to secondary organic aerosol formation. Monoterpenes, including limonene, have been shown to be precursors for the formation of these organic nitrates. Limonene has two double bonds, either of which may be oxidized by NO3 or O3. This leads to the generation of products that can subsequently condense or partition into the particle phase, producing secondary organic aerosol. In order to further elucidate the particle and gas phase product distribution of organic nitrates forming from the reactions of limonene and the nitrate radical (NO3), a series of experiments were performed in the Gothenburg Flow Reactor for Oxidation Studies at Low Temperatures (G-FROST), described by previous work. N2O5 was used as the source for NO3 and NO2, and a characterized diffusion source was used to introduce limonene into the flow reactor. All experiments were conducted in the absence of light, and the concentration of limonene was increased step-wise throughout each experiment to modify the ratio of N2O5to limonene. The experiments were conducted such that both limonene- and N2O5-limited regimes were present. Gas and particle phase products were measured using an iodide High-Resolution Time-of-Flight Mass Spectrometer (HR-ToF-CIMS) coupled to a Filter Inlet for Gases and AEROsols (FIGAERO, and particle size and SOA mass concentrations were derived using a Scanning Mobility Particle Sizer (SMPS). CIMS measurement techniques have previously been employed for the measurement of organic nitrate products of such compounds using multiple reagent ions. The use of this instrumentation allowed for the identification of chemical formulas for gas and particle phase species. The findings from the experiments will be presented in terms of the relative gas-particle partitioning of major products and the effects of N2O5/limonene ratios on product distributions. Additionally, a comparison of the distribution of the most prevalent reaction products relative to the expected distribution derived using chemical kinetics simulations based on the Master Chemical Mechanism (MCM) limonene mechanism will be discussed.

Feasibility of detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy.

PubMed

Dixon, P B; Hahn, D W

2005-01-15

The detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy (LIBS) is investigated using aerosolized Bacillus spores. Spores of Bacillus atrophaeous, Bacillus pumilus, and Bacillus stearothemophilus were introduced into an aerosol flow stream in a prescribed manner such that single-particle LIBS detection was realized. Bacillus spores were successfully detected based on the presence of the 393.4- and 396.9-nm calcium atomic emission lines. Statistical analyses based on the aerosol number density, the LIBS-based spore sampling frequency, and the distribution of the resulting calcium mass loadings support the conclusion of individual spore detection within single-shot laser-induced plasmas. The average mass loadings were in the range of 2-3 fg of calcium/Bacillus spore, which corresponds to a calcium mass percentage of approximately 0.5%. While individual spores were detected based on calcium emission, the resulting Bacillus spectra were free from CN emission bands, which has implications for the detection of elemental carbon, and LIBS-based detection of single spores based on the presence of magnesium or sodium atomic emission was unsuccessful. Based on the current instrumental setup and analyses, real-time LIBS-based detection and identification of single Bacillus spores in ambient (i.e., real life) conditions appears unfeasible.

Performance of personal inhalable aerosol samplers in very slowly moving air when facing the aerosol source.

PubMed

Witschger, O; Grinshpun, S A; Fauvel, S; Basso, G

2004-06-01

While personal aerosol samplers have been characterized primarily based on wind tunnel tests conducted at relatively high wind speeds, modern indoor occupational environments are usually represented by very slow moving air. Recent surveys suggest that elevated levels of occupational exposure to inhalable airborne particles are typically observed when the worker, operating in the vicinity of the dust source, faces the source. Thus, the first objective of this study was to design and test a new, low cost experimental protocol for measuring the sampling efficiency of personal inhalable aerosol samplers in the vicinity of the aerosol source when the samplers operate in very slowly moving air. In this system, an aerosol generator, which is located in the centre of a room-sized non-ventilated chamber, continuously rotates and omnidirectionally disperses test particles of a specific size. The test and reference samplers are equally distributed around the source at the same distance from the centre and operate in parallel (in most of our experiments, the total number of simultaneously operating samplers was 15). Radial aerosol transport is driven by turbulent diffusion and some natural convection. For each specific particle size and the sampler, the aerosol mass concentration is measured by weighing the collection filter. The second objective was to utilize the new protocol to evaluate three widely used aerosol samplers: the IOM Personal Inhalable Sampler, the Button Personal Inhalable Aerosol Sampler and the 25 mm Millipore filter holder (closed-face C25 cassette). The sampling efficiencies of each instrument were measured with six particle fractions, ranging from 6.9 to 76.9 micro m in their mass median aerodynamic diameter. The Button Sampler efficiency data demonstrated a good agreement with the standard inhalable convention and especially with the low air movement inhalabilty curve. The 25 mm filter holder was found to considerably under-sample the particles larger than 10 micro m; its efficiency did not exceed 7% for particles of 40-100 micro m. The IOM Sampler facing the source was found to over-sample compared with the data obtained previously with a slowly rotating, freely suspended sampler in a low air movement environment. It was also found that the particle wall deposition in the IOM metallic cartridge was rather significant and particle size-dependent. For each sampler (IOM, Button and C25) the precision was characterized through the relative standard deviation (RSD) of the aerosol concentration obtained with identical samplers in a specific experiment. The average RSD was 14% for the IOM Sampler, 11% for the Button Sampler and 35% for the 25 mm filter cassette. A separate set of experiments, performed with the Simplified Torso showed that in very slowly moving air a personal sampler can be adequately evaluated even when it is not attached to a body but freely suspended (confirming the data reported previously).

Aplication of LIRIC algorithm to study aerosol transport over Belsk, Poland

NASA Astrophysics Data System (ADS)

Pietruczuk, Aleksander; Posyniak, Michał

2015-04-01

In this work synergy of measurements done by of a LIDAR and a sun-sky scanning photometer is presented. The LIdar-Radiometer Inversion Code (LIRIC) was applied to study periodic events of increased values of the aerosol optical depth (AOD) observed at Belsk (Poland). Belsk is a background site located in a rural area around 50 km south from Warsaw. Events of increased AOD occur mainly during spring and they coincide with events of elevated concentrations of particulate matter (PM10). This phenomenon is observed in all eastern Europe, e.g. in Minsk, and is caused by long range aerosol transport. Our previous work showed aerosol transport from the border between Belarus, Ukraine and Russia in the planetary boundary layer (PBL), and from north Africa in the free troposphere. The LIRIC algorithm, which uses optical and microphysical properties of the aerosol derived from photometric measurements and LIDAR profiles, was applied to study vertical distribution of fine and coarse modes of aerosol. The analysis of the airmass backward trajectories and models results (DREAM and NAAPS)was also used to determine a possible aerosol type and its source region. This study proved our previous findings. Most of events with increased AODs are observed during spring. In this season the fine mode aerosol is mainly present in the PBL. On the basis of the trajectory analysis and the NAAPS results we presume that it is the absorbing aerosol originating from the regions of seasonal biomass burning in eastern Europe, i.e. the area mentioned above. The events with increased AODs were also found during summer. In this case the fine mode aerosol is transported in the PBL a like to spring season. However, our analysis of trajectories and model results indicated western Europe as a source region. It is probably urban/industrial aerosol. The coarse mode aerosol is transported mainly in the free troposphere as separate layers. The analysis of backward trajectories indicates northern Africa as a possible source region regardless the season. DREAM and NAAPS results suggest presence of mineral dust in this case over Belsk.

Insights into Submicron Aerosol Composition and Sources from the WINTER Aircraft Campaign Over the Eastern US.

NASA Astrophysics Data System (ADS)

Schroder, J. C.; Campuzano Jost, P.; Day, D. A.; Fibiger, D. L.; McDuffie, E. E.; Blake, N. J.; Hills, A. J.; Hornbrook, R. S.; Apel, E. C.; Weinheimer, A. J.; Campos, T. L.; Brown, S. S.; Jimenez, J. L.

2015-12-01

The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas pollutants and aerosols in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne aerosol mass spectrometer (AMS) was flown on the NCAR C-130 to characterize submicron aerosol composition and evolution. Thirteen research flights were conducted covering a wide range of conditions, including rural, urban, and marine environments during day and night. Organic aerosol (OA) was a large component of the submicron aerosol in the boundary layer. The fraction of OA (fOA) was smaller (35-40%) than in recent US summer campaigns (~60-70%). Biomass burning was observed to be an important source of OA in the boundary layer, which is consistent with recent wintertime studies that show a substantial contribution of residential wood burning to the OA loadings. OA oxygenation (O/C ratio) shows a broad distribution with a substantial fraction of smaller O/C ratios when compared to previous summertime campaigns. Since measurements were rarely made very close to primary sources (i.e. directly above urban areas), this is consistent with oxidative chemistry being slower during winter. SOA formation and aging in the NYC plume was observed during several flights and compared with summertime results from LA (CalNex) and Mexico City (MILAGRO). Additionally, an oxidation flow reactor (OFR) capable of oxidizing ambient air up to several equivalent days of oxidation was deployed for the first time in an aircraft platform. The aerosol outflow of the OFR was sampled with the AMS to provide real-time snapshots of the potential for aerosol formation and aging. For example, a case study of a flight through the Ohio River valley showed evidence of oxidation of SO2 to sulfate. The measured sulfate enhancements were in good agreement with our OFR chemical model. OFR results for SOA will be discussed.

Aging of biogenic secondary organic aerosol via gas-phase OH radical reactions

PubMed Central

Donahue, Neil M.; Henry, Kaytlin M.; Mentel, Thomas F.; Kiendler-Scharr, Astrid; Spindler, Christian; Bohn, Birger; Brauers, Theo; Dorn, Hans P.; Fuchs, Hendrik; Tillmann, Ralf; Wahner, Andreas; Saathoff, Harald; Naumann, Karl-Heinz; Möhler, Ottmar; Leisner, Thomas; Müller, Lars; Reinnig, Marc-Christopher; Hoffmann, Thorsten; Salo, Kent; Hallquist, Mattias; Frosch, Mia; Bilde, Merete; Tritscher, Torsten; Barmet, Peter; Praplan, Arnaud P.; DeCarlo, Peter F.; Dommen, Josef; Prévôt, Andre S.H.; Baltensperger, Urs

2012-01-01

The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases the concentration of first-generation biogenic secondary organic aerosol (SOA). OH is the dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers of very different designs, using multiple OH sources to explore a range of chemical conditions and potential sources of systematic error. We isolated the effect of OH aging, confirming our hypothesis while observing corresponding changes in SOA properties. The mass increases are consistent with an existing gap between global SOA sources and those predicted in models, and can be described by a mechanism suitable for implementation in those models. PMID:22869714

Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinman, L.I.; Daum, P. H.; Lee, Y.-N.

2011-06-21

During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O{sub 3} and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate in agreement with the dominant pollution source being SO{sub 2} from Cu smeltersmore » and power plants. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 C with dry air descending from the upper atmospheric and moist air having a BL contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (Dp > 100 nm) gives a linear relation up to a number concentration of {approx}150 cm{sup -3}, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that {approx}25% of aerosol in the PCASP size range are interstitial (not activated). One hundred and two constant altitude cloud transects were identified and used to determine properties of interstitial aerosol. One transect is examined in detail as a case study. Approximately 25 to 50% of aerosol with D{sub p} > 110 nm were not activated, the difference between the two approaches possibly representing shattered cloud droplets or unknown artifact. CDNC and interstitial aerosol were anti-correlated in all cloud transects, consistent with the occurrence of dry in-cloud areas due to entrainment or circulation mixing.« less

Molecular and immunological approaches in quantifying the air-borne food allergen tropomyosin in crab processing facilities.

PubMed

Kamath, Sandip D; Thomassen, Marte R; Saptarshi, Shruti R; Nguyen, Hong M X; Aasmoe, Lisbeth; Bang, Berit E; Lopata, Andreas L

2014-09-01

Tropomyosin is a cross-reactive allergenic protein present in ingested shellfish species. Exposure and sensitization to this protein via inhalation is particularly important in the crustacean processing industry where workers are continuously exposed to the aerosolized form of this allergen. The aim of this study was to develop an antibody-based immunoassay to enable the specific and sensitive quantification of aerosolized tropomyosin present in the environment of two crab processing facilities. Anti-tropomyosin antibody was generated in rabbits against tropomyosins from four different crustacean species. These antibodies were purified using recombinant tropomyosin using an immuno-affinity column. The recombinant tropomyosin was also used as an allergen standard for the sandwich ELISA. In order to quantify aerosolized tropomyosin, air collection was performed in the personal breathing zone of 80 workers during two crab processing activities, edible crab (Cancer pagurus) and king crab (Paralithodes camtschaticus) using polytetrafluoroethylene filters. The purified antibody was able to detect tropomyosin selectively from different crustaceans but not from vertebrate sources. The limit of detection (LOD) for the developed sandwich ELISA was 60 picogram/m(3) and limit of quantitation (LOQ) 100 picogram/m(3). Immunoassay validation was based on linearity (R(2) 0.999), matrix interference test (78.8±6.5%), intra-assay CV (9.8%) and inter-assay CV (11%). The novel immunoassay was able to successfully identify working activities, which generated low, medium or high concentrations of the aerosolized food allergen. We describe an IgG antibody-based immunoassay for quantification of the major food allergen tropomyosin, with high sensitivity and specificity. This modified immunological approach can be adapted for the detection of other aerosolized food allergens, assisting in the identification of high-risk allergen exposure areas in the food industry. Copyright © 2014 Elsevier GmbH. All rights reserved.

Contribution of Primary and Secondary Sources to Organic Aerosol and PM2.5 at SEARCH Network Sites

EPA Science Inventory

Chemical tracer methods for determining contributions to primary organic aerosol (POA) are fairly well established, whereas similar techniques for secondary organic aerosol (SOA), inherently complicated by time-dependent atmospheric processes, are only beginning to be studied. La...

Approaches to Observe Anthropogenic Aerosol-Cloud Interactions.

PubMed

Quaas, Johannes

Anthropogenic aerosol particles exert an-quantitatively very uncertain-effective radiative forcing due to aerosol-cloud interactions via an immediate altering of cloud albedo on the one hand and via rapid adjustments by alteration of cloud processes and by changes in thermodynamic profiles on the other hand. Large variability in cloud cover and properties and the therefore low signal-to-noise ratio for aerosol-induced perturbations hamper the identification of effects in observations. Six approaches are discussed as a means to isolate the impact of anthropogenic aerosol on clouds from natural cloud variability to estimate or constrain the effective forcing. These are (i) intentional cloud modification, (ii) ship tracks, (iii) differences between the hemispheres, (iv) trace gases, (v) weekly cycles and (vi) trends. Ship track analysis is recommendable for detailed process understanding, and the analysis of weekly cycles and long-term trends is most promising to derive estimates or constraints on the effective radiative forcing.

Molecular marker characterization and source appointment of particulate matter and its organic aerosols.

PubMed

Choi, Jong-Kyu; Ban, Soo-Jin; Kim, Yong-Pyo; Kim, Yong-Hee; Yi, Seung-Muk; Zoh, Kyung-Duk

2015-09-01

This study was carried out to identify possible sources and to estimate their contribution to total suspended particle (TSP) organic aerosol (OA) contents. A total of 120 TSP and PM2.5 samples were collected simultaneously every third day over a one-year period in urban area of Incheon, Korea. High concentration in particulate matters (PM) and its components (NO3(-), water soluble organic compounds (WSOCs), and n-alkanoic acids) were observed during the winter season. Among the organics, n-alkanes, n-alkanoic acids, levoglucosan, and phthalates were major components. Positive matrix factorization (PMF) analysis identified seven sources of organic aerosols including combustion 1 (low molecular weight (LMW)-polycyclic aromatic hydrocarbons (PAHs)), combustion 2 (high molecular weight (HMW)-PAHs), biomass burning, vegetative detritus (n-alkane), secondary organic aerosol 1 (SOA1), secondary organic aerosol 2 (SOA2), and motor vehicles. Vegetative detritus increased during the summer season through an increase in biogenic/photochemical activity, while most of the organic sources were prominent in the winter season due to the increases in air pollutant emissions and atmospheric stability. The correlation factors were high among the main components of the organic carbon (OC) in the TSP and PM2.5. The results showed that TSP OAs had very similar characteristics to the PM2.5 OAs. SOA, combustion (PAHs), and motor vehicle were found to be important sources of carbonaceous PM in this region. Our results imply that molecular markers (MMs)-PMF model can provide useful information on the source and characteristics of PM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic

PubMed Central

Altieri, Katye E.; Fawcett, Sarah E.; Peters, Andrew J.; Sigman, Daniel M.; Hastings, Meredith G.

2016-01-01

Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean’s external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of atmospheric organic N data, the largest uncertainties related to atmospheric N deposition are the sources and cycling of organic N, which is 20–80% of total N deposition. We studied the concentration and chemical composition of rainwater and aerosol organic N collected on the island of Bermuda in the western North Atlantic Ocean over 18 mo. Here, we show that the water-soluble organic N concentration ([WSON]) in marine aerosol is strongly correlated with surface ocean primary productivity and wind speed, suggesting a marine biogenic source for aerosol WSON. The chemical composition of high-[WSON] aerosols also indicates a primary marine source. We find that the WSON in marine rain is compositionally different from that in concurrently collected aerosols, suggesting that in-cloud scavenging (as opposed to below-cloud “washout”) is the main contributor to rain WSON. We conclude that anthropogenic activity is not a significant source of organic N to the marine atmosphere over the North Atlantic, despite downwind transport from large pollution sources in North America. This, in conjunction with previous work on ammonium and nitrate, leads to the conclusion that only 27% of total N deposition to the global ocean is anthropogenic, in contrast to the 80% estimated previously. PMID:26739561

Isotopic evidence for enhanced fossil fuel sources of aerosol ammonium in the urban atmosphere.

PubMed

Pan, Yuepeng; Tian, Shili; Liu, Dongwei; Fang, Yunting; Zhu, Xiaying; Gao, Meng; Gao, Jian; Michalski, Greg; Wang, Yuesi

2018-07-01

The sources of aerosol ammonium (NH 4 + ) are of interest because of the potential of NH 4 + to impact the Earth's radiative balance, as well as human health and biological diversity. Isotopic source apportionment of aerosol NH 4 + is challenging in the urban atmosphere, which has excess ammonia (NH 3 ) and where nitrogen isotopic fractionation commonly occurs. Based on year-round isotopic measurements in urban Beijing, we show the source dependence of the isotopic abundance of aerosol NH 4 + , with isotopically light (-33.8‰) and heavy (0 to +12.0‰) NH 4 + associated with strong northerly winds and sustained southerly winds, respectively. On an annual basis, 37-52% of the initial NH 3 concentrations in urban Beijing arises from fossil fuel emissions, which are episodically enhanced by air mass stagnation preceding the passage of cold fronts. These results provide strong evidence for the contribution of non-agricultural sources to NH 3 in urban regions and suggest that priority should be given to controlling these emissions for haze regulation. This study presents a carefully executed application of existing stable nitrogen isotope measurement and mass-balance techniques to a very important problem: understanding source contributions to atmospheric NH 3 in Beijing. This question is crucial to informing environmental policy on reducing particulate matter concentrations, which are some of the highest in the world. However, the isotopic source attribution results presented here still involve a number of uncertain assumptions and they are limited by the incomplete set of chemical and isotopic measurements of gas NH 3 and aerosol NH 4 + . Further field work and lab experiments are required to adequately characterize endmember isotopic signatures and the subsequent isotopic fractionation process under different air pollution and meteorological conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

North Atlantic Aerosol Properties and Direct Radiative Effects: Key Results from TARFOX and ACE-2

NASA Technical Reports Server (NTRS)

Russell, P. B.; Livingston, J. M.; Schmid, B.; Bergstrom, Robert A.; Hignett, P.; Hobbs, P. V.; Durkee, P. A.

2000-01-01

Aerosol effects on atmospheric radiative fluxes provide a forcing function that can change the climate In potentially significant ways. This aerosol radiative forcing is a major source of uncertainty in understanding the observed climate change of the past century and in predicting future climate. To help reduce this uncertainty, the International Global Atmospheric Chemistry Project (IGAC) has endorsed a series of multiplatform aerosol field campaigns. The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the second Aerosol Characterization Experiment (ACE-2) were the first IGAC campaigns to address the impact of anthropogenic aerosols, Both TARFOX and ACE-2 gathered extensive data sets on aerosol properties and radiative effects, TARFOX focused on the urban-industrial haze plume flowing from the eastern United States over the western Atlantic Ocean, whereas ACE-2 studied aerosols carried over the eastern Atlantic from both European urban/industrial and African mineral sources. These aerosols often have a marked influence on the top-of-atmosphere radiances measured by satellites. Shown there are contours of aerosol optical depth derived from radiances measured by the AVHRR sensor on the NOAA-11 satellite. The contours readily show that aerosols originating in North America, Europe, and Africa impact the radiative properties of air over the North Atlantic. However, the accurate derivation of flux changes, or radiative forcing, from the satellite measured radiances or retrieved optical depths remains a difficult challenge. In this paper we summarize key initial results from TARFOX and, to a lesser extent, ACE-2, with a focus on those results that allow an improved assessment of the flux changes caused by North Atlantic aerosols at middle latitudes.

Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

NASA Technical Reports Server (NTRS)

DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.;

Known and Newly Identified Semi-Volatile Organic Compounds from Biomass Burning in Amazonia: Variability and Relationship to Aerosol Physical Properties

NASA Astrophysics Data System (ADS)

Wernis, R. A.; Yee, L.; Isaacman-VanWertz, G. A.; Kreisberg, N. M.; de Sá, S. S.; Liu, Y.; Martin, S. T.; Alexander, M. L. L.; Palm, B. B.; Hu, W.; Campuzano-Jost, P.; Day, D. A.; Jimenez, J. L.; Artaxo, P.; Viegas, J.; Manzi, A. O.; Souza, R. A. F. D.; Hering, S. V.; Goldstein, A. H.

2016-12-01

Aerosols are a source of great uncertainty in radiative forcing predictions and have poorly understood impacts on human health. In many environments, biomass burning contributes a significant source of primary aerosol as well as reactive gas-phase precursors that can form secondary organic aerosol (SOA). One class of these precursors, semi-volatile organic compounds (SVOCs), has been shown to have a large contribution to the amount of SOA formed from fire emissions. At present, SVOC emissions from biomass burning are poorly constrained and understanding their contributions to SOA formation is an important research challenge. In the Amazonian dry season, biomass burning is a major source of gases and aerosols reducing regional air quality. As part of the GoAmazon 2014/5 field campaign, we deployed the Semi-Volatile Thermal desorption Aerosol Gas Chromatograph (SV-TAG) instrument at the rural T3 site, 60 km to the west of Manaus, Brazil to measure hourly concentrations of SVOCs in the gas and particle phases. This comprehensive technique detects thousands of compounds, enabling the discovery of previously unidentified compounds. In this work we explore compounds for which a correlation with well-known biomass burning tracers is observed to discover the identities of new markers. We discuss contributions to the total organic aerosol from over 30 well-known, rarely reported and newly identified biomass burning markers. We examine the relationship between biomass burning aerosol composition and aerosol physical properties as measured at the T3 site. Additionally, we report gas-particle partitioning of all identified compounds with comparison to theoretical predictions. We find that the commonly used biomass burning tracer levoglucosan existed entirely in the particle phase and contributed 0.6% and 0.3% of total organic aerosol mass in the dry and wet seasons, respectively.

