Long-term Aerosol Lidar Measurements At CNR-IMAA

NASA Astrophysics Data System (ADS)

Mona, L.; Amodeo, A.; D'Amico, G.; Pandolfi, M.; Pappalardo, G.

2006-12-01

Actual estimations of the aerosol effect on the radiation budget are affected by a large uncertainties mainly due to the high inhomogeneity and variability of atmospheric aerosol, in terms of concentration, shape, size distribution, refractive index and vertical distribution. Long-term measurements of vertical profiles of aerosol optical properties are needed to reduce these uncertainties. At CNR-IMAA (40° 36'N, 15° 44' E, 760 m above sea level), a lidar system for aerosol study is operative since May 2000 in the framework of EARLINET (European Aerosol Research Lidar Network). Until August 2005, it provided independent measurements of aerosol extinction and backscatter at 355 nm and aerosol backscatter profiles at 532 nm. After an upgrade of the system, it provides independent measurements of aerosol extinction and backscatter profiles at 355 and 532 nm, and of aerosol backscatter profiles at 1064 nm and depolarization ratio at 532 nm. For these measurements, lidar ratio at 355 and 532 nm and Angstrom exponent profiles at 355/532 nm are also obtained. Starting on May 2000, systematic measurements are performed three times per week according to the EARLINET schedule and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. A climatological study has been carried out in terms of the seasonal behavior of the PBL height and of the aerosol optical properties calculated inside the PBL itself. In the free troposphere, an high occurrences of Saharan dust intrusions (about 1 day of Saharan dust intrusion every 10 days) has been observed at CNR-IMAA because of the short distance from the Sahara region. During 6 years of observations, very peculiar cases of volcanic aerosol emitted by Etna volcano and aerosol released by large forest fires burning occurred in Alaska and Canada have been observed in the free troposphere at our site. Particular attention is devoted to lidar ratio both for the

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 (2Aerosol mass (PM 10 mass of particles smaller than 10 μm) and black carbon concentration were also measured. Particle-Induced X-ray Emission (PIXE) was used to measure the concentration of 22 trace elements at levels below 0.5 ng m -3. Quantitative aerosol source apportionment was performed using Absolute Principal Factor Analysis (APFA). Very high aerosol concentrations were observed (up to 400 μg/m 3 PM 10). The main aerosol particle sources in Santiago are resuspended soil dust and traffic emissions. Coarse particles account for 63% of PM 10 aerosol in Gotuzo and 53% in Las Condes. A major part of this component is resuspended soil dust. In the fine fraction, resuspended soil dust accounts for 15% of fine mass, and the aerosols associated with transportation activities account for a high 64% of the fine particle mass. Sulfate particle is an important component of the aerosol in Santiago, mainly originating from gas-to-particle conversion from SO 2. In the Gotuzo site, sulfates are the highest aerosol component, accounting for 64.5% of fine mass. Direct traffic emissions are generally mixed with resuspended soil dust. It is difficult to separate the two components, because the soil dust in downtown Santiago is contaminated with Pb, Br, Cl, and other heavy metals that are also tracers for traffic emissions. Residual oil combustion is observed, with the presence of V, S and Ni. An

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.

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.

Aerosol characterization over the southeastern United States using high-resolution aerosol mass spectrometry: spatial and seasonal variation of aerosol composition and sources with a focus on organic nitrates

NASA Astrophysics Data System (ADS)

Xu, L.; Suresh, S.; Guo, H.; Weber, R. J.; Ng, N. L.

2015-07-01

We deployed a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) to characterize the chemical composition of submicron non-refractory particulate matter (NR-PM1) in the southeastern USA. Measurements were performed in both rural and urban sites in the greater Atlanta area, Georgia (GA), and Centreville, Alabama (AL), for approximately 1 year as part of Southeastern Center for Air Pollution and Epidemiology study (SCAPE) and Southern Oxidant and Aerosol Study (SOAS). Organic aerosol (OA) accounts for more than half of NR-PM1 mass concentration regardless of sampling sites and seasons. Positive matrix factorization (PMF) analysis of HR-ToF-AMS measurements identified various OA sources, depending on location and season. Hydrocarbon-like OA (HOA) and cooking OA (COA) have important, but not dominant, contributions to total OA in urban sites (i.e., 21-38 % of total OA depending on site and season). Biomass burning OA (BBOA) concentration shows a distinct seasonal variation with a larger enhancement in winter than summer. We find a good correlation between BBOA and brown carbon, indicating biomass burning is an important source for brown carbon, although an additional, unidentified brown carbon source is likely present at the rural Yorkville site. Isoprene-derived OA factor (isoprene-OA) is only deconvolved in warmer months and contributes 18-36 % of total OA. The presence of isoprene-OA factor in urban sites is more likely from local production in the presence of NOx than transport from rural sites. More-oxidized and less-oxidized oxygenated organic aerosol (MO-OOA and LO-OOA, respectively) are dominant fractions (47-79 %) of OA in all sites. MO-OOA correlates well with ozone in summer but not in winter, indicating MO-OOA sources may vary with seasons. LO-OOA, which reaches a daily maximum at night, correlates better with estimated nitrate functionality from organic nitrates than total nitrates. Based

Aerosols cause intraseasonal short-term suppression of Indian monsoon rainfall.

PubMed

Dave, Prashant; Bhushan, Mani; Venkataraman, Chandra

2017-12-11

Aerosol abundance over South Asia during the summer monsoon season, includes dust and sea-salt, as well as, anthropogenic pollution particles. Using observations during 2000-2009, here we uncover repeated short-term rainfall suppression caused by coincident aerosols, acting through atmospheric stabilization, reduction in convection and increased moisture divergence, leading to the aggravation of monsoon break conditions. In high aerosol-low rainfall regions extending across India, both in deficient and normal monsoon years, enhancements in aerosols levels, estimated as aerosol optical depth and absorbing aerosol index, acted to suppress daily rainfall anomaly, several times in a season, with lags of a few days. A higher frequency of prolonged rainfall breaks, longer than seven days, occurred in these regions. Previous studies point to monsoon rainfall weakening linked to an asymmetric inter-hemispheric energy balance change attributed to aerosols, and short-term rainfall enhancement from radiative effects of aerosols. In contrast, this study uncovers intraseasonal short-term rainfall suppression, from coincident aerosol forcing over the monsoon region, leading to aggravation of monsoon break spells. Prolonged and intense breaks in the monsoon in India are associated with rainfall deficits, which have been linked to reduced food grain production in the latter half of the twentieth century.

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

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

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

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

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.

Long-term measurements of submicrometer aerosol chemistry at the Southern Great Plains (SGP) using an Aerosol Chemical Speciation Monitor (ACSM)

DOE PAGES

Parworth, Caroline; Tilp, Alison; Fast, Jerome; ...

2015-04-01

In this study the long-term trends of non-refractory submicrometer aerosol (NR-PM1) composition and mass concentration measured by an Aerosol Chemical Speciation Monitor (ACSM) at the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) site are discussed. NR-PM1 data was recorded at ~30 min intervals over a period of 19 months between November 2010 and June 2012. Positive Matrix Factorization (PMF) was performed on the measured organic mass spectral matrix using a rolling window technique to derive factors associated with distinct sources, evolution processes, and physiochemical properties. The rolling window approach also allows us to capture the dynamic variations ofmore » the chemical properties in the organic aerosol (OA) factors over time. Three OA factors were obtained including two oxygenated OA (OOA) factors, differing in degrees of oxidation, and a biomass burning OA (BBOA) factor. Back trajectory analyses were performed to investigate possible sources of major NR-PM1 species at the SGP site. Organics dominated NR-PM1 mass concentration for the majority of the study with the exception of winter, when ammonium nitrate increases due to transport of precursor species from surrounding urban and agricultural areas and also due to cooler temperatures. Sulfate mass concentrations have little seasonal variation with mixed regional and local sources. In the spring BBOA emissions increase and are mainly associated with local fires. Isoprene and carbon monoxide emission rates were obtained by the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the 2011 U.S. National Emissions Inventory to represent the spatial distribution of biogenic and anthropogenic sources, respectively. The combined spatial distribution of isoprene emissions and air mass trajectories suggest that biogenic emissions from the southeast contribute to SOA formation at the SGP site during the summer.« less

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

Characterization of distinct Arctic aerosol accumulation modes and their sources

NASA Astrophysics Data System (ADS)

Lange, R.; Dall'Osto, M.; Skov, H.; Nøjgaard, J. K.; Nielsen, I. E.; Beddows, D. C. S.; Simo, R.; Harrison, R. M.; Massling, A.

2018-06-01

In this work we use cluster analysis of long term particle size distribution data to expand an array of different shorter term atmospheric measurements, thereby gaining insights into longer term patterns and properties of Arctic aerosol. Measurements of aerosol number size distributions (9-915 nm) were conducted at Villum Research Station (VRS), Station Nord in North Greenland during a 5 year record (2012-2016). Alongside this, measurements of aerosol composition, meteorological parameters, gaseous compounds and cloud condensation nuclei (CCN) activity were performed during different shorter occasions. K-means clustering analysis of particle number size distributions on daily basis identified several clusters. Clusters of accumulation mode aerosols (main size modes > 100 nm) accounted for 56% of the total aerosol during the sampling period (89-91% during February-April, 1-3% during June-August). By association to chemical composition, cloud condensation nuclei properties, and meteorological variables, three typical accumulation mode aerosol clusters were identified: Haze (32% of the time), Bimodal (14%) and Aged (6%). In brief: (1) Haze accumulation mode aerosol shows a single mode at 150 nm, peaking in February-April, with highest loadings of sulfate and black carbon concentrations. (2) Accumulation mode Bimodal aerosol shows two modes, at 38 nm and 150 nm, peaking in June-August, with the highest ratio of organics to sulfate concentrations. (3) Aged accumulation mode aerosol shows a single mode at 213 nm, peaking in September-October and is associated with cloudy and humid weather conditions during autumn. The three aerosol clusters were considered alongside CCN concentrations. We suggest that organic compounds, that are likely marine biogenic in nature, greatly influence the Bimodal cluster and contribute significantly to its CCN activity. This stresses the importance of better characterizing the marine ecosystem and the aerosol-mediated climate effects in the

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

Long-term aerosol measurements in Gran Canaria, Canary Islands: Particle concentration, sources and elemental composition

NASA Astrophysics Data System (ADS)

Gelado-Caballero, MaríA. D.; López-GarcíA, Patricia; Prieto, Sandra; Patey, Matthew D.; Collado, Cayetano; HéRnáNdez-Brito, José J.

2012-02-01

There are very few sets of long-term measurements of aerosol concentrations over the North Atlantic Ocean, yet such data is invaluable in quantifying atmospheric dust inputs to this ocean region. We present an 8-year record of total suspended particles (TSP) collected at three stations on Gran Canaria Island, Spain (Taliarte at sea level, Tafira 269 m above sea level (a.s.l.) and Pico de la Gorra 1930 m a.s.l.). Using wet and dry deposition measurements, the mean dust flux was calculated at 42.3 mg m-2 d-1. Air mass back trajectories (HYSPLIT, NOAA) suggested that the Sahara desert is the major source of African dust (dominant during 32-50% of days), while the Sahel desert was the major source only 2-10% of the time (maximum in summer). Elemental composition ratios of African samples indicate that, despite the homogeneity of the dust in collected samples, some signatures of the bedrocks can still be detected. Differences were found for the Sahel, Central Sahara and North of Sahara regions in Ti/Al, Mg/Al and Ca/Al ratios, respectively. Elements often associated with pollution (Pb, Cd, Ni, Zn) appeared to share a common origin, while Cu may have a predominantly local source, as suggested by a decrease in the enrichment factor (EF) of Cu during dust events. The inter-annual variability of dust concentrations is investigated in this work. During winter, African dust concentration measurements at the Pico de la Gorra station were found to correlate with the North Atlantic Oscillation (NAO) index.

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.

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

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.

“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...

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

Long term aerosol and trace gas measurements in Central Amazonia

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

2016-04-01

The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

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

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.

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.

Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

PubMed Central

Radney, James G.; Zangmeister, Christopher D.

2016-01-01

Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi-continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition rate) versus continuous wave (CW). Water coating thickness was controlled by exposing the aerosol to a set relative humidity (RH). At ≈ 85 % RH, the mass of the soot particles increased by an amount comparable to a monolayer of water being deposited and enhanced the measured absorption by 36 % and 15 % for the Q-CW and CW lasers, respectively. Extinction measurements were also performed using a cavity ring-down spectrometer (extinction equals the sum of absorption and scattering) with a CW laser and negligible enhancement was observed at all RH. These findings demonstrate that source choice can impact measurements of aerosols with volatile coatings and that the absorption enhancements at high RH previously measured by Radney and Zangmeister (2015) [1] are the result of laser source used (Q-CW) and not from an increase in the particle absorption cross section. PMID:28066027

Sources and atmospheric transformations of semivolatile organic aerosols

NASA Astrophysics Data System (ADS)

Grieshop, Andrew P.

Fine atmospheric particulate matter (PM2.5) is associated with increased mortality, a fact which led the EPA to promulgate a National Ambient Air Quality Standard (NAAQS) for PM2.5 in 1997. Organic material contributes a substantial portion of the PM2.5 mass; organic aerosols (OA) are either directly emitted (primary OA or POA) or formed via the atmospheric oxidation of volatile precursor compounds as secondary OA (SOA). The relative contributions of POA and SOA to atmospheric OA are uncertain, as are the contributions from various source classes (e.g. motor vehicles, biomass burning). This dissertation first assesses the importance of organic PM within the context of current US air pollution regulations. Most control efforts to date have focused on the inorganic component of PM. Although growing evidence strongly implicates OA, especially which from motor vehicles, in the health effects of PM, uncertain and complex source-receptor relationships for OA discourage its direct control for NAAQS compliance. Analysis of both ambient data and chemical transport modeling results indicate that OA does not play a dominant role in NAAQS violations in most areas of the country under current and likely future regulations. Therefore, new regulatory approaches will likely be required to directly address potential health impacts associated with OA. To help develop the scientific understanding needed to better regulate OA, this dissertation examined the evolution of organic aerosol emitted by combustion systems. The current conceptual model of POA is that it is non-volatile and non-reactive. Both of these assumptions were experimental investigated in this dissertation. Novel dilution measurements were carried out to investigate the gas-particle partitioning of OA at atmospherically-relevant conditions. The results demonstrate that POA from combustion sources is semivolatile. Therefore its gas-particle partitioning depends on temperature and atmospheric concentrations; heating and

Source Term Experiments Project (STEP): Aerosol characterization system

NASA Astrophysics Data System (ADS)

Schlenger, B. J.; Dunn, P. F.

A series of four experiments is being conducted at Argonne National Laboratory's TREAT Reactor. They were designed to provide some of the necessary data regarding magnitude and release rates of fission products from degraded fuel pins, physical and chemical characteristics of released fission products, and aerosol formation and transport phenomena. These are in pile experiments, whereby the test fuel is heated by neutron induced fission and subsequent clad oxidation in steam environments that simulate as closely as practical predicted reactor accident conditions. The test sequences cover a range of pressure and fuel heatup rate, and include the effect of Aq/In/Cd control rod material.

Potential source identification for aerosol concentrations over a site in Northwestern India

NASA Astrophysics Data System (ADS)

Payra, Swagata; Kumar, Pramod; Verma, Sunita; Prakash, Divya; Soni, Manish

2016-03-01

The collocated measurements of aerosols size distribution (ASD) and aerosol optical thickness (AOT) are analyzed simultaneously using Grimm aerosol spectrometer and MICROTOP II Sunphotometer over Jaipur, capital of Rajasthan in India. The contrast temperature characteristics during winter and summer seasons of year 2011 are investigated in the present study. The total aerosol number concentration (TANC, 0.3-20 μm) during winter season was observed higher than in summer time and it was dominated by fine aerosol number concentration (FANC < 2 μm). Particles smaller than 0.8 μm (at aerodynamic size) constitute ~ 99% of all particles in winter and ~ 90% of particles in summer season. However, particles greater than 2 μm contribute ~ 3% and ~ 0.2% in summer and winter seasons respectively. The aerosols optical thickness shows nearly similar AOT values during summer and winter but corresponding low Angstrom Exponent (AE) values during summer than winter, respectively. In this work, Potential Source Contribution Function (PSCF) analysis is applied to identify locations of sources that influenced concentrations of aerosols over study area in two different seasons. PSCF analysis shows that the dust particles from Thar Desert contribute significantly to the coarse aerosol number concentration (CANC). Higher values of the PSCF in north from Jaipur showed the industrial areas in northern India to be the likely sources of fine particles. The variation in size distribution of aerosols during two seasons is clearly reflected in the log normal size distribution curves. The log normal size distribution curves reveals that the particle size less than 0.8 μm is the key contributor in winter for higher ANC.

Long term atmospheric aerosol characterization in the Amazon Basin

NASA Astrophysics Data System (ADS)

Artaxo, Paulo; Gerab, Fábio; Yamasoe, Marcia A.

This chapter presents a characterization of atmospheric aerosols collected in different places in the Amazon Basin. Both the biogenic aerosol emission from the forest and the particulate material which is emitted to the atmosphere due to the large scale man-made burns during the dry season were studied. The samples were collected during a three year period at three different locations in the Amazon (Cuiabá, Alta Floresta and Serra do Navio), using stacked filter units. Aerosol samples were also collected directly over fires of cerrado vegetation and tropical primary forest burns The samples were analyzed using several techniques for a number of elements. Gravimetric analyses were used to determine the total atmospheric aerosol concentration. Multivariate statistical analysis was used in order to identify and characterize the sources of the atmospheric aerosol present in the sampled regions. Cerrado burning emissions were enriched compared to forest ones, specially for Cl, K and Zn. High atmospheric aerosol concentrations were observed in large amazonian areas due to emissions from man-made burns in the period from June to September. The emissions from burns dominate the fine fraction of the atmospheric aerosol with characteristic high contents of black carbon, S and K. Aerosols emitted in biomass burning process are correlated to the increase in the aerosol optical thickness of the atmosphere during the Amazonian dry season. The Serra do Navio aerosol is characterized by biogenic emissions with strong marine influence. The presence of trace elements characteristic of soil particulate associated with this marine contribution indicates the existence of aerosol transport from Africa to South America. Similar composition characteristics were observed in the biogenic emission aerosols from Serra do Navio and Alta Floresta.

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.

Long-term particulate matter modeling for health effect studies in California - Part 2: Concentrations and sources of ultrafine organic aerosols

NASA Astrophysics Data System (ADS)

Hu, Jianlin; Jathar, Shantanu; Zhang, Hongliang; Ying, Qi; Chen, Shu-Hua; Cappa, Christopher D.; Kleeman, Michael J.

2017-04-01

Organic aerosol (OA) is a major constituent of ultrafine particulate matter (PM0. 1). Recent epidemiological studies have identified associations between PM0. 1 OA and premature mortality and low birth weight. In this study, the source-oriented UCD/CIT model was used to simulate the concentrations and sources of primary organic aerosols (POA) and secondary organic aerosols (SOA) in PM0. 1 in California for a 9-year (2000-2008) modeling period with 4 km horizontal resolution to provide more insights about PM0. 1 OA for health effect studies. As a related quality control, predicted monthly average concentrations of fine particulate matter (PM2. 5) total organic carbon at six major urban sites had mean fractional bias of -0.31 to 0.19 and mean fractional errors of 0.4 to 0.59. The predicted ratio of PM2. 5 SOA / OA was lower than estimates derived from chemical mass balance (CMB) calculations by a factor of 2-3, which suggests the potential effects of processes such as POA volatility, additional SOA formation mechanism, and missing sources. OA in PM0. 1, the focus size fraction of this study, is dominated by POA. Wood smoke is found to be the single biggest source of PM0. 1 OA in winter in California, while meat cooking, mobile emissions (gasoline and diesel engines), and other anthropogenic sources (mainly solvent usage and waste disposal) are the most important sources in summer. Biogenic emissions are predicted to be the largest PM0. 1 SOA source, followed by mobile sources and other anthropogenic sources, but these rankings are sensitive to the SOA model used in the calculation. Air pollution control programs aiming to reduce the PM0. 1 OA concentrations should consider controlling solvent usage, waste disposal, and mobile emissions in California, but these findings should be revisited after the latest science is incorporated into the SOA exposure calculations. The spatial distributions of SOA associated with different sources are not sensitive to the choice of

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

Short-term Aerosol Trends: Reality or Myth?

NASA Technical Reports Server (NTRS)

Leptoukh, Gregory; Zubko, Viktor

2009-01-01

The main questions addressed in this slide presentation involve short-term trends of MODIS aerosol optical thickness (AOT) over 6 years: (1) Why are the trends different in different regions? (2) How are these trends so high? (3) Why are they "coherent" in many areas? (4) Are these changes in aerosol concentrations real, i.e., are they monotonic changes in emissions? Several views of the Spatial Distribution of AOT from Terra are shown. In conclusion there are several trends: (1) There is a broad spatial inhomogenueity in AOT trends over 6 years of MODIS Terra and Aqua (2) Some of the areas demonstrate clear positive trends related to increase of emission (e.g., Eastern China) (3) Strong trends in some other areas are superficial and might be attributed, in part, to: (3a) Least squares linear trend sensitivity to outliers (need to use more robust linear fitting method) (3b) Spatial and temporal shifts or trends in meteorological conditions, especially in wind patterns responsible for aerosol transport (6) Aerosol trends should be studied together with changes in meteorology patterns as they might closely linked together

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

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.

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.;

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.

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

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.

Chemical characterization and source apportionment of fine particulate matter in Yangzhou, China, using offline aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Li, L.; Ge, X.; Xu, J.; Ye, Z.

2016-12-01

In recent years, Aerodyne Aerosol Mass Spectrometer (AMS) has been widely used for online and real-time monitoring of fine aerosol particles all over the world. However, due to the high cost and complex maintenance, the AMS was typically deployed for short-term intense field measurements, limiting its ability in elucidating the long-term behaviors and dominant sources of regional fine particles (PM2.5). In this study, we collected daily PM2.5 filter samples across a relatively long period (November 2015 to April 2016, in total >100 samples) using a high-volume sampler, in urban Yangzhou - a city in the Yangtze River Delta region, China. These samples were analyzed by using a suite of analytical techniques, for the water-soluble inorganic ions (WSIs), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and total nitrogen (TN), trace metal elements, etc. More importantly, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was for the first time introduced for the offline characterization of the PM2.5 samples collected in this region. In particular, Positive matrix factorization was conducted on the SP-AMS determined water-soluble fraction of organic aerosols (WSOA), and three distinct sources were separated, including a primary OA (POA), a less oxygenated OA (LOOA), and a more oxygenated OA (MOOA). Chemical characteristics and evolution processes of these OA subcomponents were further discussed. Our results are useful for the air pollution management in the YRD region, and the technique developed can be applied elsewhere as well.

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.

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

A large source of low-volatility secondary organic aerosol.

PubMed

Ehn, Mikael; Thornton, Joel A; Kleist, Einhard; Sipilä, Mikko; Junninen, Heikki; Pullinen, Iida; Springer, Monika; Rubach, Florian; Tillmann, Ralf; Lee, Ben; Lopez-Hilfiker, Felipe; Andres, Stefanie; Acir, Ismail-Hakki; Rissanen, Matti; Jokinen, Tuija; Schobesberger, Siegfried; Kangasluoma, Juha; Kontkanen, Jenni; Nieminen, Tuomo; Kurtén, Theo; Nielsen, Lasse B; Jørgensen, Solvejg; Kjaergaard, Henrik G; Canagaratna, Manjula; Maso, Miikka Dal; Berndt, Torsten; Petäjä, Tuukka; Wahner, Andreas; Kerminen, Veli-Matti; Kulmala, Markku; Worsnop, Douglas R; Wildt, Jürgen; Mentel, Thomas F

2014-02-27

Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.

A large source of low-volatility secondary organic aerosol

NASA Astrophysics Data System (ADS)

Ehn, Mikael; Thornton, Joel A.; Kleist, Einhard; Sipilä, Mikko; Junninen, Heikki; Pullinen, Iida; Springer, Monika; Rubach, Florian; Tillmann, Ralf; Lee, Ben; Lopez-Hilfiker, Felipe; Andres, Stefanie; Acir, Ismail-Hakki; Rissanen, Matti; Jokinen, Tuija; Schobesberger, Siegfried; Kangasluoma, Juha; Kontkanen, Jenni; Nieminen, Tuomo; Kurtén, Theo; Nielsen, Lasse B.; Jørgensen, Solvejg; Kjaergaard, Henrik G.; Canagaratna, Manjula; Maso, Miikka Dal; Berndt, Torsten; Petäjä, Tuukka; Wahner, Andreas; Kerminen, Veli-Matti; Kulmala, Markku; Worsnop, Douglas R.; Wildt, Jürgen; Mentel, Thomas F.

2014-02-01

Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.

Sources and geographical origins of fine aerosols in Paris (France)

NASA Astrophysics Data System (ADS)

Bressi, M.; Sciare, J.; Ghersi, V.; Mihalopoulos, N.; Petit, J.-E.; Nicolas, J. B.; Moukhtar, S.; Rosso, A.; Féron, A.; Bonnaire, N.; Poulakis, E.; Theodosi, C.

2013-12-01

The present study aims at identifying and apportioning the major sources of fine aerosols in Paris (France) - the second largest megacity in Europe -, and determining their geographical origins. It is based on the daily chemical composition of PM2.5 characterised during one year at an urban background site of Paris (Bressi et al., 2013). Positive Matrix Factorization (EPA PMF3.0) was used to identify and apportion the sources of fine aerosols; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential Source Contribution Function (PSCF) and Conditional Probability Function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors named ammonium sulfate (A.S.) rich factor, ammonium nitrate (A.N.) rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metals industry were identified; a detailed discussion of their chemical characteristics is reported. They respectively contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μg m-3) on the annual average; their seasonal variability is discussed. The A.S. and A.N. rich factors have undergone north-eastward mid- or long-range transport from Continental Europe, heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine aerosols abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in

Sources and geographical origins of fine aerosols in Paris (France)

NASA Astrophysics Data System (ADS)

Bressi, M.; Sciare, J.; Ghersi, V.; Mihalopoulos, N.; Petit, J.-E.; Nicolas, J. B.; Moukhtar, S.; Rosso, A.; Féron, A.; Bonnaire, N.; Poulakis, E.; Theodosi, C.

2014-08-01

The present study aims at identifying and apportioning fine aerosols to their major sources in Paris (France) - the second most populated "larger urban zone" in Europe - and determining their geographical origins. It is based on the daily chemical composition of PM2.5 examined over 1 year at an urban background site of Paris (Bressi et al., 2013). Positive matrix factorization (EPA PMF3.0) was used to identify and apportion fine aerosols to their sources; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential source contribution function (PSCF) and conditional probability function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors, namely ammonium sulfate (A.S.)-rich factor, ammonium nitrate (A.N.)-rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metal industry, were identified; a detailed discussion of their chemical characteristics is reported. They contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μg m-3) respectively on the annual average; their seasonal variability is discussed. The A.S.- and A.N.-rich factors have undergone mid- or long-range transport from continental Europe; heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine-aerosol abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in

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

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

Evaluation of Long-term Aerosol Data Records from SeaWiFS over Land and Ocean

NASA Astrophysics Data System (ADS)

Bettenhausen, C.; Hsu, C.; Jeong, M.; Huang, J.

2010-12-01

Deserts around the globe produce mineral dust aerosols that may then be transported over cities, across continents, or even oceans. These aerosols affect the Earth’s energy balance through direct and indirect interactions with incoming solar radiation. They also have a biogeochemical effect as they deliver scarce nutrients to remote ecosystems. Large dust storms regularly disrupt air traffic and are a general nuisance to those living in transport regions. In the past, measuring dust aerosols has been incomplete at best. Satellite retrieval algorithms were limited to oceans or vegetated surfaces and typically neglected desert regions due to their high surface reflectivity in the mid-visible and near-infrared wavelengths, which have been typically used for aerosol retrievals. The Deep Blue aerosol retrieval algorithm was developed to resolve these shortcomings by utilizing the blue channels from instruments such as the Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) to infer aerosol properties over these highly reflective surfaces. The surface reflectivity of desert regions is much lower in the blue channels and thus it is easier to separate the aerosol and surface signals than at the longer wavelengths used in other algorithms. More recently, the Deep Blue algorithm has been expanded to retrieve over vegetated surfaces and oceans as well. A single algorithm can now follow dust from source to sink. In this work, we introduce the SeaWiFS instrument and the Deep Blue aerosol retrieval algorithm. We have produced global aerosol data records over land and ocean from 1997 through 2009 using the Deep Blue algorithm and SeaWiFS data. We describe these data records and validate them with data from the Aerosol Robotic Network (AERONET). We also show the relative performance compared to the current MODIS Deep Blue operational aerosol data in desert regions. The current results are encouraging and this dataset will

Long-Term Observations on Aerosol Elemental Carbon and Mass Concentrations in Winter-Time in New Delhi: Implications for Local Source Changes

NASA Astrophysics Data System (ADS)

Aggarwal, S. G.; Singh, K.; Singh, N.; Gupta, P. K.

2009-12-01

Fossil-fuel and bio-fuel burning are the two major sources identified for high carbonaceous aerosol loadings in several mega cities in India. In the last decade, according to a report from the Central Pollution Control Board (CPCB, 1999), the vehicular emission (mostly diesel-powered engines) was contributed to ~67% of the total air pollution load in New Delhi. Therefore, a policy decision was taken by the government, and most of the diesel-powered engines were converted to compressed natural gas (CNG) -powered engines by 2003. To better understand the effect of these changes on air quality, we collected high volume aerosol samples (total suspended particles, TSP) mostly for a day basis at our institute building in New Delhi almost everyday during winter season (November to January) from 2002 to 2008. We found very high mean aerosol loading, i.e., 488±47 μg m-3 in 2002 winter, which dropped significantly to 280±73 μg m-3 in 2003 winter. Thereafter, a steadily increased trend of aerosol mass loadings was observed, i.e., 339±112, 339±120, 412±107 and 444±55 μg m-3 in 2004, 2005, 2006 and 2007 winters, respectively. Similar trend was also observed for elemental carbon (EC) concentration in TSP, which was peaked in 2002 (47±11 μg m-3) and minimized in 2003 (32±6 μg m-3), and then gradually increased to 41±8 μg m-3 in 2007 winter. These decline trends of aerosol mass and EC concentrations in 2003 can be explained well, because of the conversion of diesel engine to CNG engines of public transport facilities. However, again increase in aerosol mass and EC concentrations possibly because of a high increase in road traffic in recent years. According to the economic survey of New Delhi 2008-09, the number of vehicles (which includes all types of engines, i.e., petrol, diesel and CNG) has grown from ~3.3 millions in 1997-98 to ~5.6 millions in 2007-08. The influence of engine types and vehicle population on aerosol loading can also be explained well by SO2 and

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

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 aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

2014-12-01

An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

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

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

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

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

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

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

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

Traffic is a major source of atmospheric nanocluster aerosol

PubMed Central

Kuuluvainen, Heino; Karjalainen, Panu; Keskinen, Jorma; Hillamo, Risto; Niemi, Jarkko V.; Pirjola, Liisa; Timonen, Hilkka J.; Saarikoski, Sanna; Saukko, Erkka; Järvinen, Anssi; Silvennoinen, Henna; Rostedt, Antti; Olin, Miska; Yli-Ojanperä, Jaakko; Nousiainen, Pekka; Kousa, Anu; Dal Maso, Miikka

2017-01-01

In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3–3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20–54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·1015 (kgfuel)−1 in a roadside environment, 2.6·1015 (kgfuel)−1 in a street canyon, and 2.9·1015 (kgfuel)−1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·1012 (kgfuel)−1 to a high value of 4.3·1015 (kgfuel)−1. These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds. PMID:28674021

Traffic is a major source of atmospheric nanocluster aerosol.

PubMed

Rönkkö, Topi; Kuuluvainen, Heino; Karjalainen, Panu; Keskinen, Jorma; Hillamo, Risto; Niemi, Jarkko V; Pirjola, Liisa; Timonen, Hilkka J; Saarikoski, Sanna; Saukko, Erkka; Järvinen, Anssi; Silvennoinen, Henna; Rostedt, Antti; Olin, Miska; Yli-Ojanperä, Jaakko; Nousiainen, Pekka; Kousa, Anu; Dal Maso, Miikka

2017-07-18

In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·10 15 (kg fuel ) -1 in a roadside environment, 2.6·10 15 (kg fuel ) -1 in a street canyon, and 2.9·10 15 (kg fuel ) -1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·10 12 (kg fuel ) -1 to a high value of 4.3·10 15 (kg fuel ) -1 These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds.

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.

Aerosol Microphysics and Radiation Integration

DTIC Science & Technology

2007-09-30

http://www.nrlmry.navy.mil/ flambe / LONG-TERM GOALS This project works toward the development and support of real time global prognostic aerosol...Burning Emissions ( FLAMBE ) project were transition to the Fleet Numerical Oceanographic Center (FNMOC) Monterey in FY07. Meteorological guidance...Hyer, E. J. and J. S. Reid (2006), Evaluating the impact of improvements to the FLAMBE smoke source model on forecasts of aerosol distribution

Marine Aerosols and Clouds.

PubMed

Brooks, Sarah D; Thornton, Daniel C O

2018-01-03

The role of marine bioaerosols in cloud formation and climate is currently so uncertain that even the sign of the climate forcing is unclear. Marine aerosols form through direct emissions and through the conversion of gas-phase emissions to aerosols in the atmosphere. The composition and size of aerosols determine how effective they are in catalyzing the formation of water droplets and ice crystals in clouds by acting as cloud condensation nuclei and ice nucleating particles, respectively. Marine organic aerosols may be sourced both from recent regional phytoplankton blooms that add labile organic matter to the surface ocean and from long-term global processes, such as the upwelling of old refractory dissolved organic matter from the deep ocean. Understanding the formation of marine aerosols and their propensity to catalyze cloud formation processes are challenges that must be addressed given the major uncertainties associated with aerosols in climate models.

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

Long-term Satellite Observations of Asian Dust Storm: Source, Pathway, and Interannual Variability

NASA Technical Reports Server (NTRS)

Hsu, N. Christina

2008-01-01

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.

Long-term Chemical Characterization of Submicron Aerosol Particles in the Amazon Forest - ATTO Station

NASA Astrophysics Data System (ADS)

Carbone, S.; Brito, J.; Rizzo, L. V.; Holanda, B. A.; Cirino, G. G.; Saturno, J.; Krüger, M. L.; Pöhlker, C.; Ng, N. L.; Xu, L.; Andreae, M. O.; Artaxo, P.

