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Spectral absorption properties of atmospheric aerosols

Spectral absorption properties of atmospheric aerosols

Received: 19 June 2007 – Published in Atmos. Chem. Phys. Discuss.: 24 July 2007 Revised: 16 October 2007 – Accepted: 30 October 2007 – Published: 4 December 2007 Abstract. We have determined the solar spectral absorp- tion optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative trans- fer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral ab- sorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the at- mosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the result- ing spectral single scattering albedo for these cases.
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Evolution of Titan's atmospheric aerosols under high-altitude ultraviolet irradiation

Evolution of Titan's atmospheric aerosols under high-altitude ultraviolet irradiation

Evolution of Titan’s atmospheric aerosols under high- altitude ultraviolet irradiation S. Tigrine 1, 2 , N. Carrasco 1 , A. Mahjoub 1 , B. Fleury 1 , G. Cernogora 1 , L. Nahon 2 , P. Pernot 3 , M. S. Gudipati 4 1 LATMOS, Université Versailles St. Quentin, UPMC Univ. Paris 06, CNRS, 11 Bvd. d’Alembert, 78280 Guyancourt, France, 2 Synchrotron SOLEIL, l’Orme des Merisiers, St Aubin, BP 48, 91192 Gif sur

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Measurements of optical properties of atmospheric aerosols in Northern Finland

Measurements of optical properties of atmospheric aerosols in Northern Finland

Aerosol optical properties and their relation to other aerosol properties are key factors in investigating the di- rect radiative effects by atmospheric aerosols. The most im- portant particles in this respect are submicron accumulation mode particles (Charlson et al., 1999). However, supermi- cron sea salt and dust may also have an important role in scattering in certain conditions (O’Dowd and Smith, 1993). Measurements concerning aerosol optical properties have been made in the marine boundary layer (e.g. Hegg et al., 1996), at a few coastal sites (e.g. O’Dowd and Smith, 1993; Sheridan and Ogren, 1999; Delene and Ogren, 2002; Ander- son et al., 1999), in the free troposphere (e.g. Sheridan and Ogren, 1999), in Arctic regions (e.g. Virkkula et al., 1998; Treffeisen et al., 2004; Beine et al., 1996), and in areas with a high sulfate burden (e.g. Koloutsou-Vakakis et al., 2001; Delene and Ogren, 2002). High Arctic aerosol loadings, i.e. Arctic haze, have also been investigated (e.g. Treffeisen et al., 2004; Heintzenberg et al., 2003; Beine et al., 1996). In addition to field measurements, aerosol optical properties have been studied with airborne in-situ measurements as well as from satellites (e.g. Bodhaine et al., 1991; Kaufman et al., 2002).
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Size resolved mass concentration and elemental composition of atmospheric aerosols over the Eastern Mediterranean area

Size resolved mass concentration and elemental composition of atmospheric aerosols over the Eastern Mediterranean area

2 Experimental 2.1 Sampling site Aerosol samples were collected on Crete during the periods 10–31 July 2000 and 7–14 January 2001. According to the analysis of 10 years air mass back trajectories (WMO, 1985; Guerzoni et al., 1990; Chester et al., 1993) 39% of air masses arrive at Crete from the north across Greece, eastern Europe and the former USSR, 28% of air masses arrive from the west-northwest, crossing western Europe, 16% come from the south, transporting aerosol from the Sahara and North Africa deserts, and 17% come from the east crossing the Middle East desert regions. Mihalopoulos et al. (1997) re- port similar figures. The main sampling site was located at Finokalia on the island of Crete. Finokalia (35 ◦ 19 0 N, 25 ◦ 40 0 E) is a coastal remote site, east of Heraklion on the top a hill (∼150 m a.s.l.) facing the sea within the sector of 270 ◦ to 90 ◦ . In addition samples of atmospheric aerosol were also collected during the period 25–29 July 2000 aboard the research vessel “AEGAIEO”. The vessel cruised in the Aegean Sea along selected tracks mainly upwind the Fi- nokalia site, as indicated by forward and back trajectory modelling with the Finokalia sampling site as the end point. 2.2 Sampling
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Atmospheric aerosols in Amazonia and land use change: from natural biogenic to biomass burning conditions

Atmospheric aerosols in Amazonia and land use change: from natural biogenic to biomass burning conditions