Long-range Transport of Aerosol at a Mountain Site in the Western Mediterranean Basin

NASA Astrophysics Data System (ADS)

Roberts, Greg; Corrigan, Craig; Ritchie, John; Pont, Véronique; Claeys, Marine; Sciare, Jean; Dulac, François

2016-04-01

The Mediterranean Region has been identified as sensitive to changes in the hydrological cycle, which could affect the water resources for millions of people by the turn of the century. However, prior to recent observations, most climate models have not accounted for the impacts of aerosol in this region. Past airborne studies have shown that aerosol sources from Europe and Africa are often transported throughout the lower troposphere; yet, because of their complex vertical distribution, it is a challenge to capture the variability and quantify the contribution of these sources to the radiative budget and precipitation processes. The PAEROS ChArMEx Mountain Experiment (PACMEx) complemented the regional activities by collecting aerosol data from atop a mountain on the island of Corsica, France in order to assess boundary layer / free troposphere atmospheric processes. In June/July 2013, PACMEx instruments were deployed at 2000 m.asl near the center of Corsica, France to complement ground-based aerosol observations at 550 m.asl on the northern peninsula, as well as airborne measurements. Comparisons between the peninsula site and the mountain site show similar general trends in aerosol properties; yet, differences in aerosol properties reveal the myriad transport mechanisms over the Mediterranean Basin. Using aerosol physicochemical data coupled with back trajectory analysis, different sources have been identified including Saharan dust transport, residual dust mixed with sea salt, anthropogenic emissions from Western Europe, and a period of biomass burning from Eastern Europe. Each period exhibits distinct signatures in the aerosol related to transport processes above and below the boundary layer. In addition, the total aerosol concentrations at the mountain site revealed a strong diurnal cycling the between the atmospheric boundary layer and the free troposphere, which is typical of mountain-top observations. PACMEx was funded by the National Science Foundation (NSF) as a cooperative collaboration with French research agencies (INSU-MISTRALS, ANR-ADRIMED, and Météo France).

A Global Aerosol Model Forecast for the ACE-Asia Field Experiment

NASA Technical Reports Server (NTRS)

Chin, Mian; Ginoux, Paul; Lucchesi, Robert; Huebert, Barry; Weber, Rodney; Anderson, Tad; Masonis, Sarah; Blomquist, Byron; Bandy, Alan; Thornton, Donald

2003-01-01

We present the results of aerosol forecast during the Aerosol Characterization Experiment (ACE-Asia) field experiment in spring 2001, using the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model and the meteorological forecast fields from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The aerosol model forecast provides direct information on aerosol optical thickness and concentrations, enabling effective flight planning, while feedbacks from measurements constantly evaluate the model, making successful model improvements. We verify the model forecast skill by comparing model predicted total aerosol extinction, dust, sulfate, and SO2 concentrations with those quantities measured by the C-130 aircraft during the ACE-Asia intensive operation period. The GEOS DAS meteorological forecast system shows excellent skills in predicting winds, relative humidity, and temperature for the ACE-Asia experiment area as well as for each individual flight, with skill scores usually above 0.7. The model is also skillful in forecast of pollution aerosols, with most scores above 0.5. The model correctly predicted the dust outbreak events and their trans-Pacific transport, but it constantly missed the high dust concentrations observed in the boundary layer. We attribute this missing dust source to the desertification regions in the Inner Mongolia Province in China, which have developed in recent years but were not included in the model during forecasting. After incorporating the desertification sources, the model is able to reproduce the observed high dust concentrations at low altitudes over the Yellow Sea. Two key elements for a successful aerosol model forecast are correct source locations that determine where the emissions take place, and realistic forecast winds and convection that determine where the aerosols are transported. We demonstrate that our global model can not only account for the large-scale intercontinental transport, but also produce the small-scale spatial and temporal variations that are adequate for aircraft measurements planning.

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

EPA Science Inventory

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 ...

A smog chamber study coupling a photoionization aerosol electron/ion spectrometer to VUV synchrotron radiation: organic and inorganic-organic mixed aerosol analysis

NASA Astrophysics Data System (ADS)

Baeza-Romero, María Teresa; Gaie-Levrel, Francois; Mahjoub, Ahmed; López-Arza, Vicente; Garcia, Gustavo A.; Nahon, Laurent

2016-07-01

A reaction chamber was coupled to a photoionization aerosol time-of-flight mass spectrometer based on an electron/ion coincidence scheme and applied for on-line analysis of organic and inorganic-organic mixed aerosols using synchrotron tunable vacuum ultraviolet (VUV) photons as the ionization source. In this proof of principle study, both aerosol and gas phase were detected simultaneously but could be differentiated. Present results and perspectives for improvement for this set-up are shown in the study of ozonolysis ([O3] = 0.13-3 ppm) of α-pinene (2-3 ppm), and the uptake of glyoxal upon ammonium sulphate. In this work the ozone concentration was monitored in real time, together with the particle size distributions and chemical composition, the latter taking advantage of the coincidence spectrometer and the tuneability of the synchrotron radiation as a soft VUV ionization source.

Development of Atmospheric Chemistry-Aerosol Transport Model for Bioavailable Iron From Dust and Combustion Source

NASA Astrophysics Data System (ADS)

Ito, A.; Feng, Y.

2009-12-01

An accurate prediction of bioavailable iron fraction for ocean biota is hampered by uncertainties in modeling soluble iron fractions in atmospheric aerosols. It has been proposed that atmospheric processing of mineral aerosols by anthropogenic pollutants may be a key pathway to transform insoluble iron into soluble forms. The dissolution of dust minerals strongly depends on solution pH, which is sensitive to the heterogeneous uptake of soluble gases by the dust particle. Due to the complexity, previous model assessments generally use a common assumption in thermodynamical equilibrium between gas and aerosol phases. Here, we compiled an emission inventory of iron from combustion and dust source, and incorporated a dust iron dissolution scheme in a global chemistry-aerosol transport model (IMPACT). We will examine and discuss the uncertainties in estimation of dissolved iron as well as comparisons of the model results with available observations.

From OLS to VIIRS, an overview of nighttime satellite aerosol retrievals using artificial light sources

NASA Astrophysics Data System (ADS)

Zhang, J.; Miller, S. D.; Reid, J. S.; Hyer, E. J.; McHardy, T. M.

2015-12-01

Compared to abundant daytime satellite-based observations of atmospheric aerosol, observations at night are relatively scarce. In particular, conventional satellite passive imaging radiometers, which offer expansive swaths of spatial coverage compared to non-scanning lidar systems, lack sensitivity to most aerosol types via the available thermal infrared bands available at night. In this talk, we make the fundamental case for the importance of nighttime aerosol information in forecast models, and the need to mitigate the existing nocturnal gap. We review early attempts at estimating nighttime aerosol optical properties using the modulation of stable artificial surface lights. Initial algorithm development using DMSP Operational Linescan System (OLS) has graduated to refined techniques based on the Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB). We present examples of these retrievals for selected cases and compare the results to available surface-based point-source validation data.

Semi-continuous measurement and characteristics of water-soluble organic carbon and ions of PM2.5 aerosol with PILS-TOC-IC in Baengnyeong Island

NASA Astrophysics Data System (ADS)

Kang, S.; Kim, K.; Park, G.; Ban, J.; Park, D.; Bae, M. S.; Shin, H. J.; Lee, M.; Seo, Y.; Choi, J.; Jung, D.; Seo, S.; Lee, T.; Kim, D. S.

2016-12-01

Aerosols have an important effect from scattering and absorbing the solar energy and indirectly by acting as cloud condensation nuclei and also some of the effects of aerosols are reduction in visibility, deterioration of human health, and deposition of pollutants to ecosystems. In various experimental results were showed that organic compounds have an important fraction from 10 to 70% of the total aerosol mass. Organic carbon contains water-soluble organic carbon (WSOC) and water insoluble organic carbon. WSOC are involved in the most unknown liquid-phase chemistry of wet aerosol and clouds. It is also worked as cloud condensation nuclei (CCN). Formation of secondary organic aerosol by chemical reaction of hydrocarbon compounds is a source of main pollution of WSOC compounds. Study of pollution source of WSOC is important method for creation process of secondary organic aerosol that completely has not studied.Analysis of WSOC is important and need to real-time measurement system for definition of chemical cause and sources. In this study, Particle-into-liquid sampler (PILS) coupled with total organic carbon (TOC) analyser and ion chromatography (PILS-TOC-IC), was used for semi-continuous measurement of WSOC and ionic compounds of PM2.5 during April-June 2016 at Baengnyeong Island Atmospheric Research Center, operated by the Korea National Institute of Environmental Research (NIER). PILS-TOC-IC can provide chemical information about real-time changes from ions composition and concentrations of WSOC and ionic compounds.

[Composition and source of atmosphere aerosol water soluble ions over the East China Sea in winter].

PubMed

He, Yu-Hui; Yang, Gui-Peng; Zhang, Hong-Hai

2011-08-01

With the ion chromatographic method, the water-soluble ion concentrations of Cl(-), NO3(-), SO4(2-) , CH3SO3(-) (MSA), Na+, K+, NH4+, Mg2+ and Ca2+ in the atmospheric aerosol over the East China Sea in winter 2009 was determined and the sources of these ions was investigated through correlation analysis by SPSS (statistical package for social sciences) software. The results indicated that the concentrations of secondary ions in aerosol were the highest (non-sea-salt sulfates nss-SO4(2-), NO3(-), NH4+), accounting for 78.4% of total determining ions. The calculation results of equivalent concentration of anions and cations showed that the acid ions of aerosol were neutralized inadequately. The stoichiometry of NH4+ in different compounds showed that NH4HSO4 was the main binding form of NH4+ and SO4(2-) in the aerosol. The concentration of methanesulfonic acid (MSA) was low, and the average value was (0.0088 +/- 0.0037) microg x m(-3). According to calculation, the contribution of sea-salt sulfates was 4.5% to total sulfates, and that of biogenous sulfates was 1.4% to non-sea-salt sulfate (nss-SO4(2-)), showing that human input was the main source of sulfates in aerosol over the East China Sea. In addition, nss-SO4(2-)/NO3(-) in the aerosol was 1.08, reflecting that China's energy structure adjustment played an important role in recent years.

Characterization of aerosol composition, concentrations, and sources at Baengnyeong Island, Korea using an aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Lee, Taehyoung; Choi, Jinsoo; Lee, Gangwoong; Ahn, Junyoung; Park, Jin Soo; Atwood, Samuel A.; Schurman, Misha; Choi, Yongjoo; Chung, Yoomi; Collett, Jeffrey L.

2015-11-01

To improve understanding of the sources and chemical properties of particulate pollutants on the western side of the Korean Peninsula, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) measured non-refractory fine (PM1) particles from May to November, 2011 at Baengnyeong Island, South Korea. Organic matter and sulfate were generally the most abundant species and exhibited maximum concentrations of 36 μg/m3 and 39 μg/m3, respectively. Nitrate concentrations peaked at 32 μg/m3 but were typically much lower than sulfate and organic matter concentrations. May, September, October, and November featured the highest monthly average concentrations, with lower concentrations typically observed from June through August. Potential source contribution function (PSCF) analysis and individual case studies revealed that transport from eastern China, an area with high SO2 emissions, was associated with high particulate sulfate concentrations at the measurement site. Observed sulfate aerosol sometimes was fully neutralized by ammonium but often was acidic; the average ammonium to sulfate molar ratio was 1.49. Measured species size distributions revealed a range of sulfate particle size distributions with modes between 100 and 600 nm. Organic aerosol source regions were widespread, including contributions from eastern China and South Korea. Positive matrix factorization (PMF) analysis indicated three "factors," or types of organic aerosol, comprising one primary, hydrocarbon-like organic aerosol (HOA) and two oxidized organic aerosol (OOA) components, including a more oxidized (MO-OOA) and a less oxidized (LO-OOA) oxidized organic aerosol. On average, HOA and OOA contributed 21% and 79% of the organic mass (OM), respectively, with the MO-OOA fraction nearly three times as abundant as the LO-OOA fraction. Biomass burning contributions to observed OM were low during the late spring/early summer agricultural burning season in eastern China, since airflow into eastern China during the Asian Monsoon generally prevents transport of emissions eastward to the Korean Peninsula. Concentrations of the m/z 60 AMS biomass burning marker were more abundant in autumn, when transport patterns appeared to bring some smoke from fires in northern Asia to the island.

High summertime aerosol organic functional group concentrations from marine and seabird sources at Ross Island, Antarctica, during AWARE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Jun; Dedrick, Jeramy; Russell, Lynn M.

Observations of the organic components of the natural aerosol are scarce in Antarctica, which limits our understanding of natural aerosols and their connection to seasonal and spatial patterns of cloud albedo in the region. From November 2015 to December 2016, the ARM West Antarctic Radiation Experiment (AWARE) measured submicron aerosol properties near McMurdo Station at the southern tip of Ross Island. Submicron organic mass (OM), particle number, and cloud condensation nuclei concentrations were higher in summer than other seasons. The measurements included a range of compositions and concentrations that likely reflected both local anthropogenic emissions and natural background sources. We isolated themore » natural organic components by separating a natural factor and a local combustion factor. The natural OM was 150 times higher in summer than in winter. The local anthropogenic emissions were not hygroscopic and had little contribution to the CCN concentrations. Natural sources that included marine sea spray and seabird emissions contributed 56 % OM in summer but only 3 % in winter. The natural OM had high hydroxyl group fraction (55 %), 6 % alkane, and 6 % amine group mass, consistent with marine organic composition. In addition, the Fourier transform infrared (FTIR) spectra showed the natural sources of organic aerosol were characterized by amide group absorption, which may be from seabird populations. Finally, carboxylic acid group contributions were high in summer and associated with natural sources, likely forming by secondary reactions.« less

High summertime aerosol organic functional group concentrations from marine and seabird sources at Ross Island, Antarctica, during AWARE

DOE PAGES

Liu, Jun; Dedrick, Jeramy; Russell, Lynn M.; ...

2018-01-18

Observations of the organic components of the natural aerosol are scarce in Antarctica, which limits our understanding of natural aerosols and their connection to seasonal and spatial patterns of cloud albedo in the region. From November 2015 to December 2016, the ARM West Antarctic Radiation Experiment (AWARE) measured submicron aerosol properties near McMurdo Station at the southern tip of Ross Island. Submicron organic mass (OM), particle number, and cloud condensation nuclei concentrations were higher in summer than other seasons. The measurements included a range of compositions and concentrations that likely reflected both local anthropogenic emissions and natural background sources. We isolated themore » natural organic components by separating a natural factor and a local combustion factor. The natural OM was 150 times higher in summer than in winter. The local anthropogenic emissions were not hygroscopic and had little contribution to the CCN concentrations. Natural sources that included marine sea spray and seabird emissions contributed 56 % OM in summer but only 3 % in winter. The natural OM had high hydroxyl group fraction (55 %), 6 % alkane, and 6 % amine group mass, consistent with marine organic composition. In addition, the Fourier transform infrared (FTIR) spectra showed the natural sources of organic aerosol were characterized by amide group absorption, which may be from seabird populations. Finally, carboxylic acid group contributions were high in summer and associated with natural sources, likely forming by secondary reactions.« less

Unspeciated organic emissions from combustion sources and their influence on the secondary organic aerosol budget in the United States

EPA Science Inventory

Secondary organic aerosol (SOA) formed from the atmospheric oxidation of nonmethane organic gases (NMOG) is a major contributor to atmospheric aerosol mass. Emissions and smog chamber experiments were performed to investigate SOA formation from gasoline vehicles, diesel vehicles,...

“Modeling Trends in Aerosol Direct Radiative Effects over the Northern Hemisphere using a Coupled Meteorology-Chemistry Model”

EPA Science Inventory

While aerosol radiative effects have been recognized as some of the largest sources of uncertainty among the forcers of climate change, the verification of the spatial and temporal variability of the magnitude and directionality of aerosol radiative forcing has remained challengi...

Assessment of the Interactions Among Tropospheric Aerosol Loading, Radiative Balance and Clouds Through Examination of Their Multi-decadal Trends

EPA Science Inventory

While aerosol radiative effects have been recognized as some of the largest sources of uncertainty among the forcers of climate change, the verification of the spatial and temporal variability of aerosol radiative forcing has remained challenging. Anthropogenic emissions of prima...

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Mian; Dubovik, Oleg; Holben, Brent; Torres, Omar; Anderson, Tad; Quinn, Patricia; Ginoux, Paul

2004-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET, satellite retrievals from the TOMS instrument, and field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption. and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Mian; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

2003-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine what are the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

NASA Technical Reports Server (NTRS)

Chin, Main; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

2004-01-01

Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

Characterization of polar organic compounds and source analysis of fine organic aerosols in Hong Kong

NASA Astrophysics Data System (ADS)

Li, Yunchun

Organic aerosols, as an important fraction of airborne particulate mass, significantly affect the environment, climate, and human health. Compared with inorganic species, characterization of individual organic compounds is much less complete and comprehensive because they number in thousands or more and are diverse in chemical structures. The source contributions of organic aerosols are far from being well understood because they can be emitted from a variety of sources as well as formed from photochemical reactions of numerous precursors. This thesis work aims to improve the characterization of polar organic compounds and source apportionment analysis of fine organic carbon (OC) in Hong Kong, which consists of two parts: (1) An improved analytical method to determine monocarboxylic acids, dicarboxylic acids, ketocarboxylic acids, and dicarbonyls collected on filter substrates has been established. These oxygenated compounds were determined as their butyl ester or butyl acetal derivatives using gas chromatography-mass spectrometry. The new method made improvements over the original Kawamura method by eliminating the water extraction and evaporation steps. Aerosol materials were directly mixed with the BF 3/BuOH derivatization agent and the extracting solvent hexane. This modification improves recoveries for both the more volatile and the less water-soluble compounds. This improved method was applied to study the abundances and sources of these oxygenated compounds in PM2.5 aerosol samples collected in Hong Kong under different synoptic conditions during 2003-2005. These compounds account for on average 5.2% of OC (range: 1.4%-13.6%) on a carbon basis. Oxalic acid was the most abundant species. Six C2 and C3 oxygenated compounds, namely oxalic, malonic, glyoxylic, pyruvic acids, glyoxal, and methylglyoxal, dominated this suite of oxygenated compounds. More efforts are therefore suggested to focus on these small compounds in understanding the role of oxygenated compounds in aerosol chemistry and physics. By reference to tracers for the major organic aerosol sources, it is deduced that the oxygenated compounds are mainly of secondary origin and direct/indirect contribution from biomass burning could also be important. The chemical composition of these oxygenated species in PM2.5 samples in Hong Kong provide useful information to further ambient and model study in the aspects of chemical formation pathways and speciated organic mass distribution. (2) Source apportionment of PM2.5 organic aerosols in Hong Kong were carried out in two studies. In the first study, chemical characterization and source analysis involved samples collected on high particulate matter (PM) days (avg. PM 2.5 >84 mug m-3) at six general stations and one roadside station from October to December in 2003. Analysis of synoptic weather conditions identified three types of high PM episodes: local, regional transport (RT) and long-range transport (LRT). Roadside samples were discussed separately. Using chemical mass balance (CMB) model, contributions of major primary sources (vehicle exhaust, cooking, biomass burning, cigarette smoke, vegetative detritus, and coal combustion) were estimated, which indicate that vehicle exhaust was the most important primary source, followed by cooking and biomass burning. All primary sources except vegetative detritus had the highest contributions at roadside station, in line with its site characteristics. Primary sources dominated roadside and local samples (>64% of fine OC), while un-apportioned OC (i.e., the difference between measured OC and apportioned primary OC) dominated RT and LRT episodes (>60% of fine OC) and un-apportioned OC had characteristics of secondary OC. In the second study, cold front episodes during winter 2004 and 2005 were targeted to investigate the effect of cold front-related LRT on chemical characteristics and organic aerosol sources of PM2.5 in Hong Kong. In comparison with days under influences of mainly local emissions or RT, cold front LRT brought more organic aerosols attributable to coal combustion and biomass burning. Both cold front episodes and RT brought in significant amount of secondary OC to Hong Kong. The relative abundances of major aerosol constituents (sulfate, nitrate, ammonium, organic matter, and elemental carbon) were similar in cold front periods and RT-dominated periods.

The effectiveness of an air cleaner in controlling droplet/aerosol particle dispersion emitted from a patient's mouth in the indoor environment of dental clinics.

PubMed

Chen, Chun; Zhao, Bin; Cui, Weilin; Dong, Lei; An, Na; Ouyang, Xiangying

2010-07-06

Dental healthcare workers (DHCWs) are at high risk of occupational exposure to droplets and aerosol particles emitted from patients' mouths during treatment. We evaluated the effectiveness of an air cleaner in reducing droplet and aerosol contamination by positioning the device in four different locations in an actual dental clinic. We applied computational fluid dynamics (CFD) methods to solve the governing equations of airflow, energy and dispersion of different-sized airborne droplets/aerosol particles. In a dental clinic, we measured the supply air velocity and temperature of the ventilation system, the airflow rate and the particle removal efficiency of the air cleaner to determine the boundary conditions for the CFD simulations. Our results indicate that use of an air cleaner in a dental clinic may be an effective method for reducing DHCWs' exposure to airborne droplets and aerosol particles. Further, we found that the probability of droplet/aerosol particle removal and the direction of airflow from the cleaner are both important control measures for droplet and aerosol contamination in a dental clinic. Thus, the distance between the air cleaner and droplet/aerosol particle source as well as the relative location of the air cleaner to both the source and the DHCW are important considerations for reducing DHCWs' exposure to droplets/aerosol particles emitted from the patient's mouth during treatments.

The effectiveness of an air cleaner in controlling droplet/aerosol particle dispersion emitted from a patient's mouth in the indoor environment of dental clinics

PubMed Central

Chen, Chun; Zhao, Bin; Cui, Weilin; Dong, Lei; An, Na; Ouyang, Xiangying

2010-01-01

Dental healthcare workers (DHCWs) are at high risk of occupational exposure to droplets and aerosol particles emitted from patients' mouths during treatment. We evaluated the effectiveness of an air cleaner in reducing droplet and aerosol contamination by positioning the device in four different locations in an actual dental clinic. We applied computational fluid dynamics (CFD) methods to solve the governing equations of airflow, energy and dispersion of different-sized airborne droplets/aerosol particles. In a dental clinic, we measured the supply air velocity and temperature of the ventilation system, the airflow rate and the particle removal efficiency of the air cleaner to determine the boundary conditions for the CFD simulations. Our results indicate that use of an air cleaner in a dental clinic may be an effective method for reducing DHCWs' exposure to airborne droplets and aerosol particles. Further, we found that the probability of droplet/aerosol particle removal and the direction of airflow from the cleaner are both important control measures for droplet and aerosol contamination in a dental clinic. Thus, the distance between the air cleaner and droplet/aerosol particle source as well as the relative location of the air cleaner to both the source and the DHCW are important considerations for reducing DHCWs' exposure to droplets/aerosol particles emitted from the patient's mouth during treatments. PMID:20031985

Aerosol Characteristics in the Northern Territory of Australia During the Dry Season With an Emphasis on Biomass Burning

DTIC Science & Technology

2005-08-01

properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning ...characterize the seasonal variation (beginning to end) in the aerosol properties of the region. The main source of aerosol is biomass burning , and... Burning Emissions Part III: Intensive Optical Properties of Biomass Burning Particles , Atmos. Chem. Phys. Discuss., 4 5201-5260 45. see e. g.

