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Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondonia, Brazil: sources and source processes, time series, diel variations and size distributions

CLAEYS, M.; KOURTCHEV, I.; PASHYNSKA, V.; VAS, G.; VERMEYLEN, R.; WANG, W.; CAFMEYER, J.; CHI, X.; Artaxo Netto, Paulo Eduardo; ANDREAE, M. O.; MAENHAUT, W.
Fonte: COPERNICUS GESELLSCHAFT MBH Publicador: COPERNICUS GESELLSCHAFT MBH
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.13%
Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondonia, Brazil) using a high-volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI) within the framework of the 2002 LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign. The campaign spanned the late dry season (biomass burning), a transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including levoglucosan, malic acid, isoprene secondary organic aerosol (SOA) tracers and tracers for fungal spores. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM(2.5) size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 mu g m(-3) and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly present in the fine mode...

Evaluation of the carbon content of aerosols from the burning of biomass in the Brazilian Amazon using thermal, optical and thermal-optical analysis methods

SOTO-GARCIA, L. L.; ANDREAE, M. O.; ANDREAE, T. W.; Artaxo Netto, Paulo Eduardo; MAENHAUT, W.; KIRCHSTETTER, T.; NOVAKOV, T.; CHOW, J. C.; MAYOL-BRACERO, O. L.
Fonte: COPERNICUS GESELLSCHAFT MBH Publicador: COPERNICUS GESELLSCHAFT MBH
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.13%
Aerosol samples were collected at a pasture site in the Amazon Basin as part of the project LBA-SMOCC-2002 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall and Climate: Aerosols from Biomass Burning Perturb Global and Regional Climate). Sampling was conducted during the late dry season, when the aerosol composition was dominated by biomass burning emissions, especially in the submicron fraction. A 13-stage Dekati low-pressure impactor (DLPI) was used to collect particles with nominal aerodynamic diameters (D(p)) ranging from 0.03 to 0.10 mu m. Gravimetric analyses of the DLPI substrates and filters were performed to obtain aerosol mass concentrations. The concentrations of total, apparent elemental, and organic carbon (TC, EC(a), and OC) were determined using thermal and thermal-optical analysis (TOA) methods. A light transmission method (LTM) was used to determine the concentration of equivalent black carbon (BC(e)) or the absorbing fraction at 880 nm for the size-resolved samples. During the dry period, due to the pervasive presence of fires in the region upwind of the sampling site, concentrations of fine aerosols (D(p) < 2.5 mu m: average 59.8 mu g m(-3)) were higher than coarse aerosols (D(p) > 2.5 mu m: 4.1 mu g m(-3)). Carbonaceous matter...

Characterization of atmospheric aerosols in the city of So Paulo, Brazil: comparisons between polluted and unpolluted periods

de Almeida Albuquerque, Taciana Toledo; Andrade, Maria de Fatima; Ynoue, Rita Yuri
Fonte: SPRINGER; DORDRECHT Publicador: SPRINGER; DORDRECHT
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.96%
The objective of this study was to determine the size and composition of atmospheric aerosols in the downtown area of the city of So Paulo, Brazil, for a polluted and an unpolluted period. Aerosols were sampled with a portable air sampler (PAS), Micro-Orifice Uniform Deposit Impactor (MOUDI), and Scanning Mobility Particle Sizer. At the study site, air quality is poor, especially during the winter, high concentrations of pollutants being emitted primarily by the light- and heavy-duty vehicle fleet. We analyzed mass, black carbon (BC), Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sn, Zr, and Pb. During the polluted period, diurnal PM(10) was higher than nocturnal PM(10), whereas the inverse was true during the unpolluted period. The FPM was rich in BC, S, and Pb, whereas CPM was rich in Al, Si, Ca, Ti, and Fe. Mass balance was performed by category: ammonium sulfate, sodium chloride, crustal material, BC, and other. The PAS-determined FPM was mainly BC. The MOUDI-determined FPM crustal material explained more mass than did ammonium sulfate and BC during the polluted period, whereas ammonium sulfate had the largest mass during the unpolluted period. Crustal material was the major CPM component, followed by ammonium sulfate and BC. During the unpolluted period...

