Observation FILTER-FREE MEASUREMENT OF AEROSOLS … · 2017-03-10 · sky-scanning sun-tracking atmospheric research: Instrument Technology, Remote Sens., 5, 3872-3895, 2013. [2]

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Observation

FILTER-FREE MEASUREMENT OF AEROSOLS ABSORPTION BY PHOTOACOUTIC SPECTROSCOPY (PAS)

Gaoxuan WANG a, Hongming YI1#, Patrice HUBERT b, Alexandre DEGUINE b, Denis PETITPREZ b, Eric FERTEIN a, Dean VENABLES c, Weidong CHEN*a a Laboratoire de

Physicochimie de l’Atmosphère, Université du Littoral Côte d’Opale,

Dunkerque, France (*[email protected]; # with NIST, Gaithersburg, Maryland, USA)

b Physicochimie des Processus de Combustion et de l’Atmosphère, Université de Lille1, Villeneuve d’Ascq, France

c Environmental Research Institute, University College Cork, Cork, Ireland

Beyond their impacts on human health, atmospheric aerosols have direct and indirect effects on climate. They affect visibility, alter the structure and properties of clouds, and change the global radiation balance. Optical parameters of aerosol related to its radiative forcing effects are known with large uncertainties [1]. Photoacoustic spectroscopy (PAS) is considered as one of the most suitable tool for direct measurements of aerosols absorption with higher precision [2].

In the present work, a PAS sensor involving a blue diode laser operating at ~444 nm was developed for filter-free measurements of aerosol absorption. Mass absorption coefficients (MAC) of black carbon (BC) and volcanic ash (from Eyjafjallajökull volcano) have been determined using the PAS sensor in conjunction with SMPS and CPC measurements. Good agreements have been observed in comparison with the results obtained using reflectance measurement technique [3]. A minimum measureable absorption coefficient of ~1.2 Mm-1 (1�) was achieved. We deployed recently the developed PAS sensor to optically monitor the formation of secondary organic aerosols (SOA) resulting from the photolysis of 2-nitrophenol (2NP) [4] in a simulation chamber at University College Cork (Ireland).

The experimental detail, the preliminary measurement results, and the corresponding data analysis will be presented.

Acknowledgments. This work is supported by the French national research agency (ANR) under the CaPPA (ANR-10-LABX-005) and MABCaM (ANR-16-CE04-0009) contracts. The authors thank the funding from the French embassy in Ireland and the communauté d’Universités et d’Etablissements Lille Nord de France.

[1] IPCC report (2013): http://www.ipcc.ch/report/ar5/wg1/.

[2] A. L. Daniel, R. L. Edward, B. Tahllee, P. Anders, A. R. Ravishankara, "Aerosol Absorption Measurement using Photoacoustic Spectroscopy: Sensitivity, Calibration, and Uncertainty Developments", Aerosol Sci. Technol. 40, 697-708 (2006).

[3] A. R. Lima, J. V. Martins, L. A. Remer, N. A. Krotkov, M. H. Tabacniks, Y. B. Ami, P. Artaxo, "Optical, microphysical and compositional properties of the Eyjafjallajökull volcanic ash", Atmos. Chem. Phys. 14, 10649-10661 (2014).

[4] J. Chen, J. C. Wenger, D. S. Venables, “Near-Ultraviolet Absorption cross sections of Nitrophenols and their potential influence on Tropospheric oxidation capacity”, J. Phys. Chem. A. 115, 12235-12242 (2011).

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RETRIEVAL OF AEROSOL PROPERTIES USING SUN-TRACKING AND SKY-SCANNING MEASUREMENTS OF THE 4STAR AIRBORNE SPECTROMETER DURING ORACLES

CAMPAIGN

Yana KAROL a, Jens REDEMANN a, Connor FLYNN b, Samuel LEBLANC a

a NASA Ames Research Center, Moffett Field, CA 94035, United States

b Pacific Northwest National Laboratory, Richland, WA 99352, United States

We present the first attempt of the retrieval of aerosol microphysical and optical properties from sun-tracking and sky-scanning measurements of the NASA Ames airborne spectrometer 4STAR [1] during ORACLES campaign in 2016 [2] using the Aerosol Robotic Network (AERONET) inversion algorithm [3].

The ORACLES campaign held in August-September 2016 in South-East Atlantic when the high aerosol loading was observed due to the biomass burning emission in Southern Africa gives us a large number of 4STAR measurements with different flight geometries at the altitudes up to 6 km. This data helps us to better understand the vertical variability of aerosols, some unique detailed characteristic of aerosols such as single scattering albedo above clouds that is critically important in climate modeling.

In addition to obtaining new information about vertical distribution of aerosols, the second important goal of these resent efforts is to analyze and validate how the standard AERONET inversion algorithm performs in low aerosol optical depth (AOD) conditions and/or with incomplete and/or nonsymmetrical sky-scanning measurements. Also, we plan to explore the possibilities of improving retrievals in such conditions by using a broader spectral range than the standard 440-1020nm spectral range currently used for AERONET retrieval product.

This task is quite challenging since low aerosol loading at high altitudes may lead to significant uncertainties in retrieval results. Moreover, the full set of measurements on the aircraft is carried out at horizontal scales (usually several kilometers) where the aerosol layer may be inhomogeneous and additional uncertainties could arise.

In the near future the results of our retrieval analysis are to be validated with in-situ measurements that were collected simultaneously with 4STAR data. The validation and the large volume of data collected in various conditions will also help us to meet the main goal of the study.

[1] Dunagan, S. E., R. Johnson, J. Zavaleta, P. B. Russell, B. Schmid, C. Flynn, J. Redemann, Y. Shinozuka, J. Livingston, M. Segal-Rosenhaimer: 4STAR spectrometer for sky-scanning sun-tracking atmospheric research: Instrument Technology, Remote Sens., 5, 3872-3895, 2013.

[2] https://espo.nasa.gov/oracles Date of access: 12 January 2017.

[3] Dubovik, O. and King, M.: A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements, Journal of Geophysical Research, 105, 20 673–20 696, 2000.

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ICAC 2017

Observation

CONTINUOUS OBSERVATIONS OF CHEMICAL AND PHYSICAL PROPERTIES OF ATMOSPHERIC AEROSOLS IN SOUTHERN EUROPE

Marcos BARREIROa, Elisabeth ALONSO-BLANCOa, Marta BECERRILa, Esther COZa, Elías DÍAZa, Alfonso J. FERNÁNDEZa, Francisco Javier GÓMEZ-MORENOa, Francisco MOLEROa, Lourdes NÚÑEZa, Magdalena PALACIOSa, Pedro

SALVADORa, Manuel PUJADASa, Begoña ARTÍÑANOa

aEnvironment Department, CIEMAT, Avenida Complutense 40, 28040 Madrid (SPAIN)

Physicochemical properties of ambient aerosols and main atmospheric parameters are real-time monitored at the CIEMAT research station in Madrid. The site is located in a sub-urban area northwest the city, and it is part of the ACTRIS European infrastructure. Local anthropogenic and natural contributions determine the aerosol characteristics measured at this site, although long-range transport processes have been also documented influencing the aerosol properties under specific meteorological conditions.

A number of in-situ aerosol variables are measured in this station: number and size distribution (SMPS), hygroscopic growth (HTDMA), light-scattering (Nephelometer), light-absorption/Black Carbon (Aethalometers) and non-refractory chemical composition (ACSM). Vertical profiling of tropospheric aerosol and water vapor are obtained through a multiwavelength Raman LIDAR instrument co-located at the site. Meteorological parameters and gaseous pollutant concentrations are provided by a meteorological station (52 m mast) and an active DOAS system, respectively. The station operates under the ACTRIS protocols for instrument calibration and quality control of measurements.

Time series analysis allows characterizing seasonal and short-term variation patterns of most aerosol properties. In the absence of external inputs, an urban carbonaceous aerosol is dominant. Nevertheless, under specific situations, variations in chemical composition, indicating a change in the aerosol type, have a clear influence on other properties and parameters. For instance, increasing BC concentrations (about 40% on average of the PM1), seem to inhibit the hygroscopic growth, partially conditioned by the phase distribution within the aerosol structure. This enhancement is moderate at high RH, even during periods of high concentrations of inorganic compounds, which is typical from traffic-dominated polluted areas. Formation processes have been also characterized being nucleation typical of spring and summer periods. Aerosol shrinkage processes have been characterized by the SMPS during nucleation events linked to an increase of wind speed during the growth phase of the new particles.

Acknowledgements: This research is funded by ACTRIS-2 H-2020 (grant agreement n° 654109) and PROACLIM (CGL2014- 52877-R) projects. The Madrid Regional Research Plan has also funded this work through the TECNAIRE (P2013/MAE-2972) project.

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AEROSOL SPATIAL VARIABILITY IN NORTHERN FRANCE OBSERVED BY ON-ROAD MOBILE MEASUREMENTS

Ioana POPOVICIa,b, Philippe GOLOUBa, Luc BLARELa, Thierry PODVINa, Rodrigue LOISILa, Augustin MORTIERc, Christine DEROOa, Marie CHOËLd, Stéphane VICTORIb,

Nathalie SOHNEe,

a Univ. Lille, CNRS, UMR 8518 - LOA - Laboratoire d’Optique Atmosphérique, F-59000 Lille, France

b Cimel Electronique, Paris, 75011, France

c Norwegian Meteorological Institute, Oslo, 0313, Norway

d Univ. Lille, CNRS, UMR 8516 - LASIR - LAboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France

e ATMO Hauts-de-France, Lille, 59000, France

Aerosols are a quite variable component of the atmosphere, impacting air quality, human health and climate. In order to monitor the atmospheric aerosol, instruments are set up in networks (e.g. ACTRIS (AERONET, EARLINET)) and present complex configuration. Moreover, most of the instruments require controlled environment and regular maintenance for their operation. Therefore, their use for atmospheric profiling is limited over a fixed location. Nevertheless, aerosol distribution is highly variable especially in the case of pollution events. In these situations, field observations are a great necessity, as the spatial variability is impossible to assess from point measurements.

The mobile system described in this study is an instrumented vehicle, which integrates a Cimel eye-safe LIDAR (Pelon et al, 2008), a sunphotometer (Karol et al, 2013) and in situ instruments (e.g. optical particle counters). The photometer is able to track the sun during vehicle’s movement while the micro-LIDAR sounds the atmosphere in the zenith direction. The system is distinguished by other transportable platforms through its capabilities to perform on-road measurements.

Observation campaigns were conducted in northern France in spring-summer of 2015- 2016 and January 2017. The results show cases of strong regional contrast. For example, on 19 and 20 July 2016, the AOD at 440 nm varied from 0.03-0.1 to 0.16-0.34 over Lille-Dunkerque transect. From the synergy of lidar and sunphotometer measurements, vertical extinction and mass concentration are measured. At the ground level, mass concentrations of 10-50 μg/m3 to 40-150 μg/m3 were recorded.

Pelon et al., 2008, Journal of Geophysical Research, 113, D00C18

Karol et al., 2013, Atmospheric Measurements Techniques, 6, 2383-2389

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Observation

EVALUATION OF THE MINIATURE PARTICLE COUNTER LOAC FOR THE SURVEY OF STRATOSPHERIC AEROSOLS WITH METEOROLOGICAL BALLOONS

Damien VIGNELLES a, Jean-Baptiste RENARD a, Gwenaël BERTHET a, François DULAC b, L. Rieger c, A. Bourrassa c, D. Degenstein c, J.P. Vernier d,e, G. Taha f,g, S. Khaykin h, Fabrice

JEGOU a, T. Lurton a

a LPC2E/CNRS/University of Orléans, 3A Avenue de la recherche scientifique, Orléans, France b LSCE-CEA/IPSL, University of Paris Saclay, CEA Saclay 701, Gif-sur-Yvette, France

c Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Canada d Science Systems and Applications Inc., Hampton, USA

e NASA Langley Research Center, USA f Universities Space Research Association, Greenbelt, MD, USA

g NASA Goddard Space Flight Center, Greenbelt, MD, USA h LATMOS, CNRS, University of Versailles St Quentin, Guyancourt, France

Stratospheric aerosols have been studied for many years for their role in the terrestrial radiative budget (Kremser et al. 2016) through remote sensing and in situ techniques. A global view of the stratospheric aerosols is given by instruments on-board satellites whereas in situ measurements are made on board aircraft or under balloons. Long-term time series measurements made in situ with balloons by Deshler et al. (2003) are essential for example to improve our knowledge on time variations of the distribution in size of stratospheric aerosols in order to better constrain the remote sensing methods. We have studied the feasibility of using a new light aerosol counter on board meteorological balloons allowing time series from several locations and/or with a greater frequency.