Implementing marine organic aerosols into the GEOS-Chem model

DOE PAGES

Gantt, B.; Johnson, M. S.; Crippa, M.; ...

2015-03-17

Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Modelmore » predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.« less

Sugars in Antarctic aerosol

NASA Astrophysics Data System (ADS)

Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

2015-10-01

The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the ;Mario Zucchelli; coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

Sources, seasonality, and trends of Southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

NASA Astrophysics Data System (ADS)

Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.

2015-07-01

We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the Southeast US during the summer-fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 km × 25 km resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the Southeast US. GEOS-Chem simulation of sulfate requires a missing oxidant, taken here to be stabilized Criegee intermediates, but which could alternatively reflect an unaccounted for heterogeneous process. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 20 % in the cloud convective layer at 1.5-3 km, and 20 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42-] + [NO3-])) is only 0.5-0.7 mol mol-1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by organic aerosol. This would explain the long-term decline of ammonium aerosol in the Southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the Southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the Southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 21 %. The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from August to October. These declines are due to shutdowns in both biogenic emissions and UV-driven photochemistry. Surface PM2.5 shows far less summer-to-winter decrease than AOD due to the offsetting effect of weaker boundary layer ventilation. The SEAC4RS aircraft data demonstrate that AODs measured from space are fundamentally consistent with surface PM2.5. This implies that satellites can be used reliably to infer surface PM2.5 over monthly timescales if a good CTM representation of the aerosol vertical profile is available.

Oxidative Potential of ambient particulate matter in Athens, Greece.

NASA Astrophysics Data System (ADS)

Paraskevopoulou, Despina; Bougiatioti, Aikaterini; Fang, Ting; Liakakou, Eleni; Weber, Rodney; Nenes, Athanasios; Mihalopoulos, Nikolaos

2017-04-01

Exposure of populations to airborne particulate matter (PM) is a leading cause of premature death worldwide. Oxidative stress resulting from exposure of chemical species present in PM is a mechanism thought to cause adverse health effects. Apart from radicals present in aerosol, species that can catalytically deplete the antioxidant buffering capacity of cells, called Oxidative Potential (OP), are thought to be particularly toxic. The variability of OP over location, particle age, source and environmental conditions is virtually unknown for most populated regions of the world. Motivated by this, we have built and deployed one of the first operational measurements of OP in Europe at the National Observatory of Athens site in downtown Athens, Greece. OP for fine and coarse mode is measured using a semi-automated dithiothreitol (DTT) assay developed at the Georgia Institute of Technology; the assay measures the oxidation rate of DTT by water-soluble aerosol constituents, and simulates the rate at which the same compounds would deplete antioxidants in-vivo. The DTT oxidation rate per unit volume of air (water-soluble "DTT activity") and aerosol size class (fine, coarse) are used as a measure of aerosol toxicity. We present continuous (24hr average) OP measurements in downtown Athens from July 2016 to January 2017, conducted through quartz fiber filter analysis. The dataset covers a broad range of aerosol sources (pollution from Europe, regional and local biomass burning, dust, marine aerosol, biogenic aerosol) and meteorological conditions. The daily water-soluble DTT activity ranges between 0.02-0.81 nmolmin-1 m-3 (averaging at 0.24 nmolmin-1 m-3) for fine aerosol and between 0.01-0.52 nmolmin-1 m-3 (averaging at 0.08 nmolmin-1 m-3) for coarse particulate matter, indicating that water-soluble fine mode aerosol components possess a significant fraction of the OP. The seasonal variability demonstrates a higher DTT activity during the coldest period of the year for both aerosol fractions; correlation analysis with aerosol tracers provides insights on the relative importance of each aerosol source. We find that OP study shows a reasonable correlation of DTT activity with brown carbon (BrC) (R2=0.47) that ameliorates when BrC derived from wood burning (BrCwb) is taken into consideration (R2=0.56). Wood burning is widely used for domestic heating during wintertime in Greece in place of fuel oil and natural gas since the 2012 economic crisis, so the high OP levels associated with this particular source may exacerbate the health impacts of PM inhalation during periods of intense wood burning. Further attribution of OP with aerosol tracers is then used to quantify the drivers of OP on a seasonal basis.

The Use of Satellite-Measured Aerosol Optical Depth to Constrain Biomass Burning Emissions Source Strength in a Global Model GOCART

NASA Technical Reports Server (NTRS)

Petrenko, Mariya; Kahn, Ralph; Chin, Mian; Soja, Amber; Kuesera, Tom; harshvardhan, E. M.

2012-01-01

Small particles in the atmosphere, called "atmospheric aerosol" have a direct effect on Earth climate through scattering and absorbing sunlight, and also an indirect effect by changing the properties of clouds, as they interact with solar radiation as well. Aerosol typically stays in the atmosphere for several days, and can be transported long distances, affecting air quality, visibility, and human health not only near the source, but also far downwind. Smoke from vegetation fires is one of the main sources of atmospheric aerosol; other sources include anthropogenic pollution, dust, and sea salt. Chemistry transport models (CTMs) are among the major tools for studying the atmospheric and climate effects of aerosol. Due to the considerable variation of aerosol concentrations and properties on many temporal and spatial scales, and the complexity of the processes involved, the uncertainties in aerosol effects on climate are large, as is featured in the latest report of Intergovernmental Panel on Climate Change (IPCC) in 2007. Reducing this uncertainty in the models is very important both for predicting future climate scenarios and for regional air quality forecasting and mitigation. During vegetation fires, also called biomass burning (BB) events, complex mixture of gases and particles is emitted. The amount of BB emissions is usually estimated taking into account the intensity and size of the fire and the properties of burning vegetation. These estimates are input into CTMs to simulate BB aerosol. Unfortunately, due to large variability of fire and vegetation properties, the quantity of BB emissions is very difficult to estimate and BB emission inventories provide numbers that can differ by up to the order of magnitude in some regions. Larger uncertainties in data input make uncertainties in model output larger as well. A powerful way to narrow the range of possible model estimates is to compare model output to observations. We use satellite observations of aerosol properties, specifically aerosol optical depth, which is directly proportional to the amount of aerosol in the atmosphere, and compare it to the model output. Assuming the model represents aerosol transport and particle properties correctly, the amount of BB emissions determines the simulated aerosol optical depth. In this study, we explore the regional performance of 13 commonly used emission estimates. These are each input to global Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. We then evaluate how well each emission estimate reproduces the smoke aerosol optical depth measured by the MODIS instrument. We compared GOCART-simulate aerosol optical depth with that measured from the satellite for 124 fire cases around the world during 2006 and 2007. We summarize the regional performance of each emission inventory and discuss reasons for their differences by considering the assumptions made during their development. We also show that because stronger wind disperses smoke plumes more readily, in cases with stronger wind, a larger increase in emission amount is needed to increase aerosol optical depth. In quiet, low-wind-speed environments, BB emissions produce a more significant increase in aerosol optical depth, other things being equal. Using the region-specific, quantitative relationships derived in our paper, together with the wind speed obtained from another source for a given fire case, we can constrain the amount of emission required in the model to reproduce the observations. The results of this paper are useful to the developers of BB emission inventories, as they show the strengths and weaknesses of individual emission inventories in different regions of the globe, and also for modelers who use these inventories and wish to improve their model results.

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

NASA Astrophysics Data System (ADS)

Bourgeois, Quentin; Ekman, Annica M. L.; Renard, Jean-Baptiste; Krejci, Radovan; Devasthale, Abhay; Bender, Frida A.-M.; Riipinen, Ilona; Berthet, Gwenaël; Tackett, Jason L.

2018-06-01

The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a 9-year period (2007-2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained in Aire sur l'Adour (France) using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT - and thus potentially located above low-level clouds - is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for processes determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

Temporal Variation of Aerosol Properties at a Rural Continental Site and Study of Aerosol Evolution through Growth Law Analysis

NASA Technical Reports Server (NTRS)

Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

2006-01-01

Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) onboard the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May, 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back-trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 meters. Analyses of size dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

NASA Astrophysics Data System (ADS)

D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

2016-01-01

Remote and free-tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, British Columbia, Canada (2182 m a.s.l., hereafter referred to as Whistler Peak). We evaluate the model for predictions of aerosol number, size, and composition during periods of free-tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model-measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in cloud when the measured relative humidity (RH) was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp, > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic emissions and without biomass-burning emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of Asian anthropogenic aerosol was found to be significant throughout all particle number concentrations, and increased N80 by more than 50 %, while decreasing the number of smaller particles because of suppression of new-particle formation and enhanced coagulation sink. Similarly, biomass burning influenced Whistler Peak during summer months, with an increase in N80 exceeding 5000 cm-3. Occasionally, Whistler Peak experienced N80 > 1000 cm-3 without significant influence from Asian anthropogenic or biomass-burning aerosol. Air masses were advected at low elevations through forested valleys during times when temperature and downwelling insolation were high, ideal conditions for formation of large sources of low-volatility biogenic secondary organic aerosol (SOA). This condensable material increased particle growth and hence N80. The low-cost filtering techniques and source apportionment used in this study can be used in other global models to give insight into the sources and processes that shape the aerosol at mountain sites, leading to a better understanding of mountain meteorology and chemistry.

Source attribution of aerosol size distributions and model evaluation using Whistler Mountain measurements and GEOS-Chem-TOMAS simulations

NASA Astrophysics Data System (ADS)

D'Andrea, S. D.; Ng, J. Y.; Kodros, J. K.; Atwood, S. A.; Wheeler, M. J.; Macdonald, A. M.; Leaitch, W. R.; Pierce, J. R.

2015-09-01

Remote and free tropospheric aerosols represent a large fraction of the climatic influence of aerosols; however, aerosol in these regions is less characterized than those polluted boundary layers. We evaluate aerosol size distributions predicted by the GEOS-Chem-TOMAS global chemical transport model with online aerosol microphysics using measurements from the peak of Whistler Mountain, BC, Canada (2182 m a.s.l.). We evaluate the model for predictions of aerosol number, size and composition during periods of free tropospheric (FT) and boundary-layer (BL) influence at "coarse" 4° × 5° and "nested" 0.5° × 0.667° resolutions by developing simple FT/BL filtering techniques. We find that using temperature as a proxy for upslope flow (BL influence) improved the model measurement comparisons. The best threshold temperature was around 2 °C for the coarse simulations and around 6 °C for the nested simulations, with temperatures warmer than the threshold indicating boundary-layer air. Additionally, the site was increasingly likely to be in-cloud when the measured RH was above 90 %, so we do not compare the modeled and measured size distributions during these periods. With the inclusion of these temperature and RH filtering techniques, the model-measurement comparisons improved significantly. The slope of the regression for N80 (the total number of particles with particle diameter, Dp > 80 nm) in the nested simulations increased from 0.09 to 0.65, R2 increased from 0.04 to 0.46, and log-mean bias improved from 0.95 to 0.07. We also perform simulations at the nested resolution without Asian anthropogenic (AA) emissions and without biomass-burning (BB) emissions to quantify the contribution of these sources to aerosols at Whistler Peak (through comparison with simulations with these emissions on). The long-range transport of AA aerosol was found to be significant throughout all particle number concentrations, and increased the number of particles larger than 80 nm (N80) by more than 50 %, while decreasing the number of smaller particles because of suppression of new-particle formation and enhanced coagulation sink. Similarly, BB influenced Whistler Peak during summer months, with an increase in N80 exceeding 5000 cm-3. Occasionally, Whistler Peak experienced N80 > 1000 cm-3 without significant influence from AA or BB aerosol. Air masses were advected at low elevations through forested valleys during times when temperature and downwelling insolation were high, ideal conditions for formation of large sources of low-volatility biogenic secondary organic aerosol (SOA). This condensable material increased particle growth and hence N80. The low-cost filtering techniques and source apportionment used in this study can be used in other global models to give insight into the sources and processes that shape the aerosol at mountain sites, leading to a better understanding of mountain meteorology and chemistry.

Sources of atmospheric aerosols in Ankara (Turkey) atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuncel, S.G.; Yatin, M.; Aras, N.K.

1996-12-31

Ankara was heavily polluted owing to combustion of coal and fuel oil for space heating. Air quality over the city improved after 1993 due to use of low sulfur coal and natural gas for residential heating. These regulatory actions resulted in a dramatic decrease in SO{sub 2} concentrations measured in the air quality network, after 1990. Although concentration of particulate matter also decreased in the same period, the decrease was not as dramatic as that observed in SO{sub 2} concentrations, suggesting that sources other than space heating also contribute on observed aerosol concentrations. Currently, the concentrations of suspended particles aremore » slightly below the air quality standards effective in Turkey. A better source receptor relation must be established to reduce atmospheric levels of particulate matter. In this study, sources contributing to the observed levels of particles was determined through a receptor modeling approach. Factors controlling the observed concentrations of elements and ions were determined by relating their concentrations, to source strengths and determined by relating their concentrations, to source strengths and meteorological parameters. Residential heating was found out to be the main source of anthropogenic elements in Ankara. In the second part of the study, sources contributing on observed concentrations of elements were determined by a principal component analysis and relative contribution of each source were determined by Chemical Mass Balance study. The results indicated that, the airborne soil is the most important source of aerosol in the Ankara atmosphere during summer season, but emissions from coal combustion dominates aerosol mass during winter months.« less

The relative role of Amazonian and non-Amazonian fires in building up the aerosol optical depth in South America: A five year study (2005-2009)

NASA Astrophysics Data System (ADS)

Castro Videla, Fernando; Barnaba, Francesca; Angelini, Federico; Cremades, Pablo; Gobbi, Gian Paolo

2013-03-01

In South America (SA) biomass burning is the major source of atmospheric aerosols. Fires are mostly registered in the dry season (July-November) and are mainly concentrated in the Amazonia and Cerrado regions. Nonetheless, the growing systematic employment of fires for land clearing and pasture maintenance across the SA continent is introducing other, potentially significant, sources of BB aerosols. This study investigates the relative contributions of different SA biomass burning regions in building up the continental aerosol load. To this purpose, the SA continent is divided into four biomass burning source regions and their impact on the aerosol optical depth (AOD) is evaluated in eight different SA target domains. The dataset used includes multi-year (2005-2009) satellite observations of both aerosol and fires and model-based atmospheric trajectories. The methodology followed couples fire counts and atmospheric transport through the definition of a specific quantity, referred to as ‘fire weighted residence time’ (FWRT), which is used to assess the contribution of the four identified fire source regions to the continental aerosol load. Results show that local fires play an important role in building up the regional aerosols load all over SA. Nevertheless, in some regions, contribution of BB aerosols transported from outside their boundaries is comparable to the local one. The major ‘smoke exporter’ regions are found to be the eastern Brazil and the Amazonia-Cerrado regions. In the dry season, due to the typical continental circulation pattern, the first is estimated to contribute to half of the AOD in Northern Amazonia, Southern Amazonia and Cerrado regions, while over 30% of the AOD in Paraguay and North Argentina derives from the Amazonia-Cerrado fires. Due to the presence of the inter-tropical convergence zone, which decouples wind circulation of the two hemispheres, regions north of the Equator (Venezuela, Guyana, Suriname) are found to receive almost no contribution to the local AOD from fires occurring in the nearby active regions of Amazonia and Caatinga. Similarly, Venezuela fires are shown not to impact the Northern Amazonia AOD. Finally, in excluding the continental fire driver of some AOD enhancements observed in the wet season, this study indirectly points to an important role of aerosol transoceanic transport from Africa.

Long-term aerosol climatology over Indo-Gangetic Plain: Trend, prediction and potential source fields

NASA Astrophysics Data System (ADS)

Kumar, M.; Parmar, K. S.; Kumar, D. B.; Mhawish, A.; Broday, D. M.; Mall, R. K.; Banerjee, T.

2018-05-01

Long-term aerosol climatology is derived using Terra MODIS (Collection 6) enhanced Deep Blue (DB) AOD retrieval algorithm to investigate decadal trend (2006-2015) in columnar aerosol loading, future scenarios and potential source fields over the Indo-Gangetic Plain (IGP), South Asia. Satellite based aerosol climatology was analyzed in two contexts: for the entire IGP considering area weighted mean AOD and for nine individual stations located at upper (Karachi, Multan, Lahore), central (Delhi, Kanpur, Varanasi, Patna) and lower IGP (Kolkata, Dhaka). A comparatively high aerosol loading (AOD: 0.50 ± 0.25) was evident over IGP with a statistically insignificant increasing trend of 0.002 year-1. Analysis highlights the existing spatial and temporal gradients in aerosol loading with stations over central IGP like Varanasi (decadal mean AOD±SD; 0.67 ± 0.28) and Patna (0.65 ± 0.30) exhibit the highest AOD, followed by stations over lower IGP (Kolkata: 0.58 ± 0.21; Dhaka: 0.60 ± 0.24), with a statistically significant increasing trend (0.0174-0.0206 year-1). In contrast, stations over upper IGP reveal a comparatively low aerosol loading, having an insignificant increasing trend. Variation in AOD across IGP is found to be mainly influenced by seasonality and topography. A distinct "aerosol pool" region over eastern part of Ganges plain is identified, where meteorology, topography, and aerosol sources favor the persistence of airborne particulates. A strong seasonality in aerosol loading and types is also witnessed, with high AOD and dominance of fine particulates over central to lower IGP, especially during post-monsoon and winter. The time series analyses by autoregressive integrated moving average (ARIMA) indicate contrasting patterns in randomness of AOD over individual stations with better performance especially over central IGP. Concentration weighted trajectory analyses identify the crucial contributions of western dry regions and partial contributions from central Highlands and north-eastern India, in regulating AOD over stations across IGP. Although our analyses provide some attributes to the observed changes in aerosol loading, we conclude that the spatial and temporal pattern of aerosol properties is highly complex and dynamic over IGP, and require further investigation in order to reduce uncertainty in aerosol-climate model.

Refined Use of Satellite Aerosol Optical Depth Snapshots to Constrain Biomass Burning Emissions in the GOCART Model

NASA Technical Reports Server (NTRS)

Petrenko, Mariya; Kahn, Ralph; Chin, Mian; Limbacher, James

2017-01-01

Simulations of biomass burning (BB) emissions in global chemistry and aerosol transport models depend on external inventories, which provide location and strength of burning aerosol sources. Our previous work (Petrenko et al., 2012) shows that satellite snapshots of aerosol optical depth (AOD) near the emitted smoke plume can be used to constrain model-simulated AOD, and effectively, the assumed source strength. We now refine the satellite-snapshot method and investigate applying simple multiplicative emission correction factors for the widely used Global Fire Emission Database version 3 (GFEDv3) emission inventory can achieve regional-scale consistency between MODIS AOD snapshots and the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. The model and satellite AOD are compared over a set of more than 900 BB cases observed by the MODIS instrument during the 2004, and 2006-2008 biomass burning seasons. The AOD comparison presented here shows that regional discrepancies between the model and satellite are diverse around the globe yet quite consistent within most ecosystems. Additional analysis of including small fire emission correction shows the complimentary nature of correcting for source strength and adding missing sources, and also indicates that in some regions other factors may be significant in explaining model-satellite discrepancies. This work sets the stage for a larger intercomparison within the Aerosol Inter-comparisons between Observations and Models (AeroCom) multi-model biomass burning experiment. We discuss here some of the other possible factors affecting the remaining discrepancies between model simulations and observations, but await comparisons with other AeroCom models to draw further conclusions.

Dynamic Radioactive Source for Evaluating and Demonstrating Time-dependent Performance of Continuous Air Monitors.

PubMed

McLean, Thomas D; Moore, Murray E; Justus, Alan L; Hudston, Jonathan A; Barbé, Benoît

2016-11-01

Evaluation of continuous air monitors in the presence of a plutonium aerosol is time intensive, expensive, and requires a specialized facility. The Radiation Protection Services Group at Los Alamos National Laboratory has designed a Dynamic Radioactive Source, intended to replace plutonium aerosol challenge testing. The Dynamic Radioactive Source is small enough to be inserted into the sampler filter chamber of a typical continuous air monitor. Time-dependent radioactivity is introduced from electroplated sources for real-time testing of a continuous air monitor where a mechanical wristwatch motor rotates a mask above an alpha-emitting electroplated disk source. The mask is attached to the watch's minute hand, and as it rotates, more of the underlying source is revealed. The measured alpha activity increases with time, simulating the arrival of airborne radioactive particulates at the air sampler inlet. The Dynamic Radioactive Source allows the temporal behavior of puff and chronic release conditions to be mimicked without the need for radioactive aerosols. The new system is configurable to different continuous air monitor designs and provides an in-house testing capability (benchtop compatible). It is a repeatable and reusable system and does not contaminate the tested air monitor. Test benefits include direct user control, realistic (plutonium) aerosol spectra, and iterative development of continuous air monitor alarm algorithms. Data obtained using the Dynamic Radioactive Source has been used to elucidate alarm algorithms and to compare the response time of two commercial continuous air monitors.

Dynamic Radioactive Source for Evaluating and Demonstrating Time-dependent Performance of Continuous Air Monitors

DOE PAGES

McLean, Thomas D.; Moore, Murray E.; Justus, Alan L.; ...

2016-01-01

Evaluation of continuous air monitors in the presence of a plutonium aerosol is time intensive, expensive, and requires a specialized facility. The Radiation Protection Services Group at Los Alamos National Laboratory has designed a Dynamic Radioactive Source, intended to replace plutonium aerosol challenge testing. Furthermore, the Dynamic Radioactive Source is small enough to be inserted into the sampler filter chamber of a typical continuous air monitor. Time-dependent radioactivity is introduced from electroplated sources for real-time testing of a continuous air monitor where a mechanical wristwatch motor rotates a mask above an alpha-emitting electroplated disk source. The mask is attached tomore » the watch’s minute hand, and as it rotates, more of the underlying source is revealed. The alpha activity we measured increases with time, simulating the arrival of airborne radioactive particulates at the air sampler inlet. The Dynamic Radioactive Source allows the temporal behavior of puff and chronic release conditions to be mimicked without the need for radioactive aerosols. The new system is configurable to different continuous air monitor designs and provides an in-house testing capability (benchtop compatible). It is a repeatable and reusable system and does not contaminate the tested air monitor. Test benefits include direct user control, realistic (plutonium) aerosol spectra, and iterative development of continuous air monitor alarm algorithms. We also used data obtained using the Dynamic Radioactive Source to elucidate alarm algorithms and to compare the response time of two commercial continuous air monitors.« less

Physicochemical characterization of smoke aerosol during large-scale wildfires: Extreme event of August 2010 in Moscow

NASA Astrophysics Data System (ADS)

Popovicheva, O.; Kistler, M.; Kireeva, E.; Persiantseva, N.; Timofeev, M.; Kopeikin, V.; Kasper-Giebl, A.