"Os efeitos de aerossóis emitidos por queimadas na formação de gotas de nuvens e na composição da precipitação na Amazônia"; Effect of biomass-burning emitted aerosols on cloud droplets formation and rainwater chemistry in the Amazon Basin

Pauliquevis Junior, Theotonio Mendes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/11/2005 PT
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37.28%
Este trabalho teve como objetivo investigar a relação entre produtos de atividades antropogênicas na Amazônia e sua influência no efeito indireto dos aerossóis no clima. Para isso, foi feita uma caracterização físico-química detalhada dos aerossóis naturais e de queimadas na Amazônia e procurou-se compreender como estes diferentes tipos de aerossóis se comportam como Núcleos de Condensação de Nuvens. Foi estudado também a influência dos aerossóis de queimadas na composição química da precipitação e no transporte de nutrientes. Visando atingir estes objetivos, foram feitas medidas em regiões distintas da Amazônia com relação ao impacto por atividades antropogênicas, principalmente queimadas. Foi possível observar em várias circunstâncias uma relação entre a composição do material particulado e da precipitação, o que nos permitiu concluir que as emissões antropogênicas influenciam significativamente a composição da precipitação. Foram identificadas as principais componentes que afetam a composição do material particulado em suspensão na Amazônia, e concluimos que o material particulado originado de emissões biogênicas é predominante em regiões preservadas, com pequena contribuição também de poeira de solo e transporte de aerossóis marinhos. Em regiões sob influência de atividades antropogênicas...

Técnicas analíticas nucleares aplicadas a medida em larga escala de aerossóis atmosféricos na região amazônica; Nuclear analytical techniques applied to large-scale measurement of atmospheric aerosols in the Amazon region

Gerab, Fabio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/03/1996 PT
Relevância na Pesquisa
37.06%
Neste trabalho o aerossol atmosférico, presente em diferentes localidades da região Amazônica, foi caracterizado. Foram estudadas as emissões biogênicas naturais da floresta, bem como as emissões de material particulado para a atmosfera, devido à ocorrência em larga escala de queimadas na Amazônia durante a estação seca. O aerossol atmosférico foi coletado durante um período de aproximadamente três anos em duas diferentes regiões da Amazônia, utilizando-se amostradores de particulado fino e grosso. As amostragens foram realizadas na região de Alta Floresta (MT) e de Serra do Navio (AP). Essas regiões são representativas de condições atmosféricas distintas: as emissões de queimadas são pouco significativas para a composição do aerossol atmosférico de Serra do Navio, dominada pela emissão biogênica natural da floresta. A atmosfera de Alta Floresta caracteriza as regiões da Amazônia onde o impacto das queimadas é expressivo durante a estação seca. Em Alta Floresta foram realizadas amostragens em casas de queima de ouro, caracterizando as emissões de mercúrio para o particulado atmosférico relacionadas com as atividades garimpeiras na Amazônia. Aeronaves foram utilizadas para a amostragem de aerossóis durante as estações secas de 1992 e 1993...

An analysis of diurnal cycles in the mass of ambient aerosols derived from biomass burning and agro-industry