The LOAC (Light Optical Aerosol Counter) particle counter has been designed for balloon-borne tropospheric studies (Renard et al. 2016). Its metrological performance in the stratosphere has been characterised regarding the dependency on atmospheric pressure, inner temperature, cosmic rays, and low concentration of particles. Tests in laboratories and on-board have shown that the principal limitation of the utilisation of LOAC in the stratosphere is introduced by the temperature variations and by the influence of cosmic rays. A detection threshold has been determined in the laboratory to be of 1 particule.cm-3 in terms of concentration which also limits the use of LOAC in the stratosphere where aerosol concentrations during volcanic quiescent periods may be lower than this limit.

Inter-comparisons between two LOAC under balloons and between a LOAC and another aerosol counter (Deshler et al. 2003) have revealed good performances and have allowed us to discuss the LOAC limitations in terms of measurement reproducibility. These results also raise questions about hypotheses currently used concerning stratospheric aerosols assumed to be pure sulfates.

Finally, we have compared a dataset of 95 LOAC meteorological balloon flights obtained up to 34 km in altitude during two field campaigns (ChArMEx and Voltaire-LOAC) in the period 2013-2016 with three concurrent satellite records (OSIRIS, CALIOP and OMPS), a ground-based lidar (at OHP) and a model output (WACCM). Comparative results have revealed relatively good agreement between the various datasets up to 25 km but data significantly diverge above (Vignelles 2016).

Deshler et al. (2003) Thirty years of in situ stratospheric aerosol size distribution measurements from Laramie, Wyoming (41°N), using balloon-borne instruments. J. Geophys. Res. 108. doi:10.1029/2002JD002514 Kremser et al. (2016) Stratospheric aerosol—Observations, processes, and impact on climate. Rev. Geophys. 54, 2015RG000511. doi:10.1002/2015RG000511 Renard et al. (2016) LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements. Atmos. Meas. Technol. 9, 1721-1742. doi:10.5194/amt-9-1724-2016 Vignelles (2016) Caractérisation des performances du nouveau mini compteur de particule LOAC embarqué sous ballon météorologique - PhD Thesis, Univ. Orléans

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AEROSOL DISTRIBUTIONS OVER THE PRISTINE AREA OF THE SOUTHERN INDIAN OCEAN

Paul-Etienne MALLETa, Olivier PUJOLa, Jérôme BRIOUDEb, Stephanie EVANb, Andrew JENSENa

a Laboratoire d'Optique Atmosphérique, Université Lille 1, CNRS/INSU, UMR 8518, Villeneuve d'Ascq, France

b Laboratoire de l'Atmosphère et des Cyclones, UMR 8105, Météo-France/CNRS/Université de La Réunion, Saint-Denis de la Réunion,

France

An observational- and model-based description of aerosol spatio-temporal distributions over the marine area of the southern Indian ocean is proposed. This area is remarkable for its low AOD values and a very low contamination by terrestrial and anthropogenic aerosols. This kind of regions is very important to understand climate under relatively pure atmospheric conditions, which can be considered close to the pre-industrial climate state.

This analysis has been performed with in situ (Aeronet) and satellite (Polder, Caliop) measurements, as well as MACC transport reanalysis outputs, and results are discussed with respect to the large-scale organization of the atmospheric circulation, as represented by the ERA-Interim reanalysis.

Results are important to an assessment of aerosol radiative effect over purely marine areas and to improve aerosol-cloud interactions understanding.

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Observation

Aerosol absorption measurements and retrievals in SHADOW2 campaign

Qiaoyun HUa, Philippe GOLOUBa, Thierry PODVINa, Igor VESELOVSKIYb,c, Anton LOPATINa, Oleg DUBOVIKa, Benjamìn TORRESd,

Laura REVILINIa, Suzanne CRUMEYROLLEa, Tatsiana LAPIONAKa, Christine DEROOa

a Laboratoire d'Optique Atmosphérique, Université de Lille 1, Villeneuve d'Ascq, France

bPhysics Instrumentation Center of GPI, Troitsk, Moscow, Russia

cJoint Center for Earth Systems Technology, UMBC, Baltimore, MD, USA

dGRASP-SAS-SME, Lille, France

Mineral dust plays a critical role in the radiative forcing because it has not only direct influences on the radiation budget and can also change the cloud condensation nuclei process, thus alerting indirectly the radiation that arriving to the ground. To investigate the mineral dust properties near the main source, the SHADOW2 campaign was conducted at M'bour, Senegal, in March, April, December 2015 and January of 2016. This study is mainly about the absorption properties of mineral dust particles under different conditions, with two typical cases, analysis based on in-situ absorption measurements, Raman retrieval, and GRASP/GARRLiC retrieval are presented. The results show the potentials and our first try to quantify the absorption of mineral dust.

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PERFORMANCE OF PULSED-SHOT LII COMPARED WITH REFERENCE RBC MASS

MEASUREMENTS

J.-F. YUAN, J. C. CORBIN, R. L. MODINI and M. GYSEL

Paul Scherrer Institut, PSI Villigen 5232, Switzerland

Laser-induced incandescence (LII) is a powerful in-situ method for refractory black carbon (rBC) mass quantification. Currently there are two commercial LII instruments. One is a continuous wave LII (“SP2: Single Particle Soot Photometer, Droplet Measurement Technologies, CO, USA”) and the other one is a pulsed-shot LII (LII-300, Artium Inc, CA, USA). SP2 provides detailed physical information including rBC mass in every single particle, rBC core size distribution and mixing state. Pulsed-shot LII only provides rBC mass concentration and average effective primary particle size while it has wider detection range, with a new High-Sensitivity mode pushing down the lower limit of quantification to ~0.05-0.2 µg m-3. This study, aiming at assessing the performance of the commercial Artium pulsed LII instrument in both its Normal and new HS mode, is conducted with laboratory and field measurements following these research questions: What is the limit of detection of either mode? Does the HS mode agree with Normal mode measurement? Does measured rBC mass concentration agree with a reference measurement? Does the level of disagreement or agreement depend on BC type (fullerene soot, CAST soot and Aquadag), mass concentration and/or BC particle size? In our experiments, the reference rBC mass is that from SP2 referenced to an APM (Particle Mass Analyzer), i.e. the SP2 was specifically calibrated to each BC type using the APM. The current outcomes of the lab studies are as follows: a) The detection limit of Normal and HS mode is at rBC mass concentrations of 0.5 and 0.06 µg m-3, respectively; b) The HS mode agrees within ~10% with the Normal mode. However, this small bias only applies if the color temperature has been determined with the normal mode measurements of the same BC type c) Large discrepancy exists between Artium LII-300 reported values and reference rBC measurement (SP2-APM). The discrepancy depends mainly on BC type, rBC mass concentration and to a lesser extent on size distribution. Therefore, we recommend careful use of LII results and cross-calibration using a reference rBC measurement. In further experiments we will explore if the Artium LII-300 rBC measurement is cross-sensitive to coating around the rBC cores and how it perform in ambient measurements. Artium Inc., CA, USA, AC-LII Manual, 2015.

Schwarz et al., J. Geophys. Res. 111, D16207, 2006.

Moteki and Kondo, Aerosol Sci. Technol. 44, 663-675, 2010.

Laborde et al., Atmos. Meas. Tech. 111, D16207, 2012.

Michelsen et al., Progress Energy Combust. Sci. 44, 663-675, 201, 2015.

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Observation

COMPARISON OF ACTIVE AND PASSIVE A-TRAIN SENSORS USED IN AEROSOLS ABOVE CLOUDS RETRIEVALS AND CHARACTERIZATION

Lucia DEACONU a, Fabien WAQUET a, Damien JOSSET b, Nicolas FERLAY a, Nicolas PASCAL c, Philippe GOLOUB a, Fanny PEERS d, Fabrice DUCOS a, François THIEULEUX a

a Laboratoire d’Optique Atmosphérique (LOA), Université de Lille 1 Sciences et Technologies, Villeneuve d’Ascq France

b US Naval Research Laboratory, NASA Stennis Space Center c ICARE Data and Service center, Université de Lille 1 Sciences et Technologies,

Villeneuve d’Ascq France d College of Engineering, Mathematics and Physical Sciences (CEMPS),

University of Exeter, UK

Up to now, the impact of the aerosols located above clouds (AAC) on the Earth’s radiative budget, clouds and water cycle has not been accurately quantified (IPCC, 2014). In the assessment of the aerosol radiative effect the AAC were recently highlighted as a large source of uncertainty due to the lack of detailed knowledge on the optical properties of the aerosols, mainly aerosol optical thickness and absorption.

In this study we compare different techniques developed for the A-Train sensors CALIOP and POLDER/PARASOL to retrieve the AAC optical properties. In order to check the consistency between the retrievals of active and passive instruments we compare the optical thickness of aerosols above clouds (ACAOT) and their Ängström exponent (AE) measured with CALIOP operational method, CALIOP-based depolarization ratio method (DRM) - implemented on the ICARE archive center as SODA, and POLDER operational polarization method. We analyze six months of data over three distinctive regions characterized by different types of aerosols and clouds. We also study 4.5 years of data over the entire globe for distinct situations where aerosol and cloud layers are in contact or vertically separated.

The results of regional comparisons show an excellent ACAOT agreement between DRM and POLDER when the particle size distribution is dominated by either fine biomass burning aerosols, or coarse dust particles. Larger differences are however found for regions where complex mixtures of aerosols are expected. On the global scale, there is a good agreement between POLDER and DRM ACAOT retrievals when the aerosol layer is well distanced from the cloud layer below, but dramatic decrease of the ACAOT correlation is found when the aerosol-cloud layers are in contact, suggesting that the presence of aerosols within the cloud layer might affect the methods. Finally, we use the altitude of clouds and aerosols retrieved from CALIOP and the new POLDER ACAOT absorption product and absorption-corrected cloud optical thickness to determine the direct radiative forcing and the heating rates of AAC for regional cases.

IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp

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FIRST LIDAR REMOTE SENSING OBSERVATION OF STRONGLY LIGHT ABSORBING PARTICLES BY LIGHT-INDUCED INCANDESCENCE

Alain MIFFRE, Tahar MEHRI, Patrick RAIROUX

Institute of Light and Matte, 10 rue Ada Byron, 69622 Villeurbanne, France

In this contribution, we present the result of an Optics Express publication [1] reporting on the first Lidar remote sensing observation of light-induced-incandescence in an urban atmosphere, which allows retrieving the vertical profile of very low thermal radiation emitted by the carbon aerosol, in agreement with Planck’s law, over several hundred meters altitude.

Starting from Planck and Kirchhoff’s laws, the thermal radiation emitted by a laser-illuminated particle volume is evaluated at a range R from a Lidar laser source. Since incandescence occurs over a characteristic time �, the LII-Lidar signal takes the mathematical form of a convolution product in which the Planck’s distribution is involved. After setting the LII-Lidar equation, we identify the main requirements for operating the LII-Lidar methodology in the low troposphere by numerically simulating it. Two experimental configurations are then proposed, allowing either spectrally-resolved LII-Lidar measurements over a range interval in agreement with Planck’s law (see Fig. 1a), or range-resolved LII-Lidar measurements at a single detection wavelength (see Fig 1b). This new Lidar methodology, which allows to specifically address strongly Light-Absorbing Particles in the atmosphere, may be useful for developing carbon emission reduction strategies and for radiative forcing issues [2].

Fig. 1(a): Spectrum of the LII-lidar signal [1], in agreement with Planck’s law (continuous increase apart from Raman vibrational sidebands). (b): Vertical profile of LII-lidar signal in Lyon urban city’s troposphere [1].

References [1] Miffre, A., C. Anselmo, S. Geffroy, E. Fréjafon and P. Rairoux: Lidar remote sensing of laser-induced incandescence on light absorbing particles in the atmosphere, Opt. Expr., 23, 2347-2360 (2015). [2] IPCC, Climate Change 2013: The Physical Science Basis. Working Group I, (2013).