2014-10-01

Enhancement of biomass burning-related research is essential for the assessment of large-scale wildfires impact on pollution at regional and global scale. Starting since 6 August 2010 Moscow was covered with thick smoke of unusually high PM10 and BC concentrations, considerably affected by huge forest and peat fires around megacity. This work presents the first comprehensive physico-chemical characterization of aerosols during extreme smoke event in Moscow in August 2010. Sampling was performed in the Moscow center and suburb as well as one year later, in August 2011 during a period when no biomass burning was observed. Small-scale experimental fires of regional biomass were conducted in the Moscow region. Carbon content, functionalities of organic/inorganic compounds, tracers of biomass burning (anhydrosaccharides), ionic composition, and structure of smoke were analyzed by thermal-optical analysis, FTIR spectroscopy, liquid and ion chromatography, and electron microscopy. Carbonaceous aerosol in August 2010 was dominated by organic species with elemental carbon (EC) as minor component. High average OC/EC near 27.4 is found, comparable to smoke of regional biomass smoldering fire, and exceeded 3 times the value observed in August 2011. Organic functionalities of Moscow smoke aerosols were hydroxyl, aliphatic, aromatic, acid and non-acid carbonyl, and nitro compound groups, almost all of them indicate wildfires around city as the source of smoke. The ratio of levoglucosan (LG) to mannosan near 5 confirms the origin of smoke from coniferous forest fires around megacity. Low ratio of LG/OC near 0.8% indicates the degradation of major molecular tracer of biomass burning in urban environment. Total concentration of inorganic ions dominated by sulfates SO4 2 - and ammonium NH4+ was found about 5 times higher during large-scale wildfires than in August 2011. Together with strong sulfate and ammonium absorbance in smoke aerosols, these observations prove the formation of secondary inorganic species associated with wildfire gaseous emissions and their transformation in aged smoke. Accumulation of carbonyl compounds during extreme smoke event in Moscow resulted from photochemical aging and secondary organic aerosol (SOA) formation in the urban atmosphere. The mixture of carbonaceous particles and dust revealed multicomponent structure of Moscow smoke aerosols, pointing the difference with non-smoke ambient aerosols. The abundance of group containing soot and tar balls approached at least a half of total aerosol concentration during extreme event, relating to elevated OC, EC and SOA. Fly ash groups contained calcium sulfates and carbonates from soil entrainment by hot air convection. Small-scale open fire experiments support the identification of specific chemical features of regional biomass burning and demonstrate the strong impact of large-scale wildfires on aerosol chemistry and air quality in highly polluted megacity.

Characterization of organic compounds in the PM2.5 aerosols in winter in an industrial urban area

NASA Astrophysics Data System (ADS)

Mikuška, P.; Křůmal, K.; Večeřa, Z.

2015-03-01

Urban aerosol particles in the fine fraction (PM2.5) were collected over the sampling interval of 24-hrs on quartz filters in Ostrava (Czech Republic) in winter 2012. The collected aerosols were analysed for selected organic compounds that serve as tracers of the main emission sources. The campaign was carried out under two different meteorological scenarios. During a smog episode due to high concentration of aerosols in the first part of the campaign, high concentrations of PM2.5 aerosols (mean concentration of 159 μg m-3) and PAHs bound to particles were found, while in the second part of the campaign, after the smog episode, much lower concentrations of aerosols (mean concentration of 49.3 μg m-3) were observed. Analysis of the source specific molecular markers and diagnostic ratios of PAHs, hopanes and alkanes imply that combustion of coniferous wood and coal in residential heating and traffic belong to the biggest emission sources of organic compounds associated with the PM2.5 aerosols collected during the winter campaign in Ostrava-Radvanice. The industrial production of coke and iron is another important contributor to the concentrations of BaP and other carcinogenic PAHs. The level of air pollution in Ostrava-Radvanice was considerably determined by the overall meteorological situation during the campaign. The highest concentrations of PM2.5 and bound organic compounds were found during a smog episode characterized by poor dispersion conditions due to temperature inversion and weak north-eastern wind, while during the subsequent period characterized by north-west or west wind, the concentrations of aerosols and bound organic compounds were much lower. Transboundary transport of polluted air from the Silesian Voivodeship could have contributed to the pollution in the Moravian-Silesian region during the smog episode.

Ubiquitous influence of wildfire emissions and secondary organic aerosol on summertime atmospheric aerosol in the forested Great Lakes region

NASA Astrophysics Data System (ADS)

Gunsch, Matthew J.; May, Nathaniel W.; Wen, Miao; Bottenus, Courtney L. H.; Gardner, Daniel J.; VanReken, Timothy M.; Bertman, Steven B.; Hopke, Philip K.; Ault, Andrew P.; Pratt, Kerri A.

2018-03-01

Long-range aerosol transport affects locations hundreds of kilometers from the point of emission, leading to distant particle sources influencing rural environments that have few major local sources. Source apportionment was conducted using real-time aerosol chemistry measurements made in July 2014 at the forested University of Michigan Biological Station near Pellston, Michigan, a site representative of the remote forested Great Lakes region. Size-resolved chemical composition of individual 0.5-2.0 µm particles was measured using an aerosol time-of-flight mass spectrometer (ATOFMS), and non-refractory aerosol mass less than 1 µm (PM1) was measured with a high-resolution aerosol mass spectrometer (HR-AMS). The field site was influenced by air masses transporting Canadian wildfire emissions and urban pollution from Milwaukee and Chicago. During wildfire-influenced periods, 0.5-2.0 µm particles were primarily aged biomass burning particles (88 % by number). These particles were heavily coated with secondary organic aerosol (SOA) formed during transport, with organics (average O/C ratio of 0.8) contributing 89 % of the PM1 mass. During urban-influenced periods, organic carbon, elemental carbon-organic carbon, and aged biomass burning particles were identified, with inorganic secondary species (ammonium, sulfate, and nitrate) contributing 41 % of the PM1 mass, indicative of atmospheric processing. With current models underpredicting organic carbon in this region and biomass burning being the largest combustion contributor to SOA by mass, these results highlight the importance for regional chemical transport models to accurately predict the impact of long-range transported particles on air quality in the upper Midwest, United States, particularly considering increasing intensity and frequency of Canadian wildfires.

Source apportionment of PM2.5 light extinction in an urban atmosphere in China.

PubMed

Lan, Zijuan; Zhang, Bin; Huang, Xiaofeng; Zhu, Qiao; Yuan, Jinfeng; Zeng, Liwu; Hu, Min; He, Lingyan

2018-01-01

Haze in China is primarily caused by high pollution of atmospheric fine particulates (PM 2.5 ). However, the detailed source structures of PM 2.5 light extinction have not been well established, especially for the roles of various organic aerosols, which makes haze management lack specified targets. This study obtained the mass concentrations of the chemical compositions and the light extinction coefficients of fine particles in the winter in Dongguan, Guangdong Province, using high time resolution aerosol observation instruments. We combined the positive matrix factor (PMF) analysis model of organic aerosols and the multiple linear regression method to establish a quantitative relationship model between the main chemical components, in particular the different sources of organic aerosols and the extinction coefficients of fine particles with a high goodness of fit (R 2 =0.953). The results show that the contribution rates of ammonium sulphate, ammonium nitrate, biomass burning organic aerosol (BBOA), secondary organic aerosol (SOA) and black carbon (BC) were 48.1%, 20.7%, 15.0%, 10.6%, and 5.6%, respectively. It can be seen that the contribution of the secondary aerosols is much higher than that of the primary aerosols (79.4% versus 20.6%) and are a major factor in the visibility decline. BBOA is found to have a high visibility destroying potential, with a high mass extinction coefficient, and was the largest contributor during some high pollution periods. A more detailed analysis indicates that the contribution of the enhanced absorption caused by BC mixing state was approximately 37.7% of the total particle absorption and should not be neglected. Copyright © 2017. Published by Elsevier B.V.

Spatial and temporal variations of aerosols around Beijing in summer 2006: Model evaluation and source apportionment

NASA Astrophysics Data System (ADS)

Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Kita, K.; Miyazaki, Y.; Hu, M.; Chang, S.-Y.; Blake, D. R.; Fast, J. D.; Zaveri, R. A.; Streets, D. G.; Zhang, Q.; Zhu, T.

2009-01-01

Regional aerosol model calculations were made using the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing) intensive campaign was conducted. Model calculations captured temporal variations of primary (such as elemental carbon (EC)) and secondary (such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODIS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 × 1000 km2 under an anticyclonic pressure system. This air mass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synoptic-scale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 h, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols.

Investigating the Climatic Impacts of Globally Shifted Anthropogenic Emissions

NASA Astrophysics Data System (ADS)

Wang, Y.; Jiang, J. H.; Su, H.

2014-12-01

With a quasi-exponential growth in industrialization since the mid-1990s, Asia has undergone a dramatic increase in anthropogenic emissions of aerosol and precursor gases to the atmosphere. Meanwhile, such emissions have been stabilized or reduced over North America and Europe. This geographical shift of global emission sources could potentially perturb the regional and global climate due to impact of aerosols on cloud properties, precipitation, and large-scale circulation. We use an atmospheric general circulation model (AGCM) with different aerosol scenarios to investigate the radiative and microphysical effects of anthropogenic aerosols on the large-scale circulation and regional climate over the globe. We conduct experiments to simulate the continental shift of aerosol distribution by contrasting two simulations using 1970 and 2010 anthropogenic emission sources. We found the elevation of aerosol concentrations in East and South Asia results in regional surface temperature cooling of -0.10° to -0.17°C, respectively, due to the enhanced solar extinction by aerosols and cloud reflectivity. The reduction of the local aerosol loadings in Europe causes a significant warming of +0.4°C. However, despite recent decreasing in aerosol emission, North America shows a cooling of -0.13°C, likely caused by increasing of cloudiness under the influence of modulated general circulation. These aerosol induced temperature changes are consistent with the observed temperature trends from 1980 to 2013 in the reanalysis data. Our study also predicts weaker East/South Asia summer monsoons due to strong regional aerosol forcing. Moreover, the ascending motion in the northern tropics is found to be weakened by asymmetrical aerosol forcing, resulting in the cross-equatorial shift of Hadley Circulation.

Iron solubility driven by speciation in dust sources to the ocean

USGS Publications Warehouse

Schroth, A.W.; Crusius, John; Sholkovitz, E.R.; Bostick, B.C.

2009-01-01

Although abundant in the Earths crust, iron is present at trace concentrations in sea water and is a limiting nutrient for phytoplankton in approximately 40% of the ocean. Current literature suggests that aerosols are the primary external source of iron to offshore waters, yet controls on iron aerosol solubility remain unclear. Here we demonstrate that iron speciation (oxidation state and bonding environment) drives iron solubility in arid region soils, glacial weathering products (flour) and oil combustion products (oil fly ash). Iron speciation varies by aerosol source, with soils in arid regions dominated by ferric (oxy)hydroxides, glacial flour by primary and secondary ferrous silicates and oil fly ash by ferric sulphate salts. Variation in iron speciation produces systematic differences in iron solubility: less than 1% of the iron in arid soils was soluble, compared with 2-3% in glacial products and 77-81% in oil combustion products, which is directly linked to fractions of more soluble phases. We conclude that spatial and temporal variations in aerosol iron speciation, driven by the distribution of deserts, glaciers and fossil-fuel combustion, could have a pronounced effect on aerosol iron solubility and therefore on biological productivity and the carbon cycle in the ocean. ?? 2009 Macmillan Publishers Limited.

Using stable isotopes to trace sources and formation processes of sulfate aerosols from Beijing, China

PubMed Central

Han, Xiaokun; Guo, Qingjun; Liu, Congqiang; Fu, Pingqing; Strauss, Harald; Yang, Junxing; Hu, Jian; Wei, Lianfang; Ren, Hong; Peters, Marc; Wei, Rongfei; Tian, Liyan

2016-01-01

Particulate pollution from anthropogenic and natural sources is a severe problem in China. Sulfur and oxygen isotopes of aerosol sulfate (δ34Ssulfate and δ18Osulfate) and water-soluble ions in aerosols collected from 2012 to 2014 in Beijing are being utilized to identify their sources and assess seasonal trends. The mean δ34S value of aerosol sulfate is similar to that of coal from North China, indicating that coal combustion is a significant contributor to atmospheric sulfate. The δ34Ssulfate and δ18Osulfate values are positively correlated and display an obvious seasonality (high in winter and low in summer). Although an influence of meteorological conditions to this seasonality in isotopic composition cannot be ruled out, the isotopic evidence suggests that the observed seasonality reflects temporal variations in the two main contributions to Beijing aerosol sulfate, notably biogenic sulfur emissions in the summer and the increasing coal consumption in winter. Our results clearly reveal that a reduction in the use of fossil fuels and the application of desulfurization technology will be important for effectively reducing sulfur emissions to the Beijing atmosphere. PMID:27435991

Vertical Structure and Sources of Aerosols in the Mediterranean Region (VESSAER)

NASA Astrophysics Data System (ADS)

Roberts, G. C.; Junkermann, W.; Leon, J.; Pont, V.; Mallet, M.; Augustin, P.; Dulac, F.

2012-12-01

The Mediterranean region has been identified as one of the most prominent global "Hot-Spots" in future climate change projections [Giorgi and Lionello, 2008] and is particularly characterized by its vulnerability to changes in the water cycle. To this end, the VESSAER campaign (VErtical Structure and Sources of AERosols in the Mediterranean Region) was designed to characterize the different sources of aerosol in the Mediterranean Basin and assess their regional impact on cloud microphysical and radiative properties. VESSAER was conducted on the ENDURO-KIT ultra-light aircraft [W. Junkermann, 2001] in late June-early July 2012. Activities include ground observations as well as aerosol lidar and sunphotometer measurements in conjunction with the airborne measurements. The VESSAER campaign complements existing ChArMEx (http://charmex.lsce.ipsl.fr/ ; PI: F. Dulac) and HyMeX (http://www.hymex.org/ ; PI: V. Ducroc and P. Drobinski) activities, which are the target of many European research institutes in 2012 and 2013. The main scientific goals during VESSAER are to investigate local versus long-range sources of aerosol and cloud condensation nuclei (CCN) and their vertical stratification in the lower troposphere, use aerosol hygroscopicity to study their evolution due to atmospheric processes, and couple in-situ airborne measurements with ground-based remote sensing to determine aerosol direct radiative impacts over a larger spatial scale. The background aerosol concentrations within the boundary layer (BL) in Corsica are nearly 2000 cm-3 (Dp > 10 nm); 50 cm-3 (Dp > 300 nm). We were surprised to find that nearly all of these particles are CCN-active at 0.3% supersaturation and presume that ageing and/or cloud processing play a role in rendering the aerosol in the Mediterranean Basin more hygroscopic. The vertical profiles during VESSAER clearly show the long-range transport of dust from the Saharan Desert and pollution from the European continent -- which were the two major sources of aerosol during the campaign. Two of the research flights coincided with CALIPSO overpasses. During both dust events, Saharan Dust layers are transported within the lower 5 km. Concentrations of large particles (Dp > 0.3 um) show a corresponding increase throughout the troposphere, and aerosol optical depth increased up to 0.7 (at 440 nm). Comparisons of the overpass with the in-situ measurements and ground-based lidar will be presented. In addition, layers of pollution above the BL show higher number concentrations (up to 6000 cm-3) and lower hygroscopicity than in the BL. These results suggest that downward mixing of European continental pollution contribute to the elevated background aerosol concentrations found throughout the Mediterranean Basin. Giorgi, F. and Lionello, P. (2008). Climate change projections for the Mediterranean region. Global and Planetary Change 63: 90-104. Junkermann, W. (2001). An ultralight aircraft as platform for research in the lower troposphere: System performance and first results from radiation transfer studies in stratiform aerosol layers and broken cloud conditions. Journal of Atmospheric and Oceanic Technology 18: 934 - 946. ---------------- This work was supported by the European Facility for Airborne Research (EUFAR), Météo-France, CEA, ADEME, COST Action ES0802 (Unmanned Aerial Systems in Atmospheric Research).

Impact of particle emissions of new laser printers on modeled office room

NASA Astrophysics Data System (ADS)

Koivisto, Antti J.; Hussein, Tareq; Niemelä, Raimo; Tuomi, Timo; Hämeri, Kaarle

2010-06-01

In this study, we present how an indoor aerosol model can be used to characterize particle emitter and predict influence of the source on indoor air quality. Particle size-resolved emission rates were quantified and the source's influence on indoor air quality was estimated by using office model simulations. We measured particle emissions from three modern laser printers in a flow-through chamber. Measured parameters were used as input parameters for an indoor aerosol model, which we then used to quantify the particle emission rates. The same indoor aerosol model was used to simulate the effect of the particle emission source inside an office model. The office model consists of a mechanically ventilated empty room and the particle source. The aerosol from the ventilation air was a filtered urban background aerosol. The effect of the ventilation rate was studied using three different ventilation ratios 1, 2 and 3 h -1. According to the model, peak emission rates of the printers exceeded 7.0 × 10 8 s -1 (2.5 × 10 12 h -1), and emitted mainly ultrafine particles (diameter less than 100 nm). The office model simulation results indicate that a print job increases ultrafine particle concentration to a maximum of 2.6 × 10 5 cm -3. Printer-emitted particles increased 6-h averaged particle concentration over eleven times compared to the background particle concentration.

Fine Aerosol Associated Non-Polar Organics in Jammu, AN Urban Location in the Foothill Region of North Western Himalayas

NASA Astrophysics Data System (ADS)

Yadav, S.; Bamotra, S.

2017-12-01

A comprehensive study was done on the mass, composition and sources of fine aerosol associated non-polar organics in Jammu, an urban location in the foothill region of North - Western Himalayas. Systematic multi-scale sampling was done from October, 2015 to February, 2017 to collect fine aerosol (PM2.5) samples every week using a Fine Particulate Sampler (Envirotech, APM 550 MFC) which operates at a constant flow rate of 16.7 L/minute. The Non- polar organic compounds comprising of n-alkanes, PAHs, isoprenoid hydrocarbons and nicotine were analyzed using Thermal desorption Gas Chromatography Mass Spectrometry (TD-GC-MS) method. The n-alkane associated diagnostic parameters include—mass weighted Averaged Chain Length (ACL); Carbon number with maximum concentration (Cmax); Petroleum derived n-alkanes (PNA%), Carbon Preference Index (CPI) and the percentage contribution of Wax n-alkanes from plants (WNA%). These diagnostic parameters along with PAH based molecular ratios were used to understand the diurnal and seasonal variations in different biogenic and petrogenic source contributions in this part of Himalayas. The presence of source specific tracers like Levoglucosan, Retene, Isoquinoline and nicotine also corroborated our findings. Further Fine aerosols associated Black Carbon, an important marker for burning was determined using Optical Transmissometer. Significant multiscale variations were found in the Fine aerosol load, associated Non-polar organics, source tracers/contributions and Black Carbon.

Influence of continental organic aerosols to the marine atmosphere over the East China Sea: Insights from lipids, PAHs and phthalates.

PubMed

Kang, Mingjie; Yang, Fan; Ren, Hong; Zhao, Wanyu; Zhao, Ye; Li, Linjie; Yan, Yu; Zhang, Yingjie; Lai, Senchao; Zhang, Yingyi; Yang, Yang; Wang, Zifa; Sun, Yele; Fu, Pingqing

2017-12-31

Total suspended particle (TSP) samples were collected during a marine cruise in the East China Sea from May 18 to June 12, 2014. They were analyzed for solvent extractable organic compounds (lipid compounds, PAHs and phthalates) using gas chromatography/mass spectrometry (GC/MS) to better understand the sources and source apportionment of aerosol pollution in the western North Pacific. Higher concentrations were observed in the terrestrially influenced aerosol samples on the basis of five-day backward air mass trajectories, especially for aerosols collected near coastal areas. Phthalates were found to be the dominant species among these measured compound classes (707±401ngm -3 for daytime and 313±155ngm -3 for nighttime), followed by fatty acids, fatty alcohols, n-alkanes and PAHs. In general, the daytime abundances for these compounds are higher than nighttime, possibly attributable to more intensive anthropogenic activities during the daytime. The factor analysis indicates that biomass burning, fungal activities and fossil fuel combustion maybe the main emission sources for organic aerosols over the East China Sea. This study demonstrates that the East Asian continent can be a natural emitter of biogenic and anthropogenic organics to the marine atmosphere through long-range transport, which controls the chemical composition and concentration of organic aerosols over the East China Sea. Copyright © 2017 Elsevier B.V. All rights reserved.

Levoglucosan and phenols in Antarctic marine, coastal and plateau aerosols.

PubMed

Zangrando, Roberta; Barbaro, Elena; Vecchiato, Marco; Kehrwald, Natalie M; Barbante, Carlo; Gambaro, Andrea

2016-02-15

Due to its isolated location, Antarctica is a natural laboratory for studying atmospheric aerosols and pollution in remote areas. Here, we determined levoglucosan and phenolic compounds (PCs) at diverse Antarctic sites: on the plateau, a coastal station and during an oceanographic cruise. Levoglucosan and PCs reached the Antarctic plateau where they were observed in accumulation mode aerosols (with median levoglucosan concentrations of 6.4 pg m(-3) and 4.1 pg m(-3), and median PC concentrations of 15.0 pg m(-3) and 7.3 pg m(-3)). Aged aerosols arrived at the coastal site through katabatic circulation with the majority of the levoglucosan mass distributed on larger particulates (24.8 pg m(-3)), while PCs were present in fine particles (34.0 pg m(-3)). The low levoglucosan/PC ratios in Antarctic aerosols suggest that biomass burning aerosols only had regional, rather than local, sources. General acid/aldehyde ratios were lower at the coastal site than on the plateau. Levoglucosan and PCs determined during the oceanographic cruise were 37.6 pg m(-3) and 58.5 pg m(-3) respectively. Unlike levoglucosan, which can only be produced by biomass burning, PCs have both biomass burning and other sources. Our comparisons of these two types of compounds across a range of Antarctic marine, coastal, and plateau sites demonstrate that local marine sources dominate Antarctic PC concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

10 Years of Asian Dust Storm Observations from SeaWiFS: Source, Pathway, and Interannual Variability

NASA Technical Reports Server (NTRS)

Hsu, N. Christina; Tsay, S.-C.; King, M.D.; Jeong, M.-J.

2008-01-01

In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol optical thickness and single scattering albedo over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. The new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. We have validated the satellite retrieved aerosol optical thickness with data from AERONET sunphotometers over desert and semi-desert regions. The comparisons show reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. The multiyear satellite measurements (1998 - 2007) from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with these dust outbreaks in East Asia. The monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

Potential sources of Southern Siberia aerosols by data of AERONET site in Tomsk, Russia

NASA Astrophysics Data System (ADS)

Shukurov, K. A.; Shukurova, L. M.

2017-11-01

For all days of measurements in 2002-2015 of volume concentration of aerosols at the AERONET Tomsk/Tomsk-22 station an array of 10-day backward trajectories of air parcels arriving in Tomsk into seven layers of the troposphere with heights in the range of 0.5-5.0 km is calculated using the trajectory model NOAA HYSPLIT_4. For the three fractions of the aerosol with particle sizes < 1.0 μm, 1.0-2.5 μm, 2.5-5.0 μm and their sum (< 5.0 μm), the field of capacity of the potential sources of aerosols of these fractions for southern Siberia is determined by the CWT (concentration weighted trajectory) method using the backward trajectory array. The analysis is carried out taking into account the processes both the scavenging of the aerosols with precipitation and the dry deposition. Trajectories arriving at different heights were analyzed taking into account the weight coefficients proportional to the backward light scattering coefficients of an aerosols at corresponding heights for warm and cold seasons in Western Siberia. The most capable (in unit of volume concentration μm3 /μm2 ) potential sources of these fractions for southern Siberia are located above North Africa, Eastern Siberia, Central Asia and the Dzhungarian desert in the Xinjiang-Uyghur Autonomous Region of China.