Caetano-Silva, L.; Allen, A. G.; Lima-Souza, M.; Cardoso, A. A.; Campos, M. L A M; Nogueira, R. F P
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 8675-8687
ENG
Relevância na Pesquisa
37.13%
Strong diurnal cycles in ambient aerosol mass were observed in a rural region of Southeast Brazil where the trace composition of the lower troposphere is governed mainly by emissions from agro-industry. An optical particle counter was used to record size-segregated aerosol number concentrations between 13 May 2010 and 15 March 2011. The data were collected every 10 min and used to calculate aerosol mass concentrations. Aerosol samples were also collected onto filters during daytime (10:00-16:00 local time) and nighttime (20:00-06:00) periods, for subsequent analysis of soluble ions and water-soluble organic carbon. Biomass burning aerosols predominated during the dry winter, while secondary aerosols were most important in the summer rainy season. In both seasons, diurnal cycles in calculated aerosol mass concentrations were due to the uptake of water by the aerosols and, to a lesser extent, to emissions and secondary aerosol formation. In neither season could the observed mass changes be explained by changes in the depth of the boundary layer. In the summer, nighttime increases in aerosol mass ranged from 2.7-fold to 81-fold, depending on particle size, while in the winter, the range was narrower, from 2.2-fold to 9.5-fold, supporting the possibility that the presence of particles derived from biomass burning reduced the overall ability of the aerosols to absorb water. Key Points Diurnal cycle of agro-industrial aerosol mass governed by humidity Biomass burning emissions act to suppress particle growth Need to consider diurnal mass cycles in aerosol dry deposition models ©2013. American Geophysical Union. All Rights Reserved.

Characterization of water-soluble organic matter from urban aerosols; Caracterização da matéria orgânica solúvel em água de aerossóis urbanos

Freire, Sandra Maria Semedo Carvalho
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
37.13%
Water-soluble organic matter (WSOM) from atmospheric particles comprises a complex array of molecular structures that play an important role on the physic-chemical properties of atmospheric particles and, therefore, are linked to several global-relevant atmospheric processes which impact the climate and public health. Due to the large variety of sources and formation processes, adequate knowledge on WSOM composition and its effects on the properties of atmospheric aerosol are still limited. Therefore, this thesis aims at providing new insights on the molecular composition of WSOM from fine atmospheric aerosols typical of an urban area (Aveiro, Portugal). In a first step, adsorption phenomena of semivolatile organic compounds on quartz fibre filters employed in the collection of atmospheric aerosols were assessed. Afterwards, atmospheric aerosol samples were collected during fifteen months, on a weekly basis. A mass balance of aerosol samples was performed in order to set the relative contribution of elemental carbon, WSOM and water-insoluble organic matter to the aerosol mass collected at the urban area of Aveiro, with a special focus on the assessment of the influence of different meteorological conditions. In order to assess the chemical complexity of the WSOM from urban aerosols...

Local Radiative forcing by Saharan Dust and Forest Fire Aerosols over Portugal

Santos, Dina; Costa, Maria João; Silva, Ana Maria
Fonte: European Aerosol Conference Publicador: European Aerosol Conference
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.06%
It is well known that aerosols directly affect the climate by increasing back-scattered radiation and by absorbing solar and long wave radiation (IPCC, 2001). Continental Portugal is often affected by the long-range transport of desert dust aerosols advected from Africa, and, frequently during summer, smoke from forest fires (Silva et al., 2003). This fraction is very efficient at scattering and absorbing short-wave radiation, being then of primary importance the estimation of radiative forcing due to aerosols. In order to understand climate change implications, in particular to identify major aerosol types, aerosol long-term monitoring is necessary. This is a good way to characterise their spatial and temporal distribution and their optical and physical properties, and to estimate their local and regional radiative forcing. Since 2002, long-term monitoring is being undertaken in Portugal with measurements from ground-based instruments at Évora, and, since December 2003, extended with measurements from Cabo da Roca.

Atmospheric modeling of Desert Dust Aerosols Effects on Clouds over the Atlantic Ocean

Santos, Dina; Costa, Maria João; Silva, Ana Maria; Salgado, Rui
Fonte: International Conference on Nucleation & Atmospheric Aerosols Publicador: International Conference on Nucleation & Atmospheric Aerosols
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.96%
This work aims to study the microphysical and radiative effects of the desert dust aerosols, on cloud properties, during strong desert dust transports. This is done by examining the results obtained from a mesoscale atmospheric model (MesoNH), over Portugal and nearby Atlantic Ocean. The results obtained provide information on the cloud properties, and possible modifications that clouds may undergo, when they develop in an atmosphere where desert dust aerosols are present. The cloud radiative forcing (CRF) at the top of the atmosphere (TOA) is also estimated.