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Observation

THE TEMMAS PROJECT

Pierre-Yves FOUCHER a, Alexandre ARMENGAUD b, Guillemette COURTIER c, Philippe DELIOT a, Olivier DUCLAUX c, Amandine DURAND d, Michel FRACES a,

Thierry HUET a, Catherine Juery c, Jean-François LEON e, Yelva Roustan f, Claire SARRAT a, Brice TEMIME-ROUSSEL d, Henri WORTHAM d

a ONERA, The French Aerospace Lab, Toulouse Center, 2 Av. Edouard Belin, 31055 Toulouse, France

b AIRPACA, 146 rue Paradis, 13006 Marseille, France

c Total Raffinage Chimie, Centre de recherche TOTAL, 69360 Solaize, France

d c Aix Marseille Univ, CNRS, LCE, Laboratoire de Chimie de l'Environnement, UMR7376, 13331, Marseille, France

e Laboratoire d’Aerologie, Université Toulouse, Observatoire Midi-Pyrénées, Av Edouard Belin, Toulouse France

f CEREA, Joint Laboratory Ecole des Ponts ParisTech/EDF R&D, Université Paris-Est, 77455 Champs-sur-Marne, France

We present measurement protocols and first associated results of the TEMMAS (TEledetection, Measure, Modeling of Atmospheric pollutants on industrial Sites) project, supported by the French environment agency (ADEME). It included two intensive measurement campaigns which were conducted in the vicinity of a refinery in the south of France, in September 2015 and February 2016. During these two campaigns, a wide range of ground based and airborne instrumentation was deployed: (i) samples collection inside the principals emitters or stacks; (ii); (ii) samples collection at different locations on the ground inside the refinery ; (iii) samples collection and online measurements of microphysical properties of PM and trace gas concentrations in the first kilometers outside the refinery; (iv) balloon sounding at 300m height at a fixed point outside the refinery; (v) airborne hyperspectral imagery in the reflective domain over the refinery and the whole area of experiment, (vi) sunphotomer measurements inside and outside the refinery and (vii) LIDAR measurements inside the refinery . The aim of these campaigns were to study the refinery PM microphysical signatures and their evolution within the first kilometers away from the refinery.

The first analysis shows connections between these various observations, in particular we observe a link between PM microphysical properties at different distances from the refinery sources and gas trace concentrations consistent with wind measurement and local environment (highway or sea influences). Even though the PM concentration levels were quite low during the campaigns, optical remote sensing measurements and Lidar measurement can be locally compared to in-situ PM properties measurements and to model results.

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BIOGENIC AEROSOL FORMATION IN THE LITHUANIAN BOREAL FOREST

Vadimas DUDOITIS, Steigvilė BYČENKIENĖ, Kristina PLAUŠKAITĖ, Dalia

JASINEVIČIENĖ, Genrik MORDAS, Vidmantas ULEVIČIUS

SRI Center for Physical Sciences and Technology, Sauletekio av. 3, LT- 10257 Vilnius, Lithuania

Aerosol particle observations are needed to determine the conditions under which particles can form and grow in different environments. This research focuses on new particle formation (NPF) events in the rural-forest R�gšteliškis station (55°26’N and 26°04’E, 170 m a.s.l.). During the warm season, from April 8th to October 6th of 2016, the measurements of the ultrafine (3 – 100 nm) particle number size distributions were conducted with scanning mobility particle sizer (SMPS). Days were classified according to Yli-Juuti et al., 2009, into several categories (class Ia, Ib, II, apple, mixed-type and non-event). It was estimated that around 36% of days in spring and 19% in summer were event days. Three distinct particle modes were classified: 1st nucleation (3 – 10 nm), 2nd nucleation (10 – 25 nm) and Aitken mode (25 – 100 nm). The NPF occurred mostly in the April, May and June. The highest contribution of the 1st and 2nd nucleation particle modes was observed in May and June, reaching up to 34% of the total number concentration. Sulphuric acid was used as the primary component affecting particle growth during NPF (Kulmala et al., 2014). The estimated growth rate (GR) and condensation sink (CS) values at R�gšteliškis station in April and May were 2.9 nm·h–1, 7.0·10–3 s–1 and 5.3 nm·h–1, 6.4·10–3 s–1, respectively. The aerosol particle GR and CS were compared with the results from other measurement sites, located in the boreal forests of the Baltic sea region. The average GR and CS values were 3.9 nm·h–1, 4.8·10 –3 s–1 in Aspvreten, 3.0 nm·h–1, 3.2·10–3 s–1 in Hyytiälä and 2.5 nm·h–1, 1.2·10–3 s–1 in Pallas stations (Dal Maso et al., 2007). In comparison, the GR for the stations situated in the South was higher than for the ones – in the North. The CS in R�gšteliškis was one of the highest in the region. It suggests that biogenic VOCs were one of the factors, influencing aerosol formation process.

This work was supported by the National Research Programme "Sustainability of agro-, forest and water ecosystems" project FOREstRESS (No. SIT-3/2015).

[1] T. Yli-Juuti, I. Riipinen, P. P. Aalto et al., Characteristics of new particle formation events and cluster ions at K-puszta, Hungary. Boreal Environ. Res. 14(4), 683–698 (2009).

[2] M. Dal Maso, L. Sogacheva, P. P. Aalto et. al, Aerosol size distribution measurements at four Nordic field stations: identification, analysis and trajectory analysis of new particle formation bursts, Tellus B 59, 350 (2007).

[3] M. Kulmala, T. Petäjä, M. Ehn et al., Chemistry of atmospheric nucleation: on the recent advances on precursor characterization and atmospheric cluster composition in connection with atmospheric NPF, Annu. Rev. Phys. Chem. 65(1), 21-37 (2014).

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Observation

INFLUENCE OF AFRICAN DUST EVENTS ON THE ATMOSPHERIC MIXING LAYER HEIGHT AND SURFACE PM10 CONCENTRATIONS IN CENTRAL SPAIN.

Marcos BARREIROa, Pedro SALVADORa, Begoña ARTÍÑANO a, Francisco MOLERO a, Isabel MARTÍNEZ MARCOb, Aránzazu REVUELTAb, Marco PANDOLFI c, Aurelio TOBÍAS c,

Xavier QUEROL c

aEnvironment Department- CIEMAT-Unidad Asociada en Contaminación Atmosférica CSIC-CIEMAT, Avenida Complutense 40, 28040 Madrid,Spain

bAgencia Estatal de Meteorología (AEMET), c/Leonardo Prieto Castro 8, 28071, Madrid, Spain

cInstitute of Environmental Assessment and Water Research (IDÆA-CSIC), c/Jordi Girona 18, 08034, Barcelona, Spain

The mixing layer height (MLH) represents the depth of the lower troposphere layer through which air pollutants can be effectively dispersed. The MLH is frequently well correlated with the height of a temperature inversion base, especially at daytime. Pandolfi et al. (2014) suggested that the transport of African dust over specific geographic areas affects the MLH due to the formation of upper thermal inversions at the bottom of the warm African air mass. During the period February 2011-December 2015, a robust procedure based on the daily interpretation of air mass back trajectories and meteorological products (Escudero et al., 2007), was used to identify all the African dust events (ADE) with impact in the PM10 (particulate matter with aerodynamic diameter <10 µm) levels that occurred in the central region of Spain.This procedure also allows estimating the impact of the African dust on the PM10 daily records registered at monitoring sites by quantifying the dust load (DL) deposited during each ADE. The higher the DL levels, the more intense the ADE.The midday MLH in the Madrid area was calculated by using the data from radiosondes launched at the Madrid Airport and LIDAR products obtained at CIEMAT.A total of 1736 MLH values were determined, for the period under study. 310 out of them corresponded to ADE. Daily levels of PM10 from an urban-traffic monitoring station, belonging to the Madrid City Council Air Quality Network were also evaluated.Our results showed that under ADEin Madrid, the MLH significantly decreased and the mean PM10 levels increased in correlation with the intensity of the ADE. There is a twofold explanation for the increase in the mean PM10 levels: not onlythe DL contributed to increase the PM10 concentrations but alsothe observed MLH reduction during ADEfavored the accumulation of PM10 emissions from local sources.

Escudero M. et al., 2007. A methodology for the quantification of the net African dust load in air quality monitoring networks.Atmos. Environ. 41, 5516-5524.

Pandolfi M. et al., 2014. Effect of atmospheric mixing layer depth variations on urban air quality and daily mortality during Saharan dust outbreaks.Sci. Total Environ., 494-495, 283-289.

This work was funded by research project “Propiedades del aerosol atmosférico en diferentes escenarios espacio-temporales y su influencia en el clima (PROACLIM -CGL2014-52877-R)”.

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NANOCOMPOSITES TRACING THE PHENOMENOLOGY OF AEROSOL-LIGHTNING INTERACTIONS: PART 2. DATABASE

Marie-Agnès Courtya, Pascal ANDREb, Raymond PICCOLIc, Jean-Michel MARTINEZa

a PROMES UPR 8521 CNRS - Univ. Perpignan. Tecnosud, Perpignan, France

b LPC, Univ. Clermont Auvergne, CNRS/IN2P3, UMR6533, F-63000 Clermont-Ferrand, FR c Lab. de Recherche sur la Foudre, UR Pégase, 15270 Champs-sur-Tarentaine,

France

At present, observation do not allow to well understand how increased aerosols in response to vegetation burning results into rainfall suppression and transport of smoky clouds leading to delayed lightning activity along to violent convective storms. We present here the coupled observational/experimental method aimed to better identify the diagnostic signatures left by electrification phenomena on aerosols. The observational method comprises the collect of particulate matter issued from three types of electrification events: (1) surface materials (soil, water) sampled at the exact spots where lightning stroke the ground; (2) short rain spells of fine debris now traced for three years from a pilot region in South France (Perpignan) which occur soon after lightning on the Mediterranean coast; (3) exceptional showers of coarse scoria-like debris which occurred twice at two closed spots of the pilot region after exceptional thunderstorms with a few hours lightning flashes on the Mediterranean coast. The experimentation is based on arc discharges using a copper fuse wire within a wooden box filled with mixed materials: quartz sands, lime, chalk, charcoal and water. The experimentation is aimed to produce similar transformations and products than the ones identified in lightning situations. The database of electrification signatures is established from the characterization from meso down to nanoscales of particulate matter without upper or lower size limit, using binocular microscope, SEM-EDS, HRTEM, XRD, FTIR-Raman spectrometry and isotope analyses. Compared to the intact aerosols or experimental materials, four types of phenomena with their distinctive signatures are identified: (1) segregation of elements by charge and composition and their agglomeration into nanostructured clusters, droplets, films, filaments and cristallites, particularly synthesized quartz; (2) steam extraction of condensable products that recombine into nanostructured polymers and agglomerates, leaving dense fritted solids enriched in refractory minerals; (3) shock-induced structural transformation, i.e. vitrification and plasticization of charcoal; (4) partial melting due to transient heating leading to quenched vesicular glassy solids of heterogeneous composition with cristallites, metal and carbonaceous inclusions. The study shows how efficient extraction of metals from trace impurities in the precursor sources by repeated discharges increases electrical conductivity of aerosols, resulting into enhanced electrification. Nanocomposite synthesis is simultaneously enhanced due to the increased concentration of metal catalysts. The data base allows to link exceptional electrification events to the convective mixing of pyro-clouds and Saharan dust resulting in the gravity fall of coarse composite aerosols at considerable distance from the vegetation burning area.

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ICAC 2017

Observation

AEROSOL OPTICAL THICKNESS RETRIEVAL FOR FUTURE EARTHCARE MULTI-SPECTRAL IMAGER MEASUREMENTS

Nicole DOCTER a, Florian FILIPITSCH b, Franziska SCHMIDT a, René PREUSKER a, Jürgen FISCHER a

a Institute for Space Sciences, Freie Universität Berlin, Carl-Heinrich-Becker-Weg 6-10, 12165 Berlin, Germany

b Lindenberg Meteorological Observatory- Richard Assmann Observatory, Am Observatorium 12, 15848 Tauche (OT Lindenberg), Germany

The joint ESA and JAXA mission Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) has the objective of improving the understanding of atmospheric cloud–aerosol-radiation interactions by studying the spatial distribution of clouds and aerosol and their impact on the radiative balance by employing a combination of active and passive instruments on a single platform. A stand-alone processor is developed for the derivation of aerosol distribution in the across-track direction of the satellite in support to profile information from active measurements. Its aerosol product will be based on measurements of the passive instrument Multi-Spectral Imager (MSI) on board.