Composition and sources of carbonaceous aerosols in Northern Europe during winter

NASA Astrophysics Data System (ADS)

Glasius, M.; Hansen, A. M. K.; Claeys, M.; Henzing, J. S.; Jedynska, A. D.; Kasper-Giebl, A.; Kistler, M.; Kristensen, K.; Martinsson, J.; Maenhaut, W.; Nøjgaard, J. K.; Spindler, G.; Stenström, K. E.; Swietlicki, E.; Szidat, S.; Simpson, D.; Yttri, K. E.

2018-01-01

Sources of elemental carbon (EC) and organic carbon (OC) in atmospheric aerosols (carbonaceous aerosols) were investigated by collection of weekly aerosol filter samples at six background sites in Northern Europe (Birkenes, Norway; Vavihill, Sweden; Risoe, Denmark; Cabauw and Rotterdam in The Netherlands; Melpitz, Germany) during winter 2013. Analysis of 14C and a set of molecular tracers were used to constrain the sources of EC and OC. During the four-week campaign, most sites (in particular those in Germany and The Netherlands) were affected by an episode during the first two weeks with high concentrations of aerosol, as continental air masses were transported westward. The analysis results showed a clear, increasing north to south gradient for most molecular tracers. Total carbon (TC = OC + EC) at Birkenes showed an average concentration of 0.5 ± 0.3 μg C m-3, whereas the average concentration at Melpitz was 6.0 ± 4.3 μg C m-3. One weekly mean TC concentration as high as 11 μg C m-3 was observed at Melpitz. Average levoglucosan concentrations varied by an order of magnitude from 25 ± 13 ng m-3 (Birkenes) to 249 ± 13 ng m-3 (Melpitz), while concentrations of tracers of fungal spores (arabitol and mannitol) and vegetative debris (cellulose) were very low, showing a minor influence of primary biological aerosol particles during the North European winter. The fraction of modern carbon generally varied from 0.57 (Melpitz) to 0.91 (Birkenes), showing an opposite trend compared to the molecular tracers and TC. Total concentrations of 10 biogenic and anthropogenic carboxylic acids, mainly of secondary origin, were 4-53 ng m-3, with the lowest concentrations observed at Birkenes and the highest at Melpitz. However, the highest relative concentrations of carboxylic acids (normalized to TC) were observed at the most northern sites. Levels of organosulphates and nitrooxy organosulphates varied more than two orders of magnitude, from 2 to 414 ng m-3, between individual sites and samples. The three sites Melpitz, Rotterdam and Cabauw, located closest to source regions in continental Europe, showed very high levels of organosulphates and nitrooxy organosulphates (up to 414 ng m-3) during the first two weeks of the study, while low levels (<7 ng m-3) were found at all sites except Melpitz during the last week. The large variation in organosulphate levels probably reflects differences in the presence of acidic sulphate aerosols, known from laboratory studies to accelerate the formation of these compounds. On average, the ratio of organic sulphate to inorganic sulphate was 1.5 ± 1.0% (range 0.1-3.4%). Latin-hypercube source apportionment techniques identified biomass burning as the major source of OC for all samples at all sites (typically >40% of TC), while use and combustion of fossil fuels was the second most important source. Furthermore, EC from biomass burning accounted for 7-16% of TC, whereas EC from fossil sources contributed to <2-23% of TC, of which the highest percentages were observed for low-concentration aerosol samples. Unresolved non-fossil sources (such as cooking and biogenic secondary organic aerosols) did not account for more than 5-12% of TC. The results confirm that wood combustion is a major source to OC and EC in Northern Europe during winter.

Occurrence of pristine aerosol environments on a polluted planet.

PubMed

Hamilton, Douglas S; Lee, Lindsay A; Pringle, Kirsty J; Reddington, Carly L; Spracklen, Dominick V; Carslaw, Kenneth S

2014-12-30

Natural aerosols define a preindustrial baseline state from which the magnitude of anthropogenic aerosol effects on climate are calculated and are a major component of the large uncertainty in anthropogenic aerosol-cloud radiative forcing. This uncertainty would be reduced if aerosol environments unperturbed by air pollution could be studied in the present--day atmosphere, but the pervasiveness of air pollution makes identification of unperturbed regions difficult. Here, we use global model simulations to define unperturbed aerosol regions in terms of two measures that compare 1750 and 2000 conditions-the number of days with similar aerosol concentrations and the similarity of the aerosol response to perturbations in model processes and emissions. The analysis shows that the aerosol system in many present-day environments looks and behaves like it did in the preindustrial era. On a global annual mean, unperturbed aerosol regions cover 12% of the Earth (16% of the ocean surface and 2% of the land surface). There is a strong seasonal variation in unperturbed regions of between 4% in August and 27% in January, with the most persistent conditions occurring over the equatorial Pacific. About 90% of unperturbed regions occur in the Southern Hemisphere, but in the Northern Hemisphere, unperturbed conditions are transient and spatially patchy. In cloudy regions with a radiative forcing relative to 1750, model results suggest that unperturbed aerosol conditions could still occur on a small number of days per month. However, these environments are mostly in the Southern Hemisphere, potentially limiting the usefulness in reducing Northern Hemisphere forcing uncertainty.

"Investigation of Trends in Aerosol Direct Radiative Effects over North America Using a Coupled Meteorology-Chemistry Model"

EPA Science Inventory

While aerosol radiative effects have been recognized as some of the largest sources of uncertainty among the forcers of climate change, there has been little effort devoted to verification of the spatial and temporal variability of the magnitude and directionality of aerosol radi...

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

PubMed Central

Cheng, Yafang; Zheng, Guangjie; Wei, Chao; Mu, Qing; Zheng, Bo; Wang, Zhibin; Gao, Meng; Zhang, Qiang; He, Kebin; Carmichael, Gregory; Pöschl, Ulrich; Su, Hang

2016-01-01

Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to ~300 μg m−3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO2, which is oxidized by NO2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution. PMID:28028539

Sources and formation mechanisms of carbonaceous aerosol at a regional background site in the Netherlands: insights from a year-long radiocarbon study

NASA Astrophysics Data System (ADS)

Dusek, Ulrike; Hitzenberger, Regina; Kasper-Giebl, Anne; Kistler, Magdalena; Meijer, Harro A. J.; Szidat, Sönke; Wacker, Lukas; Holzinger, Rupert; Röckmann, Thomas

2017-03-01

We measured the radioactive carbon isotope 14C (radiocarbon) in various fractions of the carbonaceous aerosol sampled between February 2011 and March 2012 at the Cesar Observatory in the Netherlands. Based on the radiocarbon content in total carbon (TC), organic carbon (OC), water-insoluble organic carbon (WIOC), and elemental carbon (EC), we estimated the contribution of major sources to the carbonaceous aerosol. The main source categories were fossil fuel combustion, biomass burning, and other contemporary carbon, which is mainly biogenic secondary organic aerosol material (SOA). A clear seasonal variation is seen in EC from biomass burning (ECbb), with lowest values in summer and highest values in winter, but ECbb is a minor fraction of EC in all seasons. WIOC from contemporary sources is highly correlated with ECbb, indicating that biomass burning is a dominant source of contemporary WIOC. This suggests that most biogenic SOA is water soluble and that water-insoluble carbon stems mainly from primary sources. Seasonal variations in other carbon fractions are less clear and hardly distinguishable from variations related to air mass history. Air masses originating from the ocean sector presumably contain little carbonaceous aerosol from outside the Netherlands, and during these conditions measured carbon concentrations reflect regional sources. In these situations absolute TC concentrations are usually rather low, around 1.5 µg m-3, and ECbb is always very low ( ˜ 0.05 µg m-3), even in winter, indicating that biomass burning is not a strong source of carbonaceous aerosol in the Netherlands. In continental air masses, which usually arrive from the east or south and have spent several days over land, TC concentrations are on average by a factor of 3.5 higher. ECbb increases more strongly than TC to 0.2 µg m-3. Fossil EC and fossil WIOC, which are indicative of primary emissions, show a more moderate increase by a factor of 2.5 on average. An interesting case is fossil water-soluble organic carbon (WSOC, calculated as OC-WIOC), which can be regarded as a proxy for SOA from fossil precursors. Fossil WSOC has low concentrations when regional sources are sampled and increases by more than a factor of 5 in continental air masses. A longer residence time of air masses over land seems to result in increased SOA concentrations from fossil origin.

Estimation of Aerosol Direct Radiative Effects from Satellite and In Situ Measurements

NASA Technical Reports Server (NTRS)

Bergstrom, Robert W.; Russell, Philip B.; Schmid, Beat; Redemann, Jens; McIntosh, Dawn

2000-01-01

Ames researchers have combined measurements from satellite, aircraft, and the surface to estimate the effect of airborne particles (aerosols) on the solar radiation over the North Atlantic region. These aerosols (which come from both natural and pollution sources) can reflect solar radiation, causing a cooling effect that opposes the warming caused by carbon dioxide. Recently, increased attention has been paid to aerosol effects to better understand the Earth climate system.

Aerosol pollution potential from major population centers

NASA Astrophysics Data System (ADS)

Kunkel, D.; Tost, H.; Lawrence, M. G.

2012-09-01

Major population centers (MPCs) or mega-cities represent the largest of growing urban agglomerations with major societal and environmental implications. In terms of air quality they are seen as localized but strong emission sources of aerosols and trace gases which in turn affect air pollution levels in the city or in downwind regions. In the state-of-the-art atmospheric chemistry general circulation model EMAC, generic aerosol and gas phase tracers with equal emission source strengths at 46 MPC locations are used to study the balance between local pollution build up and pollution export, either vertically into the upper troposphere or horizontally, but remaining in the lower atmosphere. The insoluble gas phase tracers with fixed lifetimes are transported with the atmospheric circulation, while the aerosol tracers also undergo gravitational sedimentation as well as dry and wet deposition processes. The strength of low-level tracer export depends on the location of the emission source and prevailing meteorology, in particular on atmospheric stability and the height of the boundary layer and the mixing out of this layer. In contrast, vertical transport of tracer mass depends on the tracer's solubility: the more soluble a tracer is the less mass reaches altitudes above five kilometers. Hence, the mass of insoluble gas phase tracer above five kilometers can be up to ten times higher than the hydrophilic aerosol mass from the same source. In the case of aerosol tracers, pollution build up around the source is determined by meteorological factors which have only indirect effects on tracer lifetime, like surface wind, boundary layer height, and turbulent mixing as well as those which affect the lifetime of the tracers such as precipitation. The longer a tracer stays in the atmosphere, the lower is the relative importance of the location of the source to the atmospheric mass and thus the lower is the relative local pollution build up. We further use aerosol deposition fields to estimate regions with high deposition, that is more than 1% or more than 5% of the corresponding tracer emission deposited in this region. In doing so, we find that the high deposition areas are larger for larger aerosols, and these differ less between the MPCs than for smaller aerosols due to faster deposition. Furthermore, cities in regions with high precipitation rates or unfavorable geographic location, e.g. in a basin, suffer most of this high deposition. Most of the high deposition occurs over land, although about 50% of the MPCs are located along coastlines. By folding the aerosol deposition fields with geographical distributions of cropland, pasture, and forest, the impact on different land ecosystems is assessed. In general, forest are exhibited most to deposition from MPCs while pasture land is least affected. Moreover, the impact on humans, measured with a threshold exceedance of pollutant surface mixing ratios, is more dependent on population densities than on the size of the area holding a certain mixing ratio.

Aerosol pollution potential from major population centers

NASA Astrophysics Data System (ADS)

Kunkel, D.; Tost, H.; Lawrence, M. G.

2013-04-01

Major population centers (MPCs), or megacities, represent the largest of growing urban agglomerations with major societal and environmental implications. In terms of air quality, they are seen as localized but strong emission sources of aerosols and trace gases which in turn affect air pollution levels in the city or in downwind regions. In the state-of-the-art atmospheric chemistry general circulation model EMAC, generic aerosol and gas-phase tracers with equal emission source strengths at 46 MPC locations are used to study the balance between local pollution build-up and pollution export, either vertically into the upper troposphere or horizontally in the lower troposphere. The insoluble gas-phase tracers with fixed lifetimes are transported with the atmospheric circulation, while the aerosol tracers also undergo gravitational sedimentation as well as dry and wet deposition processes. The strength of low-level tracer export depends on the location of the emission source and prevailing meteorology, in particular on atmospheric stability and the height of the boundary layer and the mixing out of this layer. In contrast, vertical transport of tracer mass depends on the tracer's solubility: the more soluble a tracer is, the less mass reaches altitudes above five kilometers. Hence, the mass of insoluble gas-phase tracer above five kilometers can be up to ten times higher than the hydrophilic aerosol mass from the same source. In the case of aerosol tracers, pollution build-up around the source is determined by meteorological factors which have only indirect effects on tracer lifetime, like surface wind, boundary layer height, and turbulent mixing, as well as those which affect the lifetime of the tracers such as precipitation. The longer a tracer stays in the atmosphere, the lower is the relative importance of the location of the source to the atmospheric mass, and thus the lower is the relative local pollution build-up. We further use aerosol deposition fields to estimate regions with high deposition, that is more than 1% or more than 5% of the corresponding tracer emission deposited in this region. In doing so, we find that the high deposition areas are larger for aerosols with diameters of 10.0 μm, and these differ less between the MPCs than for aerosols with diameters smaller than 2.5 μm due to faster deposition. Furthermore, cities in regions with high precipitation rates or unfavorable geographic locations, e.g., in a basin, suffer most of this high deposition. Most of the high deposition occurs over land, although about 50% of the MPCs are located along coastlines. By folding the aerosol deposition fields with geographical distributions of cropland, pasture, and forest, the impact on different land ecosystems is assessed. In general, forest is exposed most to deposition from MPCs while pastureland is least affected. Moreover, the impact on humans, measured with a threshold exceedance of pollutant surface mixing ratios, is more dependent on population densities than on the size of the area with a certain mixing ratio.

Linking Barbados Mineral Dust Aerosols to North African Sources Using Elemental Composition and Radiogenic Sr, Nd, and Pb Isotope Signatures

NASA Astrophysics Data System (ADS)

Bozlaker, Ayse; Prospero, Joseph M.; Price, Jim; Chellam, Shankararaman

2018-01-01

Large quantities of African dust are carried across the Atlantic to the Caribbean Basin and southern United States where it plays an important role in the biogeochemistry of soils and waters and in air quality. Dusts' elemental and isotopic composition was comprehensively characterized in Barbados during the summers of 2013 and 2014, the season of maximum dust transport. Although total suspended insoluble particulate matter (TSIP) mass concentrations varied significantly daily and between the two summers, the abundances (μg element/g TSIP) of 50 elements during "high-dust days" (HDD) were similar. Aerosols were regularly enriched in Na, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, and W relative to the upper continental crust. Enrichment of these elements, many of which are anthropogenically emitted, was significantly reduced during HDD, attributed to mixing and dilution with desert dust over source regions. Generally, Ti/Al, Si/Al, Ca/Al, Ti/Fe, Si/Fe, and Ca/Fe ratios during HDD differed from their respective values in hypothesized North African source regions. Nd isotope composition was relatively invariant for "low-dust days" (LDD) and HDD. In contrast, HDD-aerosols were more radiogenic exhibiting higher 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios compared to LDD. Generally, Barbados aerosols' composition ranged within narrow limits and was much more homogeneous than that of hypothesized African source soils. Our results suggest that summertime Barbados aerosols are dominated by a mixture of particles originating from sources in the Sahara-Sahel regions. The Bodélé Depression, long suspected as a major source, appears to be an insignificant contributor of summertime western Atlantic dust.

Five primary sources of organic aerosols in the urban atmosphere of Belgrade (Serbia).

PubMed

Zangrando, Roberta; Barbaro, Elena; Kirchgeorg, Torben; Vecchiato, Marco; Scalabrin, Elisa; Radaelli, Marta; Đorđević, Dragana; Barbante, Carlo; Gambaro, Andrea

2016-11-15

Biomass burning and primary biological aerosol particles (PBAPs) represent important primary sources of organic compounds in the atmosphere. These particles and compounds are able to affect climate and human health. In the present work, using HPLC-orbitrapMS, we determined the atmospheric concentrations of molecular markers such as anhydrosugars and phenolic compounds that are specific for biomass burning, as well as the concentrations of sugars, alcohol sugars and d- and l-amino acids (D-AAs and L-AAs) for studying PBAPs in Belgrade (Serbia) aerosols collected in September-December 2008. In these samples, high levels of all these biomarkers were observed in October. Relative percentages of vanillic (V), syringic compounds (S) and p-coumaric acid (PA), as well as levoglucosan/mannosan (L/M) ratios, helped us discriminate between open fire events and wood combustion for domestic heating during the winter. L-AAs and D-AAs (1% of the total) were observed in Belgrade aerosols mainly in September-October. During open fire events, mean D-AA/L-AA (D/L) ratio values of aspartic acid, threonine, phenylalanine, alanine were significantly higher than mean D/L values of samples unaffected by open fire. High levels of AAs were observed for open biomass burning events. Thanks to four different statistical approaches, we demonstrated that Belgrade aerosols are affected by five sources: a natural source, a source related to fungi spores and degraded material and three other sources linked to biomass burning: biomass combustion in open fields, the combustion of grass and agricultural waste and the combustion of biomass in stoves and industrial plants. The approach employed in this work, involving the determination of specific organic tracers and statistical analysis, proved useful to discriminate among different types of biomass burning events. Copyright © 2016 Elsevier B.V. All rights reserved.

Origins of aerosol chlorine during winter over north central Colorado, USA

NASA Astrophysics Data System (ADS)

Jordan, C. E.; Pszenny, A. A. P.; Keene, W. C.; Cooper, O. R.; Deegan, B.; Maben, J.; Routhier, M.; Sander, R.; Young, A. H.

2015-01-01

The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower campaign (February-March 2011) near Boulder, Colorado, investigated nighttime ClNO2 production and processing. Virtually all particulate Cl was in the form of ionic Cl-. The size distributions of Cl- and Na+ were similar, with most of the mass in the supermicrometer size fraction, suggesting primary sources for both. Median Cl- concentrations were about half those of Na+ and Ca2+ for particle diameters centered at 1.4 and 2.5 µm. To investigate potential sources of Na+ and Cl-, four cases were studied that featured the prevalence of Na+ and Cl- and different transport pathways based on FLEXible PARTicle dispersion model (FLEXPART) retroplumes. Estimates of supermicrometer Na+ particle lifetime against deposition indicate that long-range transport of marine aerosols could account for the observed Na+. However, measured molar ratios of Ca2+ to Na+ (0.143-0.588) compared to seawater (0.022) indicate significant contributions from crustal sources to the supermicrometer aerosol composition during these four case studies. Further, low molar ratios of Mg2+ to Na+ (0.007-0.098) relative to seawater (0.114) suggest that some of the Na+, and presumably associated Cl-, originated from non-sea-salt sources. The heterogeneous chemical composition of saline soils throughout the western U.S., along with the nonlinearity of wind-driven soil deflation as a function of various surface soil properties, precludes a quantitative apportionment of soil, marine, and anthropogenic sources to the observed coarse-fraction aerosol. Nonetheless, results suggest that deflation of saline soils was a potentially important source of particulate Cl- that sustained atmospheric ClNO2 production and associated impacts on oxidation processes over northern Colorado.

Relative Contributions of the Saharan and Sahelian Sources to the Atmospheric Dust Load Over the North Atlantic

NASA Technical Reports Server (NTRS)

Ginoux, Paul; Chin, M.; Torres, O.; Prospero, J.; Dubovik, O.; Holben, B.; Einaudi, Franco (Technical Monitor)

2000-01-01

It has long been recognized that Saharan desert is the major source for long range transport of mineral dust over the Atlantic. The contribution from other natural sources to the dust load over the Atlantic has generally been ignored in previous model studies or been replaced by anthropogenically disturbed soil emissions. Recently, Prospero et.at. have identified the major dust sources over the Earth using TOMS aerosol index. They showed that these sources correspond to dry lakes with layers of sediment deposed in the late Holocene or Pleistocene. One of the most active of these sources seem to be the Bodele depression. Chiapello et al. have analyzed the mineralogical composition of dust on the West coast of Africa. They found that Sahelian dust events are the most intense but are less frequent than Saharan plumes. This suggests that the Bodele depression could contribute significantly to the dust load over the Atlantic. The relative contribution of the Sahel and Sahara dust sources is of importance for marine biogeochemistry or atmospheric radiation, because each source has a distinct mineralogical composition. We present here a model study of the relative contributions of Sahara and Sahel sources to the atmospheric dust aerosols over the North Atlantic. The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate dust distribution in 1996-1997. Dust particles are labeled depending on their sources. In this presentation, we will present the comparison between the model results and observations from ground based measurements (dust concentration, optical thickness and size distribution) and satellite data (TOMS aerosol index). The relative contribution of each source will then be analyzed spatially and temporally.

Aerosol Chemistry over a High Altitude Station at Northeastern Himalayas, India

PubMed Central

Chatterjee, Abhijit; Adak, Anandamay; Singh, Ajay K.; Srivastava, Manoj K.; Ghosh, Sanjay K.; Tiwari, Suresh; Devara, Panuganti C. S.; Raha, Sibaji

2010-01-01

Background There is an urgent need for an improved understanding of the sources, distributions and properties of atmospheric aerosol in order to control the atmospheric pollution over northeastern Himalayas where rising anthropogenic interferences from rapid urbanization and development is becoming an increasing concern. Methodology/Principal Findings An extensive aerosol sampling program was conducted in Darjeeling (altitude ∼2200 meter above sea level (masl), latitude 27°01′N and longitude 88°15′E), a high altitude station in northeastern Himalayas, during January–December 2005. Samples were collected using a respirable dust sampler and a fine dust sampler simultaneously. Ion chromatograph was used to analyze the water soluble ionic species of aerosol. The average concentrations of fine and coarse mode aerosol were found to be 29.5±20.8 µg m−3 and 19.6±11.1 µg m−3 respectively. Fine mode aerosol dominated during dry seasons and coarse mode aerosol dominated during monsoon. Nitrate existed as NH4NO3 in fine mode aerosol during winter and as NaNO3 in coarse mode aerosol during monsoon. Gas phase photochemical oxidation of SO2 during premonsoon and aqueous phase oxidation during winter and postmonsoon were the major pathways for the formation of SO4 2− in the atmosphere. Long range transport of dust aerosol from arid regions of western India was observed during premonsoon. The acidity of fine mode aerosol was higher in dry seasons compared to monsoon whereas the coarse mode acidity was higher in monsoon compared to dry seasons. Biomass burning, vehicular emissions and dust particles were the major types of aerosol from local and continental regions whereas sea salt particles were the major types of aerosol from marine source regions. Conclusions/Significance The year-long data presented in this paper provide substantial improvements to the heretofore poor knowledge regarding aerosol chemistry over northeastern Himalayas, and should be useful to policy makers in making control strategies. PMID:20585397

Aerosol chemistry over a high altitude station at northeastern Himalayas, India.