Quantifying the respective roles of aerosols and clouds in the strong brightening since the early 2000s over the Iberian Peninsula

Mateos, David; Sanchez-Lorenzo, Arturo; Antón, Manuel; Cachorro, Victoria; Calbó, J.; Costa, Maria João; Torres, Bernardo; Wild, Martin
Fonte: AGU Publicador: AGU
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.96%
The contribution of clouds and aerosols to the decadal variations of downward surface shortwave radiation (SSR) is a current controversial topic. This study proposes a method, which is based on surface-based SSR measurements, aerosol observations, and radiative transfer simulations (in cloud-free and cloud- and aerosol-free scenarios), to evaluate cloud-aerosol (CARE), cloud (CRE), and aerosol (ARE) radiative effects. This method is applied to quantify the role played by, separately, clouds and aerosols on the intense brightening of the SSR observed in the Iberian Peninsula. Clouds and Earth’s Radiation Energy Budget System (CERES) and surface-based data exhibit an increase in SSR between 2003 and 2012, exceeding +10 Wm 2 over this period for some areas of the peninsula. The calculations are performed for three surface-based sites: Barcelona and Valladolid (Spain), and Évora (Portugal). Ranges in monthly values of CARE, CRE, and ARE are ( 80, 20), ( 60, 20), and ( 30, 0), respectively (in Wm 2). The average trends for the analyzed period of CARE, CRE, and ARE are +7, +5, and +2 Wm 2 per decade, respectively. Overall, three fourths of the SSR trend is explained by clouds, while the other one fourth is related to aerosol changes. The SSR trends explained by the clouds and aerosol radiative effects are in line with the observed reductions in total cloud cover and aerosol load (both at the surface and in the whole atmospheric column). Furthermore...

Influenza Virus Aerosols in Human Exhaled Breath: Particle Size, Culturability, and Effect of Surgical Masks

Milton, Donald Kirby; Fabian, Maria Patricia; Cowling, Benjamin J.; Grantham, Michael L.; McDevitt, James J
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.13%
The CDC recommends that healthcare settings provide influenza patients with facemasks as a means of reducing transmission to staff and other patients, and a recent report suggested that surgical masks can capture influenza virus in large droplet spray. However, there is minimal data on influenza virus aerosol shedding, the infectiousness of exhaled aerosols, and none on the impact of facemasks on viral aerosol shedding from patients with seasonal influenza. We collected samples of exhaled particles (one with and one without a facemask) in two size fractions (“coarse”>5 µm, “fine”≤5 µm) from 37 volunteers within 5 days of seasonal influenza onset, measured viral copy number using quantitative RT-PCR, and tested the fine-particle fraction for culturable virus. Fine particles contained 8.8 (95% CI 4.1 to 19) fold more viral copies than did coarse particles. Surgical masks reduced viral copy numbers in the fine fraction by 2.8 fold (95% CI 1.5 to 5.2) and in the coarse fraction by 25 fold (95% CI 3.5 to 180). Overall, masks produced a 3.4 fold (95% CI 1.8 to 6.3) reduction in viral aerosol shedding. Correlations between nasopharyngeal swab and the aerosol fraction copy numbers were weak (r = 0.17, coarse; r = 0.29, fine fraction). Copy numbers in exhaled breath declined rapidly with day after onset of illness. Two subjects with the highest copy numbers gave culture positive fine particle samples. Surgical masks worn by patients reduce aerosols shedding of virus. The abundance of viral copies in fine particle aerosols and evidence for their infectiousness suggests an important role in seasonal influenza transmission. Monitoring exhaled virus aerosols will be important for validation of experimental transmission studies in humans.