2015-12-01

The study of the chemical composition of aerosol particles in the Amazon forest represents a step forward to understand the strong coupling between the atmosphere and the forest. For this reason submicron aerosol particles were investigated in the Amazon forest, where biogenic and anthropogenic aerosol particles coexist at the different seasons (wet/dry). The measurements were performed at the ATTO station, which is located about 150 km northeast of Manaus. At ATTO station the Aerosol chemical speciation monitor (ACSM, Aerodyne) and the Multiangle absorption photometer (MAAP, Thermo 5012) have been operated continuously from March 2014 to July 2015. In this study, long-term measurements (near-real-time, ~30 minutes) of PM1 chemical composition were investigated for the first time in this environment.The wet season presented lower concentrations than the dry season (~5 times). In terms of chemical composition, both seasons were dominated by organics (75 and 63%) followed by sulfate (11 and 13%). Nitrate presented different ratio values between the mass-to-charges 30 to 46 (main nitrate fragments) suggesting the presence of nitrate as inorganic and organic nitrate during both seasons. The results indicated that about 75% of the nitrate signal was from organic nitrate during the dry season. In addition, several episodes with elevated amount of chloride, likely in the form of sea-salt from the Atlantic Ocean, were observed during the wet season. During those episodes, chloride comprised up to 7% of the PM1. During the dry season, chloride was also observed; however, with different volatility, which suggested that Chloride was present in different form and source. Moreover, the constant presence of sulfate and BC during the wet season might be related to biomass burning emissions from Africa. BC concentration was 2.5 times higher during the dry season. Further characterization of the organic fraction was accomplished with the positive matrix factorization (PMF), which

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

Source apportionment revisited for long-term measurements of fine aerosol trace elements at two locations in southern Norway

NASA Astrophysics Data System (ADS)

Maenhaut, Willy

2018-02-01

Five-year-long (1991-1996) aerosol trace element data sets for the fine (PM2) size fraction from the sites of Birkenes and Skreådalen in southern Norway were reanalysed by US EPA positive matrix factorization PMF5 in order to assess the sources and their contribution to the PM2 aerosol. The data sets contained the concentrations of the particulate mass (PM), black carbon (BC) and 21 elements in over 700 samples for each of the two sites. The PM was obtained from weighing with a microbalance and BC was determined with a light reflectance technique. The data for the elements were obtained by a combination of particle-induced X-ray emission and instrumental neutron activation analysis. Eight source factors were retained for each site, i.e., (i) secondary sulfate, which accounted for around 40% of the average measured PM2 mass, (ii) wood burning, with BC, K, Zn and As, which accounted for about 17%, (iii) an iodine factor (with also Br and Se), which is probably related to a marine biogenic source and was responsible for about 6.5%, (iv) aged sea salt with Na, Mg, Cl and Ca, but heavily depleted in Cl; (v) a crustal factor containing Al, Si, Ca, Ti and Fe; (vi) a heavy oil burning factor with V and Ni in a ratio of 3-4; (vii) a general pollution factor (with Cu, Zn, As, Se, Sb and Pb), and (viii) an almost pure manganese factor, which is attributed to Mn and FeMn industries in southern Norway. The results were substantially different from those of an earlier PMF analysis, in which use was made of PMF2.

Assessment of aerosol indirect effects over Indian subcontinent using long term MODIS aerosol and cloud data

NASA Astrophysics Data System (ADS)

Das, Saurabh; Maitra, Animesh; Saha, Upal; De, Arijit

Aerosols have direct consequences on climate research and in climate change study due to its role in radiative forcing. The modulation of cloud properties due to the presence of aerosol is another important factor in understanding of the climate change scenario. However, the relationship between these two is mostly indirect as the meteorological conditions have a strong impact on the relationship. Cloud effective radius and decreases in precipitation efficiency are interlinked with the increase of aerosols. The net effect is that the cloud liquid water path and cloud lifetime increase with AOD. Though these facts are included in the global climate models (GCM), the quantitative estimation of aerosol indirect efficiency (AIE) varied widely. Some recent studies indicate an increasing trend of the aerosol optical depth over the Indian landmass. The anthropogenic activities are linked with this increase in aerosols. In general, aerosol increase can affect the cloud radius and leads to formation of non-precipitating cloud. However, the chemical composition of aerosols may also be an important factor. It is therefore necessary to have better understanding of the relationship for predicting the future climate which may be affected by such human activities. In this paper, the relation of aerosol optical depth (AOD) with cloud effective radius (CER) has been investigated over the Indian subcontinent using the long term MODIS observations. MODIS can able to provide reliable AOD information over the land surface. It also able to provide information of the cloud effective radius of the same observation point. A grid-wise correlation analysis can thus be performed to estimate the relation between AOD and CER. Result indicates both positive and negative AIE of AOD on CER. To identify the possible reason for such variability in the AIE, the role of anthropogenic aerosols and water vapor is investigated. The study on the efficiency of aerosol indirect effect indicates that a large

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

Importance of Anthropogenic Aerosols for Climate Prediction: a Study on East Asian Sulfate Aerosols

NASA Astrophysics Data System (ADS)

Bartlett, R. E.; Bollasina, M. A.

2017-12-01

Climate prediction is vital to ensure that we are able to adapt to our changing climate. Understandably, the main focus for such prediction is greenhouse gas forcing, as this will be the main anthropogenic driver of long-term global climate change; however, other forcings could still be important. Atmospheric aerosols represent one such forcing, especially in regions with high present-day aerosol loading such as Asia; yet, uncertainty in their future emissions are under-sampled by commonly used climate forcing projections, such as the Representative Concentration Pathways (RCPs). Globally, anthropogenic aerosols exert a net cooling, but their effects show large variation at regional scales. Studies have shown that aerosols impact locally upon temperature, precipitation and hydroclimate, and also upon larger scale atmospheric circulation (for example, the Asian monsoon) with implications for climate remote from aerosol sources. We investigate how future climate could evolve differently given the same greenhouse gas forcing pathway but differing aerosol emissions. Specifically, we use climate modelling experiments (using HadGEM2-ES) of two scenarios based upon RCP2.6 greenhouse gas forcing but with large differences in sulfur dioxide emissions over East Asia. Results show that increased sulfate aerosols (associated with increased sulfur dioxide) lead to large regional cooling through aerosol-radiation and aerosol-cloud interactions. Focussing on dynamical mechanisms, we explore the consequences of this cooling for the Asian summer and winter monsoons. In addition to local temperature and precipitation changes, we find significant changes to large scale atmospheric circulation. Wave-like responses to upper-level atmospheric changes propagate across the northern hemisphere with far-reaching effects on surface climate, for example, cooling over Europe. Within the tropics, we find alterations to zonal circulation (notably, shifts in the Pacific Walker cell) and monsoon

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

Multi-sensor studies of short-term interannual variations of aerosols

NASA Astrophysics Data System (ADS)

Leptoukh, G.; Zubko, V.

2009-04-01

In the present paper, we analyze in details the interannual variability of MODIS (Terra and Aqua) Aerosol Optical Depth (AOD) for years 2002 - 2008. The AOD anomaly maps of short-term trends exhibit interesting spatial variability with the AOD percent change per year reaching 10% or more in some contiguous areas ("hot" and "cold" spots). These numbers seem to be rather high to reflect the actual changes in aerosol emissions, thus prompting the following questions: Are these changes real, or some of these high trends are in fact artifacts of the analysis methods used? Can they be attributed to trends in aerosol sampling trends? Are they caused by changes in meteorological patterns affecting aerosol transport routs? Is there any relation of these changes to ENSO, NAO, and other known atmospheric cycles? Our analysis (still in progress) provides numerical answers and physical explanation to some of these questions. We investigate alternative methods for trend calculation and provide recommendations for a more robust AOD trend calculation. We correlate AOD spatial and temporal distributions with those of humidity, winds, seas surface temperature, and other geophysical parameters using remote sensing data from various space-based sensors, e.g., MODIS, AIRS, along with reanalysis data. We provide the most likely relation of AOD changes observed in some equatorial areas with the recent phase of ENSO. As a result, we identify regions where AOD short-term trends can be attributed to causes other than drastic changes in local aerosol emission and/or caused by the natural outbreaks (fires, volcano eruptions, etc.). We also identify regions with monotonic change in local pollution where the alternative explanations fail to provide different interpretation for the observed trends.

The source identification of ambient aerosols in Beijing, China by multivariate analysis coupled with {sup 14}C tracer

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

Xiaoyan Tang; Min Shao; Yuanhang Zhang

1996-12-31

Ambient aerosol is one of most important pollutants in China. This paper showed the results of aerosol sources of Beijing area revealed by combination of multivariate analysis models and 14C tracer measured on Accelerator Mass Spectrometry (AMS). The results indicated that the mass concentration of particulate (<100 (M)) didn`t increase rapidly, compared with economic development in Beijing city. The multivariate analysis showed that the predominant source was soil dust which contributed more than 50% to atmospheric particles. However, it would be a risk to conclude that the aerosol pollution from anthropogenic sources was less important in Beijing city based onmore » above phenomenon. Due to lack of reliable tracers, it was very hard to distinguish coal burning from soil source. Thus, it was suspected that the soil source above might be the mixture of soil dust and coal burning. The 14C measurement showed that carbonaceous species of aerosol had quite different emission sources. For carbonaceous aerosols in Beijing, the contribution from fossil fuel to ambient particles was nearly 2/3, as the man-made activities ( coal-burning, etc.) increased, the fossil part would contribute more to atmospheric carbonaceous particles. For example, in downtown Beijing at space-heating seasons, the fossil fuel even contributed more than 95% to carbonaceous particles, which would be potential harmful to population. By using multivariate analysis together with 14C data, two important sources of aerosols in Beijing (soil and coal) combustion were more reliably distinguished, which was critical important for the assessment of aerosol problem in China.« less

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.

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.

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 Secondary Organic Aerosol Formation From Emissions of Combustion Sources

NASA Astrophysics Data System (ADS)

Jathar, Shantanu Hemant

Atmospheric aerosols exert a large influence on the Earth's climate and cause adverse public health effects, reduced visibility and material degradation. Secondary organic aerosol (SOA), defined as the aerosol mass arising from the oxidation products of gas-phase organic species, accounts for a significant fraction of the submicron atmospheric aerosol mass. Yet, there are large uncertainties surrounding the sources, atmospheric evolution and properties of SOA. This thesis combines laboratory experiments, extensive data analysis and global modeling to investigate the contribution of semi-volatile and intermediate volatility organic compounds (SVOC and IVOC) from combustion sources to SOA formation. The goals are to quantify the contribution of these emissions to ambient PM and to evaluate and improve models to simulate its formation. To create a database for model development and evaluation, a series of smog chamber experiments were conducted on evaporated fuel, which served as surrogates for real-world combustion emissions. Diesel formed the most SOA followed by conventional jet fuel / jet fuel derived from natural gas, gasoline and jet fuel derived from coal. The variability in SOA formation from actual combustion emissions can be partially explained by the composition of the fuel. Several models were developed and tested along with existing models using SOA data from smog chamber experiments conducted using evaporated fuel (this work, gasoline, fischertropschs, jet fuel, diesels) and published data on dilute combustion emissions (aircraft, on- and off-road gasoline, on- and off-road diesel, wood burning, biomass burning). For all of the SOA data, existing models under-predicted SOA formation if SVOC/IVOC were not included. For the evaporated fuel experiments, when SVOC/IVOC were included predictions using the existing SOA model were brought to within a factor of two of measurements with minor adjustments to model parameterizations. Further, a volatility

Updates on the development of Deep Blue aerosol algorithm for constructing consistent long-term data records from MODIS to VIIRS

NASA Astrophysics Data System (ADS)

Hsu, N. Y. C.; Sayer, A. M.; Lee, J.; Kim, W. V.

2017-12-01

The impacts of natural and anthropogenic sources of air pollution on climate and human health have continued to gain attention from the scientific community. In order to facilitate these effects, high quality consistent long-term global aerosol data records from satellites are essential. Several EOS-era instruments (e.g., SeaWiFS, MODIS, and MISR) are able to provide such information with a high degree of fidelity. However, with the aging MODIS sensors and the launch of the VIIRS instrument on Suomi NPP in late 2011, the continuation of long-term aerosol data records suitable for climate studies from MODIS to VIIRS is needed urgently. Recently, we have successfully modified our MODIS Deep Blue algorithm to process the VIIRS data. Extensive works were performed in refining the surface reflectance determination scheme to account for the wavelength differences between MODIS and VIIRS. Better aerosol models (including non-spherical dust) are also now implemented in our VIIRS algorithm compared to the MODIS C6 algorithm. We will show the global (land and ocean) distributions of various aerosol products from Version 1 of the VIIRS Deep Blue data set. The preliminary validation results of these new VIIRS Deep Blue aerosol products using data from AERONET sunphotometers over land and ocean will be discussed. We will also compare the monthly averaged Deep Blue aerosol optical depth (AOD) from VIIRS with the MODIS C6 products to investigate if any systematic biases may exist between MODIS C6 and VIIRS AOD. The Version 1 VIIRS Deep Blue aerosol products are currently scheduled to be released to the public in 2018.

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.

Source apportionment of submicron organic aerosol collected from Atlanta, Georgia, during 2014-2015 using the aerosol chemical speciation monitor (ACSM)

NASA Astrophysics Data System (ADS)

Rattanavaraha, Weruka; Canagaratna, Manjula R.; Budisulistiorini, Sri Hapsari; Croteau, Philip L.; Baumann, Karsten; Canonaco, Francesco; Prevot, Andre S. H.; Edgerton, Eric S.; Zhang, Zhenfa; Jayne, John T.; Worsnop, Douglas R.; Gold, Avram; Shaw, Stephanie L.; Surratt, Jason D.

2017-10-01

The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was redeployed at the Jefferson Street (JST) site in downtown Atlanta, Georgia (GA) for 1 year (March 20, 2014-February 08, 2015) to chemically characterize non-refractory submicron particulate matter (NR-PM1) in near real-time and to assess whether organic aerosol (OA) types and amounts change from year-to-year. Submicron organic aerosol (OA) mass spectra were analyzed by season using multilinear engine (ME-2) to apportion OA subtypes to potential sources and chemical processes. A suite of real-time collocated measurements from the Southeastern Aerosol Research and Characterization (SEARCH) network was compared with ME-2 factor solutions to aid in the interpretation of OA subtypes during each season. OA tracers measured from high-volume filter samples using gas chromatography interfaced with electron ionization-mass spectrometry (GC/EI-MS) also aided in identifying OA sources. The initial application of ME-2 to the yearlong ACSM dataset revealed that OA source apportionment by season was required to better resolve sporadic OA types. Spring and fall OA mass spectral datasets were separated into finer periods to capture potential OA sources resulting from non-homogeneous emissions during transitioning periods. NR-PM1 was highest in summer (16.7 ± 8.4 μg m-3) and lowest in winter (8.0 ± 5.7 μg m-3), consistent with prior studies. OA dominated NR-PM1 mass (56-74% on average) in all seasons. Hydrocarbon-like OA (HOA) from primary emissions was observed in all seasons, averaging 5-22% of total OA mass. Strong correlations of HOA with carbon monoxide (CO) (R = 0.71-0.88) and oxides of nitrogen (NOx) (R = 0.55-0.79) indicated that vehicular traffic was the likely source. Biomass burning OA (BBOA) was observed in all seasons, with lower contributions (2%) in summer and higher in colder seasons (averaging 8-20% of total OA mass). BBOA correlated strongly with levoglucosan (R = 0.78-0.95) during colder seasons

Aerosol composition and its sources at the King Sejong Station, Antarctic peninsula

NASA Astrophysics Data System (ADS)

Mishra, Vinit K.; Kim, Ki-Hyun; Hong, Sungmin; Lee, Khanghyun

The annual cycles of major metals and ions in suspended particulate matters (SPM) have been investigated at a costal site of the Antarctic Peninsula in order to elucidate temporal variations as well as major source processes responsible for their formation. The measurements had been performed from January 2000 to December 2001 at the Korean Antarctic research station, 'King Sejong' (62°13' S, 58°47' W). The observed time series of important aerosol components showed clear seasonal variation patterns, while the mean elemental concentrations (e.g., 1875 (Al), 10.3 (Ba), 0.3 (Bi), 1.3 (Cd), 1.7 pg m -3 (Co)) were generally compatible with those reported previously. The presence of high EF values with respect to both mean crustal and seawater composition (such as Bi, Cd, Cr, Cu, Ni, V, and Zn), however, suggests a possibly important role of anthropogenic processes in this remote site. In contrast, the concentrations of ionic species were not clearly distinguishable from those of other Antarctic sites; but the consideration of ionic mass balance between cations and anions pointed out the uniqueness of their source/sink processes in the study area. The major source processes of those aerosol components were also investigated using a series of statistical analyses. The overall results of our study indicated the dominance of several processes (or sources) such as sea-salt emission, secondary aerosol formation, and anthropogenic pollution from both local and distant sources.

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.

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

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...

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

Light Absorption of Stratospheric Aerosols: Long-Term Trend and Contribution by Aircraft

NASA Technical Reports Server (NTRS)

Pueschel , R. F.; Gore, Waren J. Y. (Technical Monitor)

1997-01-01

Measurements of aerosol light-absorption coefficients are useful for studies of radiative transfer and heating rates. Ogren appears to have published the first light- absorption coefficients in the stratosphere in 1981, followed by Clarke in 1983 and Pueschel in 1992. Because most stratospheric soot appears to be due to aircraft operations, application of an aircraft soot aerosol emission index to projected fuel consumption suggests a threefold increase of soot loading and light absorption by 2025. Together, those four data sets indicate an increase in mid-visible light extinction at a rate of 6 % per year. This trend is similar to the increase per year of sulfuric acid aerosol and of commercial fleet size. The proportionality between stepped-up aircraft operations above the tropopause and increases in stratospheric soot and sulfuric acid aerosol implicate aircraft as a source of stratospheric pollution. Because the strongly light-absorbing soot and the predominantly light-scattering sulfuric acid aerosol increase at similar rates, however, the mid-visible stratospheric aerosol single scatter albedo is expected to remain constant and not approach a critical value of 0.98 at which stratospheric cooling could change to warming.

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.

Chemical composition and sources of atmospheric aerosols at Djougou (Benin)

NASA Astrophysics Data System (ADS)

Ouafo-Leumbe, Marie-Roumy; Galy-Lacaux, Corinne; Liousse, Catherine; Pont, Veronique; Akpo, Aristide; Doumbia, Thierno; Gardrat, Eric; Zouiten, Cyril; Sigha-Nkamdjou, Luc; Ekodeck, Georges Emmanuel

2017-06-01

In the framework of the INDAAF (International Network to study Deposition and Atmospheric chemistry in AFrica) program, atmospheric aerosols were collected in PM2.5 and PM10 size fractions at Djougou, Benin, in the West Africa, from November, 2005 to October, 2009. Particulate carbon, ionic species, and trace metals were analyzed. Weekly PM2.5 and PM10 total mass concentrations varied between 0.7 and 47.3 µg m-3 and 1.4-148.3 µg m-3, respectively. We grouped the aerosol chemical compounds into four classes: dust, particulate organic matter (POM), elemental carbon (EC), and ions. We studied the annual variation of each class to determine their contribution in the total aerosol mass concentration and finally to investigate their potential emission sources. On an annual basis, the species presented a well-marked seasonality, with the peak of mass concentration for both sizes registered in dry season, 67 ± 2 to 86 ± 9 versus 14 ± 9 to 34 ± 5% in wet season. These values emphasized the seasonality of the emissions and the relative weak interannual standard deviation indicates the low variability of the seasonality. At the seasonal scale, major contributions to the aerosol chemistry in the dry season are: dust (26-59%), POM (30-59%), EC (5-9%), and ions (3-5%), suggesting a predominance of Sahelian and Saharan dust emissions and biomass burning source in this season. In the wet season, POM is predominant, followed by dust, EC, and ions. These results point out the contribution of surrounded biofuel combustion used for cooking and biogenic emissions during the wet season.

Investigating water soluble organic aerosols: Sources and evolution

NASA Astrophysics Data System (ADS)

Hecobian, Arsineh N.

Many studies are being conducted on the different properties of organic aerosols (OA-s) as it is first emitted into the atmosphere and the consequent changes in these characteristics as OA-s age and secondary organic aerosol (SOA) is produced and in turn aged. This thesis attempts to address some of the significant and emerging issues that deal with the formation and transformation of water-soluble organic aerosols in the atmosphere. First, a proven method for the measurement of gaseous sulfuric acid, negative ion chemical ionization mass spectrometry (CIMS), has been modified for fast and sensitive measurements of particulate phase sulfuric acid (i.e. sulfate). The modifications implemented on this system have also been the subject of preliminary verifications for measurements of aerosol phase oxalic acid (an organic acid). Second, chemical and physical characteristics of a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS experiment are presented here. A statistical summary of the emission (or enhancement) ratios relative to carbon monoxide is presented for various gaseous and aerosol species. Extensive investigations of fire plume evolutions were undertaken during the second part of this field campaign. For four distinct Boreal fires, where plumes were intercepted by the aircraft over a wide range of down-wind distances, emissions of various compounds and the effect of aging on them were investigated in detail. No clear evidence of production of secondary compounds (e.g., WSOC and OA) was observed. High variability in emissions between the different plumes may have obscured any clear evidence of changes in the mass of various species with increasing plume age. Also, the lack if tropospheric oxidizing species (e.g., O3 and OH) may have contributed to the lack of SOA formation. Individual intercepts of smoke plumes in this study were segregated by source regions. The normalized excess mixing

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...

Characteristics and sources of carbonaceous aerosols from Shanghai, China

NASA Astrophysics Data System (ADS)

Cao, J.-J.; Zhu, C.-S.; Tie, X.-X.; Geng, F.-H.; Xu, H.-M.; Ho, S. S. H.; Wang, G.-H.; Han, Y.-M.; Ho, K.-F.

2013-01-01

An intensive investigation of carbonaceous PM2.5 and TSP (total suspended particles) from Pudong (China) was conducted as part of the MIRAGE-Shanghai (Megacities Impact on Regional and Global Environment) experiment in 2009. Data for organic and elemental carbon (OC and EC), organic species, including C17 to C40 n-alkanes and 17 polycyclic aromatic hydrocarbons (PAHs), and stable carbon isotopes OC (δ13COC) and EC (δ13CEC) were used to evaluate the aerosols' temporal variations and identify presumptive sources. High OC/EC ratios indicated a large fraction of secondary organic aerosol (SOA); high char/soot ratios indicated stronger contributions to EC from motor vehicles and coal combustion than biomass burning. Diagnostic ratios of PAHs indicated that much of the SOA was produced via coal combustion. Isotope abundances (δ13COC = -24.5 ± 0.8‰ and δ13CEC = -25.1 ± 0.6‰) indicated that fossil fuels were the most important source for carbonaceous PM2.5 (particulate matter less than 2.5 micrometers in diameter), with lesser impacts from biomass burning and natural sources. An EC tracer system and isotope mass balance calculations showed that the relative contributions to total carbon from coal combustion, motor vehicle exhaust, and SOA were 41%, 21%, and 31%; other primary sources such as marine, soil and biogenic emissions contributed 7%. Combined analyses of OC and EC, n-alkanes and PAHs, and stable carbon isotopes provide a new way to apportion the sources of carbonaceous particles.

Aerosol Mapping From Space: Strengths, Limitations, and Applications

NASA Technical Reports Server (NTRS)

Kahn, Ralph

2010-01-01

The aerosol data products from the NASA Earth Observing System's MISR and MODIS instruments provide significant advances in regional and global aerosol optical depth (AOD) mapping, aerosol type measurement, and source plume characterization from space. These products have been and are being used for many applications, ranging from regional air quality assessment, to aerosol air mass type identification and evolution, to wildfire smoke injection height and aerosol transport model validation. However, retrieval uncertainties and coverage gaps still limit the quantitative constraints these satellite data place on some important questions, such as global-scale long-term trends and direct aerosol radiative forcing. Major advances in these areas seem to require a different paradigm, involving the integration of satellite with suborbital data and with models. This presentation will briefly summarize where we stand, and what incremental improvements we can expect, with the current MISR and MODIS aerosol products, and will then elaborate on some initial steps aimed at the necessary integration of satellite data with data from other sources and with chemical transport models.

Long-term variability of aerosol optical properties and radiative effects in Northern Finland

NASA Astrophysics Data System (ADS)

Lihavainen, Heikki; Hyvärinen, Antti; Asmi, Eija; Hatakka, Juha; Viisanen, Yrjö

2017-04-01

We introduce long term dataset of aerosol scattering and absorption properties and combined aerosol optical properties measured in Pallas Atmosphere-Ecosystem Supersite in Norhern Finland. The station is located 170 km north of the Arctic Circle. The station is affected by both pristine Arctic air masses as well as long transported air pollution from northern Europe. We studied the optical properties of aerosols and their radiative effects in continental and marine air masses, including seasonal cycles and long-term trends. The average (median) scattering coefficient, backscattering fraction, absorption coefficient and single scattering albedo at the wavelength of 550 nm were 7.9 (4.4) 1/Mm, 0.13 (0.12), 0.74 (0.35) 1/Mm and 0.92 (0.93), respectively. We observed clear seasonal cycles in these variables, the scattering coefficient having high values during summer and low in fall, and absorption coefficient having high values during winter and low in fall. We found that the high values of the absorption coefficient and low values of the single scattering albedo were related to continental air masses from lower latitudes. These aerosols can induce an additional effect on the surface albedo and melting of snow. We observed the signal of the Arctic haze in marine (northern) air masses during March and April. The haze increased the value of the absorption coefficient by almost 80% and that of the scattering coefficient by about 50% compared with the annual-average values. We did not observe any long-term trend in the scattering coefficient, while our analysis showed a clear decreasing trend in the backscattering fraction and scattering Ångström exponent during winter. We also observed clear relationship with temperature and aerosol scattering coefficient. We will present also how these different features affects to aerosol direct radiative forcing.

Primary and secondary aerosols in Beijing in winter: sources, variations and processes

NASA Astrophysics Data System (ADS)

Sun, Yele; Du, Wei; Fu, Pingqing; Wang, Qingqing; Li, Jie; Ge, Xinlei; Zhang, Qi; Zhu, Chunmao; Ren, Lujie; Xu, Weiqi; Zhao, Jian; Han, Tingting; Worsnop, Douglas R.; Wang, Zifa

2016-07-01

Winter has the worst air pollution of the year in the megacity of Beijing. Despite extensive winter studies in recent years, our knowledge of the sources, formation mechanisms and evolution of aerosol particles is not complete. Here we have a comprehensive characterization of the sources, variations and processes of submicron aerosols that were measured by an Aerodyne high-resolution aerosol mass spectrometer from 17 December 2013 to 17 January 2014 along with offline filter analysis by gas chromatography/mass spectrometry. Our results suggest that submicron aerosols composition was generally similar across the winter of different years and was mainly composed of organics (60 %), sulfate (15 %) and nitrate (11 %). Positive matrix factorization of high- and unit-mass resolution spectra identified four primary organic aerosol (POA) factors from traffic, cooking, biomass burning (BBOA) and coal combustion (CCOA) emissions as well as two secondary OA (SOA) factors. POA dominated OA, on average accounting for 56 %, with CCOA being the largest contributor (20 %). Both CCOA and BBOA showed distinct polycyclic aromatic hydrocarbons (PAHs) spectral signatures, indicating that PAHs in winter were mainly from coal combustion (66 %) and biomass burning emissions (18 %). BBOA was highly correlated with levoglucosan, a tracer compound for biomass burning (r2 = 0.93), and made a considerable contribution to OA in winter (9 %). An aqueous-phase-processed SOA (aq-OOA) that was strongly correlated with particle liquid water content, sulfate and S-containing ions (e.g. CH2SO2+) was identified. On average aq-OOA contributed 12 % to the total OA and played a dominant role in increasing oxidation degrees of OA at high RH levels (> 50 %). Our results illustrate that aqueous-phase processing can enhance SOA production and oxidation states of OA as well in winter. Further episode analyses highlighted the significant impacts of meteorological parameters on aerosol composition, size

Identification of sources of aerosol particles in three locations in eastern Botswana

NASA Astrophysics Data System (ADS)

Chimidza, S.; Moloi, K.

2000-07-01

Airborne particles have been collected using a dichotomous virtual impactor at three different locations in the eastern part of Botswana: Serowe, Selibe-Phikwe, and Francistown. The particles were separated into two fractions (fine and coarse). Sampling at the three locations was done consecutively during the months of July and August, which are usually dry and stable. The sampling time for each sample was 12 hours during the day. For elemental composition, energy-dispersive x-ray fluorescence technique was used. Correlations and principal component analysis with varimax rotation were used to identify major sources of aerosol particles. In all the three places, soil was found to be the main source of aerosol particles. A copper-nickel mine and smelter at Selibe-Phikwe was found to be not only a source of copper and nickel particles in Selibe-Phikwe but also a source of these particles in far places like Serowe. In Selibe-Phikwe and Francistown, car exhaust was found to be the major source of fine particles of lead and bromine.

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.

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.

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

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.

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

Sources and atmospheric processing of winter aerosols in Seoul, Korea: insights from real-time measurements using a high-resolution aerosol mass spectrometer

NASA Astrophysics Data System (ADS)

Kim, Hwajin; Zhang, Qi; Bae, Gwi-Nam; Kim, Jin Young; Bok Lee, Seung

2017-02-01

Highly time-resolved chemical characterization of nonrefractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital and largest metropolis of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter, when elevated particulate matter (PM) pollution events are often observed. This is the first time that detailed real-time aerosol measurement results have been reported from Seoul, Korea, and they reveal valuable insights into the sources and atmospheric processes that contribute to PM pollution in this region. The average concentration of submicron aerosol (PM1 = NR-PM1+ black carbon (BC)) was 27.5 µg m-3, and the total mass was dominated by organics (44 %), followed by nitrate (24 %) and sulfate (10 %). The average atomic ratios of oxygen to carbon (O / C), hydrogen to carbon (H / C), and nitrogen to carbon (N / C) of organic aerosols (OA) were 0.37, 1.79, and 0.018, respectively, which result in an average organic mass-to-carbon (OM / OC) ratio of 1.67. The concentrations (2.6-90.7 µg m-3) and composition of PM1 varied dynamically during the measurement period due to the influences of different meteorological conditions, emission sources, and air mass origins. Five distinct sources of OA were identified via positive matrix factorization (PMF) analysis of the HR-ToF-AMS data: vehicle emissions represented by a hydrocarbon-like OA factor (HOA, O / C = 0.06), cooking activities represented by a cooking OA factor (COA, O / C = 0.14), wood combustion represented by a biomass burning OA factor (BBOA, O / C = 0.34), and secondary organic aerosol (SOA) represented by a semivolatile oxygenated OA factor (SV-OOA, O / C = 0.56) and a low-volatility oxygenated OA factor (LV-OOA, O / C = 0.68). On average, primary OA (POA = HOA + COA + BBOA) accounted for 59 % the OA mass, whereas SV-OOA and LV-OOA contributed 15 and 26 %, respectively. Our results indicate that air

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

Marine aerosol as a possible source for endotoxins in coastal areas.

PubMed

Lang-Yona, Naama; Lehahn, Yoav; Herut, Barak; Burshtein, Noa; Rudich, Yinon

2014-11-15

Marine aerosols, that are very common in the highly populated coastal cities and communities, may contain biological constituents. Some of this biological fraction of marine aerosols, such as cyanobacteria and plankton debris, may influence human health by inflammation and allergic reactions when inhaled. In this study we identify and compare sources for endotoxins sampled on filters in an on-shore and more-inland site. Filter analysis included endotoxin content, total bacteria, gram-negative bacteria and cyanobacteria genome concentrations as well as ion content in order to identify possible sources for the endotoxins. Satellite images of chlorophyll-a levels and back trajectory analysis were used to further study the cyanobacteria blooms in the sea, close to the trajectory of the sampled air. The highest endotoxin concentrations found in the shoreline site were during winter (3.23±0.17 EU/m(3)), together with the highest cyanobacteria genome (1065.5 genome/m(3)). The elevated endotoxin concentrations were significantly correlated with cyanobacterial levels scaled to the presence of marine aerosol (r=0.90), as well as to chlorophyll-a (r=0.96). Filters sampled further inland showed lower and non-significant correlation between endotoxin and cyanobacteria (r=0.70, P value=0.19), suggesting decrease in marine-originated endotoxin, with possible contributions from other sources of gram-negative non-cyanobacteria. We conclude that marine cyanobacteria may be a dominant contributor to elevated endotoxin levels in coastal areas. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

2012-02-01

Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25-0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate

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

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.

Organic aerosols over Indo-Gangetic Plain: Sources, distributions and climatic implications

NASA Astrophysics Data System (ADS)

Singh, Nandita; Mhawish, Alaa; Deboudt, Karine; Singh, R. S.; Banerjee, Tirthankar

2017-05-01

Organic aerosol (OA) constitutes a dominant fraction of airborne particulates over Indo-Gangetic Plain (IGP) especially during post-monsoon and winter. Its exposure has been associated with adverse health effects while there are evidences of its interference with Earth's radiation balance and cloud condensation (CC), resulting possible alteration of hydrological cycle. Therefore, presence and effects of OA directly link it with food security and thereby, sustainability issues. In these contexts, atmospheric chemistry involving formation, volatility and aging of primary OA (POA) and secondary OA (SOA) have been reviewed with specific reference to IGP. Systematic reviews on science of OA sources, evolution and climate perturbations are presented with databases collected from 82 publications available throughout IGP till 2016. Both gaseous and aqueous phase chemical reactions were studied in terms of their potential to form SOA. Efforts were made to recognize the regional variation of OA, its chemical constituents and sources throughout IGP and inferences were made on its possible impacts on regional air quality. Mass fractions of OA to airborne particulate showed spatial variation likewise in Lahore (37 and 44% in fine and coarse fractions, respectively), Patiala (28 and 37%), Delhi (25 and 38%), Kanpur (24 and 30%), Kolkata (11 and 21%) and Dhaka. Source apportionment studies indicate biomass burning, coal combustion and vehicular emissions as predominant OA sources. However, sources represent considerable seasonal variations with dominance of gasoline and diesel emissions during summer and coal and biomass based emissions during winter and post-monsoon. Crop residue burning over upper-IGP was also frequently held responsible for massive OA emission, mostly characterized by its hygroscopic nature, thus having potential to act as CC nuclei. Conclusively, climatic implication of particulate bound OA has been discussed in terms of its interaction with radiation balance.

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

Climatology of Aerosol Optical Properties in Southern Africa

NASA Technical Reports Server (NTRS)

Queface, Antonio J.; Piketh, Stuart J.; Eck, Thomas F.; Tsay, Si-Chee

2011-01-01

A thorough regionally dependent understanding of optical properties of aerosols and their spatial and temporal distribution is required before we can accurately evaluate aerosol effects in the climate system. Long term measurements of aerosol optical depth, Angstrom exponent and retrieved single scattering albedo and size distribution, were analyzed and compiled into an aerosol optical properties climatology for southern Africa. Monitoring of aerosol parameters have been made by the AERONET program since the middle of the last decade in southern Africa. This valuable information provided an opportunity for understanding how aerosols of different types influence the regional radiation budget. Two long term sites, Mongu in Zambia and Skukuza in South Africa formed the core sources of data in this study. Results show that seasonal variation of aerosol optical thicknesses at 500 nm in southern Africa are characterized by low seasonal multi-month mean values (0.11 to 0.17) from December to May, medium values (0.20 to 0.27) between June and August, and high to very high values (0.30 to 0.46) during September to November. The spatial distribution of aerosol loadings shows that the north has high magnitudes than the south in the biomass burning season and the opposite in none biomass burning season. From the present aerosol data, no long term discernable trends are observable in aerosol concentrations in this region. This study also reveals that biomass burning aerosols contribute the bulk of the aerosol loading in August-October. Therefore if biomass burning could be controlled, southern Africa will experience a significant reduction in total atmospheric aerosol loading. In addition to that, aerosol volume size distribution is characterized by low concentrations in the non biomass burning period and well balanced particle size contributions of both coarse and fine modes. In contrast high concentrations are characteristic of biomass burning period, combined with

Polycyclic Aromatic Hydrocarbon Sources and Trapping within Secondary Organic Aerosol

NASA Astrophysics Data System (ADS)

Wallace, H. W., IV; Sanchez, N. P.; Flynn, J. H., III; Lefer, B. L.; Bottenus, C. L. H.; VanReken, T. M.; Griffin, R. J.