PubMed

Chatterjee, Abhijit; Adak, Anandamay; Singh, Ajay K; Srivastava, Manoj K; Ghosh, Sanjay K; Tiwari, Suresh; Devara, Panuganti C S; Raha, Sibaji

2010-06-16

There is an urgent need for an improved understanding of the sources, distributions and properties of atmospheric aerosol in order to control the atmospheric pollution over northeastern Himalayas where rising anthropogenic interferences from rapid urbanization and development is becoming an increasing concern. An extensive aerosol sampling program was conducted in Darjeeling (altitude approximately 2200 meter above sea level (masl), latitude 27 degrees 01'N and longitude 88 degrees 15'E), a high altitude station in northeastern Himalayas, during January-December 2005. Samples were collected using a respirable dust sampler and a fine dust sampler simultaneously. Ion chromatograph was used to analyze the water soluble ionic species of aerosol. The average concentrations of fine and coarse mode aerosol were found to be 29.5+/-20.8 microg m(-3) and 19.6+/-11.1 microg m(-3) respectively. Fine mode aerosol dominated during dry seasons and coarse mode aerosol dominated during monsoon. Nitrate existed as NH(4)NO(3) in fine mode aerosol during winter and as NaNO(3) in coarse mode aerosol during monsoon. Gas phase photochemical oxidation of SO(2) during premonsoon and aqueous phase oxidation during winter and postmonsoon were the major pathways for the formation of SO(4)(2-) in the atmosphere. Long range transport of dust aerosol from arid regions of western India was observed during premonsoon. The acidity of fine mode aerosol was higher in dry seasons compared to monsoon whereas the coarse mode acidity was higher in monsoon compared to dry seasons. Biomass burning, vehicular emissions and dust particles were the major types of aerosol from local and continental regions whereas sea salt particles were the major types of aerosol from marine source regions. The year-long data presented in this paper provide substantial improvements to the heretofore poor knowledge regarding aerosol chemistry over northeastern Himalayas, and should be useful to policy makers in making control strategies.

An Overview of the Tropospheric Aerosol Radiative Forcing Observational Experiment

NASA Technical Reports Server (NTRS)

Russell, P. B.; Chan, K. Roland (Technical Monitor)

1997-01-01

Aerosol effects on atmospheric radiation are a leading source of uncertainty in predicting future climate. As a result, the International Global Atmospheric Chemistry Program has established a Focus on Atmospheric Aerosols (IGAC/FAA) and endorsed a series of aerosol field campaigns. TARFOX, the second in the IGAC/FAA series, was designed to reduce this uncertainty by measuring aerosol properties and effects in the US eastern seaboard, where one of the world's major plumes of industrial haze moves from the continent over the Atlantic Ocean. TARFOX's objectives are to: 1. Make simultaneous measurements of: (a) aerosol effects on radiation fields, and (b) the chemical, physical, and optical properties of the aerosols causing those effects. 2. Perform a variety of closure studies by using overdetermined data sets to test the mutual consistency of measurements and calculations of a wide range of aerosol properties and effects. 3. Use the results of the closure studies to assess and reduce uncertainties in estimates of aerosol radiative forcing, as well as to guide future field programs. An important subset of the closure studies is tests and improvements of algorithms used to derive aerosol properties and radiative effects from satellite measurements. The TARFOX Intensive Field Period (IFP) was conducted July 10-31, 1996. It included coordinated measurements from four satellites (GOES-8, NOAA-14, ERS-2, LANDSAT), four aircraft (ER-2, C-130, C-131, and a modified Cessna), land sites, and ships. A variety of aerosol conditions was sampled, ranging from relatively clean behind frontal passages to moderately polluted with aerosol optical depths exceeding 0.5 at mid-visible wavelengths. The latter conditions included separate incidents of enhancements caused primarily by anthropogenic sources and another incident of enhancement apparently influenced by recent fog processing. Spatial gradients of aerosol optical thickness were sampled to aid in isolating aerosol effects from other radiative effects and to more tightly constrain closure tests, including those of satellite retrievals. This talk gives an overview of TARFOX goals, rationale, methods, and initial key findings.

Measurement of Fukushima Aerosol Debris in Sequim and Richland, WA and Ketchikan, AK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, Harry S.; Bowyer, Ted W.; Engelmann, Mark D.

2013-05-01

Aerosol collections were initiated at several locations by PNNL shortly after the Great East Japan Earthquake of May 2011. Aerosol samples were transferred to laboratory high-resolution gamma spectrometers for analysis. Similar to treaty monitoring stations operating across the Northern hemisphere, iodine and other isotopes which could be volatilized at high temperature were detected. Though these locations are not far apart, they have significant variations with respect to water, mountain-range placement, and local topography. Variation in computed source terms will be shown to bound the variability of this approach to source estimation.

Aerosol-Cloud Interactions During Puijo Cloud Experiments - The effects of weather and local sources

NASA Astrophysics Data System (ADS)

Komppula, Mika; Portin, Harri; Leskinen, Ari; Romakkaniemi, Sami; Brus, David; Neitola, Kimmo; Hyvärinen, Antti-Pekka; Kortelainen, Aki; Hao, Liqing; Miettinen, Pasi; Jaatinen, Antti; Ahmad, Irshad; Lihavainen, Heikki; Laaksonen, Ari; Lehtinen, Kari E. J.

2013-04-01

The Puijo measurement station has provided continuous data on aerosol-cloud interactions since 2006. The station is located on top of the Puijo observation tower (306 m a.s.l, 224 m above the surrounding lake level) in Kuopio, Finland. The top of the tower is covered by cloud about 15 % of the time, offering perfect conditions for studying aerosol-cloud interactions. With a twin-inlet setup (total and interstitial inlets) we are able to separate the activated particles from the interstitial (non-activated) particles. The continuous twin-inlet measurements include aerosol size distribution, scattering and absorption. In addition cloud droplet number and size distribution are measured continuously with weather parameters. During the campaigns the twin-inlet system was additionally equipped with aerosol mass spectrometer (AMS) and Single Particle Soot Photometer (SP-2). This way we were able to define the differences in chemical composition of the activated and non-activated particles. Potential cloud condensation nuclei (CCN) in different supersaturations were measured with two CCN counters (CCNC). The other CCNC was operated with a Differential Mobility Analyzer (DMA) to obtain size selected CCN spectra. Other additional measurements included Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) for particle hygroscopicity. Additionally the valuable vertical wind profiles (updraft velocities) are available from Halo Doppler lidar during the 2011 campaign. Cloud properties (droplet number and effective radius) from MODIS instrument onboard Terra and Aqua satellites were retrieved and compared with the measured values. This work summarizes the two latest intensive campaigns, Puijo Cloud Experiments (PuCE) 2010 & 2011. We study especially the effect of the local sources on the cloud activation behaviour of the aerosol particles. The main local sources include a paper mill, a heating plant, traffic and residential areas. The sources can be categorized and identified by wind direction. Clear changes can be seen in the aerosol and cloud properties when being under the influence of a local pollutant source. Also differences in the chemical composition of aerosol activated to cloud droplet and those staying interstitial has been observed. For example, the light absorption by cloud interstitial particles is higher when the wind blows from the local pollutant sources compared to a cleaner sector. This may be due to the fact that the absorptive material, e.g. fresh soot, is generally hydrophobic and therefore inhibits activation. Another point of interest is the occasional freezing conditions during the campaign (temperature below zero), which also affects the activation behaviour. The full usage of this special data set will provide new information on the properties and differences of activating and non-activating aerosol particles, as well as on the variables affecting the activation.

Exhaled Aerosol Pattern Discloses Lung Structural Abnormality: A Sensitivity Study Using Computational Modeling and Fractal Analysis

PubMed Central

Xi, Jinxiang; Si, Xiuhua A.; Kim, JongWon; Mckee, Edward; Lin, En-Bing

2014-01-01

Background Exhaled aerosol patterns, also called aerosol fingerprints, provide clues to the health of the lung and can be used to detect disease-modified airway structures. The key is how to decode the exhaled aerosol fingerprints and retrieve the lung structural information for a non-invasive identification of respiratory diseases. Objective and Methods In this study, a CFD-fractal analysis method was developed to quantify exhaled aerosol fingerprints and applied it to one benign and three malign conditions: a tracheal carina tumor, a bronchial tumor, and asthma. Respirations of tracer aerosols of 1 µm at a flow rate of 30 L/min were simulated, with exhaled distributions recorded at the mouth. Large eddy simulations and a Lagrangian tracking approach were used to simulate respiratory airflows and aerosol dynamics. Aerosol morphometric measures such as concentration disparity, spatial distributions, and fractal analysis were applied to distinguish various exhaled aerosol patterns. Findings Utilizing physiology-based modeling, we demonstrated substantial differences in exhaled aerosol distributions among normal and pathological airways, which were suggestive of the disease location and extent. With fractal analysis, we also demonstrated that exhaled aerosol patterns exhibited fractal behavior in both the entire image and selected regions of interest. Each exhaled aerosol fingerprint exhibited distinct pattern parameters such as spatial probability, fractal dimension, lacunarity, and multifractal spectrum. Furthermore, a correlation of the diseased location and exhaled aerosol spatial distribution was established for asthma. Conclusion Aerosol-fingerprint-based breath tests disclose clues about the site and severity of lung diseases and appear to be sensitive enough to be a practical tool for diagnosis and prognosis of respiratory diseases with structural abnormalities. PMID:25105680

Sources of primary and secondary organic aerosol and their diurnal variations.

PubMed

Zheng, Mei; Zhao, Xiuying; Cheng, Yuan; Yan, Caiqing; Shi, Wenyan; Zhang, Xiaolu; Weber, Rodney J; Schauer, James J; Wang, Xinming; Edgerton, Eric S

2014-01-15

PM(2.5), as one of the criteria pollutants regulated in the U.S. and other countries due to its adverse health impacts, contains more than hundreds of organic pollutants with different sources and formation mechanisms. Daytime and nighttime PM2.5 samples from the August Mini-Intensive Gas and Aerosol Campaign (AMIGAS) in the southeastern U.S. were collected during summer 2008 at one urban site and one rural site, and were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and various individual organic compounds including some important tracers for carbonaceous aerosol sources by gas chromatography-mass spectrometry. Most samples exhibited higher daytime OC concentration, while higher nighttime OC was found in a few events at the urban site. Sources, formation mechanisms and composition of organic aerosol are complicated and results of this study showed that it exhibited distinct diurnal variations. With detailed organic tracer information, sources contributing to particulate OC were identified: higher nighttime OC concentration occurring in several occasions was mainly contributed by the increasing primary emissions at night, especially diesel exhaust and biomass burning; whereas sources responsible for higher daytime OC concentration included secondary organic aerosol (SOA) formation (e.g., cis-pinonic acid and non-biomass burning WSOC) together with traffic emissions especially gasoline engine exhaust. Primary tracers from combustion related sources such as EC, polycyclic aromatic hydrocarbons, and hopanes and steranes were significantly higher at the urban site with an urban to rural ratio between 5 and 8. However, this urban-rural difference for secondary components was less significant, indicating a relatively homogeneous distribution of SOA spatially. We found cholesterol concentrations, a typical tracer for meat cooking, were consistently higher at the rural site especially during the daytime, suggesting the likely additional sources for this tracer at rural site and that it should be used with caution as meat cooking tracer in rural areas in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

AN INITIAL ASSESSMENT OF THE CLIMATE IMPACT OF SECONDARY ORGANIC AEROSOLS

NASA Astrophysics Data System (ADS)

O'Donnell, D.; Feichter, J.

2009-12-01

Atmospheric aerosols influence the Earth’s climate by absorbing and scattering solar radiation (the direct effect) and by altering the properties of clouds (indirect effects). Measurements have shown that a substantial fraction of the tropospheric aerosol burden consists of organic compounds. Hundreds of different organic species have been identified. While progress has been made in the understanding of the role of certain aerosol types in the climate system, that of organic aerosols remains poorly understood and the climate influences resulting from their presence poorly constrained. Organic aerosols are emitted directly from the surface (primary organic aerosols, POA) and are also formed in the atmosphere from gaseous precursors by oxidation reactions (secondary organic aerosols, SOA). Both biogenic and anthropogenic precursors have been identified. Biogenic emissions of aerosol precursors are known to be climate-dependent. Thus, a bi-directional dependency exists between the biosphere and the atmosphere, whereby aerosols of biogenic origin influence the climate system, which in turn affects biogenic aerosol precursor production. This study builds upon the global aerosol-climate model ECHAM5/HAM and adds techniques to model SOA as well as the necessary global emission inventories. Emission of biogenic precursors is calculated online. Formation of SOA is modeled by the well-known two-product model of SOA formation. SOA is subject to the same aerosol microphysics and sink processes as other modeled species (sulphate, black carbon, primary organic carbon, sea salt and dust). The aerosol radiative effects are calculated on a size resolved basis, and the aerosol scheme is coupled to the model cloud microphysics, permitting estimation of both direct and indirect aerosol effects. The following results will be discussed: (i) Estimation of the direct and indirect effects of biogenic and anthropogenic SOA, (ii) Estimation of the sign and magnitude of the biospheric feedback (through biogenic aerosol precursor emission) on the climate system, and (iii) Identification of physical processes and aerosol physical properties that need further experimental investigation in order to improve our understanding of the climate impact of SOA

Cloud Physics Lidar Optical Measurements During the SAFARI-2000 Field Campaign

NASA Technical Reports Server (NTRS)

Hlavka, Dennis L.; McGill, Matt; Hart, William D.; Spinhirne, James D.; Starr, David OC. (Technical Monitor)

2002-01-01

In this presentation, we will show new optical data processing results from the Cloud Physics War during SAFARI-2000. Retrieved products include aerosol and cloud layer location and identification, layer optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary layer and occasional elevated aerosol layers found in southern Africa during August and September 2000.

Long-term Satellite Observations of Asian Dust Storm: Source, Pathway, and Interannual Variability

NASA Technical Reports Server (NTRS)

Hsu, N. Christina

2008-01-01

Among the many components that contribute to air pollution, airborne mineral dust plays an important role due to its biogeochemical impact on the ecosystem and its radiative-forcing effect on the climate system. In East Asia, dust storms frequently accompany the cold and dry air masses that occur as part of springtime cold front systems. Outbreaks of Asian dust storms occur often in the arid and semi-arid areas of northwestern China -about 1.6x10(exp 6) square kilometers including the Gobi and Taklimakan deserts- with continuous expanding of spatial coverage. These airborne dust particles, originating in desert areas far from polluted regions, interact with anthropogenic sulfate and soot aerosols emitted from Chinese megacities during their transport over the mainland. Adding the intricate effects of clouds and marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from their sources. Furthermore, these aerosols, once generated over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the Pacific into the United States and beyond. In this paper, we will demonstrate the capability of a new satellite algorithm to retrieve aerosol properties (e.g., optical thickness, single scattering albedo) over bright-reflecting surfaces such as urban areas and deserts. Such retrievals have been difficult to perform using previously available algorithms that use wavelengths from the mid-visible to the near IR because they have trouble separating the aerosol signal from the contribution due to the bright surface reflectance. This new algorithm, called Deep Blue, utilizes blue-wavelength measurements from instruments such as SeaWiFS and MODIS to infer the properties of aerosols, since the surface reflectance over land in the blue part of the spectrum is much lower than for longer wavelength channels. Reasonable agreements have been achieved between Deep Blue retrievals of aerosol optical thickness and those directly from AERONET sunphotometers over desert and semi-desert regions. New Deep Blue products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. Long-term satellite measurements (1998 - 2007) from SeaWiFS will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the Asian dust storm outbreaks. In addition, monthly averaged aerosol optical thickness during the springtime from SeaWiFS will also be compared with the MODIS Deep Blue products.

Atmospheric aerosols in Rome, Italy: sources, dynamics and spatial variations during two seasons

NASA Astrophysics Data System (ADS)

Struckmeier, Caroline; Drewnick, Frank; Fachinger, Friederike; Gobbi, Gian Paolo; Borrmann, Stephan

2016-12-01

Investigations on atmospheric aerosols and their sources were carried out in October/November 2013 and May/June 2014 consecutively in a suburban area of Rome (Tor Vergata) and in central Rome (near St Peter's Basilica). During both years a Saharan dust advection event temporarily increased PM10 concentrations at ground level by about 12-17 µg m-3. Generally, in October/November the ambient aerosol was more strongly influenced by primary emissions, whereas higher relative contributions of secondary particles (sulfate, aged organic aerosol) were found in May/June. Absolute concentrations of anthropogenic emission tracers (e.g. NOx, CO2, particulate polycyclic aromatic hydrocarbons, traffic-related organic aerosol) were generally higher at the urban location. Positive matrix factorization was applied to the PM1 organic aerosol (OA) fraction of aerosol mass spectrometer (HR-ToF-AMS) data to identify different sources of primary OA (POA): traffic, cooking, biomass burning and (local) cigarette smoking. While biomass burning OA was only found at the suburban site, where it accounted for the major fraction of POA (18-24 % of total OA), traffic and cooking were more dominant sources at the urban site. A particle type associated with cigarette smoke emissions, which is associated with a potential characteristic marker peak (m/z 84, C5H10N+, a nicotine fragment) in the mass spectrum, was only found in central Rome, where it was emitted in close vicinity to the measurement location. Regarding secondary OA, in October/November, only a very aged, regionally advected oxygenated OA was found, which contributed 42-53 % to the total OA. In May/June total oxygenated OA accounted for 56-76 % of the OA. Here a fraction (18-26 % of total OA) of a fresher, less oxygenated OA of more local origin was also observed. New particle formation events were identified from measured particle number concentrations and size distributions in May/June 2014 at both sites. While they were observed every day at the urban location, at the suburban location they were only found under favourable meteorological conditions, but were independent of advection of the Rome emission plume. Particles from sources in the metropolitan area of Rome and particles advected from outside Rome contributed 42-70 and 30-58 % to the total measured PM1, respectively. Apart from the general aerosol characteristics, in this study the properties (e.g. emission strength) and dynamics (e.g. temporal behaviour) of each identified aerosol type is investigated in detail to provide a better understanding of the observed seasonal and spatial differences.

Refined Use of Satellite Aerosol Optical Depth Snapshots to Constrain Biomass Burning Emissions in the GOCART Model

NASA Astrophysics Data System (ADS)

Petrenko, Mariya; Kahn, Ralph; Chin, Mian; Limbacher, James

2017-10-01

Simulations of biomass burning (BB) emissions in global chemistry and aerosol transport models depend on external inventories, which provide location and strength for BB aerosol sources. Our previous work shows that to first order, satellite snapshots of aerosol optical depth (AOD) near the emitted smoke plume can be used to constrain model-simulated AOD, and effectively, the smoke source strength. We now refine the satellite-snapshot method and investigate where applying simple multiplicative emission adjustment factors alone to the widely used Global Fire Emission Database version 3 emission inventory can achieve regional-scale consistency between Moderate Resolution Imaging Spectroradiometer (MODIS) AOD snapshots and the Goddard Chemistry Aerosol Radiation and Transport model. The model and satellite AOD are compared globally, over a set of BB cases observed by the MODIS instrument during the 2004, and 2006-2008 biomass burning seasons. Regional discrepancies between the model and satellite are diverse around the globe yet quite consistent within most ecosystems. We refine our approach to address physically based limitations of our earlier work (1) by expanding the number of fire cases from 124 to almost 900, (2) by using scaled reanalysis-model simulations to fill missing AOD retrievals in the MODIS observations, (3) by distinguishing the BB components of the total aerosol load from background aerosol in the near-source regions, and (4) by including emissions from fires too small to be identified explicitly in the satellite observations. The small-fire emission adjustment shows the complimentary nature of correcting for source strength and adding geographically distinct missing sources. Our analysis indicates that the method works best for fire cases where the BB fraction of total AOD is high, primarily evergreen or deciduous forests. In heavily polluted or agricultural burning regions, where smoke and background AOD values tend to be comparable, this approach encounters large uncertainties, and in some regions, other model- or measurement-related factors might contribute significantly to model-satellite discrepancies. This work sets the stage for a larger study within the Aerosol Comparison between Observations and Models (AeroCOM) multimodel biomass burning experiment. By comparing multiple model results using the refined technique presented here, we aim to separate BB inventory from model-specific contributions to the remaining discrepancies.

Real time measurements of submicrometer aerosols in Seoul, Korea: Sources, characteristics, and processing of organic aerosols during winter time.

NASA Astrophysics Data System (ADS)

Kim, H.; Zhang, Q.

2016-12-01

Highly time-resolved chemical characterization of non-refractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter when persistent air quality problems associated with elevated PM concentrations were observed. The average NR-PM1 concentration was 27.5 µg m-3 and the average mass was dominated by organics (44%), followed by nitrate (24%) and sulfate (10%). Five distinct sources of organic aerosol (OA) were identified from positive matrix factorization (PMF) analysis of the AMS data: vehicle emissions represented by a hydrocarbon-like OA factor (HOA), cooking represented by a cooking OA factor (COA), wood combustion represented by a biomass burning OA factor (BBOA), and secondary aerosol formation in the atmosphere that is represented by a semi-volatile oxygenated OA factor (SVOOA) and a low volatile oxygenated OA factor (LVOOA). These factors, on average, contributed 16, 20, 23, 15 and 26% to the total OA mass, respectively, with primary organic aerosol (POA = HOA + COA + BBOA) accounting for 59% of the OA mass. On average, both primary emissions and secondary aerosol formation are important factors affecting air quality in Seoul during winter, contributing approximately equal. However, differences in the fraction of PM source and properties were observed between high and low loading PM period. For example, during stagnant period with low wind speed (WS) (0.99 ± 0.7 m/s) and high RH (71%), high PM loadings (43.6 ± 12.4 µg m-3) with enhanced fractions of nitrate (27%) and SVOOA (8%) were observed, indicating a strong influence from locally generated secondary aerosol. On the other hand, when low PM loadings (12.6 ± 7.1 µg m-3), which were commonly associated with high WS (1.8 ± 1.1 m/s) and low RH (50 %), were observed, the fraction of regional sources, such as sulfate (12%) and LVOOA (21%) become higher whereas the fraction of locally emitted primary (COA, HOA) and locally formed secondary species (nitrate, SVOOA) become lower. Our results indicate that NR-PM1 concentrations, compositions and sources in Korea are very complex and meteorological conditions and air mass origins have a strong influence on properties of PM.

Single-particle characterization of the High Arctic summertime aerosol

NASA Astrophysics Data System (ADS)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-01-01

Single-particle mass spectrometric measurements were carried out in the High Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real-time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 nm to 3000 nm in diameter showed mass spectrometric patterns indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the High Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a~minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest a presence of a particle type of unknown composition and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS and its low hit rate. To our knowledge, this study reports on the first in-situ single-particle mass spectrometric measurements in the marine boundary layer of the High-Arctic pack-ice region.