Sources of carbonaceous aerosols over the United States and implications for natural visibility

Park, Rokjin J.; Jacob, Daniel James; Chin, Mian; Martin, Randall
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.96%
We use a global three-dimensional model (GEOS-CHEM) to better quantify the sources of elemental carbon (EC) and organic carbon (OC) aerosols in the United States through simulation of year-round observations for 1998 at a network of 45 sites (Interagency Monitoring of Protected Visual Environments (IMPROVE)). Simulation with our best a priori understanding of sources, including global satellite data to constrain fire emissions, captures most of the variance in the observations (R2 = 0.84 for EC, 0.67 for OC) with a low bias of 15% for EC and 26% for OC. Multiple linear regression to fit the IMPROVE data yields best estimates of 1998 U.S. sources of 0.60 Tg year−1 EC and 0.52 Tg year−1 OC from fossil fuel; 0.07 Tg year−1 EC and 0.89 Tg year−1 OC from biofuel; 0.08 Tg year−1 EC and 0.60 Tg year−1 OC from wildfires; and 1.10 Tg year−1 OC from vegetation. We find that fires in Mexico and Canada contributed 40–70% of annual mean natural EC in the United States for 1998 and 20–30% of annual mean natural OC. Transpacific transport from Asian pollution sources amounted to less than 10% of the natural EC and less than 2% of the natural OC; in contrast to ozone, we find that intercontinental transport of anthropogenic carbonaceous aerosols does not enhance significantly the natural background. IMPROVE observations and model simulations for the summer of 1995 show that Canadian fire emissions can produce large events of elevated EC and OC in the southeastern United States. Our best estimates of mean natural concentrations of EC and OC in the United States...

Global and regional decreases in tropospheric oxidants from photochemical effects of aerosols

Martin, Randall V.; Jacob, Daniel James; Yantosca, Robert M.; Chin, Mian; Ginoux, Paul
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.06%
We evaluate the sensitivity of tropospheric OH, O3, and O3 precursors to photochemical effects of aerosols not usually included in global models: (1) aerosol scattering and absorption of ultraviolet radiation and (2) reactive uptake of HO2, NO2, and NO3. Our approach is to couple a global 3-D model of tropospheric chemistry (GEOS-CHEM) with aerosol fields from a global 3-D aerosol model (GOCART). Reactive uptake by aerosols is computed using reaction probabilities from a recent review (γHO2 = 0.2, γNO2 = 10−4, γNO3 = 10−3). Aerosols decrease the O3 [RIGHTWARDS ARROW] O(1D) photolysis frequency by 5–20% at the surface throughout the Northern Hemisphere (largely due to mineral dust) and by a factor of 2 in biomass burning regions (largely due to black carbon). Aerosol uptake of HO2 accounts for 10–40% of total HOx radical (≡ OH + peroxy) loss in the boundary layer over polluted continental regions (largely due to sulfate and organic carbon) and for more than 70% over tropical biomass burning regions (largely due to organic carbon). Uptake of NO2 and NO3 accounts for 10–20% of total HNO3 production over biomass burning regions and less elsewhere. Annual mean OH concentrations decrease by 9% globally and by 5–35% in the boundary layer over the Northern Hemisphere. Simulated CO increases by 5–15 ppbv in the remote Northern Hemisphere...

Interactions between tropospheric chemistry and aerosols in a unified general circulation model

Liao, Hong; Adams, Peter; Chung, Serena; Seinfeld, John; Mickley, Loretta J.; Jacob, Daniel James
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.18%
A unified tropospheric chemistry-aerosol model has been developed within the Goddard Institute for Space Studies general circulation model (GCM). The model includes a detailed simulation of tropospheric ozone-NOx-hydrocarbon chemistry as well as aerosols and aerosol precursors. Predicted aerosol species include sulfate, nitrate, ammonium, black carbon, primary organic carbon, and secondary organic carbon. The partitioning of ammonia and nitrate between gas and aerosol phases is determined by on-line thermodynamic equilibrium, and the formation of secondary organic aerosols is based on equilibrium partitioning and experimentally determined parameters. Two-way coupling between aerosols and chemistry provides consistent chemical fields for aerosol dynamics and aerosol mass for heterogeneous processes and calculations of gas-phase photolysis rates. Although the current version of the unified model does not include a prognostic treatment of mineral dust, we include its effects on photolysis and heterogeneous processes by using three-dimensional off-line fields. We also simulate sulfate and nitrate aerosols that are associated with mineral dust based on currently available chemical understanding. Considering both mineral dust uptake of HNO3 and wet scavenging of HNO3 on ice leads to closer agreement between predicted gas-phase HNO3 concentrations and measurements than in previous global chemical transport model simulations...