2017-12-01

As part of the BEETEX field study, which occurred from Feburary 7 to 27, 2015, a mobile air quality laboratory was stationed near a major refinery proximate to the Houston Ship Channel to characterize the chemical nature and sources of atmospheric particulate matter (PM) using a high-resolution time-of-flight mass spectrometer. Positive matrix factorization (PMF) was performed on the organic signal of the aerosol mass spectra, resulting in five factors totaling an average of 4.1 μg/m3 of organic aerosol: hydrocarbon-like (0.67 μg/m3), cooking (0.35 μg/m3), biomass burning (1.14 μg/m3), low-volatility oxidized (1.15 μg/m3), and semi-volatile oxidized (0.78 μg/m3). As part of this study, two techniques to quantify particulate polycyclic aromatic hydrocarbons (PAHs) were compared: one capable of quantifying non-refractory molecular ion PAHs and the other sensitive only to surface bound PAHs. Together with PMF model results on the non-refractory organic PM data, we show that particulate PAHs likely are trapped inside secondary organic aerosol (SOA) as it deposits onto particles and that the two major sources of PAHs in the area are from biomass burning and use of internal combustion engines. Because this SOA may prevent particle-phase consumption of the PAH material, these results have important implications for long-range transport of particulate PAHs.

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.

Long-term Satellite Observations of Cloud and Aerosol Radiative Effects Using the (A)ATSR Satellite Data Record

NASA Astrophysics Data System (ADS)

Christensen, M.; McGarragh, G.; Thomas, G.; Povey, A.; Proud, S.; Poulsen, C. A.; Grainger, R. G.

2016-12-01

Radiative forcing by clouds, aerosols, and their interactions constitute some of the largest sources of uncertainties in the climate system (Chapter 7 IPCC, 2013). It is essential to understand the past through examination of long-term satellite observation records to provide insight into the uncertainty characteristics of these radiative forcers. As part of the ESA CCI (Climate Change Initiative) we have recently implemented a broadband radiative flux algorithm (known as BUGSrad) into the Optimal Retrieval for Aerosol and Cloud (ORAC) scheme. ORAC achieves radiative consistency of its aerosol and cloud products through an optimal estimation scheme and is highly versatile, enabling retrievals for numerous satellite sensors: ATSR, MODIS, VIIRS, AVHRR, SLSTR, SEVIRI, and AHI. An analysis of the 17-year well-calibrated Along Track Scanning Radiometer (ATSR) data is used to quantify trends in cloud and aerosol radiative effects over a wide range of spatiotemporal scales. The El Niño Southern Oscillation stands out as the largest contributing mode of variability to the radiative energy balance (long wave and shortwave fluxes) at the top of the atmosphere. Furthermore, trends in planetary albedo show substantial decreases across the Arctic Ocean (likely due to the melting of sea ice and snow) and modest increases in regions dominated by stratocumulus (e.g., off the coast of California) through notable increases in cloud fraction and liquid water path. Finally, changes in volcanic activity and biomass burning aerosol over this period show sizeable radiative forcing impacts at local-scales. We will demonstrate that radiative forcing from aerosols and clouds have played a significant role in the identified key climate processes using 17 years of satellite observational data.

Easy Volcanic Aerosol

NASA Astrophysics Data System (ADS)

Toohey, Matthew; Stevens, Bjorn; Schmidt, Hauke; Timmreck, Claudia

2016-04-01

Radiative forcing by stratospheric sulfate aerosol of volcanic origin is one of the strongest drivers of natural climate variability. Transient model simulations attempting to match observed climate variability, such as the CMIP historical simulations, rely on volcanic forcing reconstructions based on observations of a small sample of recent eruptions and coarse proxy data for eruptions before the satellite era. Volcanic forcing data sets used in CMIP5 were provided either in terms of optical properties, or in terms of sulfate aerosol mass, leading to significant inter-model spread in the actual volcanic radiative forcing produced by models and in their resulting climate responses. It remains therefore unclear to what degree inter-model spread in response to volcanic forcing represents model differences or variations in the forcing. In order to isolate model differences, Easy Volcanic Aerosol (EVA) provides an analytic representation of volcanic stratospheric aerosol forcing, based on available observations and aerosol model results, prescribing the aerosol's radiative properties and primary modes of spatial and temporal variability. In contrast to regriddings of observational data, EVA allows for the production of physically consistent forcing for historic and hypothetical eruptions of varying magnitude, source latitude, and season. Within CMIP6, EVA will be used to reconstruct volcanic forcing over the past 2000 years for use in the Paleo-Modeling Intercomparison Project (PMIP), and will provide forcing sets for VolMIP experiments aiming to quantify model uncertainty in the response to volcanic forcing. Here, the functional form of EVA will be introduced, along with illustrative examples including the EVA-based reconstruction of volcanic forcing over the historical period, and that of the 1815 Tambora eruption.

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.

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

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.

Global source attribution of sulfate aerosol and its radiative forcing

NASA Astrophysics Data System (ADS)

Yang, Y.; Wang, H.; Smith, S.; Easter, R. C.; Ma, P. L.; Qian, Y.; Li, C.; Yu, H.; Rasch, P. J.

2017-12-01

Sulfate is an important aerosol that poses health risks and influences climate. Due to long-range atmospheric transport, local sulfate pollution could result from intercontinental influences, making domestic efforts of improving air quality inefficient. Accurate understanding of source attribution of sulfate and its radiative forcing is important for both regional air quality improvement and global climate mitigation. In this study, for the first time, a sulfur source-tagging capability is implemented in the Community Atmosphere Model (CAM5) to quantify the global source-receptor relationships of sulfate and its direct and indirect radiative forcing (DRF and IRF). Near-surface sulfate concentrations are mostly contributed by local emissions in regions with high emissions, while over regions with relatively low SO2 emissions, the near-surface sulfate is primarily attributed to non-local sources from long-range transport. The export of SO2 and sulfate from Europe contributes 20% of sulfate concentrations over North Africa, Russia and Central Asia. Sources from the Middle East account for 20% of sulfate over North Africa, Southern Africa and Central Asia in winter and autumn, and 20% over South Asia in spring. East Asia accounts for about 50% of sulfate over Southeast Asia in winter and autumn, 15% over Russia in summer, and 10% over North America in spring. South Asia contributes to 25% of sulfate over Southeast Asia in spring. Lifetime of aerosols, together with regional export, is found to determine regional air quality. The simulated global total sulfate DRF is -0.42 W m-2, with 75% contributed by anthropogenic sulfate and 25% contributed by natural sulfate. In the Southern Hemisphere tropics, dimethyl sulfide (DMS) contributes the most to the total DRF. East Asia has the largest contribution of 20-30% over the Northern Hemisphere mid- and high-latitudes. A 20% perturbation of sulfate and its precursor emissions gives a sulfate IRF of -0.44 W m-2. DMS has the

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.

Organic aerosol components derived from 25 AMS data sets across Europe using a consistent ME-2 based source apportionment approach

NASA Astrophysics Data System (ADS)

Crippa, M.; Canonaco, F.; Lanz, V. A.; Äijälä, M.; Allan, J. D.; Carbone, S.; Capes, G.; Ceburnis, D.; Dall'Osto, M.; Day, D. A.; DeCarlo, P. F.; Ehn, M.; Eriksson, A.; Freney, E.; Hildebrandt Ruiz, L.; Hillamo, R.; Jimenez, J. L.; Junninen, H.; Kiendler-Scharr, A.; Kortelainen, A.-M.; Kulmala, M.; Laaksonen, A.; Mensah, A. A.; Mohr, C.; Nemitz, E.; O'Dowd, C.; Ovadnevaite, J.; Pandis, S. N.; Petäjä, T.; Poulain, L.; Saarikoski, S.; Sellegri, K.; Swietlicki, E.; Tiitta, P.; Worsnop, D. R.; Baltensperger, U.; Prévôt, A. S. H.

2014-06-01

Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) and the intensive campaigns of European Monitoring and Evaluation Programme (EMEP) during 2008 (May-June and September-October) and 2009 (February-March). In this paper we focus on the identification of the main organic aerosol sources and we define a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 data sets accounting for two urban, several rural and remote and two high altitude sites; therefore it is likely suitable for the treatment of AMS-related ambient data sets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Generally, our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling purposes.

Challenges to producing a long-term stratospheric aerosol climatology for chemistry and climate

NASA Astrophysics Data System (ADS)

Thomason, Larry; Vernier, Jean-Paul; Bourassa, Adam; Rieger, Landon; Luo, Beiping; Peter, Thomas; Arfeuille, Florian

2016-04-01

Stratospheric aerosol data sets are key inputs for climate models (GCMs, CCMs) particularly for understanding the role of volcanoes on climate and as a surrogate for understanding the potential of human-derived stratospheric aerosol as mitigation for global warming. In addition to supporting activities of individual climate models, the data sets also act as a historical input to the activities of SPARC's Chemistry-Climate Model Initiative (CCMI) and the World Climate Research Programme's Coupled Model Intercomparison Project (CMIP). One such data set was produced in 2004 as a part of the SPARC Assessment of Stratospheric Aerosol Properties (ASAP), extending from 1979 and 2004. It was primarily constructed from the Stratospheric Aerosol and Gas Experiment series of instruments but supplemented by data from other space-based sources and a number of ground-based and airborne instruments. Updates to this data set have expanded the timeframe to span from 1850 through 2014 through the inclusion of data from additional sources, such as photometer data and ice core analyses. Fundamentally, there are limitations to the reliability of the optical properties of aerosol inferred from even the most complete single instrument data sets. At the same time, the heterogeneous nature of the underlying data to this historical data set produces considerable challenges to the production of a climate data set which is both homogeneous and reliable throughout its timespan. In this presentation, we will discuss the impact of this heterogeneity showing specific examples such as the SAGE II to OSIRIS/CALIPSO transition in 2005. Potential solutions to these issues will also be discussed.

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.

Investigation of short-term effective radiative forcing of fire aerosols over North America using nudged hindcast ensembles

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

Liu, Yawen; Zhang, Kai; Qian, Yun

Aerosols from fire emissions can potentially have large impact on clouds and radiation. However, fire aerosol sources are often intermittent, and their effect on weather and climate is difficult to quantify. Here we investigated the short-term effective radiative forcing of fire aerosols using the global aerosol–climate model Community Atmosphere Model version 5 (CAM5). Different from previous studies, we used nudged hindcast ensembles to quantify the forcing uncertainty due to the chaotic response to small perturbations in the atmosphere state. Daily mean emissions from three fire inventories were used to consider the uncertainty in emission strength and injection heights. The simulated aerosolmore » optical depth (AOD) and mass concentrations were evaluated against in situ measurements and reanalysis data. Overall, the results show the model has reasonably good predicting skills. Short (10-day) nudged ensemble simulations were then performed with and without fire emissions to estimate the effective radiative forcing. Results show fire aerosols have large effects on both liquid and ice clouds over the two selected regions in April 2009. Ensemble mean results show strong negative shortwave cloud radiative effect (SCRE) over almost the entirety of southern Mexico, with a 10-day regional mean value of –3.0 W m –2. Over the central US, the SCRE is positive in the north but negative in the south, and the regional mean SCRE is small (–0.56 W m –2). For the 10-day average, we found a large ensemble spread of regional mean shortwave cloud radiative effect over southern Mexico (15.6 % of the corresponding ensemble mean) and the central US (64.3 %), despite the regional mean AOD time series being almost indistinguishable during the 10-day period. Moreover, the ensemble spread is much larger when using daily averages instead of 10-day averages. In conclusion, this demonstrates the importance of using a large ensemble of simulations to estimate the short-term

Investigation of short-term effective radiative forcing of fire aerosols over North America using nudged hindcast ensembles

DOE PAGES

Liu, Yawen; Zhang, Kai; Qian, Yun; ...

2018-01-03

Aerosols from fire emissions can potentially have large impact on clouds and radiation. However, fire aerosol sources are often intermittent, and their effect on weather and climate is difficult to quantify. Here we investigated the short-term effective radiative forcing of fire aerosols using the global aerosol–climate model Community Atmosphere Model version 5 (CAM5). Different from previous studies, we used nudged hindcast ensembles to quantify the forcing uncertainty due to the chaotic response to small perturbations in the atmosphere state. Daily mean emissions from three fire inventories were used to consider the uncertainty in emission strength and injection heights. The simulated aerosolmore » optical depth (AOD) and mass concentrations were evaluated against in situ measurements and reanalysis data. Overall, the results show the model has reasonably good predicting skills. Short (10-day) nudged ensemble simulations were then performed with and without fire emissions to estimate the effective radiative forcing. Results show fire aerosols have large effects on both liquid and ice clouds over the two selected regions in April 2009. Ensemble mean results show strong negative shortwave cloud radiative effect (SCRE) over almost the entirety of southern Mexico, with a 10-day regional mean value of –3.0 W m –2. Over the central US, the SCRE is positive in the north but negative in the south, and the regional mean SCRE is small (–0.56 W m –2). For the 10-day average, we found a large ensemble spread of regional mean shortwave cloud radiative effect over southern Mexico (15.6 % of the corresponding ensemble mean) and the central US (64.3 %), despite the regional mean AOD time series being almost indistinguishable during the 10-day period. Moreover, the ensemble spread is much larger when using daily averages instead of 10-day averages. In conclusion, this demonstrates the importance of using a large ensemble of simulations to estimate the short-term

Geographical Distribution and Sources of Nutrients in Atmospheric Aerosol Over the Pacific Ocean

NASA Astrophysics Data System (ADS)

Uematsu, M.

2016-12-01

The Pacific Ocean, the world's largest (occupying about 30% of the Earth's total surface area) has several distinguishing biogeochemical features. In the western Pacific, dust particles originating from arid and semi-arid regions in Asia and Australia are transported to the north and south, respectively. Biomass burning emissions from Southeast Asia are exported to the tropical Pacific, and anthropogenic substances flowing out of Asia and Eurasia spread both regionally and globally. Over high primary productive areas such as the subarctic North Pacific, the equatorial Pacific and the Southern Ocean, biogenic gasses are released to the atmosphere and transported to other areas. These processes may affect cloud and rainfall patterns, air quality, and the radiative balance of downwind regions. The deposition of atmospheric aerosols containing iron and other essential nutrients is important for biogeochemical cycles in the oceans because this source of nutrients helps sustain primary production and affects food-web structure; these effects in turn influence the chemical properties of marine atmosphere. From an atmospheric chemistry standpoint, sea-salt aerosols produced by strong winds and marine biogenic gases emitted from highly productive waters affect the physicochemical characteristics of marine aerosols. As phytoplankton populations are patchy and atmospheric processes sporadic, the interactions between atmospheric chemical constituents and marine biota vary for different regions as well as seasonally and over longer timescales. To address these and other emerging issues, and more generally to better understand the important biogeochemical processes and interactions occurring over the open oceans, more long-term recurrent research cruises with standardized atmospheric shipboard measurements will be needed in the future.

Multi-Decadal Change of Atmospheric Aerosols and Their Effect on Surface Radiation

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, Thomas; Tan, Qian; Wild, Martin; Qian, Yun; Yu, Hongbin; Bian, Huisheng; Wang, Weiguo

2012-01-01

We present an investigation on multi-decadal changes of atmospheric aerosols and their effects on surface radiation using a global chemistry transport model along with the near-term to long-term data records. We focus on a 28-year time period of satellite era from 1980 to 2007, during which a suite of aerosol data from satellite observations and ground-based remote sensing and in-situ measurements have become available. We analyze the long-term global and regional aerosol optical depth and concentration trends and their relationship to the changes of emissions" and assess the role aerosols play in the multi-decadal change of solar radiation reaching the surface (known as "dimming" or "brightening") at different regions of the world, including the major anthropogenic source regions (North America, Europe, Asia) that have been experiencing considerable changes of emissions, dust and biomass burning regions that have large interannual variabilities, downwind regions that are directly affected by the changes in the source area, and remote regions that are considered to representing "background" conditions.

Organic aerosol components derived from 25 AMS datasets across Europe using a newly developed ME-2 based source apportionment strategy

NASA Astrophysics Data System (ADS)

Crippa, M.; Canonaco, F.; Lanz, V. A.; Äijälä, M.; Allan, J. D.; Carbone, S.; Capes, G.; Dall'Osto, M.; Day, D. A.; DeCarlo, P. F.; Di Marco, C. F.; Ehn, M.; Eriksson, A.; Freney, E.; Hildebrandt Ruiz, L.; Hillamo, R.; Jimenez, J.-L.; Junninen, H.; Kiendler-Scharr, A.; Kortelainen, A.-M.; Kulmala, M.; Mensah, A. A.; Mohr, C.; Nemitz, E.; O'Dowd, C.; Ovadnevaite, J.; Pandis, S. N.; Petäjä, T.; Poulain, L.; Saarikoski, S.; Sellegri, K.; Swietlicki, E.; Tiitta, P.; Worsnop, D. R.; Baltensperger, U.; Prévôt, A. S. H.

2013-09-01

Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of EUCAARI and the intensive campaigns of EMEP during 2008 (May-June and September-October) and 2009 (February-March). In this paper we focus on the identification of the main organic aerosol sources and we propose a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 datasets accounting for urban, rural, remote and high altitude sites and therefore it is likely suitable for the treatment of AMS-related ambient datasets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling evaluation purposes.

Potential sea salt aerosol sources from frost flowers in the pan-Arctic region

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

Xu, Li; Russell, Lynn M.; Burrows, Susannah M.

In order to better represent observed wintertime aerosol concentrations at Barrow, Alaska, we implemented an observationally-based parameterization for estimating sea salt production from frost flowers in the Community Earth System Model (CESM). In this work, we evaluate the potential influence of this sea salt source on the pan-Arctic (60ºN-90ºN) climate. Results show that frost flower salt emissions substantially increase the modeled surface sea salt aerosol concentration in the winter months when new sea ice and frost flowers are present. The parameterization reproduces both the magnitude and seasonal variation of the observed submicron sea salt aerosol concentration at surface in Barrowmore » during winter much better than the standard CESM simulation without a frost-flower salt particle source. Adding these frost flower salt particle emissions increases aerosol optical depth by 10% and results in a small cooling at surface. The increase in salt particle mass concentrations of a factor of 8 provides nearly two times the cloud condensation nuclei concentration, as well as 10% increases in cloud droplet number and 40% increases in liquid water content near coastal regions adjacent to continents. These cloud changes reduce longwave cloud forcing by 3% and cause a small surface warming, increasing the downward longwave flux at the surface by 2 W m-2 in the pan-Arctic under the present-day climate.« less

Validating and improving long-term aerosol data records from SeaWiFS

NASA Astrophysics Data System (ADS)

Bettenhausen, C.; Hsu, N. C.; Sayer, A. M.; Huang, J.; Gautam, R.

2011-12-01

Natural and anthropogenic aerosols influence the radiative balance of the Earth through direct and indirect interactions with incoming solar radiation. However, the quantification of these interactions and their ultimate effect on the Earth's climate still have large uncertainties. This is partly due to the limitations of current satellite data records which include short satellite lifetimes, retrieval algorithm uncertainty, or insufficient calibration accuracy. We have taken the first steps in overcoming this hurdle with the production and public release of an aerosol data record using the radiances from the Sea-viewing Wide Field-of-View Sensor (SeaWiFS). SeaWiFS was launched in late 1997 and provided exceptionally well-calibrated top-of-atmosphere radiance data until December 2010, more than 13 years. We have partnered this data with an expanded Deep Blue aerosol retrieval algorithm. In accordance with Deep Blue's original focus, the latest algorithm retrieves aerosol properties not only over bright desert surfaces, but also over oceans and vegetated surfaces. With this combination of a long time series and global algorithm, we can finally identify the changing patterns of regional aerosol loading and provide insight into long-term variability and trends of aerosols on regional and global scales. In this work, we provide an introduction to SeaWiFS, the current algorithms, and our aerosol data records. We have validated the data over land and ocean with ground measurements from the Aerosol Robotic Network (AERONET) and compared them with other satellites such as MODIS and MISR. Looking ahead to the next data release, we will also provide details on the implemented and planned algorithm improvements, and subsequent validation results.

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

Forest Fires as a Possible Source of Isotopically Light Marine Fe Aerosols

NASA Astrophysics Data System (ADS)

Tegler, L. A.; Sherry, A. M.; Romaniello, S. J.; Anbar, A. D.

2016-12-01

Iron (Fe) is an important limiting micronutrient for primary productivity in many high-nutrient, low-chlorophyll (HNLC) regions of the ocean. These marine systems receive a significant fraction of their Fe from atmospheric deposition, which is thought to be dominated by mineral dust with an Fe isotopic composition at or above 0‰. However, Mead et al. (2013) observed isotopically light Fe in marine aerosols smaller than 2.5 μm, which is difficult to reconcile with known sources of marine aerosols. Based on previous experimental work, we hypothesize that biomass burning is the source of isotopically light Fe in atmospheric particles and suggest that biomass burning might represent an underappreciated source of Fe to marine ecosystems. While Guelke et al (2007) demonstrated that Fe in agricultural plants is isotopically light, few studies have examined the Fe isotope composition of naturally occurring forests likely to be a significant source of Fe during forest fires. To address this question, we measured the isotopic composition of Ponderosa pine growing in northern Arizona. Ponderosa pine is one the most common forest types in the western US and thus representative of an important North American fire region. Pine needles were chosen because they are susceptible to complete combustion during biomass burning events. To determine the Fe isotopic composition of pine trees, pine needles were sampled at various tree heights. We found that these samples had δ56Fe values between -1.5 and 0‰, indicating that pine needles can be isotopically light compared to local grasses and soil. These results support the hypothesis that biomass burning may contribute isotopically light Fe to marine aerosols.

Improving source identification of Atlanta aerosol using temperature resolved carbon fractions in positive matrix factorization

NASA Astrophysics Data System (ADS)

Kim, Eugene; Hopke, Philip K.; Edgerton, Eric S.

Daily integrated PM 2.5 (particulate matter ⩽2.5 μm in aerodynamic diameter) composition data including eight individual carbon fractions collected at the Jefferson Street monitoring site in Atlanta were analyzed with positive matrix factorization (PMF). Particulate carbon was analyzed using the thermal optical reflectance method that divides carbon into four organic carbon (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. A total of 529 samples and 28 variables were measured between August 1998 and August 2000. PMF identified 11 sources in this study: sulfate-rich secondary aerosol I (50%), on-road diesel emissions (11%), nitrate-rich secondary aerosol (9%), wood smoke (7%), gasoline vehicle (6%), sulfate-rich secondary aerosol II (6%), metal processing (3%), airborne soil (3%), railroad traffic (3%), cement kiln/carbon-rich (2%), and bus maintenance facility/highway traffic (2%). Differences from previous studies using only the traditional OC and EC data (J. Air Waste Manag. Assoc. 53(2003a)731; Atmos Environ. (2003b)) include four traffic-related combustion sources (gasoline vehicle, on-road diesel, railroad, and bus maintenance facility) containing carbon fractions whose abundances were different between the various sources. This study indicates that the temperature resolved fractional carbon data can be utilized to enhance source apportionment study, especially with respect to the separation of diesel emissions from gasoline vehicle sources. Conditional probability functions using surface wind data and identified source contributions aid the identifications of local point sources.

Long-term observations of aerosol and cloud condensation nuclei concentrations in Barbados

NASA Astrophysics Data System (ADS)

Pöhlker, Mira L.; Klimach, Thomas; Krüger, Ovid O.; Hrabe de Angelis, Isabella; Ditas, Florian; Praß, Maria; Holanda, Bruna; Su, Hang; Weber, Bettina; Pöhlker, Christopher; Farrell, David A.; Stevens, Bjorn; Prospero, Joseph M.; Andreae, Meinrat O.; Pöschl, Ulrich

2017-04-01

Long-term observation of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations has been conducted at the Ragged Point site in Barbados since August 2016. Ragged Point is a well-established station to monitor the transatlantic transport of Saharan dust outbreaks [1]. In the absence of dust plumes, it represents an ideal site to analyze the maritime boundary layer aerosol that is transported with the trade winds over the Atlantic towards Barbados [2,3]. Broad aerosol size distribution (10 nm to 10 µm) as well as size-resolved CCN measurements at 10 different supersaturations from 0.05 % to 0.84 % have been conducted. The continuous online analyses are supplemented by intensive sampling periods to probe specific aerosol properties with various offline techniques (i.e., microscopy and spectroscopy). Aerosol key properties from our measurements are compared with the continuous and in depth observation of cloud properties at Deebles Point, which is in close neighborhood to the Ragged Point site [2]. Moreover, our activities have been synchronized with the HALO-NARVAL-2 aircraft campaign in August 2016 that added further detailed information on shallow cumulus clouds, which are characteristic for the Atlantic trade winds and represent a crucial factor in the Earth climate system. Our measurements have the following two focal points: (i) We aim to obtain a detailed CCN climatology for the alternation of maritime and dust-impacted episodes at this unique coastal location. This study will complement our recent in-depth analysis for the long-term CCN variability at a remote rain forest location [4]. (ii) Furthermore, we aim to collect detailed information on the role of different aerosol populations on the properties of the climatically important shallow cumulus clouds. References: [1] Prospero, J. M., Collard, F. X., Molinie, J., Jeannot, A. (2014), Global Biogeochemical Cycles, 28, 757-773. [2] Stevens, B., et al. (2016), Bulletin of the American

Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

NASA Astrophysics Data System (ADS)

Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

2016-04-01

The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle

Studying organic aerosols during bonfire night in Manchester: ME-2 source apportionment

NASA Astrophysics Data System (ADS)

Reyes Villegas, Ernesto; Allan, James

2016-04-01

Over the past decade, there has been an increasing interest in short-term events that negatively affect air quality (Zhao et al. 2014) such as bonfires and fireworks. In general, during these episodes, high particulate matter concentrations drop within 24 hrs; however, it is the fine fraction that dominates the emissions, known to have a potentially negative impact on air quality, thus the impact of bonfires/fireworks on air quality must be considered. Aerosols and gases were measured using a variety of instruments at The University of Manchester, sampling atmospheric emissions on Bonfire night, 5 November, one week before and one week later, in 2013 and 2014. The Multilinear Engine (ME-2) factorization tool was used through the recently developed source finder interface (SoFi, Canonaco et al. 2013) to identify sources of organic aerosols (OA) sampled with an Aerosol Mass Spectrometer (AMS). ME-2 identified five sources: solid fuel OA (SFOA), hydrocarbon like OA (HOA), cooking OA (COA), semi-volatile (SVOOA) and low volatility (LVOOA) during both years. In 2014, air pollutant concentrations were particularly high, with the highest SFOA concentrations being 20 μgm-3 at 20:30 hrs. when fireworks from different parks in Manchester were launched. Black carbon (BC) concentrations started increasing before the fireworks, around 18:00 hrs; these concentrations are representative of bonfire emissions. However, traffic emissions may be contributing to BC here; further work will be done to differentiate traffic emissions from solid fuel emissions. By analysing daily aerosol concentrations according to DEFRA's Daily Air Quality Index, it is possible to observe that in 2014, PM2.5 concentrations were considered to be high (65 μgm-3) while in 2013, PM2.5 concentrations were considered low (12 μgm-3); in the case of BBOA, concentrations ranged from 2.9 μgm-3 in 2014 to 0.65 μgm-3 in 2013. The discrepancy between these studies is mainly a result of different meteorological

Tracing anthropogenic aerosol Fe sources in the North Atlantic Ocean using dissolved Fe isotope ratios

NASA Astrophysics Data System (ADS)

Conway, T. M.; Shelley, R.; Aguilar-Islas, A. M.; Landing, W. M.; Mahowald, N. M.; John, S.

2016-02-01

Supply of iron (Fe) to the surface ocean from atmospheric deposition plays a vital role in marine biogeochemical cycles, especially in Fe-limited areas or regions close to dust sources. However, large uncertainties remain over the fluxes, solubility and bioavailability of Fe supplied by aerosol dust. Additionally, aerosol Fe is likely to consist of a mixture of natural and anthropogenic (urban, biomass burning and combustion) components, which may have very different solubilities in seawater [e.g. 1]. To constrain soluble Fe supply to the oceans, it is thus vitally important to understand the relative contributions of different types of aerosol Fe, their solubilities and spatial distributions. Stable Fe isotopes (δ56Fe) may offer a way to discriminate between different dust sources [2], because of differential fractionation during a range of chemical processes. In this study, we measured δ56Fe in North Atlantic marine aerosols collected during two US GEOTRACES GA03 cruises (Lisbon to Woods Hole via Cape Verde, 2010-11) and we present δ56Fe measurements (relative to IRMM-014) from both the bulk aerosol (HF-HNO3 digested) and the water-soluble (10s ultrapure water leach) fractions. Aerosols collected from different air-masses (Saharan, European and N. American) allowed us to investigate the variability in δ56Fe due to different regional dust sources. The bulk phase was characterized by near-crustal δ56Fe values of +0.1±0.2‰, indicating the dominance of mineral dust. In contrast, the water-soluble fraction showed great variability; aerosols from European and North American air-masses were very isotopically light (-1.2±0.2‰ and -1.1±0.7‰) while those from Saharan air-masses were crustal (+0.1‰). Comparison of this data with isotope-informed model predictions of soluble Fe from mineral and anthropogenic sources (combustion, biofuels and biomass burning) [1], suggests that the data is consistent with mixing of either 1) Fe from mineral dust (+0.1‰) and

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.

Direct and semi-direct effects of aerosol climatologies on long-term climate simulations over Europe

NASA Astrophysics Data System (ADS)

Schultze, Markus; Rockel, Burkhardt

2017-08-01

This study compares the direct and semi-direct aerosol effects of different annual cycles of tropospheric aerosol loads for Europe from 1950 to 2009 using the regional climate model COSMO-CLM, which is laterally forced by reanalysis data and run using prescribed, climatological aerosol optical properties. These properties differ with respect to the analysis strategy and the time window, and are then used for the same multi-decadal period. Five simulations with different aerosol loads and one control simulation without any tropospheric aerosols are integrated and compared. Two common limitations of our simulation strategy, to fully assess direct and semi-direct aerosol effects, are the applied observed sea surface temperatures and sea ice conditions, and the lack of short-term variations in the aerosol load. Nevertheless, the impact of different aerosol climatologies on common regional climate model simulations can be assessed. The results of all aerosol-including simulations show a distinct reduction in solar irradiance at the surface compared with that in the control simulation. This reduction is strongest in the summer season and is balanced primarily by a weakening of turbulent heat fluxes and to a lesser extent by a decrease in longwave emissions. Consequently, the seasonal mean surface cooling is modest. The temperature profile responses are characterized by a shallow near-surface cooling and a dominant warming up to the mid-troposphere caused by aerosol absorption. The resulting stabilization of stratification leads to reduced cloud cover and less precipitation. A decrease in cloud water and ice content over Central Europe in summer possibly reinforce aerosol absorption and thus strengthen the vertical warming. The resulting radiative forcings are positive. The robustness of the results was demonstrated by performing a simulation with very strong aerosol forcing, which lead to qualitatively similar results. A distinct added value over the default aerosol

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.

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.

Sources of reactive nitrogen in marine aerosol over the Northwest Pacific Ocean in spring

NASA Astrophysics Data System (ADS)

Luo, Li; Kao, Shuh-Ji; Bao, Hongyan; Xiao, Huayun; Xiao, Hongwei; Yao, Xiaohong; Gao, Huiwang; Li, Jiawei; Lu, Yangyang

2018-05-01

Atmospheric deposition of long-range transport of anthropogenic reactive nitrogen (Nr, mainly comprised of NHx, NOy and water-soluble organic nitrogen, WSON) from continents may have profound impact on marine biogeochemistry. In addition, surface ocean dissolved organic nitrogen (DON) may also contribute to aerosol WSON in the overlying atmosphere. Despite the importance of off-continent dispersion and Nr interactions at the atmosphere-ocean boundary, our knowledge of the sources of various nitrogen species in the atmosphere over the open ocean remains limited due to insufficient observations. We conducted two cruises in the spring of 2014 and 2015 from the coast of China through the East China seas (ECSs, i.e. the Yellow Sea and East China Sea) to the open ocean (i.e. the Northwest Pacific Ocean, NWPO). Concentrations of water-soluble total nitrogen (WSTN), NO3- and NH4+, as well as the δ15N of WSTN and NO3- in marine aerosol, were measured during both cruises. In the spring of 2015, we also analysed the concentrations and δ15N of NO3- and the DON of surface seawater (SSW; at a depth of 5 m) along the cruise track. Aerosol NO3-, NH4+ and WSON decreased logarithmically (1-2 orders of magnitude) with distance from the shore, reflecting strong anthropogenic emission sources of NO3-, NH4+ and WSON in China. Average aerosol NO3- and NH4+ concentrations were significantly higher in 2014 (even in the remote NWOP) than in 2015 due to the stronger wind field in 2014, underscoring the role of the Asian winter monsoon in the seaward transport of anthropogenic NO3- and NH4+. However, the background aerosol WSON over the NWPO in 2015 (13.3 ± 8.5 nmol m-3) was similar to that in 2014 (12.2 ± 6.3 nmol m-3), suggesting an additional non-anthropogenic WSON source in the open ocean. Obviously, marine DON emissions should be considered in model and field assessments of net atmospheric WSON deposition in the open ocean. This study contributes information on parallel isotopic

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

Long term measurements of the estimated hygroscopic enhancement of aerosol optical properties

NASA Astrophysics Data System (ADS)

Hervo, Maxime; Sellegri, Karine; Pichon, Jean Marc; Roger, Jean Claude; Laj, Paolo

2015-04-01

Water vapour has a major impact on aerosol optical properties, thus on the Radiative Forcing for aerosol-radiation interaction (RFari). However there is few studies measuring this impact over a large period. Optical properties of aerosols were measured at the GAW Puy de Dôme station (1465m) over a seven year period (2006-2012). The impact of hygroscopicity on aerosol optical properties was calculated over a two year period (2010-2011). The analysis of the spatial and temporal variability of the dry optical properties showed that while no long term trend was found, a clear seasonal and diurnal variation was observed on the extensive parameters (scattering, absorption). Scattering and absorption coefficients were highest during the warm season and daytime, in concordance with the seasonality and diurnal variation of the planetary boundary layer height reaching the site. Intensive parameters (single scattering albedo, asymmetry factor, refractive index) did not show such a strong diurnal variability, but still indicated different values depending on the season. Both extensive and intensive optical parameters were sensitive to the air mass origin. A strong impact of hygroscopicity on aerosol optical properties was calculated, mainly on aerosol scattering, with a dependence on the aerosol type and the season. At 90% humidity, the scattering factor enhancement (fsca) was more than 4.4 for oceanic aerosol that have mixed with a pollution plume. Consequently, the aerosol radiative forcing was estimated to be 2.8 times higher at RH= 90% and 1.75 times higher at ambient RH when hygroscopic growth of the aerosol was considered. The hygroscopicity enhancement factor of the scattering coefficient was parameterized as a function of humidity and air mass type. To our knowledge, these results are one of the first presenting the impact of water vapour on the aerosol optical properties for a long period, and the first for a site at the border between the planetary boundary layer

Source apportionment of PM2.5 carbonaceous aerosol in Baghdad, Iraq

NASA Astrophysics Data System (ADS)

Hamad, Samera Hussein; Schauer, James Jay; Heo, Jongbae; Kadhim, Ahmed K. H.