MSI is a nadir push-broom imager having a 150km swath and a spatial resolution of 500m. The aerosol optical thickness (AOT) retrieval developed for its future measurements, is separated in two different approaches, one for ocean and one above land surfaces. Both procedures employ the optimal estimation technique. The forward model used in the algorithm relies on pre-calculated look-up tables of modelled reflectance. Simulations are carried out by using radiative transfer code MOMO [Hollstein and Fischer, 2012] applying the EarthCARE Hybrid End-To-End Aerosol Classification (HETEAC) model [Wandinger et al. 2016] to ensure consistency between aerosol products from the different instruments on EarthCARE.

In order to verify the proposed MSI based AOT retrieval approach before the foreseen start of EarthCARE in 2019, MODerate-resolution Imaging Spectroradiometer (MODIS) Aqua measurements as well as EarthCARE simulator (ECSIM) data are used. Hence, the retrieval and first results will be presented.

Hollstein, A. and Fischer,J.: Radiative transfer solutions for coupled atmosphere ocean systems using the matrix operator technique. Journal of Quantitative Spectroscopy and Radiative Transfer Volume 113, Issue 7, May 2012, Pages 536–548, 2012.

Wandinger, U., Baars, H., Engelmann, R., Hünerbein, A., Horn, S., Kanitz, T., Donovan, D., van Zadelhoff, G.J., Daou, D., Fischer J., von Bismarck, J., Filipitsch, F., Docter, N., Eisinger, M., Lajas, D. and Wehr, T.: HETEAC: The Aerosol Classification Model for EarthCARE. EPJ Web of Conferences, 119, 2016

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Observation

CHARACTERIZATION OF BIOAEROSOLS BY TWO DIFFERENT METHODS: OPTICAL MICROSCOPY AND A WIDEBAND INTEGRATED SPECTROMETER

Ana I. CALVOa, Darrel BAUMGARDNERb, Amaya CASTROa, Delia FERNÁNDEZ-GONZALEZc,d, Carlos BLANCO-ALEGREa, Fernanda ODUBERa, Ana M. VEGA-

MARAYc, Rosa M. VALENCIA-BARRERAc, Olivier PUJOLe, Roberto FRAILEa

aDepartment of Physics, IMARENAB University of León, 24071 León, Spain

bDroplet Measurement Technologies Inc, Boulder, CO USA

cBiodiversity and Environmental Management, University of León, Spain

dInstitute of Atmospheric Sciences and Climate-CNR, Bologna, Italy

eUniversité de Lille 1, UFR de physique, Laboratoire d’Optique Atmosphérique, F-59655 Villeneuve d’Ascq Cedex, France

A bioaerosol sampling campaign was carried out in May and June, 2015, at the university campus of León, Spain. Two different instruments were used:

i) a Wideband Integrated Bioaerosol Spectrometer (WIBS), that continuously measures bioaerosol concentration -in the size range from 0.5 to 20 µm-, using light induced fluorescence and provides a classification in four groups (bacteria, fungi, pollen or “other”);

ii) a volumetric Hirst spore trap that collects pollen grains and allows a later Optical Microscope analysis. It is a sampler for particles between 2 and 200 µm in diameter with a flow of 10 L min-1.

Hourly and daily optical microscopic counts were carried out by the method recommended by the Spanish Aerobiological Network, based on four longitudinal transects along the slides (Galán et al., 2007). The reading of the four bands represents 12.5% of the total sampling area, which is within the limit recommended by the European Aerobiology Society (EAS). Furthermore, the hourly distribution of the bioaerosol concentration as a function of the wind speed and direction was also represented and analysed.

Bioaerosol represented up to 25% of the total particle concentration in the measured size range during the studied period. The number of pollen types present in the atmosphere was 35, with Pinus, Plantago, Poaceae, Quercus, Rumex and Urticaceae contributing together 50% of the atmospheric pollen concentration.

The results obtained from data collected by both instruments were analysed and compared.

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ICAC 2017

Observation

EFFECT OF A THERMAL INVERSION ON ATMOSPHERIC PARTICULATE MATTER IN NORTHWESTERN SPAIN

Carlos BLANCO-ALEGREa, Amaya CASTROa, Ana I. CALVOa, Fernanda ODUBERa, Elisabeth ALONSO-BLANCOb, Esther COZb, André PRÉVÔTc, Olivier PUJOLd,

Roberto FRAILEa

aDepartment of Physics, IMARENAB, University of León, 24071 León, Spain

bCentre for Energy, Environment and Technology Research (CIEMAT), Department of the Environment, Madrid, Spain

cLaboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland

dUniversité de Lille 1, UFR de physique, Laboratoire d’Optique Atmosphérique, F-59655 Villeneuve d’Ascq Cedex, France

Thermal inversions are usually related to serious atmospheric pollution events. This is caused by the weather stagnating conditions consequence of a reversal of the normal temperature vertical gradient in the troposphere that produces the smallest aerosol particles to be trapped under the atmospheric mixed layer. Thus, the presence of thermal inversions in urban/industrial areas directly impacts on human health, economic activity and daily life of the population (e.g. traffic restrictions) (Viard and Fu, 2015).

The aim of this study is to examine the relationship between thermal inversions and the concentration of aerosol particles and black carbon (BC) in León (Spain). For this goal, a monitoring campaign was carried out at the university Campus of León (42° 36’ 50” N, 5° 33’ 38” W, 846 m asl), located in Northwestern Iberia, during an event of thermal inversion between 25th December 2016 and 4th January 2017.

Several instruments were used: i) an optical particle counter (PCASP-X); ii) a high resolution nanoparticle sizer (TSI-SMPS Model 3938); iii) an AE31 Aethalometer of Magee Scientific Company to measure BC concentration; iv) a Davis Weather Station, used for continuously registering the meteorological variables. In order to identify the thermal inversion, we have used the radiosounding data from La Coruña, Santander and Madrid.

The first results show an increase in the number of aerosols during the thermal inversion (about 44%), mainly for Aitken and accumulation modes with an increase of 51% and 41%, respectively. Furthermore, BC concentration increased during the inversion by 33%.

Viard, V.B. and Fu, S. (2015) The effect of Beijing’s driving restrictions on pollution and economic activity. J. Public Econ. 125, 98-115. doi:10.1016/j.jpubeco.2015.02.003

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EFFECTS ON THE RESPIRATORY TRACT OF INDOOR AND OUTDOOR AEROSOL

Fernanda ODUBERa, Amaya CASTROa, Ana I. CALVOa, Carlos BLANCO-ALEGREa, Olivier PUJOLb, Roberto FRAILEa

aDepartment of Physics, IMARENAB University of León, 24071 León, Spain

bUniversité de Lille 1, UFR de physique, Laboratoire d’Optique Atmosphérique, F-59655 Villeneuve d’Ascq Cedex, France

In this study, the aerosol size distribution between 0.1-10 µm has been measured with an optical spectrometer (PCASP-X) in two indoor and in two outdoor locations in Northwestern Spain: i) the gymnasium of the University of León (Castro et al., 2015), ii) the living room of a rural house during biomass burning in an open fireplace, and an urban area of León iii) in the transition of summer-autumn, and iv) during a vigorous forest fire, 50 km from León city, under an intense thermal inversion. The evolution of the aerosol size distributions and their characteristic parameters were analyzed. In addition, the study of the influence of this particulate matter in the respiratory health was carried out by means of the calculation of the inhalable, thoracic, tracheobronchial and respiratory fractions following the standard UNE 77213. Considering the number of particles of each size, their aerodynamic diameters and their estimated density, the percentages corresponding to the different mass fractions of aerosols deposited in the human respiratory tract were thus calculated for healthy adults and high-risk groups (children, elderly or infirm people). Since all four studied situations showed different size distributions, the particulate matter deposited on different parts of the respiratory tract has also been different, with diverse consequences on human health.

Castro et al. (2015). Indoor aerosol size distributions in a gymnasium. Sci. of the Total Env. 524-525, 178-186.

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Modeling

RELATIVISTIC CORRELATED CALCULATIONS OF THE THERMODYNAMICS PROPERTIES OF GASEOUS PLUTONIUM OXIDES

Sophie KERVAZO1,3, Florent RÉAL1, François VIROT2, André SEVERO PEREIRA GOMES1, Gosia Malgorzata OLEJNICZAK1, Paul AYERS3 and Valérie VALLET1

1UMR 8523 – PhLAM- Physique des lasers Atomes et Molécules, Univ Lille, CNRS, F-59000 Lille, France. [email protected]

2Institut de Radioprotection et de SûretéNucléaire(IRSN), PSN-RES et Laboratoire de Recherche Commun IRSN-CNRS-Lille1 ‘Cinétique Chimique, Combustion,

Réactivité (C3R), Cadarache, Saint Paul Lez Durance 13115, France

3Chemistry and Biology Chemistry, McMaster University, Hamilton, Ontario, Canada

The PUREX process has been designed for the reprocessing of spent nuclear fuel to separate uranium and plutonium from the fission products. Following the dissolution of the irradiated fuel in aqueous nitric acid, uranium and plutonium are transferred to an organic phase by intensive mixing with an organic solvent extraction (tributyl phosphate in kerosene), while fission products remain in the aqueous nitric phase. The degradation products of TBP by hydrolysis can react with nitric acid through very exothermic chemical reactions that can lead to a rapid increase of temperature in the reprocessing vessels. In the worse cases, the in-cell solvent fire is considered to be an important postulated accident even if its probability is low. In such cases plutonium is released in volatile forms such as PuO2, PuO3 or PuO2(OH)2. Our theoretical study focusses on the thermodynamics properties of those molecules, in particular the former two species for which large experimental uncertainties remain.

Figure 1: PuO2, PuO3 and PuO2(OH)2 molecules in C2v, D2h and C2 respectively

However, to assess the desired accuracy, highly accurate calculations are required including static and dynamic correlation effects as well as relativistic effects. In particular, the clear multi-reference character of the wave-function of those compounds requires that the energies of formation to be computed with multi-configurational quantum chemical methods like CASSCF and CASPT2. Spin-orbit interaction is treated a posteriori with the state-interaction RASSI method. Our results illustrate the complex multi-configurational character of PuO3 and PuO2(OH)2. The computed thermodynamics quantities reach a high accuracy allowing us to predict the composition of the released volatile products.

This work has been supported by grants funded by the French national agency for research under the contract ANR-11-LABX-0005 chemical and physical properties of the atmosphere (CaPPA).

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MODELLING IODINE INTERACTIONS WITH ATMOSPHERIC AEROSOLS

Camille FORTINa,b,c, Florent LOUISa,c, Valérie FEVRE-NOLLETa,c, Frédéric COUSINb,c, Patrick LEBEGUEa,c

aUniversité de Lille, CNRS, UMR 8522, PC2A-Physicochimie des processus de Combustion et de l'Atmosphère F-59000, France

bInstitut de Radioprotection et de Sûreté Nucléaire, IRSN, PSN-RES, Cadarache, 13115 Saint-Paul-Lez-Durance, France

cLaboratoire de recherche commun IRSN-CNRS, Lille 1 "Cinétique Chimique Combustion Réactivité (C3R), Cadarache, 13115 Saint-Paul-Lez-Durance, France

Following a severe nuclear power reactor accident, radionuclides like caesium and iodine are released into the atmosphere. Models could predict health impact and organize population evacuation if the need arises. They could be also used to evaluate the source term [1]. During the Fukushima disaster, significant differences between iodine measurements and predictions have been observed while a good agreement could be observed for caesium. This difference has to be attributed to the absence of iodine atmospheric reactivity by atmospheric dispersion codes. Indeed, parameters like deposition velocity or the dose-effect factor depends on iodine chemical speciation and physical form (gas, particle, liquid, solid). Therefore, heterogeneous reactions are important to evaluate the radiologic impact.

In a first step, an atmospheric iodine gaseous phase mechanism was developed, which contain 246 reactions resulting from a critical review of the literature data. This mechanism was implemented into 0D and 3D models. It highlighted the important reactivity of iodine with the atmospheric pollutants (NOx, O3), which can lead to formation of iodine aerosols.

In a second step, a bibliographic review was constructed about iodine species reactions and interactions with the particles. For each potentially reaction, the data are analysed and selected by following order of criteria : NIST and IUPAC recommendations, experimental data, theoretical data, and then estimations.

The gaseous phase mechanism has been completed with the heterogeneous reaction and a 0D study was performed to evaluate the iodine species speciation under various atmospheric conditions (temperature, photolysis, concentrations, ...). In the next step, it seems to be relevant to add the iodine reactivity in heterogeneous phases to the chemical-transport models (Chimere and Polair3D in our case) to have a better understanding of the Fukushima accident.