Characterization of Atmospheric Aerosols in Kathmandu, New Hampshire, and Texas: Carbonaceous, Isotopic, and Water-soluble Organic Composition

Shakya, Kabindra Man
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
37.37%
To improve the understanding of aerosol composition, sources, and spatial and temporal variations, atmospheric aerosols were characterized in three locations. Ambient aerosols were characterized using 24-hour samples collected from Kathmandu, Nepal (urban), New Hampshire (semi-rural) and Houston (urban). Results are reported in the main chapters. Chamber studies of secondary organic aerosols (SOA) formation from polycyclic aromatic hydrocarbons (PAHs) and the effects of in-situ SOA formation on atmospheric mercury oxidation are described in the appendices. Carbonaceous, ionic, and isotopic species in aerosols from Kathmandu identified local primary emissions, most likely vehicular exhaust as the most important aerosol sources. Carbonaceous aerosols collected in Kathmandu (24.5 μg C m -3 ) were much larger than those in New Hampshire (3.74 μg C m -3 ) during winter. Stable carbon isotope in aerosols of Kathmandu and New Hampshire were similar (Δδ 13 C ∠ 0.5[per thousand]) while stable nitrogen isotope were much lower in aerosols of Kathmandu (Δδ 15 N = 8.3[per thousand]). Aerosols in New Hampshire exhibited a large seasonal variation for carbonaceous aerosols, stable nitrogen isotope, and the aromatic fraction of water-soluble organic carbon (WSOC). Pure aliphatics (H-C) were the dominant functional group in WSOC. Results illustrate the importance of secondary aerosol sources throughout the year...

Physical and optical properties of aerosols over an urban location in Spain: seasonal and diurnal variability

Lyamani, H.; Olmo Reyes, Francisco Jos??; Alados-Arboledas, Lucas
Fonte: Copernicus Publications Publicador: Copernicus Publications
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.96%
Measurements of aerosol optical properties and aerosol number size distribution obtained during the period from December 2005 to November 2007 at Granada, an urban site in south-eastern Spain, are analyzed. Large variations of the measured variables have been found, and related to variations in emissions sources and meteorological conditions. High values of aerosol absorption and scattering coefficients are obtained during winter and low values are measured during summer. This seasonal pattern in the surface aerosol optical properties is opposite to the seasonal cycle showed by columnar aerosol optical depth. The differences in the seasonal features of the surface and column-integrated data are related to seasonal variations in the aerosol vertical distribution, aerosol sources and boundary layer height. In winter the number density of "fine" particles (0.5

Application of satellite and ground-based data to investigate the UV radiative effects of Australian aerosols

Kalashnikova, Olga V; Mills, Franklin; Eldering, Annmarie; Anderson, Don
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
37.06%
An understanding of the effect of aerosols on biologically- and photochemically-active UV radiation reaching the Earth's surface is important for many ongoing climate, biophysical, and air pollution studies. In particular, estimates of the UV characterist

Physical and chemical processes affecting atmospheric aerosols in the Western Mediterranean regional background