2015-04-01

Baghdad is the second largest city in the Middle East and suffers from severe air quality degradation due to the high levels of the atmospheric particulate matter (PM). Limited information exists regarding the sources of PM in Baghdad, and the lack of information on sources inhibits the development of control strategies to reduce air pollution. To better understand the nature of fine particulate matter (PM2.5) in Baghdad and the Middle East, a one year sampling campaign to collect PM2.5 was conducted from September 2012 through September 2013, missing August 2013 samples due to the security situation. 24-hour integrated samples collected on a 1-in-6 day schedule were analyzed for the major components, and monthly average samples were analyzed by gas chromatography mass spectrometry (GCMS) methods to measure particle-phase organic molecular markers. The results of organic molecular markers were used in a chemical mass balance (CMB) model to quantify the sources of PM2.5 organic carbon (OC) and PM2.5 mass. Primary sources accounted for 44% of the measured PM2.5, and secondary sources were estimated to make up 28% of the measured PM2.5. Picene, a tracer of coal combustion detected in Baghdad where there is no evidence for coal combustion, can be attributed to burning crude oil and other low quality fuels in Baghdad. Source apportionment results showed that the dominant sources of the carbonaceous aerosols in Baghdad are gasoline (37 ± 6%) and diesel engines (17 ± 3%) which can be attributed to the extensive use of gasoline and diesel powered generators in Baghdad. Wood burning and residual oil combustion contributed to 5 ± 0.4 and 1 ± 0.2% respectively of OC. The unresolved sources contributed to 42 ± 19% of the OC which represented the secondary organic aerosol (SOA) and the unidentified sources.

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

A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

NASA Astrophysics Data System (ADS)

Heringa, M. F.; Decarlo, P. F.; Chirico, R.; Tritscher, T.; Clairotte, M.; Mohr, C.; Crippa, M.; Slowik, J. G.; Pfaffenberger, L.; Dommen, J.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.

2011-10-01

Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra in the m/z range 12-250 showing Pearson's r values >0.94 for the correlations between the different SOA types after 5 h of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxidized OA (SV-OOA) observed in the ambient aerosol. The atomic O : C ratios were found to be in the range of 0.25-0.55 with no major increase during the first 5 h of aging. On average, the diesel SOA showed the lowest O : C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions based on their carbon number revealed that the SOA source with the highest O : C ratio had the largest fraction of small ions. Fragment ions containing up to 3 carbon atoms accounted for 66%, 68%, 72% and 76% of the organic spectrum of the SOA produced by the diesel car, wood burner, α-pinene and

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

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

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...

Source apportionment of carbonaceous aerosol in Sao Paulo using 13C and 14C measurements

NASA Astrophysics Data System (ADS)

Oyama, Beatriz; Andrade, Maria de Fatima; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro A. J.; Dusek, Ulrike

2016-04-01

The Metropolitan Area of Sao Paulo is affected by high aerosol concentrations, which contain a large fraction of organic material. Up to date, not much is known about the composition and origin of the organic aerosol in this city. We present the first source apportionment of the carbonaceous aerosol fraction in Sao Paulo, using stable (13C) and radioactive carbon isotopes (14C). 14C provides a clear-cut distinction between fossil sources, which contain no 14C, and contemporary sources such as biofuels, biomass burning, or biogenic sources, which contain a typical contemporary 14C/12C ratio. 13C can be used to distinguish C3 plants, such as maize and sugarcane, from C4 plants. This can help to identify a possible impact of sugarcane field burning in the rural areas of Sao Paulo State on the aerosol carbon in the city. In the first part of the study, we compare two tunnel studies: Tunnel 1 is frequented only by light duty vehicles, which run mainly on mixtures of gasoline with ethanol (gasohol, 25% ethanol and 85% gasoline) or hydrated ethanol (5% water and 95% ethanol). Tunnel 2 contains a significant fraction of heavy-duty diesel vehicles, and therefore the fraction of biofuels in the average fleet is lower. Comparison of 14C in organic and elemental carbon (OC and EC) shows that in both tunnels there is no significant contribution of biofuels to EC. Combusting ethanol-gasoline fuels in a vehicle engine does apparently not result in significant EC formation from ethanol. Biofuels contribute around 45% to OC in Tunnel 1 an only 20% in Tunnel 2, reflecting a strong impact of diesel vehicles in Tunnel 2. In the second part of the study we conduct a source apportionment of ambient aerosol carbon collected in a field study during winter (July-August) 2012. Ambient EC has two main sources, vehicular emissions and biomass burning. We estimate a contribution of vehicular sources to EC of roughly 90% during weekdays and 80% during weekends, using the 14C values measured in

Burning of olive tree branches: a major organic aerosol source in the Mediterranean

NASA Astrophysics Data System (ADS)

Kostenidou, E.; Kaltsonoudis, C.; Tsiflikiotou, M.; Louvaris, E.; Russell, L. M.; Pandis, S. N.

2013-09-01

Aerosol produced during the burning of olive tree branches was characterized with both direct source sampling (using a mobile smog chamber) and with ambient measurements during the burning season. The fresh particles were composed of 80% organic matter, 8-10% black carbon (BC), 5% potassium, 3-4% sulfate, 2-3% nitrate and 0.8% chloride. Almost half of the fresh olive tree branches burning organic aerosol (otBB-OA) consisted of alkane groups. Their mode diameter was close to 70 nm. The oxygen to carbon (O : C) ratio of the fresh otBB-OA was 0.29 ± 0.04. The mass fraction of levoglucosan in PM1 was 0.034-0.043, relatively low in comparison with most fuel types. This may lead to an underestimation of the otBB-OA contribution if levoglucosan is being used as a wood burning tracer. Chemical aging was observed during smog chamber experiments, as f44 and O : C ratio increased, due to reactions with OH radicals and O3. The otBB-OA AMS mass spectrum differs from the other published biomass burning spectra, with a main difference at m/z 60, used as levoglucosan tracer. In addition to particles, volatile organic compounds (VOCs) such as methanol, acetonitrile, acrolein, benzene, toluene and xylenes are also emitted. Positive matrix factorization (PMF) was applied to the ambient organic aerosol data and 3 factors could be identified: OOA (oxygenated organic aerosol, 55%), HOA (hydrocarbon-like organic aerosol, 11.3%) and otBB-OA 33.7%. The fresh chamber otBB-OA AMS spectrum is close to the PMF otBB-OA spectrum and resembles the ambient mass spectrum during olive tree branches burning periods. We estimated an otBB-OA emission factor of 3.5 ± 0.9 g kg-1. Assuming that half of the olive tree branches pruned is burned in Greece, 2300 ± 600 tons of otBB-OA are emitted every year. This activity is one of the most important fine aerosol sources during the winter months in Mediterranean countries.

Burning of olive tree branches: a major organic aerosol source in the Mediterranean

NASA Astrophysics Data System (ADS)

Kostenidou, E.; Kaltsonoudis, C.; Tsiflikiotou, M.; Louvaris, E.; Russell, L. M.; Pandis, S. N.

2013-03-01

Aerosol produced during the burning of olive tree branches was characterized with both direct source-sampling (using a mobile smog chamber) and with ambient measurements during the burning season. The fresh particles were composed of 80% organic matter, 8-10% black carbon (BC), 5% potassium, 3-4% sulfate, 2-3% nitrate and 0.8% chloride. Almost half of the fresh olive tree branches burning organic aerosol (otBB-OA) consisted of alkane groups. Their mode diameter was close to 70 nm. The oxygen to carbon (O:C) ratio of the fresh otBB-OA was 0.29 ± 0.04. The mass fraction of levoglucosan in PM1 was 0.034-0.043, relatively low in comparison with most fuel types. This may lead to an underestimation of the otBB-OA contribution if levoglucosan is being used as a wood burning tracer. Chemical aging was observed during smog chamber experiments, as f44 and O:C ratio increased, due to reactions with OH radicals and O3. The otBB-OA AMS mass spectrum differs from the other published biomass burning spectra, with a main difference at m/z 60, used as levoglucosan tracer. In addition to particles, volatile organic compounds (VOCs) such as methanol, acetonitrile, acrolein, benzene, toluene and xylenes are also emitted. Positive matrix factorization (PMF) was applied to the ambient organic aerosol data and 3 factors could be identified: OOA (oxygenated organic aerosol, 55%), HOA (hydrocarbon-like organic aerosol, 11.3%) and otBB-OA 33.7%. The fresh chamber otBB-OA AMS spectrum is close to the PMF otBB-OA spectrum and resembles the ambient mass spectrum during olive tree branches burning periods. We estimated an otBB-OA emission factor of 3.5 ± 0.2 g kg-1. Assuming that half of the olive tree branches pruned is burned in Greece 2280 ± 140 tons of otBB-OA are emitted every year. This activity is one of the most important fine aerosol sources during the winter months in the Mediterranean countries.

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

[Tracing Sources of Sulfate Aerosol in Nanjing Northern Suburb Using Sulfur and Oxygen Isotopes].

PubMed

Wei, Ying; Guo, Zhao-bing; Ge, Xin; Zhu, Sheng-nan; Jiang, Wen-juan; Shi, Lei; Chen, Shu

2015-04-01

Abstract: To trace the sources of sulfate contributing to atmospheric aerosol, PM2.5 samples for isotopic analysis were collected in Nanjing northern suburb during January 2014. The sulfur and oxygen isotopic compositions of sulfate from these samples were determined by EA-IRMS. Source identification and apportionment were carried out using stable isotopic and chemical evidences, combined with absolute principal component analysis (APCA) method. The Δ34S values of aerosol sulfate ranged from 2.7 per thousand to 6.4 per thousand, with an average of 5.0 per thousand ± 0.9 per thousand, while the Δ18O values ranged from 10.6 per thousand to 16.1 per thousand, with an average of 12.5 per thousand ± 1.37 per thousand. In conjunction with air mass trajectories, the results suggested that aerosol sulfates were controlled by a dominance of local anthropogenic sulfate, followed by the contributions of long-distance transported sulfate. There was a minor effect of some other low-Δ34S valued sulfates, which might be expected from biogenic sources. Absolute principal component analysis results showed that the contributions of anthropogenic sulfate and long-distance transported sulfate were 46.74% and 31.54%, respectively.

[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.

Evolution of biomass burning aerosol over the Amazon: airborne measurements of aerosol chemical composition, microphysical properties, mixing state and optical properties during SAMBBA

NASA Astrophysics Data System (ADS)

Morgan, W.; Allan, J. D.; Flynn, M.; Darbyshire, E.; Hodgson, A.; Liu, D.; O'Shea, S.; Bauguitte, S.; Szpek, K.; Johnson, B.; Haywood, J.; Longo, K.; Artaxo, P.; Coe, H.

2013-12-01

Biomass burning represents one of the largest sources of particulate matter to the atmosphere, resulting in a significant perturbation to the Earth's radiative balance coupled with serious impacts on public health. On regional scales, the impacts are substantial, particularly in areas such as the Amazon Basin where large, intense and frequent burning occurs on an annual basis for several months. Absorption by atmospheric aerosols is underestimated by models over South America, which points to significant uncertainties relating to Black Carbon (BC) aerosol properties. Initial results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil on-board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft, are presented here. Aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and a DMT Single Particle Soot Photometer (SP2). The physical, chemical and optical properties of the aerosols across the region will be characterized in order to establish the impact of biomass burning on regional air quality, weather and climate. The aircraft sampled a range of conditions including sampling of pristine Rainforest, fresh biomass burning plumes, regional haze and elevated biomass burning layers within the free troposphere. The aircraft sampled biomass burning aerosol across the southern Amazon in the states of Rondonia and Mato Grosso, as well as in a Cerrado (Savannah-like) region in Tocantins state. This presented a range of fire conditions, in terms of their number, intensity, vegetation-type and their combustion efficiencies. Near-source sampling of fires in Rainforest environments suggested that smouldering combustion dominated, while flaming combustion dominated in the Cerrado. This led to significant differences in aerosol chemical composition, particularly in terms of the BC content, with BC being enhanced in the Cerrado

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...

Chemical composition and sources of coastal marine aerosol particles during the 2008 VOCALS-REx campaign

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

Lee, Y. -N.; Springston, S.; Jayne, J.

2014-01-01

The chemical composition of aerosol particles ( D p ≤ 1.5 μm) was measured over the southeast Pacific Ocean during the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-Rex) between 16 October and 15 November 2008 using the US Department of Energy (DOE) G-1 aircraft. The objective of these flights was to gain an understanding of the sources and evolution of these aerosols, and of how they interact with the marine stratus cloud layer that prevails in this region of the globe. Our measurements showed that the marine boundary layer (MBL) aerosol mass was dominated bymore » non-sea-salt SO 4 2−, followed by Na +, Cl −, Org (total organics), NH 4 +, and NO 3 −, in decreasing order of importance; CH 3SO 3 − (MSA), Ca 2+, and K + rarely exceeded their limits of detection. Aerosols were strongly acidic with a NH 4 + to SO 4 2− equivalents ratio typically < 0.3. Sea-salt aerosol (SSA) particles, represented by NaCl, exhibited Cl − deficits caused by both HNO 3 and H 2SO 4, but for the most part were externally mixed with particles, mainly SO 4 2−. SSA contributed only a small fraction of the total accumulation mode particle number concentration. It was inferred that all aerosol species (except SSA) were of predominantly continental origin because of their strong land-to-sea concentration gradient. Comparison of relative changes in median values suggests that (1) an oceanic source of NH 3 is present between 72° W and 76° W, (2) additional organic aerosols from biomass burns or biogenic precursors were emitted from coastal regions south of 31° S, with possible cloud processing, and (3) free tropospheric (FT) contributions to MBL gas and aerosol concentrations were negligible. Finally, the very low levels of CH 3SO 3 − observed as well as the correlation between SO 4 2− and NO 3 − (which is thought primarily anthropogenic) suggest a limited contribution of DMS to SO 4 2− aerosol

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

Modeling aerosol suspension from soils and oceans as sources of micropollutants to air.

PubMed

Qureshi, Asif; MacLeod, Matthew; Hungerbühler, Konrad

2009-10-01

Soil and marine aerosol suspension are two physical mass transfer processes that are not usually included in models describing fate and transport of environmental pollutants. Here, we review the literature on soil and marine aerosol suspension and estimate aerosol suspension mass transfer velocities for inclusion in multimedia models, as a global average and on a 1 x 1 scale. The yearly, global average mass transfer velocity for soil aerosol suspension is estimated to be 6 x 10(-10)mh(-1), approximately an order of magnitude smaller than marine aerosol suspension, which is estimated to be 8 x 10(-9)mh(-1). Monthly averages of these velocities can be as high as 10(-7)mh(-1) and 10(-5)mh(-1) for soil and marine aerosol suspension, respectively, depending on location. We use a unit-world multimedia model to analyze the relevance of these two suspension processes as a mechanism that enhances long-range atmospheric transport of pollutants. This is done by monitoring a metric of long-range transport potential, phi-one thousand (phi1000), that denotes the fraction of modeled emissions to air, water or soil in a source region that reaches a distance of 1000 km in air. We find that when the yearly, globally averaged mass transfer velocity is used, marine aerosol suspension increases phi1000 only fractionally for both emissions to air and water. However, enrichment of substances in marine aerosols, or speciation between ionic and neutral forms in ocean water may increase the influence of this surface-to-air transfer process. Soil aerosol suspension can be the dominant process for soil-to-air transfer in an emission-to-soil scenario for certain substances that have a high affinity to soil. When a suspension mass transfer velocity near the maximum limit is used, soil suspension remains important if the emissions are made to soil, and marine aerosol suspension becomes important regardless of if emissions are made to air or water compartments. We recommend that multimedia models

Long-term observation of aerosol cloud relationships in the Mid-Atlantic region

NASA Astrophysics Data System (ADS)

Li, S.; Joseph, E.; Min, Q.; Yin, B.

2013-12-01

Long-term ground-based observations of aerosol and cloud properties derived from measurements of Multifilter Rotating Shadow Band Radiometer and microwave radiometer at an atmospheric measurement field station in the Baltimore-Washington corridor operated by Howard University are used to examine the temporal variation of aerosol and cloud properties and moreover aerosol indirect effect on clouds. Through statistical analysis of five years (from 2006 to 2010) of these observations, the proportion of polluted cases is found larger in 2006 and 2007 and the proportion of optically thick clouds cases is also larger in 2006 and 2007 than that in 2008, 2009 and 2010. Both the mean aerosol optical depth (AOD) and cloud optical depth (COD) are observed decreasing from 2006 to 2010 but there is no obvious trend observed on cloud liquid water path (LWP). Because of the limit of AOD retrievals under cloudy conditions surface measurements of fine particle particulate matter 2.5 (PM2.5) were used for assessing aerosol indirect effect. A positive relationship between LWP and cloud droplets effective radius (Re) and a negative relationship between PM2.5 and Re are observed based on a stringent case selection method which is used to reduce the uncertainties from retrieval and meteorological impacts. The total 5 years summer time observations are segregated according to the value of PM2.5. Examination of distributions of COD, cloud condensation nuclei (CCN), cloud droplets effective radius and LWP under polluted and pristine conditions further confirm that the high aerosol loading decreases cloud droplets effective radius and increases cloud optical depth.

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.

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.

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

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.

Aerosol composition, chemistry, and source characterization during the 2008 VOCALS Experiment

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

Lee, Y.; Springston, S.; Jayne, J.

2010-03-15

Chemical composition of fine aerosol particles over the northern Chilean coastal waters was determined onboard the U.S. DOE G-1 aircraft during the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) field campaign between October 16 and November 15, 2008. SO42-, NO3-, NH4+, and total organics (Org) were determined using an Aerodyne Aerosol Mass Spectrometer, and SO42-, NO3-, NH4+, Na+, Cl-, CH3SO3-, Mg2+, Ca2+, and K+ were determined using a particle-into-liquid sampler-ion chromatography technique. The results show the marine boundary layer (MBL) aerosol mass was dominated by non- sea-salt SO42- followed by Na+, Cl-, Org, NO3-, and NH4+, in decreasing importance; CH3SO3-, Ca2+, and K+more » rarely exceeded their respective limits of detection. The SO42- aerosols were strongly acidic as the equivalent NH4+ to SO42- ratio was only {approx}0.25 on average. NaCl particles, presumably of sea-salt origin, showed chloride deficits but retained Cl- typically more than half the equivalency of Na+, and are externally mixed with the acidic sulfate aerosols. Nitrate was observed only on sea-salt particles, consistent with adsorption of HNO3 on sea-salt aerosols, responsible for the Cl- deficit. Dust particles appeared to play a minor role, judging from the small volume differences between that derived from the observed mass concentrations and that calculated based on particle size distributions. Because SO42- concentrations were substantial ({approx}0.5 - {approx}3 {micro}g/m3) with a strong gradient (highest near the shore), and the ocean-emitted dimethylsulfide and its unique oxidation product, CH3SO3-, were very low (i.e., {le} 40 parts per trillion and <0.05 {micro}g/m3, respectively), the observed SO42- aerosols are believed to be primarily of terrestrial origin. Back trajectory calculations indicate sulfur emissions from smelters and power plants along coastal regions of Peru and Chile are the main sources of these SO4- aerosols. However, compared to observations, model

The Denver Aerosol Sources and Health (DASH) study: Overview and early findings

NASA Astrophysics Data System (ADS)

Vedal, S.; Hannigan, M. P.; Dutton, S. J.; Miller, S. L.; Milford, J. B.; Rabinovitch, N.; Kim, S.-Y.; Sheppard, L.

Improved understanding of the sources of air pollution that are most harmful could aid in developing more effective measures for protecting human health. The Denver Aerosol Sources and Health (DASH) study was designed to identify the sources of ambient fine particulate matter (PM 2.5) that are most responsible for the adverse health effects of short-term exposure to PM 2.5. Daily 24-h PM 2.5 sampling began in July 2002 at a residential monitoring site in Denver, Colorado, using both Teflon and quartz filter samplers. Sampling is planned to continue through 2008. Chemical speciation is being carried out for mass, inorganic ionic compounds (sulfate, nitrate and ammonium), and carbonaceous components, including elemental carbon, organic carbon, temperature-resolved organic carbon fractions and a large array of organic compounds. In addition, water-soluble metals were measured daily for 12 months in 2003. A receptor-based source apportionment approach utilizing positive matrix factorization (PMF) will be used to identify PM 2.5 source contributions for each 24-h period. Based on a preliminary assessment using synthetic data, the proposed source apportionment should be able to identify many important sources on a daily basis, including secondary ammonium nitrate and ammonium sulfate, diesel vehicle exhaust, road dust, wood combustion and vegetative debris. Meat cooking, gasoline vehicle exhaust and natural gas combustion were more challenging for PMF to accurately identify due to high detection limits for certain organic molecular marker compounds. Measurements of these compounds are being improved and supplemented with additional organic molecular marker compounds. The health study will investigate associations between daily source contributions and an array of health endpoints, including daily mortality and hospitalizations and measures of asthma control in asthmatic children. Findings from the DASH study, in addition to being of interest to policymakers, by

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.

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

Stable carbon isotope ratios of low molecular weight dicarboxylic acids, ketoacids and glyoxal in marine aerosols from the western North Pacific: Long-term trends in Chichijima Island

NASA Astrophysics Data System (ADS)

Kawamura, K.; Tachibana, E.

2012-12-01

Dicarboxylic acids such as oxalic, malonic and succinic acids are the most abundant water-soluble organic compound class in aerosols. To better understand the source and photochemical processes of water-soluble organic aerosols in the remote marine aerosols, we measured stable carbon isotopic composition (δ13C) of dicarboxylic acids and related compounds using a GC/IR/MS technique. The aerosol samples were collected in 2001-2011 at a remote island, Chichijima (27°04'E; 142°13'N) in the western North Pacific. Here we present decadal variations of the isotopic composition of dicarboxylic acids (C2-C9), ketoacids (C2-C8) and glyoxal in summertime aerosols (June, July and August). The molecular distributions of diacids were characterized by the predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids. Oxalic acid showed higher δ13C values than other species ranging from -18‰ to -2‰ with no clear decadal trend. In contrast, C3 and C4 diacids showed δ13C values of -24 to -5‰ and -40 to -12‰ with a decadal decline. Glyoxal (-60 to -10‰) and ωC7 acid (-34 to -12‰) also showed lower values toward 2011. However, azelaic acid (C9) (-32 to -24‰) stayed relatively constant throughout the observation period. We will discuss the detailed isotopic compositions of these organic species in terms of the photochemical aging and processing in the western North Pacific and the changes in the sources and source regions.

Interannual Variations in Aerosol Sources and Their Impact on Orographic Precipitation Over California's Central Sierra Nevada

NASA Technical Reports Server (NTRS)

Creamean, J. M.; Ault, A. P.; White, A. B.; Neiman, P. J.; Ralph, F. M.; Minnis, Patrick; Prather, K. A.

2014-01-01

Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater I field campaign (2009-2011), the impacts of aerosol sources on precipitation were investigated in the California Sierra Nevada. In 2009, the precipitation collected on the ground was influenced by both local biomass burning (up to 79% of the insoluble residues found in precipitation) and long-range transported dust and biological particles (up to 80% combined), while in 2010, by mostly local sources of biomass burning and pollution (30-79% combined), and in 2011 by mostly long-range transport from distant sources (up to 100% dust and biological). Although vast differences in the source of residues was observed from year-to-year, dust and biological residues were omnipresent (on average, 55% of the total residues combined) and were associated with storms consisting of deep convective cloud systems and larger quantities of precipitation initiated in the ice phase. Further, biological residues were dominant during storms with relatively warm cloud temperatures (up to -15 C), suggesting these particles were more efficient IN compared to mineral dust. On the other hand, lower percentages of residues from local biomass burning and pollution were observed (on average 31% and 9%, respectively), yet these residues potentially served as CCN at the base of shallow cloud systems when precipitation quantities were low. The direct connection of the source of aerosols within clouds and precipitation type and quantity can be used in models to better assess how local emissions versus long-range transported dust and biological aerosols play a role in impacting regional weather and climate, ultimately with the goal of more accurate predictive weather forecast models and water resource management.

Interannual Variations in Aerosol Sources and Their Impact on Orographic Precipitation over California's Central Sierra Nevada

NASA Astrophysics Data System (ADS)

Creamean, J.; Ault, A. P.; White, A. B.; Neiman, P. J.; Minnis, P.; Prather, K. A.

2014-12-01

Aerosols that serve as cloud condensation nuclei (CCN) and ice nuclei (IN) have the potential to profoundly influence precipitation processes. Furthermore, changes in orographic precipitation have broad implications for reservoir storage and flood risks. As part of the CalWater I field campaign (2009-2011), the impacts of aerosol sources on precipitation were investigated in the California Sierra Nevada Mountains. In 2009, the precipitation collected on the ground was influenced by both local biomass burning and long-range transported dust and biological particles, while in 2010, by mostly local sources of biomass burning and pollution, and in 2011 by mostly long-range transport of dust and biological particles from distant sources. Although vast differences in the sources of residues were observed from year-to-year, dust and biological residues were omnipresent (on average, 55% of the total residues combined) and were associated with storms consisting of deep convective cloud systems and larger quantities of precipitation initiated in the ice phase. Further, biological residues were dominant during storms with relatively warm cloud temperatures (up to -15°C), suggesting biological components were more efficient IN than mineral dust. On the other hand, when precipitation quantities were lower, local biomass burning and pollution residues were observed (on average 31% and 9%, respectively), suggesting these residues potentially served as CCN at the base of shallow cloud systems and that lower level polluted clouds of storm systems produced less precipitation than non-polluted (i.e., marine) clouds. The direct connection of the sources of aerosols within clouds and precipitation type and quantity can be used in models to better assess how local emissions versus long-range transported dust and biological aerosols play a role in impacting regional weather and climate, ultimately with the goal of more accurate predictive weather forecast models and water resource

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

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

Impact of aerosol particle sources on optical properties in urban, regional and remote areas in the north-western Mediterranean

NASA Astrophysics Data System (ADS)

Ealo, Marina; Alastuey, Andrés; Pérez, Noemí; Ripoll, Anna; Querol, Xavier; Pandolfi, Marco

2018-01-01

Further research is needed to reduce the existing uncertainties on the effect that specific aerosol particle sources have on light extinction and consequently on climate. This study presents a new approach that aims to quantify the mass scattering and absorption efficiencies (MSEs and MAEs) of different aerosol sources at urban (Barcelona - BCN), regional (Montseny - MSY) and remote (Montsec - MSA) background sites in the north-western (NW) Mediterranean. An analysis of source apportionment to the measured multi-wavelength light scattering (σsp) and absorption (σap) coefficients was performed by means of a multilinear regression (MLR) model for the periods 2009-2014, 2010-2014 and 2011-2014 at BCN, MSY and MSA respectively. The source contributions to PM10 mass concentration, identified by means of the positive matrix factorization (PMF) model, were used as dependent variables in the MLR model. With this approach we addressed both the effect that aerosol sources have on air quality and their potential effect on light extinction through the determination of their MSEs and MAEs. An advantage of the presented approach is that the calculated MSEs and MAEs take into account the internal mixing of atmospheric particles. Seven aerosol sources were identified at MSA and MSY, and eight sources at BCN. Mineral, aged marine, secondary sulfate, secondary nitrate and V-Ni bearing sources were common at the three sites. Traffic, industrial/metallurgy and road dust resuspension sources were isolated at BCN, whereas mixed industrial/traffic and aged organics sources were identified at MSY and MSA. The highest MSEs were observed for secondary sulfate (4.5 and 10.7 m2 g-1, at MSY and MSA), secondary nitrate (8.8 and 7.8 m2 g-1) and V-Ni bearing source (8 and 3.5 m2 g-1). These sources dominated the scattering throughout the year with marked seasonal trends. The V-Ni bearing source, originating mainly from shipping in the area under study, simultaneously contributed to both �

Perspectives on NO, NOy, and fine aerosol sources and variability during SONEX

NASA Astrophysics Data System (ADS)

Thompson, Anne M.; Sparling, Lynn C.; Kondo, Yutaka; Anderson, Bruce E.; Gregory, Gerald L.; Sachse, Glen W.

Distributions of upper tropospheric tracer data on each of the 14 science flights of SONEX (SASS [Subsonics Assessment] Ozone and Nitrogen Oxides Experiment) provide a statistical overview of NO, NOy and fine aerosol variability during SONEX (an aircraft mission conducted in October and November 1997). The wide range of variability of NO from all sources provides a perspective on the aircraft perturbation. Background distributions of NOy are somewhat elevated inside flight corridors relative to outside; fine aerosol and NO/NOy in and out of corridors are similar. The potential vorticity of air sampled during SONEX is low relative to the NAFC (North Atlantic Flight Corridor) as a whole, due either to advection of lower latitude air into the corridor or biases in sampling to avoid the stratosphere. High NO/NOy (>0.4) from fresh lightning and aircraft sources was usually associated with pv much lower than the NAFC as a whole. Air masses identified as tropospheric by a low ozone criterion nevertheless have high pv, a marker for stratospheric air. Thus, stratospheric and surface sources also contribute to overall variability. A statistically robust assessment of the relative aircraft NO contribution during SONEX, based on data alone, is unlikely, given the mixture of other NO sources within which the aircraft signal is embedded. This underscores the need for more data and modeling studies.

Carbon Isotopic Measurements and Aerosol Optical Determinations during CARES: Indications of the Importance of Background Biogenic Aerosols

NASA Astrophysics Data System (ADS)

Gaffney, J. S.; Marley, N. A.; Begum, M.; Sturchio, N. C.; Guilderson, T. P.

2011-12-01

High volume size-fractionated aerosol samples were obtained in Cool, CA during the Carbonaceous Aerosol and Radiative Effects Study (CARES) in June of 2010. This site was chosen to study the regional impacts of carbonaceous aerosols originating from the Sacramento area. Samples were collected for 6 to 24 hour time periods on quartz fiber filters by using slotted impactors to allow for collection of sample size cuts above and below one micron. Both total carbon content and carbon isotopic composition, including 13C/12C and 14C, were determined on the samples. In addition, Ångstrom absorption exponents (AAEs) were determined for the region of 300-900 nm on the sub-micron size cut by using state of the art diffuse reflectance UV-visible spectroscopy with integrating sphere technology. The overall carbonaceous aerosol loadings were found to be quite low and relatively constant during the study, suggesting that most of the aerosols at the site were locally formed background aerosols. The 14C data is consistent with a substantial fraction (~80 %) being from modern carbon sources and 13C/12C results indicate that the carbon source was from C-3 plants. This is consistent with a significant fraction of the aerosols in the area arising from secondary formation from biogenic precursor emissions from trees, most likely mono- and sesquiterpenes. These results are compared to past results obtained in Mexico City and discussed in terms of the potential importance of biogenic emissions to UV absorbing aerosols as these are anticipated to increase with climate change. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64328 and Grant No. DE-FG02-07-ER64329 as part of the Atmospheric Systems Research program.

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 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

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).

Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols

NASA Astrophysics Data System (ADS)

Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

2011-09-01

The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (δ13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (ωC2). δ13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ωC2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller δ13C values than TC. Based on comparisons of δ13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in δ13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in δ13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

Global distribution and sources of volatile and nonvolatile aerosol in the remote troposphere

NASA Astrophysics Data System (ADS)

Singh, Hanwant B.; Anderson, B. E.; Avery, M. A.; Viezee, W.; Chen, Y.; Tabazadeh, A.; Hamill, P.; Pueschel, R.; Fuelberg, H. E.; Hannan, J. R.

2002-06-01

Airborne measurements of aerosol (condensation nuclei, CN) and selected trace gases made over areas of the North Atlantic Ocean during Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) (October/November 1997), the south tropical Pacific Ocean during Pacific Exploratory Mission (PEM)-Tropics A (September/October 1996), and PEM-Tropics B (March/April 1999) have been analyzed. The emphasis is on interpreting variations in the number densities of fine (>17 nm) and ultrafine (>8 nm) aerosol in the upper troposphere (8-12 km). These data suggest that large number densities of highly volatile CN (104 - 105 cm-3) are present in the upper troposphere and particularly over the tropical/subtropical region. CN number densities in all regions are largest when the atmosphere is devoid of nonvolatile particles. Through marine convection and long-distance horizontal transport, volatile CN originating from the tropical/subtropical regions can frequently impact the abundance of aerosol in the middle and upper troposphere at mid to high latitudes. Nonvolatile aerosols behave in a manner similar to tracers of combustion (CO) and photochemical pollution (peroxyacetylnitrate (PAN)), implying a continental pollution source from industrial emissions or biomass burning. In the upper troposphere we find that volatile and nonvolatile aerosol number densities are inversely correlated. Results from an aerosol microphysical model suggest that the coagulation of fine volatile particles with fewer but larger nonvolatile particles, of principally anthropogenic origin, is one possible explanation for this relationship. In some instances the larger nonvolatile particles may also directly remove precursors (e.g., H2SO4) and effectively stop nucleation.

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.

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?

Sources and composition of submicron organic mass in marine aerosol particles

DOE PAGES

Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; ...

2014-11-27

Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemicalmore » reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group

Sources and composition of submicron organic mass in marine aerosol particles

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

Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.

Recent studies have proposed a variety of interpretations of the sources and composition of atmospheric marine aerosol particles (aMA) based on a range of physical and chemical measurements collected during open-ocean research cruises. To investigate the processes that affect marine organic particles, this study uses the characteristic functional group composition (from Fourier transform infrared (FTIR) spectroscopy) of aMAP from five ocean regions to show that: (i) The organic functional group composition of aMAP that can be identified as atmospheric primary marine (ocean-derived) aerosol (aPMA) is 65±12% hydroxyl, 21±9% alkane, 6±6% amine, and 7±8% carboxylic acid functional groups. Contributions from photochemicalmore » reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal emissions mix in alkane and carboxylic acid groups from coastal pollution sources. (ii) The organic composition of aPMA is nearly identical to model generated primary marine aerosol particles (gPMA) from bubbled seawater (55% hydroxyl, 32% alkane, and 13% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) While the seawater organic functional group composition was nearly invariant across all three ocean regions studied, the gPMA alkane group fraction increased with chlorophyll-a concentrations (r = 0.79). gPMA from productive seawater had a larger fraction of alkane functional groups (35%) compared to gPMA from non-productive seawater (16%), likely due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of monosaccharides and disaccharides, where the seawater OM hydroxyl group

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.

COLLABORATIVE RESEARCH: Study of Aerosol Sources and Processing at the GVAX Pantnagar Supersite

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

Thornton, Joel A.; Worsnop, Douglas

2016-09-22

This project was part of a collaborative campaign, including the participation of scientists from seven research groups as part of the Winter Intensive Operating Period (January-February 2012) of the Clean Air for London (ClearfLo) campaign at a rural site in Detling, UK, 45 km southeast of central London to study wintertime sources of urban particulate matter. The UW contribution by PI Thornton’s group was to make the first deployment of a chemical ionization mass spectrometer instrument (MOVI-CI-ToFMS) to measure both particle and gas phase organic acids. The new instrument ran nearly continuously during the ClearfLo WINTER IOP at the Detlingmore » site, producing a first-ever data set of molecular composition information that can be used for source apportionment and process studies. The UW group published a paper in Environmental Science and Technology and contributed to another (Bohnenstengel et al BAMS 2015) detailing a direct molecular connection between biomass/biofuel burning particles and aerosol light absorption. The ES&T paper (Mohr, et al ES&T 2013) has received 42 citations in just 3 years indicative of its significant impact on the field. These measurements of urban and rural aerosol properties will contribute to improved modeling of regional aerosol emissions, and of atmospheric aging and removal.« less

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

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

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...