Acknowledgements This work was part of the CaPPA project (Chemical and Physical Properties of the Atmosphere), which is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-LABX-0005-01" and by the Regional Council "Nord-Pas de Calais" and the "European Funds for Regional Economic Development".

[1] Katata et al., Atmos. Chem. Phys., 2015, 15, 1029-1070.

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ICAC 2017

Modeling

IS THE AIR QUALITY OVER HAUTS DE FRANCE REGION SENSITIVE TO CLIMATE CHANGE? PRELIMINARY RESULTS BASED ON A DYNAMIC

EVALUATION OF A CHEMISTRY-TRANSPORT MODEL.

E. POTIERa, J.C. PÉRÉa and F. MINVIELLEa


Located at the heart of a dense urbanized and industrialized area, the Hauts de France region is regularly affected by atmospheric pollution episodes of both local and regional origins. In the context of climate change, changes in regional climate could modify pollutants emissions, transformations and repartition, with significant consequences on health risk exposure. Before evaluating climate change impacts, it is primordial to improve our understanding of relationships between meteorology and development of pollution episodes. Hence, this study aims at exploring the sensitivity of major pollutants species (ozone, NO2, aerosols and its main components) to meteorological variability. As a first step the methodology is based on a dynamic evaluation of the CHIMERE regional chemistry-transport model over Hauts de France region in 2010. The simulation domain covers a large part of Europe, in order to take into account regional contributions. As a second step, such evaluation will allow to explore the response of pollutants concentrations to changes in meteorological variables.

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CURRENT CHALLENGES IN MODELLING FAR-RANGE AIR POLLUTION INDUCED BY THE 2014-2015 BARDARBUNGA FISSURE ERUPTION (ICELAND)

Marie BOICHU a, Isabelle CHIAPELLO a, Colette BROGNIEZ a, Jean-Christophe PERE a, François THIEULEUX a, Benjamin TORRES b, Luc BLAREL a, Augustin

MORTIER c, Thierry PODVIN a, Philippe GOLOUB a, Nathalie SOHNE d, Lieven CLARISSE e, Sophie BAUDUINe, François HENDRICK f, Nicolas THEYS f, Michel

VAN ROOZAENDEL f, Didier TANRE a

a Laboratoire d’Optique Atmosphérique, CNRS, Université Lille 1; bGRASP-SAS; cNorwegian Meteorological Institute; dAtmo Hauts-de-France; eSpectroscopie de l’Atmosphère, Service de Chimie Quantique et Photophysique, Université

Libre de Bruxelles; fBIRA-IASB

The 2014–2015 Holuhraun lava-flood eruption of Bárðarbunga volcano (Iceland) emitted prodigious amounts of sulfur dioxide into the atmosphere. This eruption caused a large-scale episode of air pollution throughout Western Europe in September 2014, the first event of this magnitude recorded in the modern era. We gathered chemistry-transport simulations and a wealth of complementary observations from satellite sensors (OMI, IASI), ground-based remote sensing (lidar, sunphotometry, differential optical absorption spectroscopy) and ground-level air quality monitoring networks to characterize both the spatial-temporal distributions of volcanic SO2 and sulfate aerosols as well as the dynamics of the planetary boundary layer. Time variations of dynamical and microphysical properties of sulfate aerosols in the aged low-tropospheric volcanic cloud, including loading, vertical distribution, size distribution and single scattering albedo, are provided. Retrospective chemistry transport simulations at low horizontal resolution (25 km x 25 km) capture the correct temporal dynamics of this far-range air pollution event but fail to reproduce the correct magnitude of SO2 concentration at ground-level. Simulations at higher spatial resolution, relying on two nested domains with finest resolution of 7.3 km x 7.3 km, improve substantially the far-range vertical distribution of the volcanic cloud and subsequently the description of ground-level SO2 concentrations. However, remaining discrepancies between model and observations are shown to result from an inaccurate representation of the planetary boundary layer (PBL) dynamics. Comparison with lidar observations points out a systematic under-estimation of the PBL height by the model, whichever the PBL parameterization scheme. Such a shortcoming impedes the capture of the overlying Bárðarbunga cloud into the PBL at the right time and in sufficient quantities. This study therefore demonstrates the key role played by the PBL dynamics in accurately modelling large-scale volcanogenic air pollution.

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ICAC 2017

Physico-Chemical Properties

MODIFICATION OF AEROSOL PROPERTIES DUE TO RELATIVE HUMIDITY

Danielle EL HAJJa,b, Suzanne CRUMEYROLLEa, Marie CHOËLb, Isabelle CHIAPELLOa

a Laboratoire d’optique atmosphérique, UMR 8518 UFR de physique-Bâtiment P5 Université de Lille 59655 Villeneuve d’Ascq Cedex

b Laboratoire de spectrochimie infrarouge et Raman, UMR 8516-Bâtiment C5 Université de Lille 59655 Villeneuve d’Ascq Cedex

Atmospheric aerosols are fine particles suspended in the atmosphere, they have different origins, natural (sea spray, wind erosion, volcanic eruption, biogenic emissions, etc.) or anthropogenic (combustion of fuels, transport, agriculture, etc.). Atmospheric particles have direct interaction with solar and telluric radiation by scattering and absorbing radiation, leading to a cooling or warming effect, respectively, of the atmosphere. On the other hand, these particles have indirect interaction with radiation by changing the formation and the lifetime of clouds. Indeed the ability of atmospheric aerosols to take up water, known as hygroscopic properties, allows them to act as a cloud condensation nuclei (CCN); this is known as the indirect radiative forcing (Boucher, 1995; Crumeyrolle et al. 2008). Most of the time, aerosols properties (scattering and absorption coefficients, size distribution) are measured under dry conditions. However, aerosols are present in a humid atmosphere. Knowing the physical, chemical and optical properties of the aerosol particles at variable relative humidity is, thus, crucial in order to improve the understanding of aerosol effects on climate. The aim of this work is to study the evolution of aerosols optical (scattering and absorption), physical (size and number) and chemical (soluble and insoluble) properties of aerosols at different humidity. Our study is based on laboratory measurements at controlled humidity. Pure aerosols were generated, such as sodium chloride (NaCl) aerosols and dust. A core shell mixing will be then realized between these pure aerosols. The study is first conducted under dry conditions (~35% RH) to validate the instrumental set up and then measurements are performed at higher relative humidity (from 40 up to 90%) using different instruments such as an atomic force microscope equipped with an environmental cell, a nephelometer, an aethalometer and a particle counter used at different relative humidity. The experimental results are then compared to reference tables used by climate models (OPAC (M.Hess, 1998), HITRAN (L.S.Rothman, 2013), etc.). The discrepancies found will be then presented and will be used to better understand the influence of water uptake on the radiative forcing estimated by climate models (WRF). Boucher, O. (2013). Clouds an Aerosols. In O. Boucher, Climate Change 2013: The Physical Science Basis (pp. 571-657). New York: Cambridge University Press.

Crumeyrolle. (2008). Increase of the aerosol hygroscopicity by cloud processing in a mesoscale convective system: a case study from the AMMA campaign. Atmospheric Chemistry and Physics , 6907–6924.

L.S.Rothman, I. Y. (2013). The HITRAN2012 molecular spectroscopic databe. Journal of quantitative Spectroscopy & radiative transfer .

M.Hess, P. I. (1998). Optical properties of aerosols and clouds: the software package OPAC. Bulletin of the American Meteorological society.

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98

ABSTRACTS - POSTeRSPhysico-Chemical Properties

STRATOSPHERIC AEROSOL COMPOSITION AND LOADING EXPERIMENT

Mochammad S. ROMADHON a, Daniel PETERS b, Simon Proud a, Don GRAINGER a

a Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom

b Rutherford Appleton Laboratory, Harwell OX11 0QX, United Kingdom

This work describes the development of an instrument named the Stratospheric Aerosol Composition and Loading Experiment (SPARClE) that can infer two aerosol properties: particle radius and complex refractive index from a sample. This instrument uses a CCD camera and a photomultiplier tube (PMT) to measure the phase function and scattered light. Based on these data, a numerical retrieval method can be applied to calculate the aerosol properties. The advantages of this method are that there is no physical or chemical alteration of the aerosol sample-which could affect its refractive index - and also that the instrument is designed to be compact, able to fit into unmanned aerial vehicle. Calculation of the optimised position of detectors is presented and also the signal-to noise-ratio reaching the detectors (assuming Mie scattering). It is noticed that Rayleigh noise which is generated from light scattering of air molecules present in the instrument limits the size of detectable particle.

P24*

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ICAC 2017

CHEMICAL COMPOSITION AND OPTICAL PROPERTIES OF AEROSOLS MEASURED IN

SENEGAL DURING THE SHADOW CAMPAIGN

Laura-Hélèna RIVELLINIa,b, Isabelle CHIAPELLOa, Suzanne CRUMEYROLLEa, Philippe GOLOUBa, Thierry PODVINa, Emmanuel TISONb and Véronique RIFFAULT b

a Laboratoire d’Optique Atmosphérique, Université Lille 1, Villeneuve d’Ascq, 59655, France b IMT Lille Douai, Univ. Lille, SAGE - Département Sciences de l’Atmosphère et Génie de

l’Environnement, Lille, 59500, France

The aim of this study is to investigate the links between PM1 chemical composition and optical properties of aerosols based on surface in situ and remote sensing measurements. For this purpose, instruments were implemented at the AERONET station of M’Bour (Senegal) during the SHADOW (SaHAran Dust Over West Africa) campaign, over two intensive observations periods: IOP-1 (Mar. - Jun. 2015) and IOP-2 (Nov. - Jan. 2016). Submicron aerosols were chemically characterized during both IOPs and compared with column integrated (sun/sky photometer) and vertically distributed (Lidar) measurements of optical properties. In situ PM1 optical properties, i.e. extinction derived from Nephelometer and Aethalometer measurements, were retrieved from Dec. 12th to Jan. 7th, referred as SIOP-2.

During IOP-1 the surface PM1 fraction was dominated by non-refractory (NR) species (sulfate: 29% and organic matter – OM: 23%), while aerosol optical depth (AOD440) and Angström exponent (α) were on average 0.66 and 0.15, respectively, suggesting a domination by mineral dust (MD). No correlation could be inferred between AOD and surface PM1 chemical composition at daily or higher time resolution.

During IOP-2, the total PM1 fraction at the surface was dominated by unaccounted material – mainly attributed to MD ~60% – which led to a daily correlation of 0.78/0.77 between unaccounted and total/fine mode AOD440. Nonetheless, the surface PM1 extinction at 450 nm (Extis) measured during SIOP-2 appeared to be mainly driven by Fe, Black Carbon (BC) and OM (daily time resolution: r > 0.5, ~2h average: r >0.8), showing no correlation with the unaccounted fraction (r = 0.2). Biomass burning (BB) events were observed by Lidar and photometer (AOD440,fine>0.2 and SSA440 <0.9) and at the surface through high concentrations of organics and BC.

At a daily scale, despite differences in terms of fraction and height, Extis presented a good correlation with the one measured at 300 m by the Lidar (r = 0.88) and also with total/fine mode AOD440 (r = 0.58/0.78), after discarding data influenced by high altitude aerosol layers and strong local pollution events. Only low correlations were obtained between in situ submicron extinction and remote sensing optical measurements at higher time resolution, as local pollution events on site lasted less than one hour.

Our analysis highlights that locally emitted anthropogenic aerosols are strongly influencing high time resolution surface PM1 measurements but remain minor contributors to optical properties of the atmospheric column, compared to the influence of regional background aerosols like MD, or BB events.

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THERMOCHEMICAL PROPERTIES FOR IODINE NITROGEN OXIDES IN GASEOUS AND AQUEOUS PHASES

Arnaud VILLARDa,d, Laurent CANTRELb,d, Ivan CERNUSAKc, Florent LOUISa,d

aUniversité de Lille, CNRS, UMR 8522, PC2A-Physicochimie des processus de Combustion et de l'Atmosphère F-59000, France

bInstitut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, Cadarache, St Paul Lez Durance, F-13115, France

cDepartment of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Slovakia

dLaboratoire de Recherche Commun IRSN-CNRS-Lille1 ‘Cinétique Chimique, Combustion, Réactivité’ (C3R), Cadarache, Saint Paul Lez Durance, F-13115, France

When iodine is emitted in the atmosphere, naturally by the macro algae or accidently like in Fukushima, a multitude of reactions can happen. After the Fukushima accident, the nuclear safety authority had observed an important deviation between the model and the analysed samples. Since this severe accident and in order to better protect the populations, an effort is led to improve the iodine chemistry model by different teams [1]. Thermochemical properties (ΔfH°298K, S°298K, Cp = f(T))and kinetic parameters are needed as input data for chemical transport modelling tools. Such data are relatively scarce for iodine-containing species and some of them exhibit large uncertainties. Quantum chemistry methods allow obtaining reliable quantitative data within chemical accuracy (± 1 kcal mol-1).