Single-particle characterization of the high-Arctic summertime aerosol

NASA Astrophysics Data System (ADS)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-07-01

Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of unknown composition and source. In general, the study suffered from low counting statistics due to the overall small number of particles found in this pristine environment, the small sizes of the prevailing aerosol below the detection limit of the ATOFMS, and its low hit rate. To our knowledge, this study reports on the first in situ single-particle mass-spectrometric measurements in the marine boundary layer of the high-Arctic pack ice region.

Physico-chemical characterization of African urban aerosols (Bamako in Mali and Dakar in Senegal) and their toxic effects in human bronchial epithelial cells: description of a worrying situation.

PubMed

Val, Stéphanie; Liousse, Cathy; Doumbia, El Hadji Thierno; Galy-Lacaux, Corinne; Cachier, Hélène; Marchand, Nicolas; Badel, Anne; Gardrat, Eric; Sylvestre, Alexandre; Baeza-Squiban, Armelle

2013-04-02

The involvement of particulate matter (PM) in cardiorespiratory diseases is now established in developed countries whereas in developing areas such as Africa with a high level of specific pollution, PM pollution and its effects are poorly studied. Our objective was to characterize the biological reactivity of urban African aerosols on human bronchial epithelial cells in relation to PM physico-chemical properties to identify toxic sources. Size-speciated aerosol chemical composition was analyzed in Bamako (BK, Mali, 2 samples with one having desert dust event BK1) and Dakar (DK; Senegal) for Ultrafine UF, Fine F and Coarse C PM. PM reactivity was studied in human bronchial epithelial cells investigating six biomarkers (oxidative stress responsive genes and pro-inflammatory cytokines). PM mass concentrations were mainly distributed in coarse mode (60%) and were impressive in BK1 due to the desert dust event. BK2 and DK samples showed a high content of total carbon characteristic of urban areas. The DK sample had huge PAH quantities in bulk aerosol compared with BK that had more water soluble organic carbon and metals. Whatever the site, UF and F PM triggered the mRNA expression of the different biomarkers whereas coarse PM had little or no effect. The GM-CSF biomarker was the most discriminating and showed the strongest pro-inflammatory effect of BK2 PM. The analysis of gene expression signature and of their correlation with main PM compounds revealed that PM-induced responses are mainly related to organic compounds. The toxicity of African aerosols is carried by the finest PM as with Parisian aerosols, but when considering PM mass concentrations, the African population is more highly exposed to toxic particulate pollution than French population. Regarding the prevailing sources in each site, aerosol biological impacts are higher for incomplete combustion sources resulting from two-wheel vehicles and domestic fires than from diesel vehicles (Dakar). Desert dust events seem to produce fewer biological impacts than anthropogenic sources. Our study shows that combustion sources contribute to the high toxicity of F and UF PM of African urban aerosols, and underlines the importance of emission mitigation and the imperative need to evaluate and to regulate particulate pollution in Africa.

Atmospheric aerosol compositions and sources at two national background sites in northern and southern China

NASA Astrophysics Data System (ADS)

Zhu, Qiao; He, Ling-Yan; Huang, Xiao-Feng; Cao, Li-Ming; Gong, Zhao-Heng; Wang, Chuan; Zhuang, Xin; Hu, Min

2016-08-01

Although China's severe air pollution has become a focus in the field of atmospheric chemistry and the mechanisms of urban air pollution there have been researched extensively, few field sampling campaigns have been conducted at remote background sites in China, where air pollution characteristics on a larger scale are highlighted. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), together with an Aethalometer, was deployed at two of China's national background sites in northern (Lake Hongze site; 33.23° N, 118.33° E; altitude 21 m) and southern (Mount Wuzhi site; 18.84° N, 109.49° E; altitude 958 m) China in the spring seasons in 2011 and 2015, respectively, in order to characterize submicron aerosol composition and sources. The campaign-average PM1 concentration was 36.8 ± 19.8 µg m-3 at the northern China background (NCB) site, which was far higher than that at the southern China background (SCB) site (10.9 ± 7.8 µg m-3). Organic aerosol (OA) (27.2 %), nitrate (26.7 %), and sulfate (22.0 %) contributed the most to the PM1 mass at NCB, while OA (43.5 %) and sulfate (30.5 %) were the most abundant components of the PM1 mass at SCB, where nitrate only constituted a small fraction (4.7 %) and might have contained a significant amount of organic nitrates (5-11 %). The aerosol size distributions and organic aerosol elemental compositions all indicated very aged aerosol particles at both sites. The OA at SCB was more oxidized with a higher average oxygen to carbon (O / C) ratio (0.98) than that at NCB (0.67). Positive matrix factorization (PMF) analysis was used to classify OA into three components, including a hydrocarbon-like component (HOA, attributed to fossil fuel combustion) and two oxygenated components (OOA1 and OOA2, attributed to secondary organic aerosols from different source areas) at NCB. PMF analysis at SCB identified a semi-volatile oxygenated component (SV-OOA) and a low-volatility oxygenated component (LV-OOA), both of which were found to be secondary species and could be formed from precursors co-emitted with BC. Using the total potential source contribution function model, the likely source areas of the major PM1 components at both sites were a on large regional scale in East Asia. The possible sources may include not only emissions from the Chinese mainland but also emissions from ocean-going cargo ships and biomass burning in neighboring countries.

Diurnal cycling of urban aerosols under different weather regimes

NASA Astrophysics Data System (ADS)

Gregorič, Asta; Drinovec, Luka; Močnik, Griša; Remškar, Maja; Vaupotič, Janja; Stanič, Samo

2016-04-01

A one month measurement campaign was performed in summer 2014 in Ljubljana, the capital of Slovenia (population 280,000), aiming to study temporal and spatial distribution of urban aerosols and the mixing state of primary and secondary aerosols. Two background locations were chosen for this purpose, the first one in the city center (urban background - KIS) and the second one in the suburban background (Brezovica). Simultaneous measurements of black carbon (BC) and particle number size distribution of submicron aerosols (PM1) were conducted at both locations. In the summer season emission from traffic related sources is expected to be the main local contribution to BC concentration. Concentrations of aerosol species and gaseous pollutants within the planetary boundary layer are controlled by the balance between emission sources of primary aerosols and gases, production of secondary aerosols, chemical reactions of precursor gases under solar radiation and the rate of dilution by mixing within the planetary boundary layer (PBL) as well as with tropospheric air. Only local emission sources contribute to BC concentration during the stable PBL with low mixing layer height, whereas during the time of fully mixed PBL, regionally transported BC and other aerosols can contribute to the surface measurements. The study describes the diurnal behaviour of the submicron aerosol at the urban and suburban background location under different weather regimes. Particles in three size modes - nucleation (< 25 nm, NUM), Aitken (25 - 90 nm, AIM) and accumulation mode (90 - 800 nm, ACM), as well as BC mass concentration were evaluated separately for sunny, cloudy and rainy days, taking into account modelled values of PBL height. Higher particle number and black carbon concentrations were observed at the urban background (KIS) than at the suburban background location (Brezovica). Significant diurnal pattern of total particle concentration and black carbon concentration was observed at both locations, with a distinct morning and late afternoon peak. As a consequence of different PBL dynamics and atmospheric processes (photochemical effects, humidity, wind speed and direction), diurnal profile differs for sunny, cloudy and rainy days. Nucleation mode particles were found to be subjected to lower daily variation and only slightly influenced by weather, as opposed to Aitken and accumulation mode particles. The highest correlation between BC and particle number concentration is observed during stable atmospheric conditions in the night and morning hours and is attributed to different particle size modes, depending on the distance to local BC emission sources. In sunny weather conditions, correlation between BC and particle number concentration decreases during the day due to mixing in the atmosphere and formation of secondary aerosols. Black carbon aging and mixing with secondary aerosols was additionally studied on the aerosol samples taken from the morning to the evening of a sunny day using SEM-EDX technique.

Sources, seasonality, and trends of southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

NASA Astrophysics Data System (ADS)

Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.

2015-09-01

We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the southeast US during the summer-fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 × 25 km2 resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the southeast US. OA is simulated successfully with a simple parameterization, assuming irreversible uptake of low-volatility products of hydrocarbon oxidation. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 25 % in the cloud convective layer at 1.5-3 km, and 15 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42-] + [NO3-]) is only 0.5-0.7 mol mol-1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by OA. This would explain the long-term decline of ammonium aerosol in the southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 8-28 % (consistently biased low). The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from August to October. These declines are due to shutdowns in both biogenic emissions and UV-driven photochemistry. Surface PM2.5 shows far less summer-to-winter decrease than AOD and we attribute this in part to the offsetting effect of weaker boundary layer ventilation. The SEAC4RS aircraft data demonstrate that AODs measured from space are consistent with surface PM2.5. This implies that satellites can be used reliably to infer surface PM2.5 over monthly timescales if a good CTM representation of the aerosol vertical profile is available.

Ion chemistry and source identification of coarse and fine aerosols in an urban area of eastern central India

NASA Astrophysics Data System (ADS)

Verma, Santosh K.; Deb, Manas K.; Suzuki, Yukio; Tsai, Ying I.

2010-01-01

This work focuses on size segregated atmospheric aerosol mass concentrations and water soluble inorganic components in Chhattisgarh, the eastern central India. Investigation on the monitoring of ambient air levels of atmospheric particulates were done around a large source of primary anthropogenic particulate emissions: the industrial area and coal based power plants. Chemical characterization was carried out for aerosol samples collected in urban area, Raipur, (21°14'N, 81°38'E) of Chhattisgarh region over a period of one year, using cascade impactor. Annual mean of mass concentration for coarse (PM 2.5-10) and fine (PM 2.5) aerosols were monitored to be 238.1 ± 89.9 and 167.0 ± 75.3 µg m - 3 respectively This work deals with the seasonal variation and meteorological influences of inorganic components of the aerosols viz. NO 3-, Cl - and SO 42-, Mg 2+, Na +, K +, Ca 2+ and NH 4+. The annual mean concentration of the inorganic components were monitored to be 3.8 ± 2.5, 8.9 ± 2.7, 10.2 ± 1.5, 2.6 ± 0.6, 8.7 ± 7.2, 4.6 ± 1.8, 16.4 ± 6.9 and 0.4 ± 0.5 µg m - 3 respectively in coarse particles and 8.2 ± 7.1, 6.8 ± 3.6, 46.5 ± 32.8, 1.7 ± 0.6, 7.4 ± 3.6, 5.9 ± 3.4, 10.2 ± 2.9, and 8.8 ± 7.7 µg m - 3 respectively in fine particles, for the above ions. The average distribution of nitrate and sulphate in PM 2.5-10 were found to be 1.6 and 4.2% and in PM 2.5 were 4.9 and 27.9% respectively indicating the dominance of sulphate in both PM 2.5-10 and PM 2.5 particles. Here, industrial emission plays important role for contribution of PM 2.5 particle loading in the atmosphere. The cation-anion rational analysis indicated that the PM 2.5-10 particles were mostly neutralized and PM 2.5 particle were acidic. The major ions were mainly in the form of NaCl > CaSO 4 > K 2SO 4 > MgSO 4 > KCl > NH 4Cl > Ca(NO 3) 2 > KNO 3 > MgCl 2 > Mg(NO 3) 2 > NH 4NO 3 > (NH 4) 2SO 4 in coarse aerosol particles and (NH 4) 2SO 4 > K 2SO 4 > CaSO 4 > NaCl > NH 4NO 3 > CaCl 2 > KNO 3 > MgCl 2 > Ca(NO 3) 2 > KCl > NH 4Cl in fine particles.

Aerosol algorithm evaluation within aerosol-CCI

NASA Astrophysics Data System (ADS)

Kinne, Stefan; Schulz, Michael; Griesfeller, Jan

Properties of aerosol retrievals from space are difficult. Even data from dedicated satellite sensors face contaminations which limit the accuracy of aerosol retrieval products. Issues are the identification of complete cloud-free scenes, the need to assume aerosol compositional features in an underdetermined solution space and the requirement to characterize the background at high accuracy. Usually the development of aerosol is a slow process, requiring continuous feedback from evaluations. To demonstrate maturity, these evaluations need to cover different regions and seasons and many different aerosol properties, because aerosol composition is quite diverse and highly variable in space and time, as atmospheric aerosol lifetimes are only a few days. Three years ago the ESA Climate Change Initiative started to support aerosol retrieval efforts in order to develop aerosol retrieval products for the climate community from underutilized ESA satellite sensors. The initial focus was on retrievals of AOD (a measure for the atmospheric column amount) and of Angstrom (a proxy for aerosol size) from the ATSR and MERIS sensors on ENVISAT. The goal was to offer retrieval products that are comparable or better in accuracy than commonly used NASA products of MODIS or MISR. Fortunately, accurate reference data of ground based sun-/sky-photometry networks exist. Thus, retrieval assessments could and were conducted independently by different evaluation groups. Here, results of these evaluations for the year 2008 are summarized. The capability of these newly developed retrievals is analyzed and quantified in scores. These scores allowed a ranking of competing efforts and also allow skill comparisons of these new retrievals against existing and commonly used retrievals.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

DOE PAGES

Chim, Man Mei; Cheng, Chiu Tung; Davies, James F.; ...

2017-12-05

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5Hmore » 8O 4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5) hydroxyl functionalization product (C 5H 8O 5) and a C 4 fragmentation product (C 4H 6O 3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.« less

Metals and possible sources of lead in aerosols at the Dinghushan nature reserve, southern China.

PubMed

Zhu, Xiao-min; Kuang, Yuan-wen; Li, Jiong; Schroll, Reiner; Wen, Da-zhi

2015-08-15

Aerosols play an important role in depositing metals into forest ecosystems. Better understanding of forest aerosols with regard to their metal content and their possible sources is of great significance for air quality and forest health. Particulate matter with an aerodynamic diameter less than 2.5 µm (PM(2.5)) in aerosols was collected every month for 20 months using moderate-volume samplers in the Dinghushan (DHS) nature reserve in southern China. The concentrations of metals (Al, Cd, Mn, Ni, Pb, and Zn) as well as the Pb isotopic ratios in the PM(2.5) samples were measured by inductively coupled plasma mass spectrometry (ICP-MS). Moderate pollution with aerosol PM(2.5) was detected at the DHS nature reserve with the air mass from mainland China being the predominant PM(2.5) source. The high enrichment factors (EFs) for the heavy metals Pb, Cd, and Zn, as well as the PM(2.5) mass concentrations, coupled with backward trajectory analysis, indicated the anthropogenic origins of the PM(2.5) and of the heavy metals in the PM(2.5). The Pb isotopic ratios revealed the contributions from various Pb sources, which varied between seasons. Industrial emissions and automobile exhaust from the Pearl River Delta (PRD) primarily contributed to the anthropogenic Pb in PM(2.5), although there was occasionally a contribution from coal combustion during the wet season. Pb isotopic ratios analyses are helpful for air quality assessment and Pb source tracing. Copyright © 2015 John Wiley & Sons, Ltd.

Seasonal variability in chemical composition and source apportionment of sub-micron aerosol over a high altitude site in Western Ghats, India

NASA Astrophysics Data System (ADS)

Mukherjee, Subrata; Singla, Vyoma; Pandithurai, Govindan; Safai, P. D.; Meena, G. S.; Dani, K. K.; Anil Kumar, V.

2018-05-01

This manuscript reports the seasonal variation of chemically speciated sub-micron aerosol particles (diameter < 1 μm). An Aerosol Chemical Speciation Monitor (ACSM) was used to measure the mass concentration of non-refractory particulate matter (NR-PM1) at a high-altitude site in the Western Ghats, India from March 2016 to February 2017. The mass concentration of NR-PM1 averaged at 7.5 ± 6.5 μgm-3, with major contributions from organics (59%) and sulfates (23%). Positive matrix factorization (PMF) was applied on the measured mass spectra of organic aerosol (OA) to derive the sources distinctive of each season (Summer, Monsoon, Post-Monsoon and Winter). The four OA factors (two primary OA and two oxygenated OA) resolved during summer, post-monsoon and winter season. However, only one oxygenated factor resolved during monsoon and contributed only 20% to the total OA. The factors associated with primary emissions dominated during the monsoon, whereas factors related to secondary formation dominated in other three seasons. During summer, an isoprene derived SOA - IEPOX-OA (isoprene-epoxydiol OA) contributed ∼17% to the total OA. Cluster and concentration weighted trajectory (CWT) analyses were performed to identify the possible source regions of NR-PM1 mass concentration observed at the receptor site. The analysis identifies Central India as the potential source region of transported aerosol during post-monsoon and winter season. Our study suggests that contributions from both local sources and regional transport are important in governing mass concentration of PM1 over Mahabaleshwar.

An Automated Method of MFRSR Calibration for Aerosol Optical Depth Analysis with Application to an Asian Dust Outbreak over the United States.

NASA Astrophysics Data System (ADS)

Augustine, John A.; Cornwall, Christopher R.; Hodges, Gary B.; Long, Charles N.; Medina, Carlos I.; Deluisi, John J.

2003-02-01

Over the past decade, networks of Multifilter Rotating Shadowband Radiometers (MFRSR) and automated sun photometers have been established in the United States to monitor aerosol properties. The MFRSR alternately measures diffuse and global irradiance in six narrow spectral bands and a broadband channel of the solar spectrum, from which the direct normal component for each may be inferred. Its 500-nm channel mimics sun photometer measurements and thus is a source of aerosol optical depth information. Automatic data reduction methods are needed because of the high volume of data produced by the MFRSR. In addition, these instruments are often not calibrated for absolute irradiance and must be periodically calibrated for optical depth analysis using the Langley method. This process involves extrapolation to the signal the MFRSR would measure at the top of the atmosphere (I0). Here, an automated clear-sky identification algorithm is used to screen MFRSR 500-nm measurements for suitable calibration data. The clear-sky MFRSR measurements are subsequently used to construct a set of calibration Langley plots from which a mean I0 is computed. This calibration I0 may be subsequently applied to any MFRSR 500-nm measurement within the calibration period to retrieve aerosol optical depth. This method is tested on a 2-month MFRSR dataset from the Table Mountain NOAA Surface Radiation Budget Network (SURFRAD) station near Boulder, Colorado. The resultant I0 is applied to two Asian dust-related high air pollution episodes that occurred within the calibration period on 13 and 17 April 2001. Computed aerosol optical depths for 17 April range from approximately 0.30 to 0.40, and those for 13 April vary from background levels to >0.30. Errors in these retrievals were estimated to range from ±0.01 to ±0.05, depending on the solar zenith angle. The calculations are compared with independent MFRSR-based aerosol optical depth retrievals at the Pawnee National Grasslands, 85 km to the northeast of Table Mountain, and to sun-photometer-derived aerosol optical depths at the National Renewable Energy Laboratory in Golden, Colorado, 50 km to the south. Both the Table Mountain and Golden stations are situated within a few kilometers of the Front Range of the Rocky Mountains, whereas the Pawnee station is on the eastern plains of Colorado. Time series of aerosol optical depth from Pawnee and Table Mountain stations compare well for 13 April when, according to the Naval Aerosol Analysis and Prediction System, an upper-level Asian dust plume enveloped most of Colorado. Aerosol optical depths at the Golden station for that event are generally greater than those at Table Mountain and Pawnee, possibly because of the proximity of Golden to Denver's urban aerosol plume. The dust over Colorado was primarily surface based on 17 April. On that day, aerosol optical depths at Table Mountain and Golden are similar but are 2 times the magnitude of those at Pawnee. This difference is attributed to meteorological conditions that favored air stagnation in the planetary boundary layer along the Front Range, and a west-to-east gradient in aerosol concentration. The magnitude and timing of the aerosol optical depth measurements at Table Mountain for these events are found to be consistent with independent measurements made at NASA Aerosol Robotic Network (AERONET) stations at Missoula, Montana, and at Bondville, Illinois.

The paleo-ocean characteristics of the Taklimakan dust aerosol: high sulfate from primary sources and implication for climate modeling

NASA Astrophysics Data System (ADS)

Huang, K.; Zhuang, G.; Fu, J. S.; Dong, X.

2017-12-01

Multi-year monitoring of dust aerosol from the Taklimakan Desert has been conducted at one site in the hinterland of the desert, Tazhong and another site at the southern edge of the desert, Hotan. Compared to the other two important desert source regions of China, i.e. Gobi and Loess Plateau, the Taklimakan Desert is characterized of high calcium with a Ca/Al elemental ratio of around 1.50. The unique feature of the Taklimakan dust aerosol is its abundant sulfate. For instance, the mean concentration of sulfate over Tazhong reached as high as 34.7 and 48.8 ug/m3 during the spring of 2007 and 2008, respectively. During the dust storm events, the daily concentration of sulfate frequently exceeded 100 ug/m3. Sulfate showed strong correlations with the primary aerosol species such as Ca2+, Mg2+, Na+, Cl-, Al, Fe, Ti, etc. but weakly correlated with the secondary aerosol species such as NO3- and NH4+. The mass ratio of sulfate in the total suspended particles showed a relatively stable percentage of around 2.5% regardless of the intensity of the dust events. In addition, individual particle analysis using the scanning electron microscope (SEM) technique found that gypsum (CaSO4) particles could account for 11.1% of total number of particles as well as abundant Na2SO4 and NaCl particles. All the evidences above suggested the high sulfate observed in the Taklimakan Desert were largely attributed to primary sources but not formed via the traditional gas-to-particle formation pathway. As the Taklimakan Desert was speculated to be ocean 5-7 million years, the dried sea salts from the paleo-ocean should be the major source of the dust aerosol. Also, the dried salt lakes in the northwestern China may contribute to the high sulfate. Based on two different methods, the contribution of primary sources to sulfate over the Taklimakan Desert is estimated to be around 43% - 82%. This study implied that the cooling effect of the Taklimakan dust aerosol could be underestimated if the explicit dust chemical composition is not considered for modeling.

Quantifying the sources of atmospheric ice nuclei from carbonaceous combustion aerosol

NASA Astrophysics Data System (ADS)

Schill, G. P.; Jathar, S.; Galang, A.; Farmer, D.; Friedman, B.; Levin, E. J.; DeMott, P. J.; Kreidenweis, S. M.

2015-12-01

Ice nucleation on particles is a fundamental atmospheric process, which governs precipitation, cloud lifetimes, and climate. Despite being a basic atmospheric process, our current understanding of ice nucleation in the atmosphere is low. One reason for this low understanding is that ice nuclei concentrations are low (only ~1 in 105 particles in the free troposphere nucleate ice), making it challenging to identify both the composition and sources of ambient ice nuclei. Carbonaceous combustion aerosol produced from biomass and fossil fuel combustion are one potential source of these ice nuclei, as they contribute to over one-third of all aerosol in the North American free troposphere. Unfortunately, previous results from field measurements in-cloud, aircraft measurements, and laboratory studies are in conflict, with estimates of the impact of combustion aerosol ranging from no effect to rivaling the well-known atmospheric ice nuclei mineral dust. It is, however, becoming clear that aerosols from combustion processes are more complex than model particles, and their ice activity depends greatly on both fuel type and combustion conditions. Given these dependencies, we propose that sampling from real-world biomass burning and fossil fuel sources would provide the most useful new information on the contribution of carbonaceous combustion aerosols to atmospheric ice nuclei particles. To determine the specific contribution of refractory black carbon (rBC) to ice nuclei concentrations, we have coupled the Single Particle Soot Photometer (SP2) to the Colorado State University Continuous Flow Diffusion Chamber (CFDC). The SP2 utilizes laser-induced incandescence to quantify rBC mass on a particle-by-particle basis; in doing so, it also selectively destroys rBC particles by heating them to their vaporization temperature. Thus, the SP2 can be used as a selective pre-filter for rBC into the CFDC. In this work, we will present recent results looking at contribution of diesel engine exhaust to ice nuclei concentrations. Sampling was done for both diesel and biodiesel on fresh emissions and emissions aged up to 18 days equivalent photochemical aging with a Potential Aerosol Mass chamber. Our results show that, for mixed-phase clouds, both fresh and aged (bio)diesel are not likely a significant source of ice nuclei.