Long-term observation of aerosol-cloud relationships in the Mid-Atlantic of the United States

NASA Astrophysics Data System (ADS)

Li, S.; Joseph, E.; Min, Q.; Yin, B.

2014-07-01

Long-term ground-based observations (2006 to 2010) of aerosol and cloud properties derived from passive radiometric sensors deployed at an atmospheric measurement field station in the Baltimore-Washington corridor operated by Howard University were used to examine aerosol indirect effect on cloud optical depth (COD), liquid water path (LWP), cloud droplets effective radius (Re) and cloud droplets number concentration (Nd). A higher frequency of clouds with large COD (> 20) and small Re (< 7 m) was found during summer of 2006 and 2007 along with higher frequency of abundant aerosol loading. The five-year data are screened for summer months only and are separated into clean and polluted cases based on aerosol particulate matter with aerodynamic diameter ≤ 2.5 m (PM2.5) value. Evidence of aerosol indirect effect is found where for polluted cases the mean and median values of COD and Nd distributions were elevated while the mean and median values of Re were decreased. Further reinforcing this conclusion is the result that the mean and median values of LWP distributions did not show prominent difference between clean and polluted cases, this implies that differences between the two cases of influential factors on cloud properties were relatively controlled. Moreover aerosol indirect effects were found insignificant when LWP was small but significant when LWP was large through the analysis of sensitivity of Nd to LWP under different aerosol loading and the measurements of aerosol size distribution.

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

Aerosol Complexity and Implications for Predictability and Short-Term Forecasting

NASA Technical Reports Server (NTRS)

Colarco, Peter

2016-01-01

There are clear NWP and climate impacts from including aerosol radiative and cloud interactions. Changes in dynamics and cloud fields affect aerosol lifecycle, plume height, long-range transport, overall forcing of the climate system, etc. Inclusion of aerosols in NWP systems has benefit to surface field biases (e.g., T2m, U10m). Including aerosol affects has impact on analysis increments and can have statistically significant impacts on, e.g., tropical cyclogenesis. Above points are made especially with respect to aerosol radiative interactions, but aerosol-cloud interaction is a bigger signal on the global system. Many of these impacts are realized even in models with relatively simple (bulk) aerosol schemes (approx.10 -20 tracers). Simple schemes though imply simple representation of aerosol absorption and importantly for aerosol-cloud interaction particle-size distribution. Even so, more complex schemes exhibit a lot of diversity between different models, with issues such as size selection both for emitted particles and for modes. Prospects for complex sectional schemes to tune modal (and even bulk) schemes toward better selection of size representation. I think this is a ripe topic for more research -Systematic documentation of benefits of no vs. climatological vs. interactive (direct and then direct+indirect) aerosols. Document aerosol impact on analysis increments, inclusion in NWP data assimilation operator -Further refinement of baseline assumptions in model design (e.g., absorption, particle size distribution). Did not get into model resolution and interplay of other physical processes with aerosols (e.g., moist physics, obviously important), chemistry

Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.

2012-07-01

Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

Dust Aerosols at the Source Region During ACE-ASIA: A Surface/Satellite Perspective

NASA Technical Reports Server (NTRS)

Tsay, Si-Chee; Lau, William K. M. (Technical Monitor)

2001-01-01

ACE (Aerosol Characterization Experiment)-Asia is designed to study the compelling variability in spatial and temporal scale of both pollution-derived and naturally occurring aerosols, which often exist in high concentrations over eastern Asia and along the rim of the western Pacific. The phase-I of ACE-Asia was conducted from March-May 2001 in the vicinity of the Gobi desert, East Coast of China, Yellow Sea, Korea, and Japan, along the pathway of Kosa (severe events that blanket East Asia with yellow desert dust, peaked in the Spring season). Asian dust typically originates in desert areas far from polluted urban regions. During transport, dust layers can interact with anthropogenic sulfate and soot aerosols from heavily polluted urban areas. Added to the complex effects of clouds and natural marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from the source. Thus, understanding the unique temporal and spatial variations of Asian dust is of special importance in regional-to-global climate issues such as radiative forcing, the hydrological cycle, and primary biological productivity in the mid-Pacific Ocean. During ACE-Asia we have measured continuously aerosol physical/optical/radiative properties, column precipitable water amount, and surface reflectivity over homogeneous areas from surface. The inclusion of flux measurements permits the determination of dust aerosol radiative flux in addition to measurements of loading and optical thickness. At the time of the Terra/MODIS, SeaWiFS, TOMS and other satellite overpasses, these ground-based observations can provide valuable data to compare with satellite retrievals over land. Preliminary results will be presented and discussed their implications in regional climatic effects.

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

Global Distribution and Sources of Volatile and Nonvolatile Aerosol In the Remote Troposphere

NASA Technical Reports Server (NTRS)

Singh, Hanwant B.; Avery, M.; Viezee, W.; Che, Y.; Tabazadeh, A.; Hamill, P.; Pueschel, R.; Hannan, J. R.; Anderson, B.; Fuelberg, H. E.;

Organic aerosol source apportionment in London 2013 with ME-2: exploring the solution space with annual and seasonal analysis

NASA Astrophysics Data System (ADS)

Reyes-Villegas, Ernesto; Green, David C.; Priestman, Max; Canonaco, Francesco; Coe, Hugh; Prévôt, André S. H.; Allan, James D.

2016-12-01

The multilinear engine (ME-2) factorization tool is being widely used following the recent development of the Source Finder (SoFi) interface at the Paul Scherrer Institute. However, the success of this tool, when using the a value approach, largely depends on the inputs (i.e. target profiles) applied as well as the experience of the user. A strategy to explore the solution space is proposed, in which the solution that best describes the organic aerosol (OA) sources is determined according to the systematic application of predefined statistical tests. This includes trilinear regression, which proves to be a useful tool for comparing different ME-2 solutions. Aerosol Chemical Speciation Monitor (ACSM) measurements were carried out at the urban background site of North Kensington, London from March to December 2013, where for the first time the behaviour of OA sources and their possible environmental implications were studied using an ACSM. Five OA sources were identified: biomass burning OA (BBOA), hydrocarbon-like OA (HOA), cooking OA (COA), semivolatile oxygenated OA (SVOOA) and low-volatility oxygenated OA (LVOOA). ME-2 analysis of the seasonal data sets (spring, summer and autumn) showed a higher variability in the OA sources that was not detected in the combined March-December data set; this variability was explored with the triangle plots f44 : f43 f44 : f60, in which a high variation of SVOOA relative to LVOOA was observed in the f44 : f43 analysis. Hence, it was possible to conclude that, when performing source apportionment to long-term measurements, important information may be lost and this analysis should be done to short periods of time, such as seasonally. Further analysis on the atmospheric implications of these OA sources was carried out, identifying evidence of the possible contribution of heavy-duty diesel vehicles to air pollution during weekdays compared to those fuelled by petrol.

Biomass burning in the Amazon region: Aerosol source apportionment and associated health risk assessment

NASA Astrophysics Data System (ADS)

de Oliveira Alves, Nilmara; Brito, Joel; Caumo, Sofia; Arana, Andrea; de Souza Hacon, Sandra; Artaxo, Paulo; Hillamo, Risto; Teinilä, Kimmo; Batistuzzo de Medeiros, Silvia Regina; de Castro Vasconcellos, Pérola

2015-11-01

The Brazilian Amazon represents about 40% of the world's remaining tropical rainforest. However, human activities have become important drivers of disturbance in that region. The majority of forest fire hotspots in the Amazon arc due to deforestation are impacting the health of the local population of over 10 million inhabitants. In this study we characterize western Amazonia biomass burning emissions through the quantification of 14 Polycyclic Aromatic Hydrocarbons (PAHs), Organic Carbon, Elemental Carbon and unique tracers of biomass burning such as levoglucosan. From the PAHs dataset a toxic equivalence factor is calculated estimating the carcinogenic and mutagenic potential of biomass burning emissions during the studied period. Peak concentration of PM10 during the dry seasons was observed to reach 60 μg m-3 on the 24 h average. Conversely, PM10 was relatively constant throughout the wet season indicating an overall stable balance between aerosol sources and sinks within the filter sampling resolution. Similar behavior is identified for OC and EC components. Levoglucosan was found in significant concentrations (up to 4 μg m-3) during the dry season. Correspondingly, the estimated lung cancer risk calculated during the dry seasons largely exceeded the WHO health-based guideline. A source apportionment study was carried out through the use of Absolute Principal Factor Analysis (APFA), identifying a three-factor solution. The biomass burning factor is found to be the dominating aerosol source, having 75.4% of PM10 loading. The second factor depicts an important contribution of several PAHs without a single source class and therefore was considered as mixed sources factor, contributing to 6.3% of PM10. The third factor was mainly associated with fossil fuel combustion emissions, contributing to 18.4% of PM10. This work enhances the knowledge of aerosol sources and its impact on climate variability and local population, on a site representative of the

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

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

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.

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.

Carbon isotope-constrained seasonality of carbonaceous aerosol sources from an urban location (Kanpur) in the Indo-Gangetic Plain

NASA Astrophysics Data System (ADS)

Bikkina, Srinivas; Andersson, August; Ram, Kirpa; Sarin, M. M.; Sheesley, Rebecca J.; Kirillova, Elena N.; Rengarajan, R.; Sudheer, A. K.; Gustafsson, Örjan

2017-05-01

The Indo-Gangetic Plain (IGP) in northern India, Pakistan, and Bangladesh is a major source of carbonaceous aerosols in South Asia. However, poorly constrained seasonality of their sources over the IGP leads to large uncertainty in climate and health effects. Here we present a first data set for year-round radiocarbon (Δ14C) and stable carbon (δ13C)-based source apportionment of total carbon (TC) in ambient PM10 (n = 17) collected from an urban site (Kanpur: 26.5°N, 80.3°E) in the IGP during January 2007 to January 2008. The year-round 14C-based fraction biomass (fbio-TC) estimate at Kanpur averages 77 ± 7% and emphasizes an impact of biomass burning emissions (BBEs). The highest fbio-TC (%) is observed in fall season (October-November, 85 ± 6%) followed by winter (December-February, 80 ± 4%) and spring (March-May, 75 ± 8%), while lowest values are found in summer (June-September, 69 ± 2%). Since biomass/coal combustion and vehicular emissions mostly contribute to carbonaceous aerosols over the IGP, we predict δ13CTC (δ13Cpred) over Kanpur using known δ13C source signatures and the measured Δ14C value of each sample. The seasonal variability of δ13Cobs - δ13Cpred versus Δ14CTC together with air mass back trajectories and Moderate Resolution Imaging Spectroradiometer fire count data reveal that carbonaceous aerosols in winter/fall are significantly influenced by atmospheric aging (downwind transport of crop residue burning/wood combustion emissions in the northern IGP), while local sources (wheat residue combustion/vehicular emissions) dominate in spring/summer. Given the large temporal and seasonal variability in sources and emission strength of TC over the IGP, 14C-based constraints are, thus, crucial for reducing their uncertainties in carbonaceous aerosol budgets in climate models.

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

The Denver Aerosol Sources and Health (DASH) Study: Overview and Early Findings

PubMed Central

Vedal, S.; Hannigan, M.P.; Dutton, S.J.; Miller, S. L.; Milford, J.B.; Rabinovitch, N.; Kim, S.-Y.; Sheppard, L.

2012-01-01

Improved understanding of the sources of air pollution that are most harmful could aid in developing more effective measures for protecting human health. The Denver Aerosol Sources and Health (DASH) study was designed to identify the sources of ambient fine particulate matter (PM2.5) that are most responsible for the adverse health effects of short-term exposure to PM 2.5. Daily 24-hour PM2.5 sampling began in July 2002 at a residential monitoring site in Denver, Colorado, using both Teflon and quartz filter samplers. Sampling is planned to continue through 2008. Chemical speciation is being carried out for mass, inorganic ionic compounds (sulfate, nitrate and ammonium), and carbonaceous components, including elemental carbon, organic carbon, temperature-resolved organic carbon fractions and a large array of organic compounds. In addition, water soluble metals were measured daily for 12 months in 2003. A receptor-based source apportionment approach utilizing positive matrix factorization (PMF) will be used to identify PM 2.5 source contributions for each 24-hour period. Based on a preliminary assessment using synthetic data, the proposed source apportionment should be able to identify many important sources on a daily basis, including secondary ammonium nitrate and ammonium sulfate, diesel vehicle exhaust, road dust, wood combustion and vegetative debris. Meat cooking, gasoline vehicle exhaust and natural gas combustion were more challenging for PMF to accurately identify due to high detection limits for certain organic molecular marker compounds. Measurements of these compounds are being improved and supplemented with additional organic molecular marker compounds. The health study will investigate associations between daily source contributions and an array of health endpoints, including daily mortality and hospitalizations and measures of asthma control in asthmatic children. Findings from the DASH study, in addition to being of interest to policymakers, by

Long term change in atmospheric dust absorption, dust scattering and black carbon aerosols scattering coefficient parameters over western Indian locations

NASA Astrophysics Data System (ADS)

Satoliya, Anil Kumar; Vyas, B. M.; Shekhawat, M. S.

2018-05-01

The first time satellite space based measurement of atmospheric black carbon (BC) aerosols scattering coefficient at 550nm (BC SC at 550nm), dust aerosols scattering and dust aerosols extinction coefficient (DSC at 550nm and DEC at 550nm) parameters have been used to understand their long term trend of natural and anthropogenic aerosols behavior with its close association with ground based measured precipitation parameters such as Total Rain Fall (TRF), and Total Number of Rainy Days (TNRD) for the same period over western Indian regions concerned to the primary aerosols sources of natural activities. The basic objective of this study is an attempt to investigate the inter-correlation between dust and black carbon aerosols loading characteristics with a variation of rainfall pattern parameters as indirect aerosols induced effect i.e., aerosols-cloud interaction. The black carbon aerosols generated by diverse anthropogenic or human made activities are studied by choosing of measured atmospheric BC SC at 550nm parameter, whereas desert dust mineral aerosols primarily produced by varieties of natural activities pre-dominated of dust mineral desert aerosols mainly over Thar desert influenced area of hot climate and rural tropical site are investigated by selecting DSC at 550nm and DEC at 550nm of first semi-urban site i.e., Udaipur (UDP, 24.6°N, 73.35°E, 580m above surface level (asl)) situated in southern Rajasthan part as well as over other two Great Indian Thar desert locations i.e., Jaisalmer (JSM, 26.90°N, 69.90°E, 220m asl)) and Bikaner (BKN, 28.03°N, 73.30°E, 224m asl) located in the vicinity of the Thar desert region situated in Rajasthan state of the western Indian region. The source of the present study would be collection of longer period of monthly values of the above parameters of spanning 35 years i.e., 1980 to 2015. Such types of atmospheric aerosols-cloud monsoon interaction investigation is helpful in view of understanding their direct and

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.

Preferential aerosolization of bacteria in bioaerosols generated in vitro.

PubMed

Perrott, P; Turgeon, N; Gauthier-Levesque, L; Duchaine, C

2017-09-01

Little is known about how bacteria are aerosolized in terms of whether some bacteria will be found in the air more readily than others that are present in the source. This report describes in vitro experiments to compare aerosolization rates (also known as preferential aerosolization) of Gram-positive and Gram-negative bacteria as well as rod- and coccus-shaped bacteria, using two nebulization conditions. A consortium of five bacterial species was aerosolized in a homemade chamber. Aerosols generated with a commercial nebulizer and a homemade bubble-burst aerosol generator were compared. Data suggest that Pseudomonas aeruginosa was preferentially aerosolized in comparison to Moraxella catarrhalis, Lactobacillus paracasei, Staphylococcus aureus and Streptococcus suis, independently of the method of aerosolization. Bacterial integrity of Strep. suis was more preserved compared to other bacteria studied as revealed with PMA-qPCR. We reported the design of an aerosol chamber and bubble-burst generator for the in vitro study of preferential aerosolization. In our setting, preferential aerosolization was influenced by bacterial properties instead of aerosolization mechanism. These findings could have important implications for predicting the composition of bioaerosols in various locations such as wastewater treatment plants, agricultural settings and health care settings. © 2017 The Society for Applied Microbiology.

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

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

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

Informing Aerosol Transport Models With Satellite Multi-Angle Aerosol Measurements

NASA Technical Reports Server (NTRS)

Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.

2011-01-01

As the aerosol products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the aerosol amount and type data products, and aerosol plume heights, to constrain aerosol transport models. We have demonstrated the ability to map aerosol air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the aerosol type information content, that varies depending upon retrieval conditions. We have shown that MISR aerosol type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution aerosol components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS aerosol optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining aerosol transport models, planet-wide.

Toxicological Evaluation of Realistic Emission Source Aerosols (TERESA): Introduction and overview

PubMed Central

Godleski, John J.; Rohr, Annette C.; Kang, Choong M.; Diaz, Edgar A.; Ruiz, Pablo A.; Koutrakis, Petros

2013-01-01

Determining the health impacts of sources and components of fine particulate matter (PM2.5) is an important scientific goal. PM2.5 is a complex mixture of inorganic and organic constituents that are likely to differ in their potential to cause adverse health outcomes. The Toxicological Evaluation of Realistic Emissions of Source Aerosols (TERESA) study focused on two PM sources—coal-fired power plants and mobile sources—and sought to investigate the toxicological effects of exposure to emissions from these sources. The set of papers published here document the power plant experiments. TERESA attempted to delineate health effects of primary particles, secondary (aged) particles, and mixtures of these with common atmospheric constituents. TERESA involved withdrawal of emissions from the stacks of three coal-fired power plants in the United States. The emissions were aged and atmospherically transformed in a mobile laboratory simulating downwind power plant plume processing. Toxicological evaluations were carried out in laboratory rats exposed to different emission scenarios with extensive exposure characterization. The approach employed in TERESA was ambitious and innovative. Technical challenges included the development of stack sampling technology that prevented condensation of water vapor from the power plant exhaust during sampling and transfer, while minimizing losses of primary particles; development and optimization of a photochemical chamber to provide an aged aerosol for animal exposures; development and evaluation of a denuder system to remove excess gaseous components; and development of a mobile toxicology laboratory. This paper provides an overview of the conceptual framework, design, and methods employed in the study. PMID:21639692

Impact of the ozone monitoring instrument row anomaly on the long-term record of aerosol products

NASA Astrophysics Data System (ADS)

Torres, Omar; Bhartia, Pawan K.; Jethva, Hiren; Ahn, Changwoo

2018-05-01

Since about three years after the launch the Ozone Monitoring Instrument (OMI) on the EOS-Aura satellite, the sensor's viewing capability has been affected by what is believed to be an internal obstruction that has reduced OMI's spatial coverage. It currently affects about half of the instrument's 60 viewing positions. In this work we carry out an analysis to assess the effect of the reduced spatial coverage on the monthly average values of retrieved aerosol optical depth (AOD), single scattering albedo (SSA) and the UV Aerosol Index (UVAI) using the 2005-2007 three-year period prior to the onset of the row anomaly. Regional monthly average values calculated using viewing positions 1 through 30 were compared to similarly obtained values using positions 31 through 60, with the expectation of finding close agreement between the two calculations. As expected, mean monthly values of AOD and SSA obtained with these two scattering-angle dependent subsets of OMI observations agreed over regions where carbonaceous or sulphate aerosol particles are the predominant aerosol type. However, over arid regions, where desert dust is the main aerosol type, significant differences between the two sets of calculated regional mean values of AOD were observed. As it turned out, the difference in retrieved desert dust AOD between the scattering-angle dependent observation subsets was due to the incorrect representation of desert dust scattering phase function. A sensitivity analysis using radiative transfer calculations demonstrated that the source of the observed AOD bias was the spherical shape assumption of desert dust particles. A similar analysis in terms of UVAI yielded large differences in the monthly mean values for the two sets of calculations over cloudy regions. On the contrary, in arid regions with minimum cloud presence, the resulting UVAI monthly average values for the two sets of observations were in very close agreement. The discrepancy under cloudy conditions was found

Global-scale combustion sources of organic aerosols: sensitivity to formation and removal mechanisms

NASA Astrophysics Data System (ADS)

Tsimpidi, Alexandra P.; Karydis, Vlassis A.; Pandis, Spyros N.; Lelieveld, Jos

2017-06-01

Organic compounds from combustion sources such as biomass burning and fossil fuel use are major contributors to the global atmospheric load of aerosols. We analyzed the sensitivity of model-predicted global-scale organic aerosols (OA) to parameters that control primary emissions, photochemical aging, and the scavenging efficiency of organic vapors. We used a computationally efficient module for the description of OA composition and evolution in the atmosphere (ORACLE) of the global chemistry-climate model EMAC (ECHAM/MESSy Atmospheric Chemistry). A global dataset of aerosol mass spectrometer (AMS) measurements was used to evaluate simulated primary (POA) and secondary (SOA) OA concentrations. Model results are sensitive to the emission rates of intermediate-volatility organic compounds (IVOCs) and POA. Assuming enhanced reactivity of semi-volatile organic compounds (SVOCs) and IVOCs with OH substantially improved the model performance for SOA. The use of a hybrid approach for the parameterization of the aging of IVOCs had a small effect on predicted SOA levels. The model performance improved by assuming that freshly emitted organic compounds are relatively hydrophobic and become increasingly hygroscopic due to oxidation.

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

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.

Seasonal variations in elemental carbon aerosol, carbon monoxide and sulfur dioxide: Implications for sources

NASA Astrophysics Data System (ADS)

Antony Chen, L.-W.; Doddridge, Bruce G.; Dickerson, Russell R.; Chow, Judith C.; Mueller, Peter K.; Quinn, John; Butler, William A.

As part of Maryland Aerosol Research and CHaracterization (MARCH-Atlantic) study, measurements of 24-hr average elemental carbon (EC) aerosol concentration were made at Fort Meade, Maryland, USA, a suburban site within the Baltimore-Washington corridor during July 1999, October 1999, January 2000, April 2000 and July 2000. Carbon monoxide (CO) and sulfur dioxide (SO2) were also measured nearly continuously over the period. Tight correlation between EC and CO in every month suggests common or proximate sources, likely traffic emissions. The EC versus CO slope varies in different seasons and generally increases with ambient temperature. The temperature dependence of EC/CO ratios suggests that EC source strength peaks in summer. By using the well established emission inventory for CO, and EC/CO ratio found in this study, EC emission over North America is estimated at 0.31±0.12 Tg yr-1, on the low end but in reasonable agreement with prior inventories based on emission factors and fuel consumption.

Seasonal variations in elemental carbon aerosol, carbon monoxide and sulfur dioxide: Implications for sources

NASA Astrophysics Data System (ADS)

Chen, L.-W. Antony; Doddridge, Bruce G.; Dickerson, Russell R.; Chow, Judith C.; Mueller, Peter K.; Quinn, John; Butler, William A.

2001-05-01

As part of Maryland Aerosol Research and CHaracterization (MARCH-Atlantic) study, measurements of 24-hr average elemental carbon (EC) aerosol concentration were made at Fort Meade, Maryland, USA, a suburban site within the Baltimore-Washington corridor during July 1999, October 1999, January 2000, April 2000 and July 2000. Carbon monoxide (CO) and sulfur dioxide (SO2) were also measured nearly continuously over the period. Tight correlation between EC and CO in every month suggests common or proximate sources, likely traffic emissions. The EC versus CO slope varies in different seasons and generally increases with ambient temperature. The temperature dependence of EC/CO ratios suggests that EC source strength peaks in summer. By using the well established emission inventory for CO, and EC/CO ratio found in this study, EC emission over North America is estimated at 0.31+/-0.12Tgyr-1, on the low end but in reasonable agreement with prior inventories based on emission factors and fuel consumption.

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

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

Spectral solar attenuation due to aerosol loading over an urban area in India

NASA Astrophysics Data System (ADS)

Latha, K. Madhavi; Badarinath, K. V. S.

2005-06-01

Anthropogenic activities in urban areas are sources for atmospheric aerosols and are increasing due to population explosion and migration. Many large cities in the developing world are presently plagued by high levels of atmospheric pollution and long-term effect of urban aerosol on climate is an important topic. In the present study, ground-based measurements of solar irradiance, aerosol loading and black carbon (BC) aerosol concentration have been analyzed during different aerosol loading conditions during 2003 over an urban environment. BC aerosols concentration has been observed to be enhanced during high aerosol optical depth day suggesting influence of local anthropogenic activities. The analysis of wind fields over the study area during the measurement period is from north with continental air mass prevailing over the region. Spectral measurements of solar irradiance exhibited variations based on aerosol loading in urban atmosphere. Relative attenuations caused by aerosols have been found to be of the order of 21% and 17% on the irradiance on visible and near infrared respectively.

Sea spray aerosol as a unique source of ice nucleating particles.

PubMed

DeMott, Paul J; Hill, Thomas C J; McCluskey, Christina S; Prather, Kimberly A; Collins, Douglas B; Sullivan, Ryan C; Ruppel, Matthew J; Mason, Ryan H; Irish, Victoria E; Lee, Taehyoung; Hwang, Chung Yeon; Rhee, Tae Siek; Snider, Jefferson R; McMeeking, Gavin R; Dhaniyala, Suresh; Lewis, Ernie R; Wentzell, Jeremy J B; Abbatt, Jonathan; Lee, Christopher; Sultana, Camille M; Ault, Andrew P; Axson, Jessica L; Diaz Martinez, Myrelis; Venero, Ingrid; Santos-Figueroa, Gilmarie; Stokes, M Dale; Deane, Grant B; Mayol-Bracero, Olga L; Grassian, Vicki H; Bertram, Timothy H; Bertram, Allan K; Moffett, Bruce F; Franc, Gary D

2016-05-24

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using "dry" geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.

Sea spray aerosol as a unique source of ice nucleating particles

PubMed Central

DeMott, Paul J.; Hill, Thomas C. J.; McCluskey, Christina S.; Prather, Kimberly A.; Ruppel, Matthew J.; Mason, Ryan H.; Irish, Victoria E.; Lee, Taehyoung; Hwang, Chung Yeon; Snider, Jefferson R.; McMeeking, Gavin R.; Dhaniyala, Suresh; Lewis, Ernie R.; Wentzell, Jeremy J. B.; Abbatt, Jonathan; Lee, Christopher; Sultana, Camille M.; Ault, Andrew P.; Axson, Jessica L.; Diaz Martinez, Myrelis; Venero, Ingrid; Santos-Figueroa, Gilmarie; Stokes, M. Dale; Deane, Grant B.; Mayol-Bracero, Olga L.; Grassian, Vicki H.; Bertram, Timothy H.; Bertram, Allan K.; Moffett, Bruce F.; Franc, Gary D.

2016-01-01

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using “dry” geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean. PMID:26699469

Characterization and source apportionment of organic aerosol at 260 m on a meteorological tower in Beijing, China

NASA Astrophysics Data System (ADS)

Zhou, Wei; Wang, Qingqing; Zhao, Xiujuan; Xu, Weiqi; Chen, Chen; Du, Wei; Zhao, Jian; Canonaco, Francesco; Prévôt, André S. H.; Fu, Pingqing; Wang, Zifa; Worsnop, Douglas R.; Sun, Yele

2018-03-01

Despite extensive efforts toward the characterization of submicron aerosols at ground level in the megacity of Beijing, our understanding of aerosol sources and processes at high altitudes remains low. Here we conducted a 3-month real-time measurement of non-refractory submicron aerosol (NR-PM1) species at a height of 260 m from 10 October 2014 to 18 January 2015 using an aerosol chemical speciation monitor. Our results showed a significant change in aerosol composition from the non-heating period (NHP) to the heating period (HP). Organics and chloride showed clear increases during HP due to coal combustion emissions, while nitrate showed substantial decreases from 28 to 15-18 %. We also found that NR-PM1 species in the heating season can have average mass differences of 30-44 % under similar emission sources yet different meteorological conditions. Multi-linear engine 2 (ME-2) using three primary organic aerosol (OA) factors as constraints, i.e., fossil-fuel-related OA (FFOA) dominantly from coal combustion emissions, cooking OA (COA), and biomass burning OA (BBOA) resolved from ground high-resolution aerosol mass spectrometer measurements, was applied to OA mass spectra of ACSM. Two types of secondary OA (SOA) that were well correlated with nitrate and chloride-CO, respectively, were identified. SOA played a dominant role in OA during all periods at 260 m although the contributions were decreased from 72 % during NHP to 58-64 % during HP. The SOA composition also changed significantly from NHP to HP. While the contribution of oxygenated OA (OOA) was decreased from 56-63 to 32-40 %, less oxidized OOA (LO-OOA) showed a large increase from 9-16 to 24-26 %. COA contributed a considerable fraction of OA at high altitude, and the contribution was relatively similar across different periods (10-13 %). In contrast, FFOA showed a large increase during HP due to the influences of coal combustion emissions. We also observed very different OA composition between ground level

A Long-term Record of Saharan Dust Aerosol Properties from TOMS Observations: Optical Depth and Single Scattering Albedo

NASA Technical Reports Server (NTRS)

Torres, Omar; Bhartia, P. K.; Herman, J. R.; Einaudi, Franco (Technical Monitor)

2000-01-01

The interaction between the strong Rayleigh scattering in the near UV spectral region (330-380 nm) and the processes of aerosol absorption and scattering, produce a clear spectral signal in the upwelling radiance at the top of the atmosphere. This interaction is the basis of the TOMS (Total Ozone Mapping Spectrometer) aerosol retrieval technique that can be used for their characterization and to differentiate non-absorbing sulfates from strongly UV-absorbing aerosols such as mineral dust. For absorbing aerosols, the characterization is in terms of the optical depth and single scattering albedo with assumptions about the aerosol plume height. The results for non-absorbing aerosols are not dependent on plume height. Although iron compounds represent only between 5% to 8% of desert dust aerosol mass, hematite (Fe2O3) accounts for most of the near UV absorption. Because of the large ultraviolet absorption characteristic of hematite, the near UV method of aerosol sensing is especially suited for the detection and characterization of desert dust aerosols. Using the combined record of near UV measurements by the Nimbus7 (1978-1992) and Earth Probe (1996-present) TOMS instruments, a global longterm climatology of near UV optical depth and single scattering albedo has been produced. The multi-year long record of mineral aerosol properties over the area of influence of the Saharan desert, will be discussed.

Local source impacts on primary and secondary aerosols in the Midwestern United States

NASA Astrophysics Data System (ADS)

Jayarathne, Thilina; Rathnayake, Chathurika M.; Stone, Elizabeth A.

2016-04-01

Atmospheric particulate matter (PM) exhibits heterogeneity in composition across urban areas, leading to poor representation of outdoor air pollutants in human exposure assessments. To examine heterogeneity in PM composition and sources across an urban area, fine particulate matter samples (PM2.5) were chemically profiled in Iowa City, IA from 25 August to 10 November 2011 at two monitoring stations. The urban site is the federal reference monitoring (FRM) station in the city center and the peri-urban site is located 8.0 km to the west on the city edge. Measurements of PM2.5 carbonaceous aerosol, inorganic ions, molecular markers for primary sources, and secondary organic aerosol (SOA) tracers were used to assess statistical differences in composition and sources across the two sites. PM2.5 mass ranged from 3 to 26 μg m-3 during this period, averaging 11.2 ± 4.9 μg m-3 (n = 71). Major components of PM2.5 at the urban site included organic carbon (OC; 22%), ammonium (14%), sulfate (13%), nitrate (7%), calcium (2.9%), and elemental carbon (EC; 2.2%). Periods of elevated PM were driven by increases in ammonium, sulfate, and SOA tracers that coincided with hot and dry conditions and southerly winds. Chemical mass balance (CMB) modeling was used to apportion OC to primary sources; biomass burning, vegetative detritus, diesel engines, and gasoline engines accounted for 28% of OC at the urban site and 24% of OC at the peri-urban site. Secondary organic carbon from isoprene and monoterpene SOA accounted for an additional 13% and 6% of OC at the urban and peri-urban sites, respectively. Differences in biogenic SOA across the two sites were associated with enhanced combustion activities in the urban area and higher aerosol acidity at the urban site. Major PM constituents (e.g., OC, ammonium, sulfate) were generally well-represented by a single monitoring station, indicating a regional source influence. Meanwhile, nitrate, biomass burning, food cooking, suspended dust, and

Exploring Climatology and Long-Term Variations of Aerosols from NASA Reanalysis MERRA-2 with Giovanni

NASA Technical Reports Server (NTRS)

Shen, Suhung; Ostrenga, Dana; Vollmer, Bruce; Li, Zhanqing

2016-01-01

Dust plays important roles in energy cycle and climate variations. The dust deposition is the major source of iron in the open ocean, which is an essential micronutrient for phytoplankton growth and therefore may influence the ocean uptake of atmospheric CO2. Mineral dust can also act as fertilizer for forests over long time periods. Over 35 years of simulated global aerosol products from NASA atmospheric reanalysis, second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) are available from NASA Goddard Earth Science Data and Information Services Center (GES DISC). The MERRA-2 covers the period 1980-present, continuing as an ongoing climate analysis. Aerosol assimilation is included throughout the period, using MODIS, MISR, AERONET, and AVHRR (in the pre-EOS period). The aerosols are assimilated by using MERRA-2 aerosol model, which interact directly with the radiation parameterization, and radiatively coupled with atmospheric model dynamics in the Goddard Earth Observing System Model, Version 5 (GEOS-5). Dust deposition data along with other major aerosol compositions (e.g. black carbon, sea salt, and sulfate, etc.) are simulated as dry and wet deposition, respectively. The hourly and monthly data are available at spatial resolution of 0.5ox0.625o (latitude x longitude). Quick data exploration of climatology and interannual variations of MERRA-2 aerosol can be done through the online visualization and analysis tool, Giovanni. This presentation, using dust deposition as an example, demonstrates a number of MERRA-2 data services at GES DISC. Global distributions of dust depositions, and their seasonal and inter-annual variations are investigated from MERRA-2 monthly aerosol products.

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.

Turbulent aerosol fluxes over the Arctic Ocean: 2. Wind-driven sources from the sea

NASA Astrophysics Data System (ADS)

Nilsson, E. D.; Rannik, Ü.; Swietlicki, E.; Leck, C.; Aalto, P. P.; Zhou, J.; Norman, M.