The thermodynamic properties (Henry's law constant and standard solvation enthalpy) in aqueous phase for iodine nitrogen oxides (INO, INO2, Cis-IONO, Trans-IONO, and IONO2) have been calculated using the Turbomole and CosmothermX suite of programs [2]. The main results are shown in Figures 1-2. These properties are fundamental to know their speciation in the atmospheric conditions.

Figure 1: Comparison between the calculations and the literature for some organic groups and some halogen compounds

Figure 2: Henry's law constant for some iodine nitrogen oxides as function of the temperature between 273 and 373 K.

Acknowledgements This work was part of the MiRE project (Mitigation of outside releases in case of nuclear accident), which is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-RSNR-0013-01". This work was part of the CaPPA project (Chemical and Physical Properties of the Atmosphere), which is funded by the ANR through the PIA under contract "ANR-11-LABX-0005-01" and by the Regional Council "Nord-Pas de Calais" and the "European Funds for Regional Economic Development". We thank Slovak Grant Agencies VEGA (Grant 1/0092/14) and APVV (Project APVV-15-0105) for support. This work was performed in the frame of the international collaboration agreement between IRSN, Comenius, Lille 1, and CNRS.

[1] Saiz-Lopez et al., Atmos. Chem. Phys., 2014, 14, 13119-13143. [2] Parnis et al., Atmos. Environ., 2015, 110, 27-35.

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ICAC 2017


LONG TERM AEROSOL AGING UNDER ATMOSPHERICALLY RELEVANT CONDITIONS IN A CSTR-LIKE AEROSOL TANK

Franz FRIEBEL a, Prem LOBO b, Saskia DROSSAART VAN DUSSELDORP a, Evelyn MÜHLHOFER a, and Amewu. A. MENSAH a

a ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland b Center of Excellence for Aerospace Particulate Emissions Reduction Research,

Missouri University of Science and Technology, Rolla, Missouri, USA

Aerosol particles which are emitted into the atmosphere are exposed to different reactants and therefore change their properties. The average atmospheric lifetime ranges from several hours to more than a week. Experimental approaches which investigate the occurring changes in aerosol particle properties should ideally cover this time scale. Generally, there are two approaches to achieve/mimic these time frames. One, the concentration of reactants, e.g. Ozone or OH-radicals can be increased to trigger faster reaction rates. Two, larger aerosol tanks can be constructed to extend the observation time. Both approaches imply their specific challenges. Treating aerosols with high concentrations of oxidants bears the risk that atmospheric processes are not represented well. Extending the observation time by extending the tank volume is often technically and financially limited.

Here we present a new concept which decouples long observation times from high chamber volumes thereby allowing for low reactants concentrations and low aerosol flows.

Generally, aerosol tanks get filled once and provide a flow of aged aerosol until the reservoir is exploited. In contrary to that, the CSTR-like aerosol tank is continuously filled with fresh aerosol and provides a constant sample flow over an unlimited time scale after the tank reached its steady state. The sample flow does not consist of uniform aerosol particles but aerosol particles at different aging stages. Nevertheless, statistical challenges in subsequent data analysis can be disentangled by incorporation of the well-defined aerosol age distribution.

In Summer 20016 we conducted a lab campaign at ETH Zurich successfully applying the CSTR-like aerosol tank concept. Size selected soot particles were exposed to different ozone concentrations (0-200 ppb) and different levels of humidity (0-80%) in a 3 m3 stainless steel tank. The setup allowed observing changes in the CCN-activity of soot particles throughout an ageing period of up to 12 h.

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MORPHOLOGY AND COMPOSITION OF ATMOSPHERIC AEROSOLS IN DESERT AND URBAN ENVIRONMENTS OBSERVED BY ANALYTICAL MICROSCOPY. EFFECTS

ON OPTICAL PROPERTIES.

Florin UNGA a,b, Marie CHOËL b, Yevgeny DERIMIAN a, Karine DEBOUDT c and Philippe GOLOUB a


b Univ. Lille, CNRS, UMR 8516 - LASIR - LAboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France

c Univ. du Littoral Côte d'Opale, CNRS, EA 4493 - LPCA - Laboratoire de Physico-Chimie de l’Atmosphére, 59140 Dunkerque, France

Aerosol particles are present in the atmosphere in various sizes, shapes and chemical composition and they can exist in different mixing states, for example external or internal mixture, e.g. [Deboudt et al., 2010]. Even though the aerosols can be a heterogeneous mixture, such as internally mixed particles, most of the atmospheric remote sensing applications relies on the assumption of homogeneous particles and their external mixture. As the aerosol optical properties strongly depend on their morphology and mixing state, it is essential to observe these characteristics on real aerosol particles. Often used to determine such properties are the individual particle analyses techniques by analytical electron microscopy.

Our observations by TEM/EDX of 2569 and 5872 particles collected in urban (Lille, northern France, March 2014) and desert (Mbour, Senegal, January 2016) environments reveal that approximately 60% and 20% of the investigated particles, respectively, present a complex morphology of “core-shell” structure. The coatings appear on particles of biomass burning (e.g. C-rich), metallic rich (e.g. Fe-rich, Zn-rich) and urban dust (e.g. Si-rich, aluminiosilicate-rich, Ca-rich) in the case of urban pollution. Coatings on desert dust were found predominant on Si-rich, aluminosilicate-rich and Ca-rich particles.

Given the important presence of the observed coated particles, we, therefore, evidence the changes produced in optical properties using Mie computational code in single scattering approximation for polydisperse particle ensemble [Dubovik et al., 2006] and in particular for the case of coating using the assumption of concentric core-shell model [Yang et al., 2002]. Characteristics of the directional scattering, degree of linear polarization and the single scattering albedo have a significant role in estimation of aerosol radiative effects and in interpretation of observations. Our numerical simulations show how the particles radiative properties depend on the thickness of the shell and on its chemical composition, for a case of typical volume size distribution of urban and desert dust aerosol.

Deboudt, K. et al. (2010), J. Geophys. Res., doi:10.1029/2010JD013921. Dubovik, O. et al. (2006), J. Geophys. Res., doi:10.1029/2005JD006619. Yang, P. et al. (2002), Appl. Opt., doi:10.1364/AO.41.002740.

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ICAC 2017


GRASP RETRIEVALS OF AEROSOL CHEMICAL COMPOSITION FROM PARASOL SATELLITE OBSERVATIONS OVER AFRICA

Lei LI1, Oleg DUBOVIK1, Yevgeny DERIMIAN1, Tatyana LAPYONOK1, Gregory L

SCHUSTER2, Fabrice DUCOS1

1 Laboratoire d’Optique Atmosphérique, UMR8518, CNRS – Université Lille 1,

Villeneuve d’Ascq, France 2 NASA Langley Research Center, USA

The information about composition of atmospheric aerosols has a great importance for various aspects of monitoring and understanding of climate and environment dynamics. Such information can be obtained using in situ measurements or simulation by chemical transport models. However, in situ sampling has limited spatial and temporal coverage, while model estimations have large uncertainties. The present work enables the monitoring of aerosol chemical species from space-borne observations, providing observationally-based results with wide spatial and extensive temporal coverage. Following the ideas of Schuster et al.(2005, 2009, 2016), we relate complex refractive index to the chemical composition of aerosol particles. However, we retrieve chemical composition directly from remote sensing measurements without intermediate retrieval of the refractive index (in contrast with the above approach). Thus, the variability of complex refractive index is constrained in the retrieval by the assumed model of chemical composition. This approach is expected to both reduce the influence of modeling uncertainties on the retrieval results, and to provide additional constraints in situations where remote sensing observations do not have enough sensitivity to refractive index variability throughout the measured spectral range. The initial effort of this work has focused on identifying an optimal “chemical composition to refractive index” conversion model. With that purpose, we first tested the retrieval approach using a simplified volume-weighting model that links complex refractive index to fractions of chemical components such as black and brown carbon, quartz, iron and water, in fine and coarse size fractions of aerosol. Then the model was updated by using the Maxwell Garnett mixing rule. The retrieval concept was incorporated into the versatile GRASP algorithm (Dubovik et al. 2014), which has been designed to retrieve an extended set of atmospheric parameters from diverse remote sensing observations. Then a series of sensitivity tests using synthetic data of POLDER/PARASOL polarimeter data were conducted, and these tests were followed by inversion of real PARASOL observations. The sensitivity tests showed that utilization of both the volume-weighted and Maxwell Garnett based models allows the retrieval to distinguish amongst the assumed chemical species. Results obtained from real PARASOL data demonstrated good agreement with the optical characteristics provided by AERONET (e.g., r2 of ~0.9 or higher for aerosol optical thickness). In addition, the obtained patterns of chemical component distribution agreed with known physical expectations. For example, the fine mode mass concentration of black and brown carbon in the biomass burning region was found about five times higher than in the region mainly affected by dust. On the contrary, the coarse mode mass concentration of quartz in western Africa is up to seven times higher than in southern Africa.

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ENVIRONMENTAL MOLECULAR BEAM STUDIES OF MOLECULAR LEVEL INTERACTIONS BETWEEN WATER AND A CONDENSED NOPINONE SURFACE

Sofia M. JOHANSSONa, Xiangrui KONGa,b, Erik S. THOMSONa, and Jan B. C. PETTERSSONa

a Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, Sweden

b Laboratory of Environmental Chemistry, Department of Energy and Environment, Paul Scherrer Institute, Switzerland

Biogenic highly volatile organic compounds such as β-pinene are emitted to the atmosphere in abundance by coniferous vegetation where they undergo rapid gas phase oxidation, and thereby produce lower volatility compounds like nopinone. These lower volatility compounds may participate in new particle formation or condense on existing particles. Water uptake on these organic surfaces will influence their chemical composition as well as their physical properties and thus alter the impact these aerosol particles may have on the climate. In this work we present novel experimental observations of water interactions with nopinone employing the Environmental Molecular Beam (EMB) method.1 The EMB technique enables studies of molecular level interactions at near ambient pressure, generating information about molecular collision dynamics, including scattering, desorption, and accommodation. Here a solid nopinone surface is condensed from the vapour phase and probed at a temperature of 200 K using pulses of water (D2O) molecules. The water molecules are directed onto the nopinone surface and the resulting molecular flux from the surface is detected over a wide range of scattering angles. The experimental results indicate that water accommodation on the nopinone surface is close to unity after which a large fraction is rapidly desorbed. Despite the seemingly hydrophobic properties of individual nopinone molecules, the efficient surface uptake is substantial on the time scale of the experiments. This work illuminates the underlying molecular processes that control water interactions with the atmospherically relevant nopinone surface. Connections to and the implications for the behaviour of the large reservoir of atmospheric volatile biogenic compounds are discussed.

References:

S.M. Johansson, X.R. Kong, P. Papagiannakopoulos, E. S. Thomson, and J.B.C. Pettersson, A Novel Gas-Vacuum Interface for Near Ambient Pressure Molecular Beam Studies. Submitted to: Review of Scientific Instruments

P30*

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ICAC 2017


CHEMICAL AND OPTICAL PROPERTIES OF VOLCANIC ASHES: EXTINCTION SPECTRA IN INFRARED AND UV-VISIBE SPECTRAL REGION

A. DEGUINE 1,2, D. PETITPREZ 2, O. PUJOL 1, L. CLARISSE 3, P. HUBERT2,1, H. HERBIN 1

2 Univ. Lille, CNRS, UMR 8522 - PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère, F-59000 Lille, France.

1 Univ. Lille, CNRS, UMR8518 - LOA – Laboratoire d’Optique Atmosphérique, F-59000 Lille, France.

3 Laboratoire de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, B-1050, Belgium

During a volcanic eruption, a large amount of aerosols are emitted into the atmosphere and are transported over large distances. By absorbing and scattering solar radiation, volcanic ashes influence strongly the Earth radiative budget (1). These particles may also affect human health (2) and for some intense event may interrupt air traffic causing significant economic losses.