Black Carbon and Sulfate Aerosols in the Arctic: Long-term Trends, Radiative Impacts, and Source Attributions

NASA Astrophysics Data System (ADS)

Wang, H.; Zhang, R.; Yang, Y.; Smith, S.; Rasch, P. J.

2017-12-01

The Arctic has warmed dramatically in recent decades. As one of the important short-lived climate forcers, aerosols affect the Arctic radiative budget directly by interfering radiation and indirectly by modifying clouds. Light-absorbing particles (e.g., black carbon) in snow/ice can reduce the surface albedo. The direct radiative impact of aerosols on the Arctic climate can be either warming or cooling, depending on their composition and location, which can further alter the poleward heat transport. Anthropogenic emissions, especially, BC and SO2, have changed drastically in low/mid-latitude source regions in the past few decades. Arctic surface observations at some locations show that BC and sulfate aerosols had a decreasing trend in the recent decades. In order to understand the impact of long-term emission changes on aerosols and their radiative effects, we use the Community Earth System Model (CESM) equipped with an explicit BC and sulfur source-tagging technique to quantify the source-receptor relationships and decadal trends of Arctic sulfate and BC and to identify variations in their atmospheric transport pathways from lower latitudes. The simulation was conducted for 36 years (1979-2014) with prescribed sea surface temperatures and sea ice concentrations. To minimize potential biases in modeled large-scale circulations, wind fields in the simulation are nudged toward an atmospheric reanalysis dataset, while atmospheric constituents including water vapor, clouds, and aerosols are allowed to evolve according to the model physics. Both anthropogenic and open fire emissions came from the newly released CMIP6 datasets, which show strong regional trends in BC and SO2 emissions during the simulation time period. Results show that emissions from East Asia and South Asia together have the largest contributions to Arctic sulfate and BC concentrations in the upper troposphere, which have an increasing trend. The strong decrease in emissions from Europe, Russia and North America contributed significantly to the overall decreasing trend in Arctic BC and sulfate, especially, in the lower troposphere. The long-term changes in the spatial distributions of aerosols, their radiative impacts and source attributions, along with implications for the Arctic warming trend, will be discussed.

A one-dimensional sectional aerosol model integrated with mesoscale meteorological data to study marine boundary layer aerosol dynamics

NASA Astrophysics Data System (ADS)

Caffrey, Peter F.; Hoppel, William A.; Shi, Jainn J.

2006-12-01

The dynamics of aerosols in the marine boundary layer are simulated with a one-dimensional, multicomponent, sectional aerosol model using vertical profiles of turbulence, relative humidity, temperature, vertical velocity, cloud cover, and precipitation provided by 3-D mesoscale meteorological model output. The Naval Research Laboratory's (NRL) sectional aerosol model MARBLES (Fitzgerald et al., 1998a) was adapted to use hourly meteorological input taken from NRL's Coupled Ocean-Atmosphere Prediction System (COAMPS). COAMPS-generated turbulent mixing coefficients and large-scale vertical velocities determine vertical exchange within the marine boundary layer and exchange with the free troposphere. Air mass back trajectories were used to define the air column history along which the meteorology was retrieved for use with the aerosol model. Details on the integration of these models are described here, as well as a description of improvements made to the aerosol model, including transport by large-scale vertical motions (such as subsidence and lifting), a revised sea-salt aerosol source function, and separate tracking of sulfate mass from each of the five sources (free tropospheric, nucleated, condensed from gas phase oxidation products, cloud-processed, and produced from heterogeneous oxidation of S(IV) on sea-salt aerosol). Results from modeling air masses arriving at Oahu, Hawaii, are presented, and the relative contribution of free-tropospheric sulfate particles versus sea-salt aerosol from the surface to CCN concentrations is discussed. Limitations and benefits of the method are presented, as are sensitivity analyses of the effect of large-scale vertical motions versus turbulent mixing.

Deep Blue Retrievals of Asian Aerosol Properties During ACE-Asia

NASA Technical Reports Server (NTRS)

Hsu, N. Christina; Tsay, Si-Cee; King, Michael D.; Herman, Jay R.

2006-01-01

During the ACE-Asia field campaign, unprecedented amounts of aerosol property data in East Asia during springtime were collected from an array of aircraft, shipboard, and surface instruments. However, most of the observations were obtained in areas downwind of the source regions. In this paper, the newly developed satellite aerosol algorithm called "Deep Blue" was employed to characterize the properties of aerosols over source regions using radiance measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). Based upon the ngstr m exponent derived from the Deep Blue algorithm, it was demonstrated that this new algorithm is able to distinguish dust plumes from fine-mode pollution particles even in complex aerosol environments such as the one over Beijing. Furthermore, these results were validated by comparing them with observations from AERONET sites in China and Mongolia during spring 2001. These comparisons show that the values of satellite-retrieved aerosol optical thickness from Deep Blue are generally within 20%-30% of those measured by sunphotometers. The analyses also indicate that the roles of mineral dust and anthropogenic particles are comparable in contributing to the overall aerosol distributions during spring in northern China, while fine-mode particles are dominant over southern China. The spring season in East Asia consists of one of the most complex environments in terms of frequent cloudiness and wide ranges of aerosol loadings and types. This paper will discuss how the factors contributing to this complexity influence the resulting aerosol monthly averages from various satellite sensors and, thus, the synergy among satellite aerosol products.

Seasonal inhomogeneity in cloud precursors over Gangetic Himalayan region during GVAX campaign

NASA Astrophysics Data System (ADS)

Dumka, U. C.; Bhattu, Deepika; Tripathi, S. N.; Kaskaoutis, D. G.; Madhavan, B. L.

2015-03-01

Atmospheric aerosols are key elements in cloud microphysics, the hydrological cycle and climate by serving as cloud condensation nuclei (CCN). The present work analyzes simultaneous measurements of number concentration of CCN (NCCN) and condensation nuclei (NCN) obtained at Nainital, in the Gangetic-Himalayan (GH) region, during the frameworks of Ganges Valley Aerosol Experiment (GVAX), June 2011 to March 2012. The NCCN, NCN and activation (AR = NCCN/NCN) at 0.31-0.33% S (supersaturation ratio), exhibit significant daily, monthly and seasonal variations within a range of 684-2065 cm- 3 for NCCN, 1606-4124 cm- 3 for NCN, and 0.38-0.60 for AR, suggesting large inhomogeneity in aerosol properties, types and sources, which control the degree of aerosol potential activation. Thus, transported aerosols from the Ganges valley and abroad, the boundary-layer dynamics and atmospheric modification processes play an important role in aerosol-cloud interactions over the GH region. The NCN and NCCN show monthly-dependent diurnal variations with afternoon maxima due to transported aerosols from the Ganges valley up to the Himalayan foothills, while the AR is lower during these hours implying lower hygroscopicities or smaller sizes of the transported aerosols. The dependence of NCCN on S is highest during Dec-Mar and lowest during monsoon (Jun-Sep), suggesting different aerosol chemical composition. Comparison between Nainital and Kanpur shows that NCN and NCCN are much lower at Nainital, while the similarity in AR suggests aerosols of similar type, source and chemical composition uplifted from the Ganges valley to the Himalayan foothills.

Aerosol Size and Chemical Composition in the Canadian High Arctic

NASA Astrophysics Data System (ADS)

Chang, R. Y. W.; Hayes, P. L.; Leaitch, W. R.; Croft, B.; O'Neill, N. T.; Fogal, P.; Drummond, J. R.; Sloan, J. J.

2015-12-01

Arctic aerosol have a strong annual cycle, with winter months dominated by long range transport from lower latitudes resulting in high mass loadings. Conversely, local emissions are more prominent in the summer months because of the decreased influence of transported aerosol, allowing us to regularly observe both transported and local aerosol. This study will present observations of aerosol chemical composition and particle number size distribution collected at the Polar Environment Artic Research Laboratory and the Alert Global Atmospheric Watch Observatory at Eureka (80N, 86W) and Alert (82N, 62W), Nunavut, respectively. Summer time observations of the number size distribution reveal a persistent mode of particles centered between 30-50 nm, with occasional bursts of smaller particles. The non-refractory aerosol chemical composition, measured by the Canadian Network for the Detection of Atmospheric Change quadrupole aerosol mass spectrometer, is primarily organic, with contributions from both aged and fresher organic aerosol. Factor analysis will be conducted to better understand these sources. The site at Eureka is more susceptible to long range transport since it is at the top of a mountain ridge (610 m above sea level) and will be compared to the site at Alert on an elevated plain (200 m above sea level). This will allow us to determine the relative contributions from processes and sources at the sites at different elevations. Comparisons with aerosol optical depth and GEOS-Chem model output will also be presented to put these surface measurements into context with the overlying and regional atmosphere. Results from this study contribute to our knowledge of aerosol in the high Arctic.

Broadband Measurement of Aerosol Extinction in the Visible Range

NASA Astrophysics Data System (ADS)

He, Quanfu; Bluvshtein, Nir; Segev, Lior; Flores, Michel; Rudich, Yinon; Washenfelder, Rebecca; Brown, Steven

2017-04-01

Atmospheric aerosols influence the Earth's radiative budget directly by scattering and absorbing incoming solar radiation. Aerosol direct forcing remains one of the largest uncertainties in quantifying the role that aerosols play in the Earth's radiative budget. The optical properties of aerosols vary as a function of wavelength, but few measurements reported the wavelength dependence of aerosol extinction cross section and complex refractive indices, particularly in the blue and visible spectral range. There is also currently a large gap in our knowledge of how the optical properties evolve as a function of atmospheric aging in the visible spectrum. In this study, we constructed a new and novel laboratory instrument to measure aerosol extinction as a function of wavelength, using cavity enhanced spectroscopy with a white light source. This broadband cavity enhanced spectroscopy (BBCES) covers the 395-700 nm spectral region using a broadband light source and a grating spectrometer with charge-coupled device detector (CCD). We evaluated this BBCES by measuring extinction cross section for aerosols that are pure scattering, slightly absorbing and strongly absorbing atomized from standard materials. We also retrieved the refractive indices from the measured extinction cross sections. Secondary organic aerosols from biogenic and anthropogenic precursors were "aged" to differential time scales (1 to 10 days) in an Oxidation Flow Reactor (OFR) under the combined influence of OH, O3 and UV light. The new BBCES was used to online measure the extinction cross sections of the SOA. This talk will provide a comprehensive understanding of aerosol optical properties alerting during aging process in the 395 - 700 nm spectrum.

Global Distribution of Dust, Smoke, Volcanic Ash, and Pollutant Aerosols Seen from Space

NASA Technical Reports Server (NTRS)

Herman, Jay R.; Hsu, Christina; Krotkov, Nickolay; Torres, Omar

1998-01-01

New technique for observing aerosols from space, using ultraviolet (UV) wavelengths, have been developed during the past three years. The chief benefit from observing aerosols in the UV is that they are easily visible over both land and water. While there is presently more than one satellite that can observe aerosols in the UV, only Total Ozone Mapping Spectrometer (TOMS) has a long-term record (since 1979) and adequate spatial resolutions (50 to 100 km) to observe the seasonal and interannual variations, and to locate some of the land sources of dust, smoke, volcanic ash and sulfate pollutants. The data has been assembled into daily images of the atmospheric aerosol loading in terms of optical depth and UV transmittance. For the major sources of aerosols, it is common for at least 50% of the total UV to be absorbed underneath aerosol plumes. This is particularly true for the spectacular smoke plumes originating from the recent Indonesian and Mexican fires, as well as under the huge African dust plumes. The sulfate pollutants are mostly present in the Northern Hemisphere and are associated with regions of high industrial activity. The location and seasonal dependence of these aerosol plumes over Europe and North America will be contrasted with the relatively clean Southern Hemisphere. Because of the success of this technique, it has formed the basis for a new generation of space-borne aerosol detection instruments. These new instruments combine the UV observations with the more traditional visible-wavelength data to obtain a more comprehensive characterization of aerosols that is possible with either UV or visible techniques by themselves.

Carbonaceous Aerosol Characterization during 2016 KOR-US 2016

NASA Astrophysics Data System (ADS)

Rodriguez, B.; Santos, G. M.; Sanchez, D.; Jeong, D.; Czimczik, C. I.; Kim, S.

2017-12-01

Atmospheric carbonaceous aerosols are a major component of fine particulate matter and assume important roles in Earth's climate and human health. Because atmospheric carbonaceous aerosols exist as a continuum ranging from small, light-scattering organic carbon (OC), to highly-condensed, light-absorbing elemental carbon (EC) they have contrasting effects on interaction with incoming and outgoing radiation, cloud formation, and snow/ice albedo. By strengthening our understanding of the relative contribution and sources of OC and EC we will be able to further describe aerosol formation and mixing at the regional level. To understand the relative anthropogenic and biogenic contributions to carbonaceous aerosol, 12 PM10 aerosols samples were collected on quartz fiber filters at the Mt. Taewha Research Forest in South Korea during the KORUS-AQ 2016 campaign over periods of 24-48 hours with a high-volume air sampler. Analysis of bulk C and N concentrations and absorption properties of filter extracts interspersed with HYSPLIT model results indicated that continental outflow across the Yellow Sea in enriched in bulk nitrogen loading and enhanced bulk absorptive properties of the aerosols. Bulk radiocarbon analysis also indicated enriched values in all samples indicating contamination from a nuclear power plant or the combustion of biomedical waste nearby. Here, we aim to investigate further the chemical characterization of VOCs adsorbed unto the aerosol through TD-GC-TOFMS. With this dataset we aim to determine the relative contribution of anthropogenic and biogenic aerosols by utilizing specific chemical tracers for source apportionment.

Climatological Aspects of the Optical Properties of Fine/Coarse Mode Aerosol Mixtures

NASA Technical Reports Server (NTRS)

Eck, T. F.; Holben, B. N.; Sinyuk, A.; Pinker, R. T.; Goloub, P.; Chen, H.; Chatenet, B.; Li, Z.; Singh, R. P.; Tripathi, S.N.;

Is there an aerosol signature of aqueous processing?

NASA Astrophysics Data System (ADS)

Ervens, B.; Sorooshian, A.

2017-12-01

The formation of aerosol mass in cloud water has been recognized as a substantial source of atmospheric aerosol mass. While sulfate formation can be relatively well constrained, the formation of secondary organic aerosol mass in the aqueous phase (aqSOA) is much more complex due to the multitude of precursors and variety in chemical processes. Aqueous phase processing adds aerosol mass to the droplet mode, which is formed due to mass addition to activated particles in clouds. In addition, it has been shown that aqSOA mass has specific characteristics in terms of oxidation state and hygroscopicity that might help to distinguish it from other SOA sources. Many models do not include detailed chemical mechanisms of sulfate and aqSOA formation and also lack details on the mass distribution of newly formed mass. Mass addition inside and outside clouds modifies different parts of an aerosol population and consequently affects predictions of properties and lifetime of particles. Using a combination of field data analysis and model studies for a variety of air masses, we will show which chemical and physical aerosol properties can be used, in order to identify an `aqueous phase signature' in processed aerosol populations. We will discuss differences in this signature in clean (e.g., background), moderately polluted (e.g., urban) and highly polluted (e.g., biomass burning) air masses and suggest air-mass-specific chemical and/or physical properties that will help to quantify the aqueous-phase derived aerosol mass.

Combustion Aerosol over Marine Stratus: Long Range Transport, Subsidence and Aerosol-Cloud Interactions over the South East Pacific

NASA Astrophysics Data System (ADS)

Clarke, A. D.; Snider, J.; Freitag, S.; Feingold, G.; Campos, T. L.; Breckhovskikh, V.; Kazil, J.

2011-12-01

The worlds largest stratus deck over the South East Pacific (SEP) was a study target for the VOCALS (http://www.eol.ucar.edu/projects/vocals/) experiment in October 2008. Aerosol-cloud interactions were one major goal of several ship and aircraft studies including results from 14 flights of the NCAR C-130 aircraft reported here. Each flight covered about a 1000 km range with multiple profiles and legs below, in and above the Sc deck. Strong aerosol sources along the coast of Chile were expected and found to influence cloud condensation nuclei (CCN) in coastal clouds. However; "rivers" of elevated CO, black carbon (BC) associated with combustion aerosol effective as CCN at <0.3%S were also common in subsiding FT air overlying the extensive Sc deck for over 1000km offshore. This subsidence, linked to the Hadley circulation, brought in aerosol from sources over the western Pacific as well as South America. Observed entrainment of this aerosol appeared linked to cloud related turbulence. When present, this combustion aerosol increased available CCN and decreased effective radius compared to clouds in "clean" MBL air advected from the South Pacific. We hypothesize that this entrainment can help buffer MBL clouds over the SEP against depletion of CCN by drizzle. This may delay transition of closed cell to open cell convection, potentially leading to increased lifetimes of Sc clouds that entrain such aerosol.

Aerosols in Northern Morocco: Input pathways and their chemical fingerprint

NASA Astrophysics Data System (ADS)

Benchrif, A.; Guinot, B.; Bounakhla, M.; Cachier, H.; Damnati, B.; Baghdad, B.

2018-02-01

The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. Deserts and marine aerosols combine with combustion aerosols from maritime traffic, large urban centers, and at a larger scale from populated industrialized regions in Europe. From Tetouan city located in the North of Morocco, we attempted to better figure out the main aerosol transport pathways and their respective aerosol load and chemical profile by examining air mass back trajectory patterns and aerosol chemical compositions from May 2011 to April 2012. The back trajectory analysis throughout the sampling period led to four clusters, for which meteorological conditions and aerosol chemical characteristics have been investigated. The most frequent cluster (CL3: 39%) corresponds to polluted air masses coming from the Mediterranean Basin, characterized by urban and marine vessels emissions out of Spain and of Northern Africa. Two other polluted clusters were characterized. One is of local origin (CL1: 22%), with a marked contribution from urban aerosols (Rabat, Casablanca) and from biomass burning aerosols. The second (CL2: 32%) defines air masses from the near Atlantic Ocean, affected by pollutants emitted from the Iberian coast. A fourth cluster (CL4: 7%) is characterized by rather clean, fast and rainy oceanic air masses, influenced during their last 24 h before reaching Tetouan by similar sources with those affecting CL2, but to a lesser extent. The chemical data show that carbonaceous species are found in the fine aerosols fraction and are generally from local primary sources (low OC/EC) rather than long-range transported. In addition to fresh traffic and maritime vessel aerosols, our results suggest the contribution of local biomass burning.

Primary aerosol and secondary inorganic aerosol budget over the Mediterranean Basin during 2012 and 2013

NASA Astrophysics Data System (ADS)

Guth, Jonathan; Marécal, Virginie; Josse, Béatrice; Arteta, Joaquim; Hamer, Paul

2018-04-01

In the frame of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), we analyse the budget of primary aerosols and secondary inorganic aerosols over the Mediterranean Basin during the years 2012 and 2013. To do this, we use two year-long numerical simulations with the chemistry-transport model MOCAGE validated against satellite- and ground-based measurements. The budget is presented on an annual and a monthly basis on a domain covering 29 to 47° N latitude and 10° W to 38° E longitude. The years 2012 and 2013 show similar seasonal variations. The desert dust is the main contributor to the annual aerosol burden in the Mediterranean region with a peak in spring, and sea salt being the second most important contributor. The secondary inorganic aerosols, taken as a whole, contribute a similar level to sea salt. The results show that all of the considered aerosol types, except for sea salt aerosols, experience net export out of our Mediterranean Basin model domain, and thus this area should be considered as a source region for aerosols globally. Our study showed that 11 % of the desert dust, 22.8 to 39.5 % of the carbonaceous aerosols, 35 % of the sulfate and 9 % of the ammonium emitted or produced into the study domain are exported. The main sources of variability for aerosols between 2012 and 2013 are weather-related variations, acting on emissions processes, and the episodic import of aerosols from North American fires. In order to assess the importance of the anthropogenic emissions of the marine and the coastal areas which are central for the economy of the Mediterranean Basin, we made a sensitivity test simulation. This simulation is similar to the reference simulation but with the removal of the international shipping emissions and the anthropogenic emissions over a 50 km wide band inland along the coast. We showed that around 30 % of the emissions of carbonaceous aerosols and 35 to 60 % of the exported carbonaceous aerosols originates from the marine and coastal areas. The formation of 23, 27 and 27 %, respectively of, ammonium, nitrate and sulfate aerosols is due to the emissions within the marine and coastal area.

Impacts of Aerosols on Seasonal Precipitation and Snowpack in California Based on Convection-Permitting WRF-Chem Simulations

NASA Astrophysics Data System (ADS)

Gu, Y.; Wu, L.; Jiang, J. H.; Su, H.; Yu, N.; Zhao, C.; Qian, Y.; Zhao, B.; Liou, K. N.; Choi, Y. S.

2017-12-01

A version of the WRF-Chem model with fully coupled aerosol-meteorology-snowpack is employed to investigate the impacts of various aerosol sources on precipitation and snowpack in California. In particular, the impacts of locally emitted anthropogenic and dust aerosols, and aerosols transported from outside of California are studied. We differentiate three pathways of aerosol effects including aerosol-radiation interaction (ARI), aerosol-snow interaction (ASI), and aerosol-cloud interaction (ACI). The convection-permitting model simulations show that precipitation, snow water equivalent (SWE), and surface air temperature averaged over the whole domain (34-42°N, 117-124°W, not including ocean points) are reduced when aerosols are included, therefore reducing the high model biases of these variables when aerosol effects are not considered. Aerosols affect California water resources through the warming of mountain tops and anomalously low precipitation, however, different aerosol sources play different roles in changing surface temperature, precipitation and snowpack in California by means of various weights of the three pathways. ARI by all aerosols mainly cools the surface, leading to slightly increased SWE over the mountains. Locally emitted dust aerosols warm the surface of mountain tops through ASI, in which the reduced snow albedo associated with dirty snow leads to more surface absorption of solar radiation and reduced SWE. Transported and local anthropogenic aerosols play a dominant role in increasing cloud water amount but reducing precipitation through ACI, leading to reduced SWE and runoff over the Sierra Nevada, as well as the warming of mountain tops associated with decreased SWE and hence lower surface albedo. The average changes in surface temperature from October to June are about -0.19 K and 0.22 K for the whole domain and over mountain tops, respectively. Overall, the averaged reduction during October to June is about 7% for precipitation, 3% for SWE, and 7% for surface runoff for the whole domain, while the corresponding numbers are 12%, 10%, and 10% for mountain tops. The reduction in SWE is more significant in a dry year, with 9% for the whole domain and 16% for mountain tops.