2001-12-01

An eddy-covariance flux system was successfully applied over open sea, leads and ice floes during the Arctic Ocean Expedition in July-August 1996. Wind-driven upward aerosol number fluxes were observed over open sea and leads in the pack ice. These particles must originate from droplets ejected into the air at the bursting of small air bubbles at the water surface. The source flux F (in 106 m-2 s-1) had a strong dependency on wind speed, log>(F>)=0.20U¯-1.71 and 0.11U¯-1.93, over the open sea and leads, respectively (where U¯ is the local wind speed at about 10 m height). Over the open sea the wind-driven aerosol source flux consisted of a film drop mode centered at ˜100 nm diameter and a jet drop mode centered at ˜1 μm diameter. Over the leads in the pack ice, a jet drop mode at ˜2 μm diameter dominated. The jet drop mode consisted of sea-salt, but oxalate indicated an organic contribution, and bacterias and other biogenic particles were identified by single particle analysis. Particles with diameters less than -100 nm appear to have contributed to the flux, but their chemical composition is unknown. Whitecaps were probably the bubble source at open sea and on the leads at high wind speed, but a different bubble source is needed in the leads owing to their small fetch. Melting of ice in the leads is probably the best candidate. The flux over the open sea was of such a magnitude that it could give a significant contribution to the condensation nuclei (CCN) population. Although the flux from the leads were roughly an order of magnitude smaller and the leads cover only a small fraction of the pack ice, the local source may till be important for the CCN population in Arctic fogs. The primary marine aerosol source will increase both with increased wind speed and with decreased ice fraction and extent. The local CCN production may therefore increase and influence cloud or fog albedo and lifetime in response to greenhouse warming in the Arctic Ocean region.

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

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.

Remote Sensing of Aerosol in the Terrestrial Atmosphere from Space: New Missions

NASA Technical Reports Server (NTRS)

Milinevsky, G.; Yatskiv, Ya.; Degtyaryov, O.; Syniavskyi, I.; Ivanov, Yu.; Bovchaliuk, A.; Mishchenko, M.; Danylevsky, V.; Sosonkin, M.; Bovchaliuk, V.

2015-01-01

The distribution and properties of atmospheric aerosols on a global scale are not well known in terms of determination of their effects on climate. This mostly is due to extreme variability of aerosol concentrations, properties, sources, and types. Aerosol climate impact is comparable to the effect of greenhouse gases, but its influence is more difficult to measure, especially with respect to aerosol microphysical properties and the evaluation of anthropogenic aerosol effect. There are many satellite missions studying aerosol distribution in the terrestrial atmosphere, such as MISR/Terra, OMI/Aura, AVHHR, MODIS/Terra and Aqua, CALIOP/CALIPSO. To improve the quality of data and climate models, and to reduce aerosol climate forcing uncertainties, several new missions are planned. The gap in orbital instruments for studying aerosol microphysics has arisen after the Glory mission failed during launch in 2011. In this review paper, we describe several planned aerosol space missions, including the Ukrainian project Aerosol-UA that obtains data using a multi-channel scanning polarimeter and wide-angle polarimetric camera. The project is designed for remote sensing of the aerosol microphysics and cloud properties on a global scale.

Stratospheric Aerosol--Observations, Processes, and Impact on Climate

NASA Technical Reports Server (NTRS)

Kresmer, Stefanie; Thomason, Larry W.; von Hobe, Marc; Hermann, Markus; Deshler, Terry; Timmreck, Claudia; Toohey, Matthew; Stenke, Andrea; Schwarz, Joshua P.; Weigel, Ralf;

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.

Primary sources and secondary formation of organic aerosols in Beijing, China.

PubMed

Guo, Song; Hu, Min; Guo, Qingfeng; Zhang, Xin; Zheng, Mei; Zheng, Jun; Chang, Chih Chung; Schauer, James J; Zhang, Renyi

2012-09-18

Ambient aerosol samples were collected at an urban site and an upwind rural site of Beijing during the CAREBEIJING-2008 (Campaigns of Air quality REsearch in BEIJING and surrounding region) summer field campaign. Contributions of primary particles and secondary organic aerosols (SOA) were estimated by chemical mass balance (CMB) modeling and tracer-yield method. The apportioned primary and secondary sources explain 73.8% ± 9.7% and 79.6% ± 10.1% of the measured OC at the urban and rural sites, respectively. Secondary organic carbon (SOC) contributes to 32.5 ± 15.9% of the organic carbon (OC) at the urban site, with 17.4 ± 7.6% from toluene, 9.7 ± 5.4% from isoprene, 5.1 ± 2.0% from α-pinene, and 2.3 ± 1.7% from β-caryophyllene. At the rural site, the secondary sources are responsible for 38.4 ± 14.4% of the OC, with the contributions of 17.3 ± 6.9%, 13.9 ± 9.1%, 5.6 ± 1.9%, and 1.7 ± 1.0% from toluene, isoprene, α-pinene, and β-caryophyllene, respectively. Compared with other regions in the world, SOA in Beijing is less aged, but the concentrations are much higher; between the sites, SOA is more aged and affected by regional transport at the urban site. The high SOA loading in Beijing is probably attributed to the high regional SOC background (~2 μg m(-3)). The toluene SOC concentration is high and comparable at the two sites, implying that some anthropogenic components, at least toluene SOA, are widespread in Beijing and represents a major factor in affecting the regional air quality. The aerosol gaseous precursor concentrations and temperature correlate well with SOA, both affecting SOA formation. The significant SOA enhancement with increasing water uptake and acidification indicates that the aqueous-phase reactions are largely responsible SOA formation in Beijing.

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.

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.

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

In situ measurement and source apportionment of aerosols in the Kathmandu valley, Nepal, April 2015.

NASA Astrophysics Data System (ADS)

DeCarlo, P. F.; Werden, B.; Goetz, J. D.; Giordano, M.; Bhave, P.; Jayarathne, T. S.; Stockwell, C.; Christian, T. J.; Nadler, W.; Panday, A. K.; Yokelson, R. J.; Stone, E. A.

2017-12-01

The Kathmandu Valley in Nepal is home to over 2.5 Million people, and is one of the fastest growing metropolitan areas in South Asia. It is subject to extreme pollution events due to numerous unregulated localized pollution sources and regional transport from the Indo-Gangetic Plain (IGP). Over 10% of Nepali fatalities are from lung disorders, making it the most common cause of death in the country. Previous field work has studied gas species, wintertime VOCs and PM in the valley. The Nepal Ambient Measurement and Site Testing Experiment [NAMaSTE] is the first deployment of a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) in Nepal and allows for a more comprehensive analysis of aerosol species and their source contributions. Ambient measurements for the NAMaSTE campaign were made in Bode, 8 km east of Kathmandu. Intensive measurements were made in April 2015, but cut short by the 2015 Gorka earthquake. HR-ToF-AMS measurements provided detailed chemical composition information on particulate matter in the valley. Ancillary measurements of chemical species CO, CO2, CH4, H2O, O3, NOx, BC and PM were carried out and compared to AMS data and meteorological parameters. AMS species show a clear diurnal pattern, with extremely elevated concentrations in the morning, with a wind shift to westerly in the afternoon. PMF was performed on the ambient data set, and mass spectral data was compared to source mass spectra generated from emission testing of various local sources measured during the campaign. The mean concentration of PM2.5 was 83 ± 45 µg/m3, which is above the 24 hour WHO exposure threshold of 25 µg/m3 and annual continous exposure limit of 10 µg/m3­­. Localized sources of anthropogenic emissions such as garbage burning, coal for brick kilns, dung and biomass burning for cooking and agriculture are likely sources of elevated pollutant emissions. Unmitigated burning of trash and biomass coupled with irregular fuels are a major source of

Highly controlled, reproducible measurements of aerosol emissions from combustion of a common African biofuel source

NASA Astrophysics Data System (ADS)

Haslett, Sophie L.; Thomas, J. Chris; Morgan, William T.; Hadden, Rory; Liu, Dantong; Allan, James D.; Williams, Paul I.; Keita, Sekou; Liousse, Cathy; Coe, Hugh

2018-01-01

Particulate emissions from biomass burning can both alter the atmosphere's radiative balance and cause significant harm to human health. However, due to the large effect on emissions caused by even small alterations to the way in which a fuel burns, it is difficult to study particulate production of biomass combustion mechanistically and in a repeatable manner. In order to address this gap, in this study, small wood samples sourced from Côte D'Ivoire in West Africa were burned in a highly controlled laboratory environment. The shape and mass of samples, available airflow and surrounding thermal environment were carefully regulated. Organic aerosol and refractory black carbon emissions were measured in real time using an Aerosol Mass Spectrometer and a Single Particle Soot Photometer, respectively. This methodology produced remarkably repeatable results, allowing aerosol emissions to be mapped directly onto different phases of combustion. Emissions from pyrolysis were visible as a distinct phase before flaming was established. After flaming combustion was initiated, a black-carbon-dominant flame was observed during which very little organic aerosol was produced, followed by a period that was dominated by organic-carbon-producing smouldering combustion, despite the presence of residual flaming. During pyrolysis and smouldering, the two phases producing organic aerosol, distinct mass spectral signatures that correspond to previously reported variations in biofuel emissions measured in the atmosphere are found. Organic aerosol emission factors averaged over an entire combustion event were found to be representative of the time spent in the pyrolysis and smouldering phases, rather than reflecting a coupling between emissions and the mass loss of the sample. Further exploration of aerosol yields from similarly carefully controlled fires and a careful comparison with data from macroscopic fires and real-world emissions will help to deliver greater constraints on the

Water soluble ions in aerosols (TSP) : Characteristics, sources and seasonal variation over the central Himalayas, Nepal

NASA Astrophysics Data System (ADS)

Tripathee, Lekhendra; Kang, Shichang; Zhang, Qianggong; Rupakheti, Dipesh

2016-04-01

Atmspheric pollutants transported from South Asia could have adverse impact on the Himalayan ecosystems. Investigation of aerosol chemistry in the Himalayan region in Nepal has been limited on a temporal and spatial scale to date. Therefore, the water-soluble ionic composition of aerosol using TSP sampler was investigated for a year period from April 2013 to March 2014 at four sites Bode, Dhunche, Lumbini and Jomsom characterized as an urban, rural, semi-urban and remote sites in Nepal. During the study period, the highest concentration of major cation was Ca2+ with an average concentration of 8.91, 2.17, 7.85 and 6.42 μg m-3 and the highest concentration of major anion was SO42- with an average of 10.96, 4.06, 6.85 and 3.30 μg m-3 at Bode, Dhunche, Lumbini and Jomsom respectively. The soluble ions showed the decrease in concentrations from urban to the rural site. Correlations and PCA analysis suggested that that SO42-, NO3- and NH4+ were derived from the anthropogenic sources where as the Ca2+ and Mg2+ were from crustal sources. Our results also suggest that the largest acid neutralizing agent at our sampling sites in the central Himalayas are Ca2+ followed by NH4+. Seasonal variations of soluble ions in aerosols showed higher concentrations during pre-monsoon and winter (dry-periods) due to limited precipitation amount and lower concentrations during the monsoon which can be explained by the dilution effect, higher the precipitation lower the concentration. K+ which is regarded as the tracer of biomss burning had a significant peaks during pre-monsoon season when the forest fires are active around the regions. In general, the results of this study suggests that the atmospheric chemistry is influenced by natural and anthropogenic sources. Thus, soluble ionic concentrations in aerosols from central Himalayas, Nepal can provide a useful database to assess atmospheric environment and its impacts on human health and ecosystem in the southern side of central

Possible indicators of long-range transport for aerosol emitted from various source regions in Northeast Asia

NASA Astrophysics Data System (ADS)

Park, S.; Kim, C.

2013-12-01

Air pollutant is affected by both long-range transboundary processes and local air pollution emission. Therefore it is important to identify the origin of air pollutant, for example, by classifying air pollutants into long-range transport (LRT) dominant process and local emission dominant (LED) cases. This study proposed several chemical and physical indicators of LRT process of aerosol concentrations observed at Korean peninsula. In order to identify the source regions and to estimate the contributions of both LRT and LED, we performed Lagrangian particle dispersion model(FLEXPART) and selected high pollution days over the three source regions in China inland and one Korea peninsula defined in this study; LRT-I to III and LED case. Next, we investigated the chemical and physical characteristics of LRT process of aerosol, and contrasted to those in the LED case over the Northeast Asia. We examined the difference of both modeled features simulated by CMAQ and as well measured aerosol optical properties of satellite-based sensor MODIS and AERONET data. Modeling study showed that the most effective indicator is the sulfur conversion ratios such as SO42-/(SO2+ SO42-) and SO42-/ SO2 for high sulfate condition. The ratio of N-containing species such as NOx (or NOy) to CO were the next best alternative indicators. In the meteorological fields, the results showed that pressure pattern and streamline flow are similar on a case by case basis. For observational physical features, we obtained the spatial distributions of the mean AOD, fine mode fraction (FMF), angstrom exponent (AE) by taking the average of MODIS aerosol products for the each analysis period. The highest AOD was found over the industrialized coastal region regardless of cases. AERONET data showed that aerosol size distribution showed significantly higher concentration of fine-mode particle in LED cases in comparison with that of LRT groups, suggesting that the amplitude fine modes of LRT relative to LED could

Water soluble organic aerosols in the Colorado Rocky Mountains, USA: composition, sources and optical properties

PubMed Central

Xie, Mingjie; Mladenov, Natalie; Williams, Mark W.; Neff, Jason C.; Wasswa, Joseph; Hannigan, Michael P.

2016-01-01

Atmospheric aerosols have been shown to be an important input of organic carbon and nutrients to alpine watersheds and influence biogeochemical processes in these remote settings. For many remote, high elevation watersheds, direct evidence of the sources of water soluble organic aerosols and their chemical and optical characteristics is lacking. Here, we show that the concentration of water soluble organic carbon (WSOC) in the total suspended particulate (TSP) load at a high elevation site in the Colorado Rocky Mountains was strongly correlated with UV absorbance at 254 nm (Abs254, r = 0.88 p < 0.01) and organic carbon (OC, r = 0.95 p < 0.01), accounting for >90% of OC on average. According to source apportionment analysis, biomass burning had the highest contribution (50.3%) to average WSOC concentration; SOA formation and motor vehicle emissions dominated the contribution to WSOC in the summer. The source apportionment and backward trajectory analysis results supported the notion that both wildfire and Colorado Front Range pollution sources contribute to the summertime OC peaks observed in wet deposition at high elevation sites in the Colorado Rocky Mountains. These findings have important implications for water quality in remote, high-elevation, mountain catchments considered to be our pristine reference sites. PMID:27991554

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

Sea spray aerosol as a unique source of ice nucleating particles

DOE PAGES

DeMott, Paul J.; Hill, Thomas C. J.; McCluskey, Christina S.; ...

2016-05-24

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. In addition, data in the present study are also in accord with previously published INPmore » measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0°C, averaging an order of magnitude increase per 5°C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using “dry” geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. Lastly, these findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.« less

Measurements of Organic Composition of Aerosol and Rainwater Samples Using Offline Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

OBrien, R. E.; Ridley, K. J.; Canagaratna, M. R.; Croteau, P.; Budisulistiorini, S. H.; Cui, T.; Green, H. S.; Surratt, J. D.; Jayne, J. T.; Kroll, J. H.

2016-12-01

A thorough understanding of the sources, evolution, and budgets of atmospheric organic aerosol requires widespread measurements of the amount and chemical composition of atmospheric organic carbon in the condensed phase (within particles and water droplets). Collecting such datasets requires substantial spatial and temporal (long term) coverage, which can be challenging when relying on online measurements by state-of-the-art research-grade instrumentation (such as those used in atmospheric chemistry field studies). Instead, samples are routinely collected using relatively low-cost techniques, such as aerosol filters, for offline analysis of their chemical composition. However, measurements made by online and offline instruments can be fundamentally different, leading to disparities between data from field studies and those from more routine monitoring. To better connect these two approaches, and take advantage of the benefits of each, we have developed a method to introduce collected samples into online aerosol instruments using nebulization. Because nebulizers typically require tens to hundreds of milliliters of solution, limiting this technique to large samples, we developed a new, ultrasonic micro-nebulizer that requires only small volumes (tens of microliters) of sample for chemical analysis. The nebulized (resuspended) sample is then sent into a high-resolution Aerosol Mass Spectrometer (AMS), a widely-used instrument that provides key information on the chemical composition of aerosol particulate matter (elemental ratios, carbon oxidation state, etc.), measurements that are not typically made for collected atmospheric samples. Here, we compare AMS data collected using standard on-line techniques with our offline analysis, demonstrating the utility of this new technique to aerosol filter samples. We then apply this approach to organic aerosol filter samples collected in remote regions, as well as rainwater samples from across the US. This data provides

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

Using Long-Term Satellite Observations to Identify Sensitive Regimes and Active Regions of Aerosol Indirect Effects for Liquid Clouds Over Global Oceans

NASA Astrophysics Data System (ADS)

Zhao, Xuepeng; Liu, Yangang; Yu, Fangquan; Heidinger, Andrew K.

2018-01-01

Long-term (1981-2011) satellite climate data records of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effects (AIEs) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT). An aerosol optical thickness (AOT) range of 0.13 < AOT < 0.3 is identified as the sensitive regime of the conventional first AIE where CDER is more susceptible to AOT than the other cloud variables. The first AIE that manifests as the change of long-term averaged CDER appears only in limited oceanic regions. The signature of aerosol invigoration of water clouds as revealed by the increase of cloud cover fraction (CCF) and CTH with increasing AOT at the middle/high latitudes of both hemispheres is identified for a pristine atmosphere (AOT < 0.08). Aerosol invigoration signature is also revealed by the concurrent increase of CDER, COD, and CWP with increasing AOT for a polluted marine atmosphere (AOT > 0.3) in the tropical convergence zones. The regions where the second AIE is likely to manifest in the CCF change are limited to several oceanic areas with high CCF of the warm water clouds near the western coasts of continents. The second AIE signature as represented by the reduction of the precipitation efficiency with increasing AOT is more likely to be observed in the AOT regime of 0.08 < AOT < 0.4. The corresponding AIE active regions manifested themselves as the decline of the precipitation efficiency are mainly limited to the oceanic areas downwind of continental aerosols. The sensitive regime of the conventional AIE identified in this observational study is likely associated with the

Two years of near real-time chemical composition of submicron aerosols in the region of Paris using an Aerosol Chemical Speciation Monitor (ACSM) and a multi-wavelength Aethalometer

NASA Astrophysics Data System (ADS)

Petit, J.-E.; Favez, O.; Sciare, J.; Crenn, V.; Sarda-Estève, R.; Bonnaire, N.; Močnik, G.; Dupont, J.-C.; Haeffelin, M.; Leoz-Garziandia, E.

2015-03-01

Aerosol mass spectrometer (AMS) measurements have been successfully used towards a better understanding of non-refractory submicron (PM1) aerosol chemical properties based on short-term campaigns. The recently developed Aerosol Chemical Speciation Monitor (ACSM) has been designed to deliver quite similar artifact-free chemical information but for low cost, and to perform robust monitoring over long-term periods. When deployed in parallel with real-time black carbon (BC) measurements, the combined data set allows for a quasi-comprehensive description of the whole PM1 fraction in near real time. Here we present 2-year long ACSM and BC data sets, between mid-2011 and mid-2013, obtained at the French atmospheric SIRTA supersite that is representative of background PM levels of the region of Paris. This large data set shows intense and time-limited (a few hours) pollution events observed during wintertime in the region of Paris, pointing to local carbonaceous emissions (mainly combustion sources). A non-parametric wind regression analysis was performed on this 2-year data set for the major PM1 constituents (organic matter, nitrate, sulfate and source apportioned BC) and ammonia in order to better refine their geographical origins and assess local/regional/advected contributions whose information is mandatory for efficient mitigation strategies. While ammonium sulfate typically shows a clear advected pattern, ammonium nitrate partially displays a similar feature, but, less expectedly, it also exhibits a significant contribution of regional and local emissions. The contribution of regional background organic aerosols (OA) is significant in spring and summer, while a more pronounced local origin is evidenced during wintertime, whose pattern is also observed for BC originating from domestic wood burning. Using time-resolved ACSM and BC information, seasonally differentiated weekly diurnal profiles of these constituents were investigated and helped to identify the main

Variability of aerosol vertical distribution in the Sahel

NASA Astrophysics Data System (ADS)

Cavalieri, O.; Cairo, F.; Fierli, F.; di Donfrancesco, G.; Snels, M.; Viterbini, M.; Cardillo, F.; Chatenet, B.; Formenti, P.; Marticorena, B.; Rajot, J. L.

2010-12-01

In this work, we have studied the seasonal and inter-annual variability of the aerosol vertical distribution over Sahelian Africa for the years 2006, 2007 and 2008, characterizing the different kind of aerosols present in the atmosphere in terms of their optical properties observed by ground-based and satellite instruments, and their sources searched for by using trajectory analysis. This study combines data acquired by three ground-based micro lidar systems located in Banizoumbou (Niger), Cinzana (Mali) and M'Bour (Senegal) in the framework of the African Monsoon Multidisciplinary Analysis (AMMA), by the AEROsol RObotic NETwork (AERONET) sun-photometers and by the space-based Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the CALIPSO satellite (Cloud-Aerosol Lidar and Infrared Pathfinder Observations). During winter, the lower levels air masses arriving in the Sahelian region come mainly from North, North-West and from the Atlantic area, while in the upper troposphere air flow generally originates from West Africa, crossing a region characterized by the presence of large biomass burning sources. The sites of Cinzana, Banizoumbou and M'Bour, along a transect of aerosol transport from East to West, are in fact under the influence of tropical biomass burning aerosol emission during the dry season, as revealed by the seasonal pattern of the aerosol optical properties, and by back-trajectory studies. Aerosol produced by biomass burning are observed mainly during the dry season and are confined in the upper layers of the atmosphere. This is particularly evident for 2006, which was characterized by a large presence of biomass burning aerosols in all the three sites. Biomass burning aerosol is also observed during spring when air masses originating from North and East Africa pass over sparse biomass burning sources, and during summer when biomass burning aerosol is transported from the southern part of the continent by the monsoon flow. During summer

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

Tracing of aerosol sources in an urban environment using chemical, Sr isotope, and mineralogical characterization.

PubMed

Duarte, Regina M B O; Matos, João T V; Paula, Andreia S; Lopes, Sónia P; Ribeiro, Sara; Santos, José Francisco; Patinha, Carla; da Silva, Eduardo Ferreira; Soares, Rosário; Duarte, Armando C

2017-04-01

In the framework of two national research projects (ORGANOSOL and CN-linkAIR), fine particulate matter (PM 2.5 ) was sampled for 17 months at an urban location in the Western European Coast. The PM 2.5 samples were analyzed for organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), major water-soluble inorganic ions, mineralogical, and for the first time in this region, strontium isotope ( 87 Sr/ 86 Sr) composition. Organic matter dominates the identifiable urban PM 2.5 mass, followed by secondary inorganic aerosols. The acquired data resulted also in a seasonal overview of the carbonaceous and inorganic aerosol composition, with an important contribution from primary biomass burning and secondary formation processes in colder and warmer periods, respectively. The fossil-related primary EC seems to be continually present throughout the sampling period. The 87 Sr/ 86 Sr ratios were measured on both the labile and residual PM 2.5 fractions as well as on the bulk PM 2.5 samples. Regardless of the air mass origin, the residual fractions are more radiogenic (representative of a natural crustal dust source) than the labile fractions, whose 87 Sr/ 86 Sr ratios are comparable to that of seawater. The 87 Sr/ 86 Sr ratios and the mineralogical composition data further suggest that sea salt and mineral dust are important primary natural sources of fine aerosols throughout the sampling period.

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.

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.

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...

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

NASA Astrophysics Data System (ADS)

Jathar, Shantanu H.; Woody, Matthew; Pye, Havala O. T.; Baker, Kirk R.; Robinson, Allen L.

2017-03-01

Gasoline- and diesel-fueled engines are ubiquitous sources of air pollution in urban environments. They emit both primary particulate matter and precursor gases that react to form secondary particulate matter in the atmosphere. In this work, we updated the organic aerosol module and organic emissions inventory of a three-dimensional chemical transport model, the Community Multiscale Air Quality Model (CMAQ), using recent, experimentally derived inputs and parameterizations for mobile sources. The updated model included a revised volatile organic compound (VOC) speciation for mobile sources and secondary organic aerosol (SOA) formation from unspeciated intermediate volatility organic compounds (IVOCs). The updated model was used to simulate air quality in southern California during May and June 2010, when the California Research at the Nexus of Air Quality and Climate Change (CalNex) study was conducted. Compared to the Traditional version of CMAQ, which is commonly used for regulatory applications, the updated model did not significantly alter the predicted organic aerosol (OA) mass concentrations but did substantially improve predictions of OA sources and composition (e.g., POA-SOA split), as well as ambient IVOC concentrations. The updated model, despite substantial differences in emissions and chemistry, performed similar to a recently released research version of CMAQ (Woody et al., 2016) that did not include the updated VOC and IVOC emissions and SOA data. Mobile sources were predicted to contribute 30-40 % of the OA in southern California (half of which was SOA), making mobile sources the single largest source contributor to OA in southern California. The remainder of the OA was attributed to non-mobile anthropogenic sources (e.g., cooking, biomass burning) with biogenic sources contributing to less than 5 % to the total OA. Gasoline sources were predicted to contribute about 13 times more OA than diesel sources; this difference was driven by differences in

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.

Arctic Sea Salt Aerosol from Blowing Snow and Sea Ice Surfaces - a Missing Natural Source in Winter

NASA Astrophysics Data System (ADS)

Frey, M. M.; Norris, S. J.; Brooks, I. M.; Nishimura, K.; Jones, A. E.

2015-12-01

Atmospheric particles in the polar regions consist mostly of sea salt aerosol (SSA). SSA plays an important role in regional climate change through influencing the surface energy balance either directly or indirectly via cloud formation. SSA irradiated by sunlight also releases very reactive halogen radicals, which control concentrations of ozone, a pollutant and greenhouse gas. However, models under-predict SSA concentrations in the Arctic during winter pointing to a missing source. It has been recently suggested that salty blowing snow above sea ice, which is evaporating, to be that source as it may produce more SSA than equivalent areas of open ocean. Participation in the 'Norwegian Young Sea Ice Cruise (N-ICE 2015)' on board the research vessel `Lance' allowed to test this hypothesis in the Arctic sea ice zone during winter. Measurements were carried out from the ship frozen into the pack ice North of 80º N during February to March 2015. Observations at ground level (0.1-2 m) and from the ship's crows nest (30 m) included number concentrations and size spectra of SSA (diameter range 0.3-10 μm) as well as snow particles (diameter range 50-500 μm). During and after blowing snow events significant SSA production was observed. In the aerosol and snow phase sulfate is fractionated with respect to sea water, which confirms sea ice surfaces and salty snow, and not the open ocean, to be the dominant source of airborne SSA. Aerosol shows depletion in bromide with respect to sea water, especially after sunrise, indicating photochemically driven release of bromine. We discuss the SSA source strength from blowing snow in light of environmental conditions (wind speed, atmospheric turbulence, temperature and snow salinity) and recommend improved model parameterisations to estimate regional aerosol production. N-ICE 2015 results are then compared to a similar study carried out previously in the Weddell Sea during the Antarctic winter.

Global combustion sources of organic aerosols: model comparison with 84 AMS factor-analysis data sets

NASA Astrophysics Data System (ADS)

Tsimpidi, Alexandra P.; Karydis, Vlassis A.; Pandis, Spyros N.; Lelieveld, Jos

2016-07-01

Emissions of organic compounds from biomass, biofuel, and fossil fuel combustion strongly influence the global atmospheric aerosol load. Some of the organics are directly released as primary organic aerosol (POA). Most are emitted in the gas phase and undergo chemical transformations (i.e., oxidation by hydroxyl radical) and form secondary organic aerosol (SOA). In this work we use the global chemistry climate model ECHAM/MESSy Atmospheric Chemistry (EMAC) with a computationally efficient module for the description of organic aerosol (OA) composition and evolution in the atmosphere (ORACLE). The tropospheric burden of open biomass and anthropogenic (fossil and biofuel) combustion particles is estimated to be 0.59 and 0.63 Tg, respectively, accounting for about 30 and 32 % of the total tropospheric OA load. About 30 % of the open biomass burning and 10 % of the anthropogenic combustion aerosols originate from direct particle emissions, whereas the rest is formed in the atmosphere. A comprehensive data set of aerosol mass spectrometer (AMS) measurements along with factor-analysis results from 84 field campaigns across the Northern Hemisphere are used to evaluate the model results. Both the AMS observations and the model results suggest that over urban areas both POA (25-40 %) and SOA (60-75 %) contribute substantially to the overall OA mass, whereas further downwind and in rural areas the POA concentrations decrease substantially and SOA dominates (80-85 %). EMAC does a reasonable job in reproducing POA and SOA levels during most of the year. However, it tends to underpredict POA and SOA concentrations during winter indicating that the model misses wintertime sources of OA (e.g., residential biofuel use) and SOA formation pathways (e.g., multiphase oxidation).

Aerosol and monsoon climate interactions over Asia

NASA Astrophysics Data System (ADS)

Li, Zhanqing; Lau, W. K.-M.; Ramanathan, V.; Wu, G.; Ding, Y.; Manoj, M. G.; Liu, J.; Qian, Y.; Li, J.; Zhou, T.; Fan, J.; Rosenfeld, D.; Ming, Y.; Wang, Y.; Huang, J.; Wang, B.; Xu, X.; Lee, S.-S.; Cribb, M.; Zhang, F.; Yang, X.; Zhao, C.; Takemura, T.; Wang, K.; Xia, X.; Yin, Y.; Zhang, H.; Guo, J.; Zhai, P. M.; Sugimoto, N.; Babu, S. S.; Brasseur, G. P.

2016-12-01

The increasing severity of droughts/floods and worsening air quality from increasing aerosols in Asia monsoon regions are the two gravest threats facing over 60% of the world population living in Asian monsoon regions. These dual threats have fueled a large body of research in the last decade on the roles of aerosols in impacting Asian monsoon weather and climate. This paper provides a comprehensive review of studies on Asian aerosols, monsoons, and their interactions. The Asian monsoon region is a primary source of emissions of diverse species of aerosols from both anthropogenic and natural origins. The distributions of aerosol loading are strongly influenced by distinct weather and climatic regimes, which are, in turn, modulated by aerosol effects. On a continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulations. The atmospheric thermodynamic state, which determines the formation of clouds, convection, and precipitation, may also be altered by aerosols serving as cloud condensation nuclei or ice nuclei. Absorbing aerosols such as black carbon and desert dust in Asian monsoon regions may also induce dynamical feedback processes, leading to a strengthening of the early monsoon and affecting the subsequent evolution of the monsoon. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of different monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from

Aerosol measurements during COPE: composition, size, and sources of CCN and INPs at the interface between marine and terrestrial influences

NASA Astrophysics Data System (ADS)

Taylor, Jonathan W.; Choularton, Thomas W.; Blyth, Alan M.; Flynn, Michael J.; Williams, Paul I.; Young, Gillian; Bower, Keith N.; Crosier, Jonathan; Gallagher, Martin W.; Dorsey, James R.; Liu, Zixia; Rosenberg, Philip D.

2016-09-01

Heavy rainfall from convective clouds can lead to devastating flash flooding, and observations of aerosols and clouds are required to improve cloud parameterisations used in precipitation forecasts. We present measurements of boundary layer aerosol concentration, size, and composition from a series of research flights performed over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) of summer 2013. We place emphasis on periods of southwesterly winds, which locally are most conducive to convective cloud formation, when marine air from the Atlantic reached the peninsula. Accumulation-mode aerosol mass loadings were typically 2-3 µg m-3 (corrected to standard cubic metres at 1013.25 hPa and 273.15 K), the majority of which was sulfuric acid over the sea, or ammonium sulfate inland, as terrestrial ammonia sources neutralised the aerosol. The cloud condensation nuclei (CCN) concentrations in these conditions were ˜ 150-280 cm-3 at 0.1 % and 400-500 cm-3 at 0.9 % supersaturation (SST), which are in good agreement with previous Atlantic measurements, and the cloud drop concentrations at cloud base ranged from 100 to 500 cm-3. The concentration of CCN at 0.1 % SST was well correlated with non-sea-salt sulfate, meaning marine sulfate formation was likely the main source of CCN. Marine organic aerosol (OA) had a similar mass spectrum to previous measurements of sea spray OA and was poorly correlated with CCN. In one case study that was significantly different to the rest, polluted anthropogenic emissions from the southern and central UK advected to the peninsula, with significant enhancements of OA, ammonium nitrate and sulfate, and black carbon. The CCN concentrations here were around 6 times higher than in the clean cases, and the cloud drop number concentrations were 3-4 times higher. Sources of ice-nucleating particles (INPs) were assessed by comparing different parameterisations used to predict INP concentrations, using measured

Long-term analysis of aerosol optical depth over Northeast Asia using a satellite-based measurement: MI Yonsei Aerosol Retrieval Algorithm (YAER)

NASA Astrophysics Data System (ADS)

Kim, Mijin; Kim, Jhoon; Yoon, Jongmin; Chung, Chu-Yong; Chung, Sung-Rae

2017-04-01

In 2010, the Korean geostationary earth orbit (GEO) satellite, the Communication, Ocean, and Meteorological Satellite (COMS), was launched including the Meteorological Imager (MI). The MI measures atmospheric condition over Northeast Asia (NEA) using a single visible channel centered at 0.675 μm and four IR channels at 3.75, 6.75, 10.8, 12.0 μm. The visible measurement can also be utilized for the retrieval of aerosol optical properties (AOPs). Since the GEO satellite measurement has an advantage for continuous monitoring of AOPs, we can analyze the spatiotemporal variation of the aerosol using the MI observations over NEA. Therefore, we developed an algorithm to retrieve aerosol optical depth (AOD) using the visible observation of MI, and named as MI Yonsei Aerosol Retrieval Algorithm (YAER). In this study, we investigated the accuracy of MI YAER AOD by comparing the values with the long-term products of AERONET sun-photometer. The result showed that the MI AODs were significantly overestimated than the AERONET values over bright surface in low AOD case. Because the MI visible channel centered at red color range, contribution of aerosol signal to the measured reflectance is relatively lower than the surface contribution. Therefore, the AOD error in low AOD case over bright surface can be a fundamental limitation of the algorithm. Meanwhile, an assumption of background aerosol optical depth (BAOD) could result in the retrieval uncertainty, also. To estimate the surface reflectance by considering polluted air condition over the NEA, we estimated the BAOD from the MODIS dark target (DT) aerosol products by pixel. The satellite-based AOD retrieval, however, largely depends on the accuracy of the surface reflectance estimation especially in low AOD case, and thus, the BAOD could include the uncertainty in surface reflectance estimation of the satellite-based retrieval. Therefore, we re-estimated the BAOD using the ground-based sun-photometer measurement, and

Aerosol Indirect Effects on Cirrus Clouds in Global Aerosol-Climate Models

NASA Astrophysics Data System (ADS)

Liu, X.; Zhang, K.; Wang, Y.; Neubauer, D.; Lohmann, U.; Ferrachat, S.; Zhou, C.; Penner, J.; Barahona, D.; Shi, X.