Human activities in Amazonia over the last 50 years have had a signicant impact on a considerable part of the region, especially along the southern perimeter. 14 A recent steep decline in annual deforestation rates in the Brazilian Amazon from 27 800 km 2 yr 1 in 2004 to 4660 km 2 yr 1 in 2012 is recorded in the time series shown in Fig. 1, as measured by the PRODES (Projeto de Monitor- amento do Desorestamento na Amazˆonia Legal) program from INPE (The Bra- zilian National Institute for Space Research) for the Brazilian Amazon. The reduction from 2004 to 2012 observed in Fig. 1 is an impressive achievement, but there are questions if these relatively recent low deforestation rates can be maintained over the next decades, 12 because of socio-economic pressures as well as a result of a changing global climate. 13,15 The dominant factors of public policies, climate, economic issues, and so forth that successfully contributed to the reduction of deforestation rates in recent years have not been fully dissected. There is also increased uncertainty over the sensitivity of carbon storage in the tropics to climate warming, increasing atmospheric CO 2 concentrations, and
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Size resolved mass concentration and elemental composition of atmospheric aerosols over the eastern Mediterranean area

Size resolved mass concentration and elemental composition of atmospheric aerosols over the eastern Mediterranean area

Aerosol samples were collected on Crete during the periods 10–31 July 2000 and 7–14 January 2001. According to analysis of 10 years air mass back trajectories 15 (WMO, 1985; Guerzoni et al., 1990; Chester et al., 1993) 39% of air masses arrive at Crete from the north across Greece, eastern Europe and the former USSR, 28% of air masses arrive from the west-northwest, crossing western Europe, 16% come from the south, carrying with them aerosols from the Sahara and North Africa deserts, and 17% come from the east crossing the Middle East desert regions. Mihalopoulos

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Sugars in atmospheric aerosols over the Eastern Mediterranean

Sugars in atmospheric aerosols over the Eastern Mediterranean

Compounds to Water-Soluble Organic Carbon in the Western Pacific Aerosols in 865. Relation to Photochemical Oxidation Reactions.[r]

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Measurements of optical properties of atmospheric aerosols in Northern Finland

Measurements of optical properties of atmospheric aerosols in Northern Finland

4. Summary and conclusions Three years of continuous measurements of aerosol optical properties have been anal- 10 ysed at Pallas GAW station, a remote subarctic site in the northern border of the boreal forest zone. The measurements were analysed as a function of aerosol size distribu- tion and atmospheric long-range transport. The seasonal variation of the data was also studied. The scattering coe fficient at 550 nm varied from 0.2 to 94.4 Mm −1 with an av- erage of 7.1±8.6 Mm −1 . Both the scattering and backscattering coe fficients had a clear

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Modelizatin and numerical simulation of atmospheric aerosols dynamics

Modelizatin and numerical simulation of atmospheric aerosols dynamics

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignemen[r]

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A new feedback mechanism linking forests, aerosols, and climate

A new feedback mechanism linking forests, aerosols, and climate

growth: Increasing CO 2 concentrations accelerate photosyn- thesis which in turn consumes more CO 2 (Lenton, 2000; Ne- mani et al., 2003). On the other hand, forest ecosystems also act as significant sources of atmospheric aerosols (Kulmala et al., 2001). Terrestrial vegetation contributes substantially to emissions of a variety of BVOCs (Fuentes et al., 2000) and newly formed particles in forested areas have been found to contain large amounts of organic material (O’Dowd et al., 2002). The ratio of BVOC emission to carbon assimilation is generally a few percent (Grace and Rayment, 2000; Guen- ther et al., 1995), and if increased CO 2 concentrations en-
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Experimental simulation of aerosols evolution in Titan’s ionosphere

Experimental simulation of aerosols evolution in Titan’s ionosphere

(audrey.chatain@latmos.ipsl.fr) Abstract Many recent studies on Titan are concerned with aerosols. In particular, questions are asked on how these complex organic molecules are formed and evolve in Titan’s atmosphere. Here for the first time we experimentally study how harsh plasma environment simulating Titan ionosphere can affect these aerosols. Titan tholins are placed in a N 2 -H 2

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Atmospheric Science with InSight

Atmospheric Science with InSight

2, wind and temperature measurements at the surface of Mars will help to characterize the properties and seasonal variability of both the local meteorology in Elysium Planitia boundary l[r]

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Atmospheric Science with InSight

Atmospheric Science with InSight

2, wind and temperature measurements at the surface of Mars will help to characterize the properties and seasonal variability of both the local meteorology in Elysium Planitia boundary l[r]

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Photoelectrons produced by Far-UV radiation on Titan's aerosols

Photoelectrons produced by Far-UV radiation on Titan's aerosols

3. Results Photoelectron spectra of aerosols analogs are shown on Figure 1. The ionization onset appears at a photon energy of 6.0±0.1 eV, well below any free molecules ionization energy. This ionization threshold is consistent with the data of the Permittivity, Waves and Altimetry instrument on board Huygens between 160 and 80 km in Titan’s atmosphere [4] [5].