Aerosols may be detected by remote sensing using for example spectrometers embarked on satellites. These instruments record the extinction signal of an atmospheric column mixing gas and aerosols contribution. In the infrared spectral region, absorption spectra are well characterized for the gas phase but some spectral features can be also identified as extinction from air mass load with aerosol. From these observations, the challenge would be to estimate the chemical composition, the size and the number concentration of the particles. For that, the knowledge of the optical properties is needed, because it is the link between the chemical and the physical properties to the optical properties.

For this purpose, a new experimental setup has been used in order to measure the extinction spectra of various sampling aerosols in a large spectral range. Mechanical system is used to generate a cloud of volcanic ashes carried by a flow of nitrogen (5L/min). The aerosols are directed through two spectrometers recording the extinction spectra from UV-visible (MAYA 2000 PRO, Ocean Optics 200 to 1100nm) to Infrared spectral region (Antaris IGS Analyser, Thermo Scientific 2,5 to 25 µm. Furthermore, aerosols are characterized by their size distribution using an aerodynamique particle sizer (0,). These experimental data are used to retrieve the optical constants n and k leading to the complex refractive index m. The knowledge of m at each wavelength allows identifying in an atmospheric column probed by satellite the contribution of aerosols in absorption spectra.

This methodology has been applied for nine volcanic ashes samples collected from Chile (Cordon Caulle, Chaiten, Calbuco) and Island (Grimsvötn, Eyjafjallajökull). Moreover, a chemical analysis has been performed for each sample using X-ray diffraction (XRD) in order to determine the link between chemical and optical properties.

(1) Zhon Qingbo. A STUDY ON THE INFLUENCE OF VOLCANIC ERUPTION ON ATMOSPHERIC RADIATION TRANSFER [J]. GEOGRAPHICAL RESEARCH, 1993, 12(3): 19-25. (2) Durant, A. J., Bonadonna, C.,&Horwell, C. J. (2010). Atmospheric and environmental impacts of volcanic particulates. Elements, 6, 235-240

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ANALYSIS OF THE 3-METHOXYPHENOL CONFORMERS STABILITY BY MEAN OF HIGH–RESOLUTION THZ SPECTROSCOPY

Anthony ROUCOUa, Arnaud CUISSETa, Gael MOURETa, Daniele FONTANARIa, Cédric BRAYa, Franck HINDLEa, Robin BOCQUETa

a Laboratoire de Physico-Chimie de l’Atmosphère, Dunkerque

High-resolution THz spectroscopy of methoxyphenol compounds subscribe in the 1st Package of the CAPPA LABEX where the biogenic COSV are targeted as secondary organic aerosol precursor. Methoxyphenols are emitted in quantities during biomass fires and participate in the production of secondary aerosol whose the climate impact seems to be decisive. Biomass burning tracors present in gaseous and particular phases, there are known to be able to evolve chemically very quickly in the atmosphere. The most convincing results on the methoxyphenols were obtained at the LPCA in an atmospheric simulation chamber where their reactivity with the main oxidants of the atmosphere was studied[1] and on the AILES beamline of the SOLEIL synchrotron where the IR vibrational cross sections were recorded at low-resolution[2]. New high-resolution measurements were carried with two complementary experiments (70-210GHz):

- The Chirp Pulse - FTMW spectrometer - The versatile solid-state subTHz spectrometer (frequency multiplier chain)

First high-resolution measurements of one conformer were available from the MW region[3], new measurements of 3-methoxyphenol permit to analyse the vibrational ground and excited states of the four conformers (0,0), (180,0), (0, 180) and (180,180).

Fig.1 : Experimental subTHz spectrum and the four calculated spectra.

The fully resolved rotational spectrum of the conformers, from which amounts of informations can be derived, permits an analysis of the conformational stability.

[1] A. LAURAGUAIS et al. Atmospheric Environment 86 (2016), 155-163 [2] A. CUISSET et al. Journal of Quant. Spec. and Rad. Trans. 179 (2016), 51-58 [3] W. CAMINATI et al. Journal of mol. Spec. 161 (1993), 427-434

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ICAC 2017


THE HYDRATION PROCESS OF OXYGENATED MONOTERPENES STUDIED BY HIGH RESOLUTION SPECTROSCOPY AND QUANTUM CALCULATIONS:

A CASE STUDY OF FENCHONE

Mhamad CHRAYTEH a, Pascal DREAN a, Thérèse R. HUET a, Donatella LORU b, M. Eugenia SANZ b

a Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM, UMR CNRS 8523), Université de Lille, 59000 Lille, France

b Department of Chemistry, King’s College London, London SE1 1DB, United Kingdom

Fenchone (C10H16O) is a natural oxygenated monoterpene found for instance in essential oils of aromatic plants. Its gas phase molecular structure was recently obtained by Loru et al. [1]. The ketone (C=O) functional group is believed to be a hydration site. In this work, we present a spectroscopic study of the hydration process of fenchone in the gas phase. In order to predict their spectra, the structure of the different conformers of the mono-, di- and trihydrates as well as the components of the dipole moments along the three principal axis and the relative energies between conformers were predicted using ab initio calculations. The experimental rotational spectra of the hydrates of fenchone (C10H16O).(H2O)n (n=1,2,3) were obtained using a Fourier transform microwave spectrometer coupled to a free supersonic jet, and analyzed using a Watson Hamiltonian.

Two mono-, two di- and three tri-hydrates were experimentally found, and their structures were identified by comparison with the calculated ones. Our results are compared with those obtained in the very first study of multi-hydrates of camphor by Schnell. et al. [2].

References:

[1] D. Loru, M. A. Bermudez and M. E. Sanz, Structure of fenchone by broadband rotational spectroscopy, J. Chem. Phys. 2016, 145, 074311. [2] C. Pérez, A. Krin, A. L. Steber, J. C. López, Z. Kisiel, and M. Schnell. Wetting Camphor: Multi-Isotopic Substitution Identifies the Complementary Roles of Hydrogen Bonding and Dispersive Forces. J. Phys. Chem. Lett., 2016, 7, 154–160.

Acknowledgement: The present work was funded by the French ANR Labex CaPPA through the PIA under contract ANR-11-LABX-0005-01. The authors thank the Région Hauts de France and the European Fund for Regional Economic Development for their financial support.

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DEVELOPMENT OF A METHODOLOGY OF CHARACTERIZATION OF SECONDARY

INORGANIC AEROSOLS BY CRYO-TSEM-EDS

Sarah GUILBAUD a, Karine DEBOUDT a, Pascal FLAMENT a, Marc FOURMENTIN a

a Laboratoire de Physico-Chimie de l’Atmosphère, 189A, rue Maurice Schumann 59140 DUNKERQUE

Because of their impact on climate, biogeochemical cycles and human health (via inhalation and/or ingestion), the study of atmospheric aerosols has increased considerably in recent years. The physical and chemical characteristics of primary particles can rapidly change after their emission, by gas condensation, aggregation or heterogeneous reaction. This is especially the case for industrial aerosols, generally released in the troposphere by high-temperature processes (e.g. for steelworks and metallurgy emissions) (1). Thus, the internal composition of these individual atmospheric particles turns rapidly to a complex mixture of primary and secondary phases. Then this mixing state evolves with the aging of air masses, resulting in changes of chemical and physical properties. In this context, we challenge to describe the mixing state of aerosols and its evolution by analytical microscopy (SEM-EDS). Primary atmospheric components (aluminosilicates, calcite, soot, sodium chloride…) are relatively refractory and so stable under the electronic beam and the vacuum of the microscope. In the opposite, secondary components (ammonium nitrate or sulfate, semi-volatile organic compounds…) are rather instable and their study in conventional microscopy is very difficult. Indeed, the electron beam affects the particles very quickly and causes their destruction and evaporation in the chamber vacuum, avoiding the acquisition of EDS spectra or pictures. To prevent or limit this phenomenon called “beam damage”, a cryo-stage could be used (2). In this study, we developed a methodology for the cryo-TSEM-EDS analysis of semi-volatile particles with a diameter ranging from 100 nanometers to a few micrometers. For this purpose, a parametric study using model particles (NaCl, AlN, (NH4)2SO4 and NH4NO3) was performed. Different parameters were considered as the power and duration of the initial plasma cleaning, the beam acceleration voltage or the probe current. The influence of the spectral acquisition duration was also investigated and the different steps of the sample cryo-preparation optimized. A parallel study was carried out on the best storage temperature (ambient, 4°C, -18°C) of samples and on the choice of the sampling substrate. REFERENCES 1. Marris, H., Deboudt, K., Augustin, P., Flament, P., Blond, F., Fiani, E., Fourmentin, M. and Delbarre, H. (2012) Science of the Total Environment, 427-428, 126-138 2. Veghte, D.P., Bittner, D.R. and Freedman, M.A. (2014) Analytical Chemistry, 86, 2436-2442

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ICAC 2017


SPECTROSCOPIC STUDY OF METHYLGLYOXAL AND ITS HYDRATES: A GASEOUS PRECURSOR OF SECONDARY ORGANIC AEROSOLS

Sabath B. BTEICH, Manuel GOUBET, Laurent MARGULES, Roman. A. MOTIYENKO, Thérèse R. HUET

a Laboratoire PhLAM, UMR 8523 CNRS - Université Lille 1, Villeneuve d’Ascq,

France.

Atmospheric aerosols play an important role in influencing climate, human health and air quality. Particularly, secondary organic aerosols (SOA) have a significant effect on climate change. They are mainly produced in the atmosphere by oxidation of gaseous precursors. Fu et al. [1] have suggested α-dicarbonil compounds, such as trans-methylglyoxal (MG), as a possible precursor of SOA in clouds for its presence in large quantities in the atmosphere. Untill now, the pathway to SOA by MG is not fully characterized. Several reactions are put in competition: oxidation, oligomerization, complexes and aldol condensation reaction [2]. The characterization of SOAs precursors by laboratory techniques allows providing elements for the understanding of the process of formation of these aerosols. For this purpose, we complemented the existing pure rotational spectrum of MG in the 12-40 GHz range [3] by new records in a supersonic jet in the 4-20 GHz range (FTMW) and at room temperature in the 150-500 GHz range (mm/submm-wave spectrometer). The adjustment of the spectroscopic parameters, taking into account the internal rotation related to the presence of a methyl group, was performed using the RAM36 code. The spectra have been reproduced at the experimental accuracy. Following the study of the monomer, we have recorded and analyzed the microwave spectrum (4-20 GHz) of the MG-water complex. The most stable monohydrated complexes predicted by theoretical calculations have been identified unambiguously. The good agreement between experimental and theoretical results will permit to provide a good estimate, although purely theoretical, of the hydration energy.

[1] T.- M. Fu et al., J. Geophys. Res., 113, (2008). [2] H. E. Krizner, D. O. De Haan, J. Kua, J. Phys. Chem. A, 113,6994-7001 (2009) [3]C.E. Dyltick-Brenzinger and A. Bauder, Chem. Phys. 30, 147 (1978). [4]Acknowledgments: The CaPPA project (Chemical and Physical Properties of the Atmosphere) is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-LABX-0005-01" and by the Regional Council “ Nord-Pas de Calais » and the "European Funds for Regional Economic Development (FEDER)

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MOLECULAR MODELING OF ORGANIC COATED SEA-SALT PARTICLES

Josip LOVRIC a, Stéphane BRIQUEZ a, Denis DUFLOT a, Maurice MONNERVILLE a, Céline TOUBIN a

a PhLAM institute, UMR CNRS 8523, University of Lille, F-59655, Villeneuve d’Ascq

Sea Spray Aerosols (SSA) are among the most abundant aerosols in the troposphere (109T/year)1. These particles exhibit a significant coating by fatty acids (FA), palmitic acid (PA) being the most abundant2. As the coating can alter the interface of the aerosol, the topic of the interactions between SSA, FA and incoming gases has inspired numerous laboratory studies3. Complementary to these experiments, computational modeling at the molecular level provides valuable insights on the elementary chemical and physical mechanisms responsible for particle growth, ageing or heterogeneous reactivity.

In a first study4, we have modeled, by means of classical molecular dynamics (GROMACS Package5), a NaCl(100) surface coated with PA molecules with varying the PA coverage and the humidity at two different temperatures. We have shown that the structural organization depends strongly on the humidity with formation of organized islands of PA on the NaCl surface, as observed experimentally3.

In a second step, we have studied the uptake and reactivity of incoming NO2 molecules at the SSA surface. To describe the reactive processes, a hybrid Quantum Mechanical/Molecular Mechanics (QM/MM) approach has been used. These QM/MM studies were performed with the CP2K Package6.