2015-12-01

Cirrus clouds play an important role in regulating the Earth's radiative budget and water vapor distribution in the upper troposphere. Aerosols can act as solution droplets or ice nuclei that promote ice nucleation in cirrus clouds. Anthropogenic emissions from fossil fuel and biomass burning activities have substantially perturbed and enhanced concentrations of aerosol particles in the atmosphere. Global aerosol-climate models (GCMs) have now been used to quantify the radiative forcing and effects of aerosols on cirrus clouds (IPCC AR5). However, the estimate uncertainty is very large due to the different representation of ice cloud formation and evolution processes in GCMs. In addition, large discrepancies have been found between model simulations in terms of the spatial distribution of ice-nucleating aerosols, relative humidity, and temperature fluctuations, which contribute to different estimates of the aerosol indirect effect through cirrus clouds. In this presentation, four GCMs with the start-of-the art representations of cloud microphysics and aerosol-cloud interactions are used to estimate the aerosol indirect effects on cirrus clouds and to identify the causes of the discrepancies. The estimated global and annual mean anthropogenic aerosol indirect effect through cirrus clouds ranges from 0.1 W m-2 to 0.3 W m-2 in terms of the top-of-the-atmosphere (TOA) net radiation flux, and 0.5-0.6 W m-2 for the TOA longwave flux. Despite the good agreement on global mean, large discrepancies are found at the regional scale. The physics behind the aerosol indirect effect is dramatically different. Our analysis suggests that burden of ice-nucleating aerosols in the upper troposphere, ice nucleation frequency, and relative role of ice formation processes (i.e., homogeneous versus heterogeneous nucleation) play key roles in determining the characteristics of the simulated aerosol indirect effects. In addition to the indirect effect estimate, we also use field campaign

Spatial and Temporal Variations of EC and OC Aerosol Combustion Sources in a Polluted Metropolitan Area

NASA Astrophysics Data System (ADS)

Mouteva, G.; Randerson, J. T.; Fahrni, S.; Santos, G.; Bush, S. E.; Ehleringer, J. R.; Czimczik, C. I.

2015-12-01

Anthropogenic emissions of carbonaceous aerosols are a major component of fine air particulate matter (PM2.5) in polluted metropolitan areas and in the global atmosphere. Elemental (EC) and organic carbon (OC) aerosols influence Earth's energy balance by means of direct and indirect pathways and EC has been suggested as a better indicator of public health impacts from combustion-related sources than PM mass. Quantifying the contribution of fossil fuel and biomass combustion to the EC and OC emissions and their temporal and spatial variations is critical for developing efficient legislative air pollution control measures and successful climate mitigation strategies. In this study, we used radiocarbon (14C) to separate and quantify fossil and biomass contributions to a time series of EC and OC collected at 3 locations in Salt Lake City (SLC). Aerosol samples were collected on quartz fiber filters and a modified OC/EC analyzer was used with the Swiss_4S protocol to isolate and trap the EC fraction. Together with the total carbon (TC) content of the samples, the EC was analyzed for its 14C content with accelerator mass spectrometry. The 14C of OC was derived as a mass balance difference between TC and EC. EC had an annual average fraction modern of 0.13±0.06 and did not vary significantly across seasons. OC had an annual average FM of 0.49±0.13, with the winter mean (0.43±0.11) lower than the summer mean (0.64±0.13) at the 5% significance level. While the 3 stations were chosen to represent a variety of environmental conditions within SLC, no major differences in this source partitioning were observed between stations. During winter, the major sources of air pollutants in SLC are motor vehicles and wood stove combustion and determining their relative contributions has been the subject of debate. Our results indicated that fossil fuels were the dominant source of carbonaceous aerosols during winter, contributing 87% or more of the total EC mass and 40-75% of the OC

Characteristics, sources and evolution of fine aerosol (PM1) at urban, coastal and forest background sites in Lithuania

NASA Astrophysics Data System (ADS)

Masalaite, A.; Holzinger, R.; Remeikis, V.; Röckmann, T.; Dusek, U.

2017-01-01

The chemical and isotopic composition of organic aerosol (OA) samples collected on PM1 filters was determined as a function of desorption temperature to investigate the main sources of organic carbon and the effects of photochemical processing on atmospheric aerosol. The filter samples were collected at an urban (54°38‧ N, 25°18‧ E), coastal (55°55‧ N, 21°00‧ E) and forest (55°27‧ N, 26°00' E) site in Lithuania in March 2013. They can be interpreted as winter-time samples because the monthly averaged temperature was -4 °C. The detailed chemical composition of organic compounds was analysed with a thermal desorption PTR-MS. The mass concentration of organic aerosol at the forest site was roughly by a factor of 30 lower than at the urban and coastal site. This fact could be an indication that in this cold month the biogenic secondary organic aerosol (SOA) formation was very low. Moreover, the organic aerosol collected at the forest site was more refractory and contained a larger fraction of heavy molecules with m/z > 200. The isotopic composition of the aerosol was used to differentiate the two main sources of organic aerosol in winter, i.e. biomass burning (BB) and fossil fuel (FF) combustion. Organic aerosol from biomass burning is enriched in 13C compared to OA from fossil fuel emissions. δ13COC values of the OA samples showed a positive correlation with the mass fraction of several individual organic compounds. Most of these organic compounds contained nitrogen indicating that organic nitrogen compounds formed during the combustion of biomass may be indicative of BB. Other compounds that showed negative correlations with δ13COC were possibly indicative of FF. These compounds included heavy hydrocarbons and were on the average less oxidized than the bulk organic carbon. The correlation of δ13COC and the O/C ratio was positive at low but negative at high desorption temperatures at the forest site. We propose that this might be due to

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.

Primary to secondary organic aerosol: evolution of organic emissions from mobile combustion sources

NASA Astrophysics Data System (ADS)

Presto, A. A.; Gordon, T. D.; Robinson, A. L.

2014-05-01

A series of smog chamber experiments were conducted to investigate the transformation of primary organic aerosol (POA) and formation of secondary organic aerosol (SOA) during the photooxidation of dilute exhaust from a fleet of gasoline and diesel motor vehicles and two gas-turbine engines. In experiments where POA was present in the chamber at the onset of photooxidation, positive matrix factorization (PMF) was used to determine separate POA and SOA factors from aerosol mass spectrometer data. A 2-factor solution, with one POA factor and one SOA factor, was sufficient to describe the organic aerosol for gasoline vehicles, diesel vehicles, and one of the gas-turbine engines. Experiments with the second gas-turbine engine required a 3-factor PMF solution with a POA factor and two SOA factors. Results from the PMF analysis were compared to the residual method for determining SOA and POA mass concentrations. The residual method apportioned a larger fraction of the organic aerosol mass as POA because it assumes that all mass at m / z 57 is associated with POA. The POA mass spectrum for the gasoline and diesel vehicles exhibited high abundances of the CnH2n+1 series of ions (m / z 43, 57, etc.) and was similar to the mass spectra of the hydrocarbon-like organic aerosol factor determined from ambient data sets with one exception, a diesel vehicle equipped with a diesel oxidation catalyst. POA mass spectra for the gas-turbine engines are enriched in the CnH2n-1 series of ions (m / z 41, 55, etc.), consistent with the composition of the lubricating oil used in these engines. The SOA formed from the three sources exhibits high abundances of m / z 44 and 43, indicative of mild oxidation. The SOA mass spectra are consistent with less-oxidized ambient SV-OOA (semivolatile oxygenated organic aerosols) and fall within the triangular region of f44 versus f43 defined by ambient measurements. However there is poor absolute agreement between the experimentally derived SOA mass

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.

The Effect of Aerosol Hygroscopicity and Volatility on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

NASA Astrophysics Data System (ADS)

Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

2014-12-01

Secondary organic aerosol (SOA) from biogenic sources can influence optical properties of ambient aerosol by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon ("lensing effect"). The magnitude of these effects remains highly uncertain. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of relative humidity and temperature on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). The sample-conditioning system provided measurements at ambient RH, 10%RH ("dry"), 85%RH ("wet"), and 200 C ("TD"). In parallel to these measurements, a long residence time temperature-stepping thermodenuder (TD) and a variable residence time constant temperature TD in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. We will present results of the on-going analysis of the collected data set. We will show that both temperature and relative humidity have a strong effect on aerosol optical properties. SOA appears to increase aerosol light absorption by about 10%. TD measurements suggest that aerosol equilibrated fairly quickly, within 2 s. Evaporation varied substantially with ambient aerosol loading and composition and meteorology.

Understanding sources of organic aerosol during CalNex-2010 using the CMAQ-VBS

NASA Astrophysics Data System (ADS)

Woody, M. C.; Baker, K. R.; Hayes, P. L.; Jimenez, J. L.; Koo, B.; Pye, H. O. T.

2015-10-01

Community Multiscale Air Quality (CMAQ) model simulations utilizing the volatility basis set (VBS) treatment for organic aerosols (CMAQ-VBS) were evaluated against measurements collected at routine monitoring networks (Chemical Speciation Network (CSN) and Interagency Monitoring of Protected Visual Environments (IMPROVE)) and those collected during the 2010 California at the Nexus of Air Quality and Climate Change (CalNex) field campaign to examine important sources of organic aerosol (OA) in southern California. CMAQ-VBS (OA lumped by volatility, semivolatile POA) underpredicted total organic carbon (OC) at CSN (-25.5 % Normalized Median Bias (NMdnB)) and IMPROVE (-63.9 % NMdnB) locations and total OC was underpredicted to a greater degree compared to the CMAQ-AE6 (9.9 and -55.7 % NMdnB, respectively; semi-explicit OA treatment, SOA lumped by parent hydrocarbon, nonvolatile POA). However, comparisons to aerosol mass spectrometer (AMS) measurements collected at Pasadena, CA indicated that CMAQ-VBS better represented the diurnal profile and the primary/secondary split of OA. CMAQ-VBS secondary organic aerosol (SOA) underpredicted the average measured AMS oxygenated organic aerosol (OOA, a surrogate of SOA) concentration by a factor of 5.2 (4.7 μg m-3 measured vs. 0.9 μg m-3 modeled), a considerable improvement to CMAQ-AE6 SOA predictions, which were approximately 24× lower than the average AMS OOA concentration. We use two new methods, based on species ratios and on a simplified SOA parameterization from the observations, to apportion the SOA underprediction for CMAQ-VBS to too slow photochemical oxidation (estimated as 1.5× lower than observed at Pasadena using - log (NOx: NOy)), low intrinsic SOA formation efficiency (low by 1.6 to 2× for Pasadena), and too low emissions or too high dispersion for the Pasadena site (estimated to be 1.6 to 2.3× too low/high). The first and third factors will be similar for CMAQ-AE6, while the intrinsic SOA formation

Understanding sources of organic aerosol during CalNex-2010 using the CMAQ-VBS

NASA Astrophysics Data System (ADS)

Woody, Matthew C.; Baker, Kirk R.; Hayes, Patrick L.; Jimenez, Jose L.; Koo, Bonyoung; Pye, Havala O. T.

2016-03-01

Community Multiscale Air Quality (CMAQ) model simulations utilizing the traditional organic aerosol (OA) treatment (CMAQ-AE6) and a volatility basis set (VBS) treatment for OA (CMAQ-VBS) were evaluated against measurements collected at routine monitoring networks (Chemical Speciation Network (CSN) and Interagency Monitoring of Protected Visual Environments (IMPROVE)) and those collected during the 2010 California at the Nexus of Air Quality and Climate Change (CalNex) field campaign to examine important sources of OA in southern California. Traditionally, CMAQ treats primary organic aerosol (POA) as nonvolatile and uses a two-product framework to represent secondary organic aerosol (SOA) formation. CMAQ-VBS instead treats POA as semivolatile and lumps OA using volatility bins spaced an order of magnitude apart. The CMAQ-VBS approach underpredicted organic carbon (OC) at IMPROVE and CSN sites to a greater degree than CMAQ-AE6 due to the semivolatile POA treatment. However, comparisons to aerosol mass spectrometer (AMS) measurements collected at Pasadena, CA, indicated that CMAQ-VBS better represented the diurnal profile and primary/secondary split of OA. CMAQ-VBS SOA underpredicted the average measured AMS oxygenated organic aerosol (OOA, a surrogate for SOA) concentration by a factor of 5.2, representing a considerable improvement to CMAQ-AE6 SOA predictions (factor of 24 lower than AMS). We use two new methods, one based on species ratios (SOA/ΔCO and SOA/Ox) and another on a simplified SOA parameterization, to apportion the SOA underprediction for CMAQ-VBS to slow photochemical oxidation (estimated as 1.5 × lower than observed at Pasadena using -log(NOx : NOy)), low intrinsic SOA formation efficiency (low by 1.6 to 2 × for Pasadena), and low emissions or excessive dispersion for the Pasadena site (estimated to be 1.6 to 2.3 × too low/excessive). The first and third factors are common to CMAQ-AE6, while the intrinsic SOA formation efficiency for that model is

Understanding sources of organic aerosol during CalNex-2010 using the CMAQ-VBS

DOE PAGES

Woody, Matthew C.; Baker, Kirk R.; Hayes, Patrick L.; ...

2016-03-29

In this paper, Community Multiscale Air Quality (CMAQ) model simulations utilizing the traditional organic aerosol (OA) treatment (CMAQ-AE6) and a volatility basis set (VBS) treatment for OA (CMAQ-VBS) were evaluated against measurements collected at routine monitoring networks (Chemical Speciation Network (CSN) and Interagency Monitoring of Protected Visual Environments (IMPROVE)) and those collected during the 2010 California at the Nexus of Air Quality and Climate Change (CalNex) field campaign to examine important sources of OA in southern California. Traditionally, CMAQ treats primary organic aerosol (POA) as nonvolatile and uses a two-product framework to represent secondary organic aerosol (SOA) formation. CMAQ-VBS insteadmore » treats POA as semivolatile and lumps OA using volatility bins spaced an order of magnitude apart. The CMAQ-VBS approach underpredicted organic carbon (OC) at IMPROVE and CSN sites to a greater degree than CMAQ-AE6 due to the semivolatile POA treatment. However, comparisons to aerosol mass spectrometer (AMS) measurements collected at Pasadena, CA, indicated that CMAQ-VBS better represented the diurnal profile and primary/secondary split of OA. CMAQ-VBS SOA underpredicted the average measured AMS oxygenated organic aerosol (OOA, a surrogate for SOA) concentration by a factor of 5.2, representing a considerable improvement to CMAQ-AE6 SOA predictions (factor of 24 lower than AMS). We use two new methods, one based on species ratios (SOA/ΔCO and SOA/O x) and another on a simplified SOA parameterization, to apportion the SOA underprediction for CMAQ-VBS to slow photochemical oxidation (estimated as 1.5 × lower than observed at Pasadena using -log(NO x:NO y)), low intrinsic SOA formation efficiency (low by 1.6 to 2 × for Pasadena), and low emissions or excessive dispersion for the Pasadena site (estimated to be 1.6 to 2.3 × too low/excessive). The first and third factors are common to CMAQ-AE6, while the intrinsic SOA formation

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

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.

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

Aerosol layer height from synergistic use of VIIRS and OMPS

NASA Astrophysics Data System (ADS)

Lee, J.; Hsu, N. Y. C.; Sayer, A. M.; Kim, W.; Seftor, C. J.

2017-12-01

This study presents an Aerosol Single-scattering albedo and Height Estimation (ASHE) algorithm, which retrieves the height of UV-absorbing aerosols by synergistically using the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Ozone Mapping and Profiler Suite (OMPS). ASHE provides height information over a much broader area than ground-based or spaceborne lidar measurements by benefitting from the wide swaths of the two instruments used. As determination of single-scattering albedo (SSA) of the aerosol layer is the most critical part for the performance and coverage of ASHE, here we demonstrate three different strategies to constrain the SSA. First, ASHE is able to retrieve the SSA of UV-absorbing aerosols when Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) provides vertical profiles of the aerosol layer of interest. Second, Aerosol Robotic Network (AERONET) inversions can directly constrain the SSA of the aerosol layer when collocated with VIIRS or OMPS. Last, a SSA climatology from ASHE, AERONET, or other data sources can be used for large-scale, aged aerosol events, for which climatological SSA is well-known, at the cost of a slight decrease in retrieval accuracy. The same algorithm can be applied to measurements of similar type, such as those made by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI), for a long-term, consistent data record.

Global dust sources detection using MODIS Deep Blue Collection 6 aerosol products

NASA Astrophysics Data System (ADS)

Pérez García-Pando, C.; Ginoux, P. A.

2015-12-01

Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Remote sensing sensors are the most useful tool to locate dust sources. These sensors include microwaves, visible channels, and lidar. On the global scale, major dust source regions have been identified using polar orbiting satellite instruments. The MODIS Deep Blue algorithm has been particularly useful to detect small-scale sources such as floodplains, alluvial fans, rivers, and wadis , as well as to identify anthropogenic sources from agriculture. The recent release of Collection 6 MODIS aerosol products allows to extend dust source detection to the entire land surfaces, which is quite useful to identify mid to high latitude dust sources and detect not only dust from agriculture but fugitive dust from transport and industrial activities. This presentation will overview the advantages and drawbacks of using MODIS Deep Blue for dust detection, compare to other instruments (polar orbiting and geostationary). The results of Collection 6 with a new dust screening will be compared against AERONET. Applications to long range transport of anthropogenic dust will be presented.

Classifying aerosol type using in situ surface spectral aerosol optical properties

NASA Astrophysics Data System (ADS)

Schmeisser, Lauren; Andrews, Elisabeth; Ogren, John A.; Sheridan, Patrick; Jefferson, Anne; Sharma, Sangeeta; Kim, Jeong Eun; Sherman, James P.; Sorribas, Mar; Kalapov, Ivo; Arsov, Todor; Angelov, Christo; Mayol-Bracero, Olga L.; Labuschagne, Casper; Kim, Sang-Woo; Hoffer, András; Lin, Neng-Huei; Chia, Hao-Ping; Bergin, Michael; Sun, Junying; Liu, Peng; Wu, Hao

2017-10-01

Knowledge of aerosol size and composition is important for determining radiative forcing effects of aerosols, identifying aerosol sources and improving aerosol satellite retrieval algorithms. The ability to extrapolate aerosol size and composition, or type, from intensive aerosol optical properties can help expand the current knowledge of spatiotemporal variability in aerosol type globally, particularly where chemical composition measurements do not exist concurrently with optical property measurements. This study uses medians of the scattering Ångström exponent (SAE), absorption Ångström exponent (AAE) and single scattering albedo (SSA) from 24 stations within the NOAA/ESRL Federated Aerosol Monitoring Network to infer aerosol type using previously published aerosol classification schemes.Three methods are implemented to obtain a best estimate of dominant aerosol type at each station using aerosol optical properties. The first method plots station medians into an AAE vs. SAE plot space, so that a unique combination of intensive properties corresponds with an aerosol type. The second typing method expands on the first by introducing a multivariate cluster analysis, which aims to group stations with similar optical characteristics and thus similar dominant aerosol type. The third and final classification method pairs 3-day backward air mass trajectories with median aerosol optical properties to explore the relationship between trajectory origin (proxy for likely aerosol type) and aerosol intensive parameters, while allowing for multiple dominant aerosol types at each station.The three aerosol classification methods have some common, and thus robust, results. In general, estimating dominant aerosol type using optical properties is best suited for site locations with a stable and homogenous aerosol population, particularly continental polluted (carbonaceous aerosol), marine polluted (carbonaceous aerosol mixed with sea salt) and continental dust/biomass sites

Sensitive glow discharge ion source for aerosol and gas analysis

DOEpatents

Reilly, Peter T. A. [Knoxville, TN

2007-08-14

A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.

Impact of Aerosols on Convective Clouds and Precipitation

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong; Li, Xiaowen

2012-01-01

Aerosols are a critical.factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosols have a major impact on the dynamics, microphysics, and electrification properties of continental mixed-phase convective clouds. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing a significant source of cloud condensation nuclei (CCN). Such pollution . effects on precipitation potentially have enormous climatic consequences both in terms of feedbacks involving the land surface via rainfall as well as the surface energy budget and changes in latent heat input to the atmosphere. Basically, aerosol concentrations can influence cloud droplet size distributions, the warm-rain process, the cold-rain process, cloud-top heights, the depth of the mixed-phase region, and the occurrence of lightning. Recently, many cloud resolution models (CRMs) have been used to examine the role of aerosols on mixed-phase convective clouds. These modeling studies have many differences in terms of model configuration (two- or three-dimensional), domain size, grid spacing (150-3000 m), microphysics (two-moment bulk, simple or sophisticated spectral-bin), turbulence (1st or 1.5 order turbulent kinetic energy (TKE)), radiation, lateral boundary conditions (i.e., closed, radiative open or cyclic), cases (isolated convection, tropical or midlatitude squall lines) and model integration time (e.g., 2.5 to 48 hours). Among these modeling studies, the most striking difference is that cumulative precipitation can either increase or decrease in response to higher concentrations of CCN. In this presentation, we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes. Specifically, this paper addresses the following topics

simplified aerosol representations in global modeling

NASA Astrophysics Data System (ADS)

Kinne, Stefan; Peters, Karsten; Stevens, Bjorn; Rast, Sebastian; Schutgens, Nick; Stier, Philip

2015-04-01

The detailed treatment of aerosol in global modeling is complex and time-consuming. Thus simplified approaches are investigated, which prescribe 4D (space and time) distributions of aerosol optical properties and of aerosol microphysical properties. Aerosol optical properties are required to assess aerosol direct radiative effects and aerosol microphysical properties (in terms of their ability as aerosol nuclei to modify cloud droplet concentrations) are needed to address the indirect aerosol impact on cloud properties. Following the simplifying concept of the monthly gridded (1x1 lat/lon) aerosol climatology (MAC), new approaches are presented and evaluated against more detailed methods, including comparisons to detailed simulations with complex aerosol component modules.

Using Long-term Satellite Observations to Identify Sensitive Regimes and Active Regions of Aerosol Indirect Effects for Liquid Clouds over Global Oceans

DOE PAGES

Zhao, Xuepeng; Liu, Yangang; Yu, Fangquan; ...

2017-11-16

Long-term (1981-2011) satellite climate data records (CDRs) of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effect (AIE) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT). An aerosol optical thickness (AOT) range of 0.13 < AOT < 0.3 is identifiedmore » as the sensitive regime of the conventional first AIE where CDER is more susceptible to AOT than the other cloud variables. The first AIE that manifests as the change of long-term averaged CDER appears only in limited oceanic regions. The signature of aerosol invigoration of water clouds as revealed by the increase of cloud cover fraction (CCF) and CTH with increasing AOT at the middle/high latitudes of both hemispheres is identified for a pristine atmosphere (AOT < 0.08). Aerosol invigoration signature is also revealed by the concurrent increase of CDER, COD, and CWP with increasing AOT for a polluted marine atmosphere (AOT > 0.3) in the tropical convergence zones. The regions where the second AIE is likely to manifest in the CCF change are limited to several oceanic areas with high CCF of the warm water clouds near the western coasts of continents. The second AIE signature as represented by the reduction of the precipitation efficiency with increasing AOT is more likely to be observed in the AOT regime of 0.08 < AOT < 0.4. The corresponding AIE active regions manifested themselves as the decline of the precipitation efficiency are mainly limited to the oceanic areas downwind of continental aerosols. Furthermore, the sensitive regime of the conventional AIE identified in this observational study is

Using Long-term Satellite Observations to Identify Sensitive Regimes and Active Regions of Aerosol Indirect Effects for Liquid Clouds over Global Oceans

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

Zhao, Xuepeng; Liu, Yangang; Yu, Fangquan

Long-term (1981-2011) satellite climate data records (CDRs) of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effect (AIE) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT). An aerosol optical thickness (AOT) range of 0.13 < AOT < 0.3 is identifiedmore » as the sensitive regime of the conventional first AIE where CDER is more susceptible to AOT than the other cloud variables. The first AIE that manifests as the change of long-term averaged CDER appears only in limited oceanic regions. The signature of aerosol invigoration of water clouds as revealed by the increase of cloud cover fraction (CCF) and CTH with increasing AOT at the middle/high latitudes of both hemispheres is identified for a pristine atmosphere (AOT < 0.08). Aerosol invigoration signature is also revealed by the concurrent increase of CDER, COD, and CWP with increasing AOT for a polluted marine atmosphere (AOT > 0.3) in the tropical convergence zones. The regions where the second AIE is likely to manifest in the CCF change are limited to several oceanic areas with high CCF of the warm water clouds near the western coasts of continents. The second AIE signature as represented by the reduction of the precipitation efficiency with increasing AOT is more likely to be observed in the AOT regime of 0.08 < AOT < 0.4. The corresponding AIE active regions manifested themselves as the decline of the precipitation efficiency are mainly limited to the oceanic areas downwind of continental aerosols. Furthermore, the sensitive regime of the conventional AIE identified in this observational study is

Using Long-Term Satellite Observations to Identify Sensitive Regimes and Active Regions of Aerosol Indirect Effects for Liquid Clouds Over Global Oceans.

PubMed

Zhao, Xuepeng; Liu, Yangang; Yu, Fangquan; Heidinger, Andrew K

2018-01-16

Long-term (1981-2011) satellite climate data records of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effects (AIEs) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT). An aerosol optical thickness (AOT) range of 0.13 < AOT < 0.3 is identified as the sensitive regime of the conventional first AIE where CDER is more susceptible to AOT than the other cloud variables. The first AIE that manifests as the change of long-term averaged CDER appears only in limited oceanic regions. The signature of aerosol invigoration of water clouds as revealed by the increase of cloud cover fraction (CCF) and CTH with increasing AOT at the middle/high latitudes of both hemispheres is identified for a pristine atmosphere (AOT < 0.08). Aerosol invigoration signature is also revealed by the concurrent increase of CDER, COD, and CWP with increasing AOT for a polluted marine atmosphere (AOT > 0.3) in the tropical convergence zones. The regions where the second AIE is likely to manifest in the CCF change are limited to several oceanic areas with high CCF of the warm water clouds near the western coasts of continents. The second AIE signature as represented by the reduction of the precipitation efficiency with increasing AOT is more likely to be observed in the AOT regime of 0.08 < AOT < 0.4. The corresponding AIE active regions manifested themselves as the decline of the precipitation efficiency are mainly limited to the oceanic areas downwind of continental aerosols. The sensitive regime of the conventional AIE identified in this observational study is likely associated

Sources and composition of submicron organic mass in marine aerosol particles

NASA Astrophysics Data System (ADS)

Frossard, Amanda A.; Russell, Lynn M.; Burrows, Susannah M.; Elliott, Scott M.; Bates, Timothy S.; Quinn, Patricia K.

2014-11-01

The sources and composition of atmospheric marine aerosol particles (aMA) have been investigated with a range of physical and chemical measurements from open-ocean research cruises. This study uses the characteristic functional group composition (from Fourier transform infrared spectroscopy) of aMA from five ocean regions to show the following: (i) The organic functional group composition of aMA that can be identified as mainly atmospheric primary marine (ocean derived) aerosol particles (aPMA) is 65 ± 12% hydroxyl, 21 ± 9% alkane, 6 ± 6% amine, and 7 ± 8% carboxylic acid functional groups. Contributions from photochemical reactions add carboxylic acid groups (15%-25%), shipping effluent in seawater and ship emissions add additional alkane groups (up to 70%), and coastal or continental emissions mix in alkane and carboxylic acid groups. (ii) The organic composition of aPMA is nearly identical to model-generated primary marine aerosol particles from bubbled seawater (gPMA, which has 55 ± 14% hydroxyl, 32 ± 14% alkane, and 13 ± 3% amine functional groups), indicating that its overall functional group composition is the direct consequence of the organic constituents of the seawater source. (iii) 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 gPMA remained nearly constant over a broad range of chlorophyll a concentrations, the gPMA alkane group fraction appeared to increase with chlorophyll a concentrations (r = 0.66). gPMA from productive seawater had a larger fraction of alkane functional groups (42 ± 9%) compared to gPMA from nonproductive seawater (22 ± 10%), perhaps due to the presence of surfactants in productive seawater that stabilize the bubble film and lead to preferential drainage of the more soluble (lower alkane group fraction) organic components. gPMA has a hydroxyl group absorption peak location characteristic of

Future Arctic temperature change resulting from a range of aerosol emissions scenarios

DOE PAGES

Wobus, Cameron; Flanner, Mark; Sarofim, Marcus C.; ...

2016-05-17

The Arctic temperature response to emissions of aerosols – specifically black carbon (BC), organic carbon (OC), and sulfate – depends on both the sector and the region where these emissions originate. Thus, the net Arctic temperature response to global aerosol emissions reductions will depend strongly on the blend of emissions sources being targeted. We use recently published equilibrium Arctic temperature response factors for BC, OC, and sulfate to estimate the range of present-day and future Arctic temperature changes from seven different aerosol emissions scenarios. Globally, Arctic temperature changes calculated from all of these emissions scenarios indicate that present-day emissions frommore » the domestic and transportation sectors generate the majority of present-day Arctic warming from BC. However, in all of these scenarios, this warming is more than offset by cooling resulting from SO 2 emissions from the energy sector. Thus, long-term climate mitigation strategies that are focused on reducing carbon dioxide (CO 2) emissions from the energy sector could generate short-term, aerosol-induced Arctic warming. As a result, a properly phased approach that targets BC-rich emissions from the transportation sector as well as the domestic sectors in key regions – while simultaneously working toward longer-term goals of CO 2 mitigation – could potentially avoid some amount of short-term Arctic warming.« less

Calculating Capstone Depleted Uranium Aerosol Concentrations from Beta Activity Measurements

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

Szrom, Fran; Falo, Gerald A.; Parkhurst, MaryAnn

2009-03-01

Beta activity measurements were used as surrogate measurements of uranium mass in aerosol samples collected during the field testing phase of the Capstone Depleted Uranium (DU) Aerosol Study. These aerosol samples generated by the perforation of armored combat vehicles were used to characterize the depleted uranium (DU) source term for the subsequent human health risk assessment (HHRA) of Capstone aerosols. Establishing a calibration curve between beta activity measurements and uranium mass measurements is straightforward if the uranium isotopes are in equilibrium with their immediate short-lived, beta-emitting progeny. For DU samples collected during the Capstone study, it was determined that themore » equilibrium between the uranium isotopes and their immediate short lived, beta-emitting progeny had been disrupted when penetrators had perforated target vehicles. Adjustments were made to account for the disrupted equilibrium and for wall losses in the aerosol samplers. Correction factors for the disrupted equilibrium ranged from 0.16 to 1, and the wall loss correction factors ranged from 1 to 1.92.« less

Constraining Upper Troposphere/Lower Stratosphere Aerosol Physical Processes with High-Altitude Aircraft Measurements

NASA Technical Reports Server (NTRS)

Jensen, Eric; Rosenlof, Karen H.; Thornberry, Troy

2018-01-01

Interest in a more complete understanding of the sources, composition and microphysics of stratospheric aerosol particles has intensified during recent years for several reasons: (1) small volcanic eruptions have been recognized as a driver of short-term changes in climate forcing; (2) emissions of sulfur dioxide (SO2) and other aerosol precursors have shifted to south Asia and other low latitude regions with intense vertical transport; (3) organic material has been recognized as a key contributor to lower stratospheric aerosol mass; and (4) interest in possible solar radiation management (geoengineering) through significant enhancements in stratospheric aerosols has intensified. To address stratospheric aerosol science issues, we are proposing a NASA Earth Ventures mission to NASA to provide extensive high-altitude aircraft measurements of critical gas-phase and aerosol properties at multiple locations across the planet. In this presentation, we will discuss the objectives of the proposed campaign, the measurements provided, the sampling strategy, and the modeling and analysis approaches that would be used to address specific science questions.

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.

Source characterization of ambient fine aerosol in Singapore during a haze episode in 2015

NASA Astrophysics Data System (ADS)

Hapsari Budisulistiorini, Sri; Riva, Matthieu; Williams, Michael; Miyakawa, Takuma; Komazaki, Yuichi; Chen, Jing; Surratt, Jason; Kuwata, Mikinori

2017-04-01

Recurring transboundary haze from Indonesia peatland fires in the previous decades has significantly elevated particulate matter (PM) concentration in Southeast Asia, particularly during the 2015 El Niño event. Previous studies have investigated chemical composition of particles emitted during haze episodes; however, they were limited to time-integrated samples and the number of identified compounds. Low time-resolution measurement results in co-variance of PM sources; therefore, higher time-resolution measurement is important in PM source apportionment. Between October 10-31, 2015, Aerodyne Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) was deployed for real-time chemical characterization of ambient submicron PM (NR-PM1) in Singapore. Simultaneously, PM2.5 filter samples were collected for molecular-level organic aerosol (OA) constituents, organic carbon (OC), elemental carbon (EC) and water-soluble OC (WSOC) analyses. OA constituents were quantified by gas chromatography interfaced to electron ionization mass spectrometry (GC/EI-MS) and ultra-performance liquid chromatography interfaced to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometer operated in the negative ion mode (UPLC/(-)ESI-HR-Q-TOFMS). OA and SO42- are dominant components of the haze particles, accounting for ˜77% and ˜12% of the total NR-PM1 mass, respectively. OC/EC ratio of 4.8 might indicate formation of secondary OA (SOA) and aerosols from biomass burning, including those from peat burning. OA fraction from ToF-ACSM measurements was analyzed for source apportionment using a bilinear model through multi-linear engine algorithm (ME-2) in graphical user interface SoFi (Source Finder). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), peat burning OA (PBOA), low-volatility oxygenated OA (LV-OOA), and semi-volatile oxygenated OA (SV-OOA). The HOA factor shows a distinct diurnal profile peaking in the morning and

A global modeling study on carbonaceous aerosol microphysical characteristics and radiative forcing

NASA Astrophysics Data System (ADS)

Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

2010-02-01

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, cloud-indirect and semi-direct forcing 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 forcing. Our best estimate for net direct and indirect aerosol radiative forcing 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 forcing can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Assuming that sulfates, nitrates and secondary organics form a coating around a black carbon core, rather than forming a uniformly mixed particle, changes the overall net aerosol radiative forcing from negative to positive. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Black carbon absorption is amplified by sulfate and nitrate coatings, but even more strongly by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative forcing when 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 climate benefits.

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.

Oil Sands Operations in Alberta, Canada: A large source of secondary organic aerosol

NASA Astrophysics Data System (ADS)

Liggio, J.; Li, S. M.; Hayden, K.; Taha, Y. M.; Stroud, C.; Darlington, A. L.; Drollette, B.; Gordon, M.; Lee, P.; Liu, P.; Leithead, A.; Moussa, S.; Wang, D.; O'Brien, J.; Mittermeier, R. L.; Brook, J.; Lu, G.; Staebler, R. M.; Han, Y.; Tokarek, T. W.; Osthoff, H. D.; Makar, P.; Zhang, J.; Plata, D.; Gentner, D. R.

2015-12-01

Little is known of the reaction products of emissions to the atmosphere from extraction of oil from unconventional sources in the oil sands (OS) region of Alberta, Canada. This study examines these reaction products, and in particular, the extent to which they form secondary organic aerosol (SOA), which can significantly contribute to regional particulate matter formation. An aircraft measurement campaign was conducted over the Athabasca oil sands region between August 13 and September 7, 2013. A broad suite of measurements were made during 22 flights, including organic aerosol mass and composition with a High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and organic aerosol gas-phase precursors by Proton Transfer Reaction (PTR) and off-line gas chromatography mass spectrometry. Large concentrations of organic aerosol were measured downwind of the OS region, which we show to be entirely secondary in nature. Laboratory experiments demonstrated that bitumen (the mined product) contains semi-volatile vapours in the C12-C18 range that will be emitted at ambient temperatures. When oxidized, these vapours form SOA with highly similar HR-ToF-AMS spectra to the SOA measured in the flights. Box modelling of the OS plume evolution indicated that the measured levels of traditional volatile organic compounds (VOCs) are not capable of accounting for the amount of SOA formed in OS plumes. This discrepancy is only reconciled in the model by including bitumen vapours along with their oxidation and condensation into the model. The concentration of bitumen vapours required to produce SOA matching observations is similar to that of traditional VOC precursors of SOA. It was further estimated that the cumulative SOA mass formation approximately 100 km downwind of the OS during these flights, and under these meteorological conditions was up to 82 tonnes/day. The combination of airborne measurements, laboratory experiments and box modelling indicated that semi

Marine aerosol source regions to Prince of Wales Icefield, Ellesmere Island, and influence from the tropical Pacific, 1979-2001

NASA Astrophysics Data System (ADS)

Criscitiello, Alison S.; Marshall, Shawn J.; Evans, Matthew J.; Kinnard, Christophe; Norman, Ann-Lise; Sharp, Martin J.