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Forecasting global atmospheric CO2

Forecasting global atmospheric CO2

at https://icos-atc-demo.lsce.ipsl.fr. The authors acknowledge the European Commission for the support of the preparatory phase of ICOS (2008–2013), the Netherlands Ministry of IenM and ECN for the support of the observations at Cabauw, and the monitoring network SNO-RAMCES/ICOS-France which is in charge of Ivittuut, Mace Head and Lamto stations with the support of CNRS, CEA and OVSQ. Thanks to F. Truong (LSCE) and to A. Diawara and Y. Palmer for the maintenance of Station Géophysique de LAMTO with the support of University of Abidjan. Thanks to J. L. Bonne and M. Delmotte for the data from Ivittuut station, with the support of Greenland’s Kommando, Danish Armed Forces, Island Commander Greenland and Kommuneqarfik Sermersooq. Thanks to V. Kazan and G. Spain for the maintenance of Mace Head station with the support of the Irish Environmental Protection Agency, and the National University of Ireland, Galway. Thanks to Harri Portin, Juha Hatakka, Tuomas Laurila (FMI) for providing the data from the ICOS station at Puijo, Finland. We are grateful to Jérôme Tarniewicz for his technical support with the ICOS database and to Miha Razinger for his help in the development and maintenance of the ICOS monitoring plots in the MACC website. Thanks to the NOAA/ESRL Global Monitoring Division for providing their data from the baseline observatories at Barrow (Alaska), American Samoa, South Pole (Antarctica), the tall towers at Argyle (Maine), Park Falls (Wisconsin), West Branch (Iowa), and the vertical profiles from the NOAA GMD Carbon Cycle Vertical Profile Network. TCCON data were obtained from the TCCON Data Archive, operated by the California Institute of Technology from the website at http://tccon.ipac.caltech.edu/. We acknowledge financial support of the Bialystok TCCON site from the Senate of Bremen and EU projects IMECC, GEOmon and InGOS, as well as maintenance and logistical work provided by the AeroMeteo Service and additional operational funding from the National Institute for Environmental Studies (NIES, Japan). POW and DW thank NASA’s Carbon Cycle Science program (NNX10AT83G and NNX11AG01G) and the Orbiting Carbon Observatory Program for support of TCCON and this research. The HIPPO Merged 10 s data set was obtained from the website at http://hippo.ornl.gov/dataaccess. The HIPPO Programme was supported by NSF grants ATM-0628575, ATM-0628519 and ATM-0628388 to Harvard University, University of California (San Diego), University Corporation for Atmospheric Research, NOAA Earth System Research Laboratory, University of Colorado/CIRES and by the NCAR. The NCAR is supported by the National Science Foundation. The feedback from Britton Stephens is greatly appreciated.
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CALIPSO observations of stratospheric aerosols: a preliminary assessment

CALIPSO observations of stratospheric aerosols: a preliminary assessment

(Winker et al., 2007). As part of the Aqua satellite constel- lation that includes the Aqua, CloudSat, Aura, and PARA- SOL satellites, CALIPSO is in a 98 ◦ inclination orbit with an altitude of 705 km that provides daily global maps of the distribution of aerosol and clouds. The CALIPSO pay- load consists of three instruments: the Cloud-Aerosol Li- dar with Orthogonal Polarization (CALIOP), an Imaging In- frared Radiometer (IIR), and a moderate spatial resolution Wide Field-of-view Camera (WFC). CALIOP provides pro- files of backscatter at 532 and 1064 nm, as well as two orthogonal (parallel and perpendicular) polarization com- ponents at 532 nm. CALIOP instrument characteristic are shown in Table 1 and the vertical and horizontal resolution of the data products is shown in Table 2. A detailed dis- cussion of CALIOP data products can be found in Vaughan et al. (2004). In the routine processing, the parallel compo- nent of the 532-nm backscatter is calibrated to the expected molecular volume backscatter coefficient between 30 and 34 km altitude where the molecular density is derived from the GEOS-4 atmospheric analyses provided by the Global Modeling and Assimilation Office (Bloom et al., 2005; Lin, 2004). The current calibration algorithm does not account
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How Adsorption of Pheromones on Aerosols Controls Their Transport