Cusack, Michael
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis Formato: application/pdf
Publicado em //2014 ENG; ENG
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En este trabajo se muestra un estudio detallado de las fuentes de emisión y de los procesos físico-químicos que afectan a los aerosoles atmosféricos en el entorno regional de Montseny, situado en el Mediterráneo Occidental, una región relativamente poco estudiada en cuanto a calidad del aire. En el marco de calidad del aire, el estudio de los aerosoles atmosféricos está siendo de gran y creciente interés en la actualidad debido tanto a los potenciales efectos perjudiciales en la salud derivados de la exposición a estos contaminantes, como a sus efectos en el clima. Se ha llevado a cabo el análisis de una extensa serie temporal (2002-2010) de niveles de PM2.5 (material particulado de diámetro menor de 2.5 µm) y de su composición química, con el objetivo de describir las tendencias y fluctuaciones en las concentraciones, así como de identificar las posibles causas de estas variaciones. El análisis de la tendencia temporal de PM2.5 mostró una disminución estadísticamente significativa, generalizada a lo largo de Europa. Esta tendencia de disminución se atribuye a la eficacia de estrategias de reducción de la contaminación aplicadas por los países miembros de la UE, dado que muchos de los compuestos asociados a actividades antropogénicos...

Variability of atmospheric aerosols at urban, regional and continental backgrounds in the Western Mediterranean Basin

Pérez Lozano, Noemí
Fonte: Bellaterra: Universitat Autònoma de Barcelona, Publicador: Bellaterra: Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis Formato: application/pdf
Publicado em //2010 ENG; ENG
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37.18%
Descripció del recurs: el 14 de febrer de 2011; El estudio de los niveles y composición del material particulado atmosférico (PM) medido simultáneamente en diferentes ambientes a escala regional se llevó a cabo en la cuenca del Mediterráneo Occidental con el fin de entender las fuentes y patrones de transformación y transporte de aerosoles en esta zona. Para esto, la medida de niveles y caracterización química de PM10, PM2.5 y PM1 se llevó a cabo en tres estaciones de monitoreo: Montsec (MSC, fondo continental, 1570 msnm), Montseny (MSY, fondo regional, 720 msnm) y Barcelona (BCN, fondo urbano, 68 msnm). Además, se midieron niveles de número de partículas (N) y carbono negro (BC) en BCN. Durante el invierno, la frecuente estabilidad atmosférica induce el estancamiento de masas de aire produciendo importantes episodios de contaminación en BCN. Sin embargo, MSY y, más frecuentemente MSC, quedan aislados de la contaminación regional. En determinados escenarios, el desarrollo de la capa límite y las brisas resultan en el transporte de masas de aire contaminadas a zonas rurales, aumentando notablemente los niveles de PM en función de la altitud y la distancia a las zonas fuente. Durante el verano, la circulación de brisas favorece la dispersión...

Variations in sulphate aerosols concentration during winter monsoon season for two consecutive years using a general circulation model

VERMA,S.; BOUCHER,O.; UPADHYAYA,H. C.; SHARMA,O. P.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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During the field cruises of the Indian Ocean Experiment (INDOEX) extensive measurements on the atmospheric chemical and aerosol composition are undertaken to study the long-range transport of air pollution from south and southeast Asia towards the Indian Ocean during the dry monsoon season in 1998 and 1999. The present paper discusses the temporal and spatial variations in aerosols and aerosol forcing during the winter monsoon season (January-March) for INDOEX first field phase (FFP) in 1998 and INDOEX intensive field phase (IFP) in 1999. An interactive chemistry/aerosol model (LMDZ.3.3) is used to investigate the variation in the spatial distribution of tropospheric sulphate aerosols during 1998 and 1999. The model results depict major enhancement in the sulphate aerosol concentrations, radiative forcing (RF) and optical depth over the Indian subcontinent and adjoining marine areas between INDOEX-FFP and IFP. A significant increase in transport of sulphate aerosols from the continents to the Indian Ocean region has also been simulated during the winter monsoon in 1999. The mean RF over INDOEX-FFP in 1998 is found to be -1.2 Wm-2 while it increased to -1.85 Wm-2 during INDOEX-IFP in 1999. Model results reveal a mean sulphate aerosol optical depth (AOD) of 0.08 and 0.14 over Indian subcontinent during 1998 and 1999...