2016-08-01

Using a coastal ice core collected from Prince of Wales (POW) Icefield on Ellesmere Island, we investigate source regions of sea ice-modulated chemical species (methanesulfonic acid (MSA) and chloride (Cl-)) to POW Icefield and the influence of large-scale atmospheric variability on the transport of these marine aerosols (1979-2001). Our key findings are (1) MSA in the POW Icefield core is derived primarily from productivity in the sea ice zone of Baffin Bay and the Labrador Sea, with influence from waters within the North Water (NOW) polynya, (2) sea ice formation processes within the NOW polynya may be a significant source of sea-salt aerosols to the POW core site, in addition to offshore open water source regions primarily in Hudson Bay, and (3) the tropical Pacific influences the source and transport of marine aerosols to POW Icefield through its remote control on regional winds and sea ice variability. Regression analyses during times of MSA deposition reveal sea level pressure (SLP) anomalies favorable for opening of the NOW polynya and subsequent oceanic dimethyl sulfide production. Regression analyses during times of Cl- deposition reveal SLP anomalies that indicate a broader oceanic region of sea-salt sources to the core site. These results are supported by Scanning Multichannel Microwave Radiometer- and Special Sensor Microwave/Imager-based sea ice reconstructions and air mass transport density analyses and suggest that the marine biogenic record may capture local polynya variability, while sea-salt transport to the site from larger offshore source regions in Baffin Bay is likely. Regression analyses show a link to tropical dynamics via an atmospheric Rossby wave.

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.

Fingerprinting the Impacts of Aerosols on Long-Term Trends of the Indian Summer Monsoon Regional Rainfall

NASA Technical Reports Server (NTRS)

Laul, K. M.; Kim, K. M.

2010-01-01

In this paper, we present corroborative observational evidences from satellites, in-situ observations, and re-analysis data showing possible impacts of absorbing aerosols (black carbon and dust) on subseasonal and regional summer monsoon rainfall over India. We find that increased absorbing aerosols in the Indo-Gangetic Plain in recent decades may have lead to long-term warming of the upper troposphere over northern India and the Tibetan Plateau, enhanced rainfall in northern India and the Himalayas foothill regions in the early part (may-June) of the monsoon season, followed by diminished rainfall over central and southern India in the latter part (July-August) of the monsoon season. These signals which are consistent with current theories of atmospheric heating and solar dimming by aerosol and induced cloudiness in modulating the Indian monsoon, would have been masked by conventional method of using al-India rainfall averaged over the entire monsoon season.

Sources markers in aerosols, oceanic particles and sediments

NASA Astrophysics Data System (ADS)

Saliot, A.

2009-02-01

This review presents some diagnostic criteria used for identifying and quantifying terrestrial organic matter inputs to the ocean. Coupled to the isotopic composition of total organic carbon, the analysis of stable biomarkers permits to trace higher plant contributions in aerosols, dusts, sedimenting particles and dissolved phase in the water column and ultimately in recent and ancient sediments and soils. Some applications are presented, based on the analysis of n-alkyl compounds by a combination of gas chromatography and mass spectrometry (n-alkanes, n-alkanols, n-alkanoic acids and wax esters). Another approach has been developed using the analysis of macromolecular compounds present in higher plants. Abundances of the phenolic compounds from lignin, benzene carboxylic acids obtained during cupric oxide oxidation, Curie pyrolysis are used to characterise terrestrial organic matter sources and inputs. Finally due to the importance of biomass burning in continent-ocean transfers, biomarkers are presented in the polycyclic aromatic hydrocarbon class and for monosaccharide derivatives from the breakdown of cellulose.

Complex anthropogenic sources of platinum group elements in aerosols on Cape Cod, USA.

PubMed

Sen, Indra S; Peucker-Ehrenbrink, Bernhard; Geboy, Nicholas

2013-09-17

Platinum group elements (PGE) of anthropogenic origin have been reported in rainwater, snow, roadside soil and vegetation, industrial waste, and urban airborne particles around the world. As recent studies have shown that PGE are bioavailable in the environment and pose health risks at chronic levels, the extent of PGE pollution is of global concern. In this study, we report PGE concentrations and osmium isotope ((187)Os/(188)Os) ratios of airborne particles (particulate matter, PM10) collected in Woods Hole, a small coastal village on Cape Cod, Massachusetts, U.S.A. The sampling site is more than 100 km away from the nearest urban centers (Boston, Providence) and has no large industrial emission center within a 30 km radius. The study reveals that, although PGE concentrations in rural airborne particulate matter are orders of magnitude lower than in urban aerosols, 69% of the total osmium is of anthropogenic origin. Anthropogenic PGE signatures in airborne particles are thus not restricted to large cities with high traffic flows and substantial industries; they can also be found in rural environments. We further conclude that the combination of Pt/Rh concentration ratios and (187)Os/(188)Os composition can be used to trace PGE sources. The Pt/Rh and (187)Os/(188)Os composition of Woods Hole aerosols indicate that the anthropogenic PGE fraction is primarily sourced from ore smelting processes, with possible minor contributions from fossil fuel burning and automobile catalyst-derived materials. Our results further substantiate the use of (187)Os/(188)Os in source apportionment studies on continental scales.

Smoke aerosol chemistry and aging of Siberian biomass burning emissions in a large aerosol chamber

NASA Astrophysics Data System (ADS)

Kalogridis, A.-C.; Popovicheva, O. B.; Engling, G.; Diapouli, E.; Kawamura, K.; Tachibana, E.; Ono, K.; Kozlov, V. S.; Eleftheriadis, K.

2018-07-01

Vegetation open fires constitute a significant source of particulate pollutants on a global scale and play an important role in both atmospheric chemistry and climate change. To better understand the emission and aging characteristics of smoke aerosols, we performed small-scale fire experiments using the Large Aerosol Chamber (LAC, 1800 m3) with a focus on biomass burning from Siberian boreal coniferous forests. A series of burn experiments were conducted with typical Siberian biomass (pine and debris), simulating separately different combustion conditions, namely, flaming, smoldering and mixed phase. Following smoke emission and dispersion in the combustion chamber, we investigated aging of aerosols under dark conditions. Here, we present experimental data on emission factors of total, elemental and organic carbon, as well as individual organic compounds, such as anhydrosugars, phenolic and dicarboxylic acids. We found that total carbon accounts for up to 80% of the fine mode (PM2.5) smoke aerosol. Higher PM2.5 emission factors were observed in the smoldering compared to flaming phase and in pine compared to debris smoldering phase. For low-temperature combustion, organic carbon (OC) contributed to more than 90% of total carbon, whereas elemental carbon (EC) dominated the aerosol composition in flaming burns with a 60-70% contribution to the total carbon mass. For all smoldering burns, levoglucosan (LG), a cellulose decomposition product, was the most abundant organic species (average LG/OC = 0.26 for pine smoldering), followed by its isomer mannosan or dehydroabietic acid (DA), an important constituent of conifer resin (DA/OC = 0.033). A levoglucosan-to-mannosan ratio of about 3 was observed, which is consistent with ratios reported for coniferous biomass and more generally softwood. The rates of aerosol removal for OC and individual organic compounds were investigated during aging in the chamber in terms of mass concentration loss rates over time under dark

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. ...

Long-term visibility variation in Athens (1931-2013): a proxy for local and regional atmospheric aerosol loads

NASA Astrophysics Data System (ADS)

Founda, Dimitra; Kazadzis, Stelios; Mihalopoulos, Nikolaos; Gerasopoulos, Evangelos; Lianou, Maria; Raptis, Panagiotis I.

2016-09-01

This study explores the interdecadal variability and trends of surface horizontal visibility at the urban area of Athens from 1931 to 2013, using the historical archives of the National Observatory of Athens (NOA). A prominent deterioration of visibility in the city was detected, with the long-term linear trend amounting to -2.8 km decade-1 (p < 0.001), over the entire study period. This was not accompanied by any significant trend in relative humidity or precipitation over the same period. A slight recovery of visibility levels seems to be established in the recent decade (2004-2013). It was found that very good visibility (> 20 km) occurred at a frequency of 34 % before the 1950s, while this percentage drops to just 2 % during the decade 2004-2013. The rapid impairment of the visual air quality in Athens around the 1950s points to the increased levels of air pollution on a local and/or regional scale, related to high urbanization rates and/or increased anthropogenic emissions on a global scale at that period. Visibility was found to be negatively/positively correlated with relative humidity/wind speed, the correlation being statistically valid at certain periods. Wind regime and mainly wind direction and corresponding air mass origin were found to highly control visibility levels in Athens. The comparison of visibility variation in Athens and at a non-urban reference site on Crete island revealed similar negative trends over the common period of observations. This suggests that apart local sources, visibility in Athens is highly determined by aerosol load of regional origin. AVHRR and MODIS satellite-derived aerosol optical depth (AOD) retrievals over Athens and surface measurements of PM10 confirmed the relation of visibility to aerosol load.

Sources of non-fossil-fuel emissions in carbonaceous aerosols during early winter in Chinese cities

NASA Astrophysics Data System (ADS)

Liu, Di; Li, Jun; Cheng, Zhineng; Zhong, Guangcai; Zhu, Sanyuan; Ding, Ping; Shen, Chengde; Tian, Chongguo; Chen, Yingjun; Zhi, Guorui; Zhang, Gan

2017-09-01

China experiences frequent and severe haze outbreaks from the beginning of winter. Carbonaceous aerosols are regarded as an essential factor in controlling the formation and evolution of haze episodes. To elucidate the carbon sources of air pollution, source apportionment was conducted using radiocarbon (14C) and unique molecular organic tracers. Daily 24 h PM2. 5 samples were collected continuously from October 2013 to November 2013 in 10 Chinese cities. The 14C results indicated that non-fossil-fuel (NF) emissions were predominant in total carbon (TC; average = 65 ± 7 %). Approximately half of the EC was derived primarily from biomass burning (BB) (average = 46 ± 11 %), while over half of the organic carbon (OC) fraction comprised NF (average = 68 ± 7 %). On average, the largest contributor to TC was NF-derived secondary OC (SOCnf), which accounted for 46 ± 7 % of TC, followed by SOC derived from fossil fuels (FF) (SOCf; 16 ± 3 %), BB-derived primary OC (POCbb; 13 ± 5 %), POC derived from FF (POCf; 12 ± 3 %), EC derived from FF (ECf; 7 ± 2 %) and EC derived from BB (ECbb; 6 ± 2 %). The regional background carbonaceous aerosol composition was characterized by NF sources; POCs played a major role in northern China, while SOCs contributed more in other regions. However, during haze episodes, there were no dramatic changes in the carbon source or composition in the cities under study, but the contribution of POC from both FF and NF increased significantly.

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.

Evidencing lead deposition at the urban scale using "short-lived" isotopic signatures of the source term (Pb-Zn refinery)

NASA Astrophysics Data System (ADS)

Franssens, Matthias; Flament, Pascal; Deboudt, Karine; Weis, Dominique; Perdrix, Espéranza

2004-09-01

To demonstrate the ability of the lead isotope signature technique to evidence the spatial extent of an industrial Pb deposition plume at a local scale, dry deposition of lead in the urban environment of a Pb-Zn refinery was investigated, as a study case, using transient ("short-lived") isotopic signatures of the industrial source. Sampling campaigns were achieved in representative weather conditions, on an 8-h basis. Dry deposition rates measured downwind from refinery emissions (≈102-103 μg Pb m-2 h-1), cross-sectionally in a 3-5 km radius area around the plant, represent 10-100 times the urban background dry fallout, measured upwind, as well as fallout measured near other potential sources of anthropogenic Pb. The Pb-Zn refinery isotopic signature (approx. 1.100<206Pb/207Pb<1.135) is made identifiable, using the same set of Pb and Zn ores for 2 days before sampling and during field experiments, by agreement with the executive staff of the plant. This source signature is less radiogenic than signatures of urban background Pb aerosols (1.155<206Pb/207Pb<1.165) and minor sources of Pb aerosols (1.147<206Pb/207Pb<1.165). By a simple binary mixing model calculation, we established the extension of the industrial Pb deposition plume. Fifty to eighty percents of total lead settled by the dry deposition mode, 3-4 km away from the refinery, still have an industrial origin. That represents from 40 to 80 μg Pb m-2 h-1, in an area where the blood lead level exceeds 100 μg Pb l-1 for 30% of men and 12% of women living there. We demonstrate here that stable Pb isotope analysis is able to evidence the Pb dry deposition plume in stabilised aerodynamic conditions, using a short-lived source term, suggesting that this methodology is able to furnish valuable data to validate industrial Pb aerosols dispersion models, at the urban scale.

Volatility-resolved source apportionment of primary and secondary organic aerosol over Europe

NASA Astrophysics Data System (ADS)

Skyllakou, Ksakousti; Fountoukis, Christos; Charalampidis, Panagiotis; Pandis, Spyros N.

2017-10-01

A three-dimensional regional chemical transport model (Particulate Matter Comprehensive Air Quality Model with Extensions, PMCAMx) was applied over Europe combined with a source apportionment algorithm, the Particulate Source Apportionment Technology (PSAT), in order to quantify the sources which contribute to the primary and secondary organic aerosol (OA) during different seasons. The PSAT algorithm was first extended to allow the quantification of the sources of OA as a function of volatility. The most significant OA sources during May were biogenic, while during February residential wood combustion and during September wildfires dominated. The contributions of the various sources have strong spatial dependence. Wildfires were significant OA sources (38% of the OA) for Russia during September, but had a much lower impact (5%) in Scandinavia. The above results are in general consistent with the findings of the CARBOSOL project for selected sites in Europe. For remote sites such as Finokalia in Crete, more than 90% of the OA has undergone two or more generations of oxidation for all seasons. This highly processed oxidized OA is predicted to also dominate over much of Europe during the summer and fall. The first generation SOA is predicted to represent 20-30% of the OA in central and northern Europe during these photochemically active periods.

Capstone Depleted Uranium Aerosol Biokinetics, Concentrations, and Doses

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

Guilmette, Raymond A.; Miller, Guthrie; Parkhurst, MaryAnn

2009-02-26

One of the principal goals of the Capstone Depleted Uranium (DU) Aerosol Study was to quantify and characterize DU aerosols generated inside armored vehicles by perforation with a DU penetrator. This study consequently produced a database in which the DU aerosol source terms were specified both physically and chemically for a variety of penetrator-impact geometries and conditions. These source terms were used to calculate radiation doses and uranium concentrations for various scenarios as part of the Capstone DU Human Health Risk Assessment (HHRA). This paper describes the scenario-related biokinetics of uranium, and summarizes intakes, chemical concentrations to the organs, andmore » E(50) and HT(50) for organs and tissues based on exposure scenarios for personnel in vehicles at the time of perforation as well as for first responders. For a given exposure scenario (duration time and breathing rates), the range of DU intakes among the target vehicles and shots was not large, about a factor of 10, with the lowest being from a ventilated operational Abrams tank and the highest being for an unventilated Abrams with DU penetrator perforating DU armor. The ranges of committed effective doses were more scenario-dependent than were intakes. For example, the largest range, a factor of 20, was shown for scenario A, a 1-min exposure, whereas, the range was only a factor of two for the first-responder scenario (E). In general, the committed effective doses were found to be in the tens of mSv. The risks ascribed to these doses are discussed separately.« less

The Impact of Biogenic and Anthropogenic Atmospheric Aerosol on Climate in Egypt

NASA Astrophysics Data System (ADS)

Ibrahim, A. I.; Zakey, A.; Steiner, A. L.; Shokr, M. E.; El-Raey, M.; Ahmed, Y.; Al-Hadidi, A.; Zakey, A.

2014-12-01

Aerosols are indicators of air quality as they reduce visibility and adversely affect public health. Aerosol optical depth (AOD) is a measure of the radiation extinction due to interaction of radiation with aerosol particles in the atmosphere. Using this optical measure of atmospheric aerosols we explore the seasonal and annual patterns of aerosols from both anthropogenic and biogenic sources over Egypt. Here, we use an integrated environment-climate-aerosol model in conjunction with inversion technique to identify the aerosol particle size distribution over different locations in Egypt. The online-integrated Environment-Climate-Aerosol model (EnvClimA), which is based on the International Center for Theoretical Physics Regional Climate Model (ICTP-RegCM), is used to study the emission of different aerosols and their impact on climate parameters for a long-term base line simulation run over Egypt and North Africa. The global emission inventory is downscaled and remapping them over Egypt using local factors such as population, traffic and industrial activities to identify the sources of anthropogenic and biogenic emission from local emission over Egypt. The results indicated that the dominant natural aerosols over Egypt are dust emissions that frequently occur during the transitional seasons (Spring and Autumn). From the local observation we identify the number of dust and sand storm occurrences over Egypt. The Multiangle Imaging SpectroRadiometer (MISR) is used to identify the optical characterizations of different types of aerosols over Egypt. Modeled aerosol optical depth and MISR observed (at 555 nm) are compared from March 2000 through November 2013. The results identify that the MISR AOD captures the maximum peaks of AOD in March/April that coincide with the Khamasin dust storms. However, peaks in May are either due to photochemical reactions or anthropogenic activities. Note: This presentation is for a Partnerships for Enhanced Engagement in Research (PEER

Antarctic aerosols - A review

NASA Astrophysics Data System (ADS)

Shaw, Glenn E.

1988-02-01

Tropospheric aerosols with the diameter range of half a micron reside in the atmosphere for tens of days and teleconnect Antarctica with other regions by transport that reaches planetary scales of distances; thus, the aerosol on the Antarctic ice represents 'memory modules' of events that took place at regions separated from Antarctica by tens of thousands of kilometers. In terms of aerosol mass, the aerosol species include insoluble crustal products (less than 5 percent), transported sea-salt residues (highly variable but averaging about 10 percent), Ni-rich meteoric material, and anomalously enriched material with an unknown origin. Most (70-90 percent by mass) of the aerosol over the Antarctic ice shield, however, is the 'natural acid sulfate aerosol', apparently deriving from biological processes taking place in the surrounding oceans.

Long-term measurements of aerosols and carbon monoxide at the ZOTTO tall tower to characterize polluted and pristine air in the Siberian Taiga

NASA Astrophysics Data System (ADS)

Chi, X.; Winderlich, J.; Mayer, J.-C.; Panov, A. V.; Heimann, M.; Birmili, W.; Heintzenberg, J.; Cheng, Y.; Andreae, M. O.

2013-07-01

Siberia is one of few background regions in the Northern Hemisphere where the atmosphere may sometimes approach pristine conditions. We present the time series of aerosol and carbon monoxide (CO) measurements between September~2006 and December 2010 at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia (61° N; 90° E). We investigate the seasonal, weekly and diurnal variations of aerosol properties (including absorption and scattering coefficients and derived parameters, like equivalent black carbon (BCe), Ångström exponent, single scattering albedo, and backscattering ratio) and the CO mixing ratios. Criteria were established to distinguish polluted and near-pristine air masses and characterize them separately. Depending on the season, 15-47% of the sampling time at ZOTTO was representative of a clean atmosphere. The summer pristine data indicates that primary biogenic and/or secondary organic aerosol formation are quite strong particle sources in the Siberian Taiga. The summer seasons 2007-2008 are dominated by an Aitken mode of 80 nm size, whereas the summer 2009 with prevailing easterly winds produced aerosols in the accumulation mode around 200 nm size. We found these differences mainly related to air temperature, in parallel with production rates of biogenic volatile organic compounds (VOC). In winter, the footprint and aerosol size distribution (with a peak at 160 nm) of the clean background air are characteristic for aged aerosols from anthropogenic sources at great distances from ZOTTO and diluted biofuel burning emissions from heating. The wintertime polluted air originates from the large cities to the south and southwest of the site; these aerosols have a dominant mode around 100 nm, and the Δ BCe/Δ CO ratio of 7-11 ng m-3 ppb-1 suggests dominant contributions from coal and biofuel burning for heating. During summer, anthropogenic emissions are the dominant contributor to the pollution aerosols at ZOTTO, while only 12% of the polluted

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

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.

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

Distribution of Aerosols in the Arctic as Observed by CALIOP

NASA Astrophysics Data System (ADS)

Winker, D.; Kittaka, C.

2007-12-01

The Arctic climate is now recognized to be uniquely sensitive to atmospheric perturbations. Pollution aerosols and smoke from boreal fires have potentially important impacts on Arctic climate but there are many uncertainties. Aerosol in the Arctic, generally referred to as "Arctic haze", has been studied with great interest for over thirty years. Much has been learned about the composition and sources of the haze yet our knowledge is largely based on long term measurements at a very few widely dispersed sites, augmented by modeling activities and occasional field campaigns. Transport pathways from source regions into the Arctic are not well understood. Emission patterns have changed over the last several decades, but the impact of this on concentrations and distribution of Arctic haze are understood only in the crudest sense. Due to poor lighting conditions, extended periods of darkness, and surfaces covered by snow and ice, satellite sensors have been unable to provide much information on Arctic haze to date. The CALIPSO satellite carries CALIOP, a two-wavelength polarization lidar, optimized for profiling clouds and aerosols. CALIOP has been acquiring global observations since June 2006 and provides our first opportunity to observe the distribution and seasonal variation of aerosol in the Arctic. The Arctic is characterized by the prevalence of optically thin ice clouds and clouds composed of supercooled water, often occurring in the same atmospheric column along with aerosol. CALIOP depolarization signals are used to discriminate Arctic haze from optically thin cirrus and diamond dust. Two-wavelength returns aid in the discrimination of aerosol and optically thin water cloud. Results of initial analyses of CALIOP aerosol observations in the Arctic will be presented. This work is a preliminary analysis in support of the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign planned for April 2008.

Modeling Atmospheric Aerosols in WRF/Chem

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

Zhang, Yang; Hu, X.-M.; Howell, G.

2005-06-01

In this study, three aerosol modules are tested and compared. The first module is the Modal Aerosol Dynamics Model for Europe (MADE) with the secondary organic aerosol model (SORGAM) (referred to as MADE/SORGAM). The second module is the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC). The third module is the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID). The three modules differ in terms of size representation used, chemical species treated, assumptions and numerical algorithms used. Table 1 compares the major processes among the three aerosol modules.

A thermoluminescent method for aerosol characterization

NASA Technical Reports Server (NTRS)

Long, E. R., Jr.; Rogowski, R. S.

1976-01-01

A thermoluminescent method has been used to study the interactions of aerosols with ozone. The preliminary results show that ozone reacts with many compounds found in aerosols, and that the thermoluminescence curves obtained from ozonated aerosols are characteristic of the aerosol. The results suggest several important applications of the thermoluminescent method: development of a detector for identification of effluent sources; a sensitive experimental tool for study of heterogeneous chemistry; evaluation of importance of aerosols in atmospheric chemistry; and study of formation of toxic, electronically excited species in airborne particles.

Assessment of carbonaceous aerosols in Shanghai, China - Part 1: long-term evolution, seasonal variations, and meteorological effects

NASA Astrophysics Data System (ADS)

Chang, Yunhua; Deng, Congrui; Cao, Fang; Cao, Chang; Zou, Zhong; Liu, Shoudong; Lee, Xuhui; Li, Jun; Zhang, Gan; Zhang, Yanlin

2017-08-01

Carbonaceous aerosols are major chemical components of fine particulate matter (PM2. 5) with major impacts on air quality, climate change, and human health. Gateway to fast-rising China and home of over twenty million people, Shanghai throbs as the nation's largest mega city and the biggest industrial hub. From July 2010 to December 2014, hourly mass concentrations of ambient organic carbon (OC) and elemental carbon (EC) in the PM2. 5 fraction were quasi-continuously measured in Shanghai's urban center. The annual OC and EC concentrations (mean ±1σ) in 2013 (8.9 ± 6.2 and 2.6 ± 2.1 µg m-3, n = 5547) and 2014 (7.8 ± 4.6 and 2.1 ± 1.6 µg m-3, n = 6914) were higher than those of 2011 (6.3 ± 4.2 and 2.4 ± 1.8 µg m-3, n = 8039) and 2012 (5.7 ± 3.8 and 2.0 ± 1.6 µg m-3, n = 4459). We integrated the results from historical field measurements (1999-2012) and satellite observations (2003-2013), concluding that carbonaceous aerosol pollution in Shanghai has gradually reduced since 2006. In terms of monthly variations, average OC and EC concentrations ranged from 4.0 to 15.5 and from 1.4 to 4.7 µg m-3, accounting for 13.2-24.6 and 3.9-6.6 % of the seasonal PM2. 5 mass (38.8-94.1 µg m-3), respectively. The concentrations of EC (2.4, 2.0, 2.2, and 3.0 µg m-3 in spring, summer, fall, and winter, respectively) showed little seasonal variation (except in winter) and weekend-weekday dependence, indicating EC is a relatively stable constituent of PM2. 5 in the Shanghai urban atmosphere. In contrast to OC (7.3, 6.8, 6.7, and 8.1 µg m-3 in spring, summer, fall, and winter, respectively), EC showed marked diurnal cycles and correlated strongly with CO across all seasons, confirming vehicular emissions as the dominant source of EC at the targeted site. Our data also reveal that both OC and EC showed concentration gradients as a function of wind direction (WD) and wind speed (WS), generally with higher values associated with winds from the southwest, west, and northwest

Sources of volcanic aerosols: Petrologic and volcanological constraints

NASA Technical Reports Server (NTRS)

Sigurdsson, Haraldur

1991-01-01

Global climatic effects brought about by volcanism are related to the impact of volcanic gases and their derivative aerosols on the atmosphere, rather than the effects of volcanic ash. Evidence from both historic eruptions and polar ice cores indicate that volcanic sulfur gases are the dominant aerosol-forming component, resulting in produciton of a sulfuric acid-rich stratosphere aerosol that can have profound effects on the earth radiation budget over periods of a few years. Due to highly variable sulfur content of different magma types, the climatic effects do not relate simply to total erupted mass. There is a close relationship between volcanic sulfur yield to the atmospheric and hemispheric surface temperature decrease following an eruption, with up to 1 C surface temperature decrease indicated following a major volcanic event such as the 1815 Tambora eruption. While the erupted mass of HCl and HF is equal to or greater than that of sulfur gases in some volcanic events, the halogens do not form known aerosols nor are they abundant in ice core acidity layers. The early removal of halogens from eruption columns occurs by rain flushing and adsorption onto tephra particles, but the fate of halogens in the atmosphere following very large explosive eruptions is unknown. The CO2 flux to the atmosphere from volcanic eruptions is volumetrically one of the most important of the gas species, but owing to the huge size of the atmospheric reservoir of this gas, the volcanic contribution is likely to have negligible effects.

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.

Disentangling the major source areas for an intense aerosol advection in the Central Mediterranean on the basis of Potential Source Contribution Function modeling of chemical and size distribution measurements

NASA Astrophysics Data System (ADS)

Petroselli, Chiara; Crocchianti, Stefano; Moroni, Beatrice; Castellini, Silvia; Selvaggi, Roberta; Nava, Silvia; Calzolai, Giulia; Lucarelli, Franco; Cappelletti, David

2018-05-01

In this paper, we combined a Potential Source Contribution Function (PSCF) analysis of daily chemical aerosol composition data with hourly aerosol size distributions with the aim to disentangle the major source areas during a complex and fast modulating advection event impacting on Central Italy in 2013. Chemical data include an ample set of metals obtained by Proton Induced X-ray Emission (PIXE), main soluble ions from ionic chromatography and elemental and organic carbon (EC, OC) obtained by thermo-optical measurements. Size distributions have been recorded with an optical particle counter for eight calibrated size classes in the 0.27-10 μm range. We demonstrated the usefulness of the approach by the positive identification of two very different source areas impacting during the transport event. In particular, biomass burning from Eastern Europe and desert dust from Sahara sources have been discriminated based on both chemistry and size distribution time evolution. Hourly BT provided the best results in comparison to 6 h or 24 h based calculations.

Identification and characterisation of local aerosol sources using high temporal resolution measurements.

PubMed

Contini, D; Donateo, A; Cesari, D; Belosi, F; Francioso, S

2010-09-01

Aerosol and gaseous pollution measurements were carried out at an urban background site in the south of Italy located near an industrial complex. Collection of 24 h samples of PM10 and PM2.5 and successive chemical quantification of metals were performed. Data were compared with measurements taken at a suburban background site, located at 25 km distance. The comparison showed the presence of an industrial contribution with a well defined chemical emission profile, similar, in terms of metals content, to urban emissions. As this made difficult the quantitative characterisation of the contribution of the two sources to atmospheric PM, a statistical method based on the treatment of data arising from high temporal resolution measurements was developed. Data were taken with a micrometeorological station based on an integrating nephelometer (Mie pDR-1200) for optical detection of PM2.5 concentration, with successive evaluation of vertical turbulent fluxes using the eddy-correlation method. Results show that the contribution from the two sources (urban emissions and industrial releases) have a very different behaviour, with the industrial contribution being present at high wind velocity with short concentration peaks (average duration 4 min) associated to strong positive and negative vertical fluxes. The estimated contribution to PM2.5 is 2.3% over long-term averages. The urban emissions are mainly present at low wind velocity, with longer concentration peaks in the morning and late evening hours, generally associated to small positive vertical fluxes. The characterisation of the contribution was performed using deposition velocity V(d) that is on average -3.5 mm s(-1) and has a diurnal pattern, with negligible values during the night and a minimum value of around -9 mm s(-1) late in the afternoon. Results show a correlation between V(d), friction velocity and wind velocity that could be the basis for a parameterisation of V(d) to be used in dispersion codes.

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.

Evaluating the impact of improvements to the FLAMBE smoke source model on forecasts of aerosol distribution from NAAPS

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Reid, J. S.

2006-12-01

As more forecast models aim to include aerosol and chemical species, there is a need for source functions for biomass burning emissions that are accurate, robust, and operable in real-time. NAAPS is a global aerosol forecast model running every six hours and forecasting distributions of biomass burning, industrial sulfate, dust, and sea salt aerosols. This model is run operationally by the U.S. Navy as an aid to planning. The smoke emissions used as input to the model are calculated from the data collected by the FLAMBE system, driven by near-real-time active fire data from GOES WF_ABBA and MODIS Rapid Response. The smoke source function uses land cover data to predict properties of detected fires based on literature data from experimental burns. This scheme is very sensitive to the choice of land cover data sets. In areas of rapid land cover change, the use of static land cover data can produce artifactual changes in emissions unrelated to real changes in fire patterns. In South America, this change may be as large as 40% over five years. We demonstrate the impact of a modified land cover scheme on FLAMBE emissions and NAAPS forecasts, including a fire size algorithm developed using MODIS burned area data. We also describe the effects of corrections to emissions estimates for cloud and satellite coverage. We outline areas where existing data sources are incomplete and improvements are required to achieve accurate modeling of biomass burning emissions in real time.

PARAGON: A Systematic, Integrated Approach to Aerosol Observation and Modeling

NASA Technical Reports Server (NTRS)

Diner, David J.; Kahn, Ralph A.; Braverman, Amy J.; Davies, Roger; Martonchik, John V.; Menzies, Robert T.; Ackerman, Thomas P.; Seinfeld, John H.; Anderson, Theodore L.; Charlson, Robert J.;

Aerosol-Cloud-Precipitation Interactions over Indo-Gangetic Basin

NASA Technical Reports Server (NTRS)

Tsay, S.-C.; Lau, K. .; Holben, B. N.; Hsu, N. C.; Bhartia, P. K.

2005-01-01

About 60% of world population reside in Asia, in term of which sheer population density presents a major environmental stress. Economic expansion in this region is, in fact, accompanied by increases in bio-fuel burning, industrial pollution, and land cover and land use changes. With a growth rate of approx. 8%/yr for Indian economy, more than 600 million people from Lahore, Pakistan to Calcutta, India over the Indo-Gangetic Basin have particularly witnessed increased frequencies of floods and droughts as well as a dramatic increase in atmospheric loading of aerosols (i.e., anthropogenic and natural aerosol) in recent decades. This regional change (e.g., aerosol, cloud, precipitation, etc.) will constitute a vital part of the global change in the 21st century. Better understanding of the impacts of aerosols in affecting monsoon climate and water cycles is crucial in providing the physical basis to improve monsoon climate prediction and for disaster mitigation. Based on climate model simulations, absorbing aerosols (dust and black carbon) play a critical role in affecting interannual and intraseasonal variability of the Indian monsoon. An initiative on the integrated (aerosols, clouds, and precipitation) measurements approach over the Indo-Gangetic Basin will be discussed. An array of ground-based (e.g., AERONET, MPLNET, SMART-COMMIT, etc.) and satellite (e.g., Terra, A-Train, etc.) sensors will be utilized to acquire aerosol characteristics, sources/sinks, and transport processes during the pre-monsoon (April-May, aerosol forcing) season, and to obtain cloud and precipitation properties during the monsoon (May-June, water cycle response) season. Close collaboration with other international programs, such as ABC, CLIVAR, GEWEX, and CEOP in the region is anticipated.

Long-term (2001-2012) trends of carbonaceous aerosols from a remote island in the western North Pacific: an outflow region of Asian pollutants

NASA Astrophysics Data System (ADS)

Boreddy, Suresh K. R.; Mozammel Haque, M.; Kawamura, Kimitaka

2018-01-01

The present study reports on long-term trends of carbonaceous aerosols in total suspended particulate (TSP) samples collected at Chichijima in the western North Pacific during 2001-2012. Seasonal variations of elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC) concentrations showed maxima in winter to spring and minima in summer. These seasonal differences in the concentrations of carbonaceous aerosols were associated with the outflows of polluted air masses from East Asia, which are clearly distinguishable from pristine air masses from the central Pacific. The higher concentrations of carbonaceous aerosols during winter to spring are associated with long-range atmospheric transport of East Asian continental polluted air masses, whereas lower concentrations may be due to pristine air masses from the central Pacific in summer. The annual trends of OC / EC (+0.46 % yr-1), WSOC (+0.18 % yr-1) and WSOC / OC (+0.08 % yr-1) showed significant (p < 0.05) increases during the period of 2001-2012, suggesting that photochemical formation of WSOC and its contributions to secondary organic aerosols (SOAs) have increased over the western North Pacific via long-range atmospheric transport. We found a significant increase (+0.33 % yr-1) in nss-K+ / EC ratios, demonstrating that concentrations of biomass-burning-derived carbonaceous aerosols have increased, while those of primary fossil-fuel-derived aerosols have decreased over the western North Pacific. Further, secondary biogenic emissions are also important over the western North Pacific as inferred from a significant increase (+0.14 % yr-1) in the concentrations of methanesulfonate (MSA-, a tracer for biogenic sources). This point was further supported by a moderate correlation (r = 0.40) between WSOC and MSA-. We also found a significant increase in OC / TC (total carbon) and WSOC / TC ratios, further suggesting that photochemical formation of WSOC and its contributions to SOAs have increased

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.