How Adsorption of Pheromones on Aerosols Controls Their Transport

impacting the surface gets adsorbed. Hypotheses i and ii are true for ideal gas. The third hypothesis is more questionable. Some authors 28−31 consider a Knudsen correction factor that accounts for the possibility of bouncing back. On the other hand, several molecular dynamic simulations, regarding liquid/ vapor systems developed by di fferent groups, 32−35 support the Hertz relation and the absence of this phenomenon. The Hertz equation corresponds to the transition state theory (TST) approximation 36 when the transition state is de fined as the surface of the aerosols. In fact, gas pheromones become adsorbed on the aerosol surface. Their concentration in air close to the surface is depleted, and di ffusion has to compensate this depletion. Thus, gas di ffusion of pheromones toward aerosols can limit the adsorption kinetics depending on the size of the aerosols. This limitation of the adsorption kinetics can be taken into account by modifying the adsorption rate ( eq 6 ) by a factor ϵ that explicitly depends on aerosol radius: 37
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Atmospheric corrosion of metals

Atmospheric corrosion of metals

Much has been said about pollution in the last few years, but in the context of atmospheric corrosion only sulphur dioxide has been shown to accelerate corrosion in a predictable way. Particulate matter such as sea salts, soot and soil has not been directly correlated with the rate of corrosion, although it has been demonstrated that particulates deposited on a metal surface can be responsible for the initiation of corrosion.

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Identification and characterization of natural aerosols over the Arctic

Identification and characterization of natural aerosols over the Arctic

59 4. Conclusions Paper 1 was an original and, we believe, an innovative article published in Atmospheric Environment. It deals with an extreme smoke event observed over Eureka in August of 2017. First and foremost this paper was original in terms of the event it reported (the largest optical depth ever recorded over Eureka) and in terms of the instrumental infrastructure and expertise that we developed over many years at Eureka. The paper was also original in terms of the production of a 10-year 𝜏 𝑓 (fine mode optical depth) smoke climatology (based on AEROCAN / AERONET data collected at our two sites in Eureka) that had to be pre-filtered to exclude events such as the 2008 and 2009 Kasatochi and Sarychev stratospheric intrusion of fine mode sulphates. An additional and original constraint on the labelling of 𝜏 𝑓 events as smoke events was the correlation between 𝜏 𝑓 and CO abundance measured using a FTIR 13 (CO being a classical smoke product): the level of correlation observable in Figure 5 of that paper is to our knowledge unprecedented and, in the presence of severe variations of cloud optical depth, speaks to the reliability of the retrieval method (the SDA retrieval of AERONET). To demonstrate the extreme nature of the event we employed a "peak over threshold" (POT) analysis of individual 𝜏 𝑓 peaks during our 10-year sampling period. This process involved a careful analysis of all significant smoke events during that period and the conversion of that manual analysis into an automatic routine for extraction of all smoke events above a certain 𝜏 𝑓 threshold. This generated a distribution of extreme smoke events from which the statistical inference of a significant extreme could be drawn. Conversely, the August 2017 event was not found to be an extreme event in terms of a simple monthly average approach: this observation is consistent with the notion that extreme event statistics were needed to demonstrate the uniqueness of the event.
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Global Modeling of the Oceanic Source of Organic Aerosols

Global Modeling of the Oceanic Source of Organic Aerosols

4. Conclusions The global 3-dimensional chemistry/transport model TM4- ECPL has been adapted to simulate the temporal and spatial distribution of primary and secondary marine organic aerosols. The annual global source of marine SOA is estimated at about 5.1 Tg yr −1 . Monoterpenes and isoprene oxidation is calculated to produce about 0.1 Tg yr −1 , MS − contribution to SOA is 4 Tg yr −1 and in the case of taking into account marine alkyl amine salts marine SOA production is increasing by 1 Tg yr −1 . On the global scale, most of marine SOA (∼78%) originates from the dimethylsulfide oxidation to methanesulfonic acid seconded by alkyl amines salts (∼21%). Note that these results depend on the adopted parameterisations of marine sources of DMS, marine amines, and marine volatile organic compounds as well as the parameterizations of SOA formation from the oxidation of these marine precursors. For instance, if the oceanic source of isoprene and monoterpenes is one and two orders of magnitude larger, respectively, as evaluated by Luo and Yu [ 68 ], then the contribution of these compounds to the marine SOA formation could be significant. The annual global marine source of POA is evaluated at about 7 to 8 Tg POA yr −1 with an additional uncertainty of a factor of 4 associated with our calculations. The lowest estimates are issued when the sea-salt source is calculated on line by TM4 driven by wind speed whereas about 4 times higher estimates are derived using the AEROCOM derived sea-salt emission inventory [ 40 ] that differs from the online estimates to the
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