This research was supported by the CaPPA project (Chemical and Physical Properties of the Atmosphere), funded by the French National Research Agency (ANR)through the PIA (Programme d’Investissement d’Avenir) under contract ANR-10-LABX-005.

1 R. Lewis, and S. E. Schwartz. Sea Salt Aerosol Production. W., DC: Am. Geophys. Union, (2004)

2 Mochida et al. (2002) J. Geophys. Res 107 (D17), 4325

3 S. Sobanska et al., Phys. Chem. Chem. Phys. 17, 10963-10977 (2015)

4 J. Lovric et al., J. Phys. Chem. A, 120,10141-10149(2016)

5 D. van der Spoel et al, Gromacs, J. Comp. Chem. 26, 1701-1718(2015) ; www.gromacs.org (2015) 6 The CP2K developers group, 2016. Available at : www.cp2k.org(accessed 2016)

P36*

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ICAC 2017


CHARACTERIZATION OF AIRPLANE SOOT SURROGATES BY RAMAN SPECTROSCOPY

R. IKHENAZENE a, C. PIRIM a, Y. CARPENTIER a, C. FOCSA a, B. CHAZALLON a

a Univ. Lille, CNRS, UMR 8523- PhLAM- Physique des lasers Atomes et Molécules,

F- 59000 Lille, France.

The number of flights and air passengers has steadily increased in the recent years, hence intensifying the emission of solid particles in the atmosphere (soot), such as those emitted by aircraft engines. These particles can have a direct or indirect effect on climate that bears consequences on the atmospheric radiative forcing, cloud formation and their lifetime (Lee et al. 2010).

In this work, we used micro-Raman spectroscopy (at 514 nm excitation wavelengths) to characterize soot particles produced by either a kerosene flame or a combustion Aerosol Standard (CAST) burner supplied with various propane-air mixture ratios producing soot samples with a wide range of organic carbon to total carbon ratios (OC/TC). The soot were design to be analogues of air-plane soot (Parent et al., 2016) to further analyzed how their physico-chemical properties influence ice nucleation in the atmosphere. The analysis of the first-order Raman bands of these soot samples is based on the deconvolution model proposed by Sadezky et al (2005). In doing so, we investigated the effects of two parameters (irradiance at sample and exposure time) on soot samples. The deconvolution of the Raman spectra allowed to determine spectral parameters (position, full width at half maximum (FWHM), ratio between the D1 band and the G band area (AD1/AG)) that shows a correlation with the structural and chemical changes of soot sample (Seong et al. 2013, Knauer et al. 2009).

Acknowledgment: This work was supported by the CORAC MERMOSE project, funded by French Civil Aviation Authority (DGAC) and by the French National Research Agency (ANR) through the PIA Programme d’Investissement d’Avenir) under contract ANR-10-LABX-005 (LABEX CaPPA-Chemical and Physical Properties of the Atmosphere).

References:

Lee, D.S., G. Pitari, V. Grewe, K. Gierens, J.E. Penner,A. Petzold, M.J. Prather, U. Schumann, A. Bais, T. Berntsen, D. Iachetti, L.L Lim, R. Sausen (2010). Atmos. Environ, 44, 4678-4734. Parent., P., Laffon, C., Marhaba, I., Ferry, D.,Regier, T.Z., Ortega, I.K.Chazallon, B., Carpentier, Y.,Focsa, C. (2016) Carbon, 101, 86-100. Sadezky, A., Muckenhuber, H., Grothe, H., Niessner, R., Poschl, U. (2005). Carbon, 43, 1731-1742. Seong, H.J., Boehman, A.L. (2013). Energy & fuels, 27,1613-1624. Knauer, M., Carrara, M., Rothe, D., Niessner, R., Ivleva, N.P. (2009). Aerosol Science and Technology, 43,1-8.

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QUEST FOR THE ATMOSPHERICALLY RELEVANT HYDROXYMETHYL RADICAL, CH2OH: ITS ROTATIONAL-TUNNELING SPECTRUM UNVEILED

Stéphane BAILLEUX a and Celina BERMUDEZ a

a Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers, Atomes et Molécules, F-59000 Lille, France

Hydroxymethyl radical, CH2OH, plays a fundamental role in many oxidative chain reactions such as those occurring in environmental chemistry. Indeed, reactions of the most abundant volatile organic gas in the atmosphere: methane, methanol and ethene with OH or O all imply the title species as a reactive intermediate. The reaction products formed are susceptible to generate atmospheric aerosols. Hydroxymethyl is also a direct product of the photolysis of glycolaldehyde which has been detected in urban air and identified as a direct emission of biomass fires. CH2OHCHO is known to be formed from the OH initiated oxidation of ethene and isoprene (C5H8, an abundant non-methane hydrocarbon in the atmosphere). Combustion chemistry is another area where CH2OH is of high relevance. For instance, the initial combustion reaction of methanol (potentially a viable green alternative fuel for compression ignition engines) is thought to be: CH3OH + O2 → CH2OH + HO2. Many of the subsequent chain propagation steps again involve CH2OH, e.g. CH3OH + HO2 → CH2OH + H2O2. These numerous reaction mechanisms show that a good knowledge of the fundamental properties of the hydroxymethyl radical is highly desirable. As a matter of fact more than 100 papers have been devoted (on both theoretical and experimental levels) to the kinetics, reaction mechanisms, the thermochemistry and spectroscopic properties of CH2OH. However since the matrix infrared spectrum of CH2OH was reported in 1973 by Jacox and Milligan,1 and until very recently,2 the quest for its rotational spectrum has defied spectroscopists. The identification we reveal together with its role in environmental chemistry is a significant advance towards the understanding of many of its key properties.

This work was supported in part by the CaPPA project (Chemical and Physical Properties of the Atmosphere: ANR-11-LBX-0005-01), the Regional Council "Nord Pas de Calais - Picardie" and the "European Funds for Regional Economic Development". The French program PCMI, the CNES and the IMOLABS project (ANR-13-BS05-0008-02) are also acknowledged. 1. Matrix isolation study of the vacuum-ultraviolet photolysis of methanol: the infrared spectrum of the CH2OH free radical – M.E. Jacox & D.E. Milligan, J. Mol. Spectrosc. (1973), 47, 148-162 2. Laboratory detection of the rotational-tunnelling spectrum of the hydroxymethyl radical, CH2OH – C. Bermudez, S. Bailleux & J. Cernicharo, Astron. Astrophys. (2017), in press.

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MODELING THE PHASE CHANGES OF BINARY AEROSOL PARTICLES INTERACTING WITH WATER: A MOLECULAR DYNAMICS STUDY

Bastien RADOLAa, Delphine VARDANEGAa, Sylvain PICAUDa, Pál JEDLOVSZKYb,c,d

a Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne Franche-Comté, Besançon, 25030, France

b Laboratory of Interfaces and Nanosized Systems, Institute of Chemistry, Eötvös Loránd University, Budapest, 1117, Hungary

c HAS Research Group of Technical Analytical Chemistry, Budapest, 1111, Hungary

d EKF Department of Chemistry, Eger, 3300, Hungary

Aerosols formed by carboxylic acids represent a significant fraction of the total organic matter in the atmosphere. These aerosols, which are often characterized by an intricate composition, generally have carboxyl groups and free hydroxyls on their surface that can form hydrogen bonds with water molecules. Organic aerosols are thus suspected to be effective condensation nuclei for water molecules in the atmosphere. The importance of such aerosols on the physico-chemistry of the atmosphere therefore requires a better understanding of their interaction with the surrounding water molecules, to which studies at the molecular level can contribute.

In the present work, we have used Molecular Dynamics (MD) simulations to study the interaction of small organic acid aggregates with water. Aerosols have been modeled by binary aggregates of formic and acetic acids interacting with a variable amount of water molecules representing different relative humidity level. Calculations have then been carried out in a temperature range of 150 K to 275 K.

Our results showed that both the temperature and the water content have an influence on the structure of the systems. Different phases have been evidenced, corresponding to a large acid core surrounded by water at low temperatures, or a water droplet with acid molecules adsorbed at the surface at higher temperature and high water content. A mixed phase was obtained at intermediate temperatures and at low water content. A slight difference was also observed in the behavior of the two acid species that can be related to the results previously obtained by considering aggregates containing only one single acid species.[Vardanega, 2014; Radola, 2015]

The present results represent an additional step toward modeling of organic Cloud Condensation Nuclei (CCN), leading to a deeper understanding of the heterogeneous nucleation of water, in the environmentally relevant context.

References

Vardanega, D., Picaud, S. (2014) J. Chem. Phys. 141, 104701.

Radola, B., Picaud, S., Vardanega, D., Jedlovszky, P. (2015) J. Phys. Chem. B 119, 15662.

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INFLUENCE OF HUMIDITY ON THE PHASE OF CARBOXYLIC ACID AEROSOLS: A MOLECULAR DYNAMICS STUDY

D. VARDANEGA a, B. RADOLA a and S. PICAUD a

a Institut UTINAM, UMR 6213 CNRS/Univ Bourgogne Franche-Comté, F-25030 Besançon, France

Organic material is ubiquitous in the Earth’s atmosphere, coming from both natural sources and anthropogenic activities. The interactions between water and organic molecules are thus currently investigated in the context of atmospheric chemistry because liquid droplets and ice particles may scavenge some of these organic molecules from the atmosphere, thus modifying the atmospheric composition and chemistry. Organic matter represents an important fraction of the fine aerosol mass which comes also from sea salt, mineral dust, black carbon, sulfates, and nitrate ammonium whose relative abundance depends on, e.g., location, time, and meteorological conditions. Atmospheric aerosols play a central role on current atmospheric research, because aerosol particles have a direct effect on climate not only by scattering and absorbing solar radiation but also by scattering, absorbing, and emitting thermal radiation.

For all these reasons, a better understanding of the interactions between water and aerosols is urgent, in order to describe in detail the capacity of aerosols to serve as condensation nuclei for water, either in a liquid or a solid state. Given the complexity of aerosol chemistry, the modeling of systems by numerical simulations is an interesting way to describe the interactions between water molecules and aerosols at the molecular level.

Classical molecular dynamics simulations have been performed to study the interaction between a variable amount of water (modeling different humidity levels) and organic aerosols. Organic aerosols were modeled by small aggregates composed by carboxylic acids, i.e. formic, acetic, propionic and butyric acids [Vardanega, 2014; Radola, 2015]. Calculations have been carried out in the temperature range of 150–275 K. The results have evidenced two situations for the acid−water aggregates, corresponding either to water adsorption on large acid grains at very low temperatures or to the formation of demixed droplets consisting of acid molecules adsorbed at the surface of water aggregates at higher temperatures and high water content. At low water content and high temperature, only a partial mixing between water and acid molecules is observed, in particular, at the surface of the aggregate. At moderate temperatures, an intermediate situation is obtained, which is characterized by a partial deliquescence of the acid aggregate.

D. Vardanega and S. Picaud, J. Chem. Phys. (2014) 141, 104701.

B. Radola, S. Picaud, D. Vardanega and P. Jedlovsky J. Phys. Chem. B (2015) 119, 15662–15674.

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ICAC 2017


PARALLEL RETRIEVAL OF AEROSOL AND CLOUD PROPERTIES AT 1KM

Adam POVEY a, Mochammad S. ROMADHON a, Greg McGARRAGH a, Caroline POULSEN b, Gareth THOMAS b, Matthew CHRISTENSEN a,b, Don

GRAINGER a



Due to similarities in their radiometric signatures, it is rarely possible to retrieve aerosol and cloud properties simultaneously from passive satellite imagery. A plethora of filtering techniques have been developed to ensure aerosol and cloud are analysed separately, which neglects interesting regions of interaction between the two and limits the spatial coverage of such products. The Optimal Retrieval of Aerosol and Cloud (ORAC) is a single algorithm that can retrieve both the aerosol and cloud properties consistent with a single measurement at the native resolution of the satellite sensor. Various metrics to identify acceptable fits to observations are provided, through which an a posteriori classification of particle type can be obtained. The ensemble of retrievals produced allows investigation of the effects of contamination and data coverage on existing products and a potential window to study aerosol-cloud interactions. Results produced within the Aerosol_cci and Cloud_cci projects will be presented, highlighting the utility of ensemble retrieval products in poorly constrained analyses.

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LABORATORY MASS EXTINCTION AND SIZE DISTRIBUTION MEASUREMENTS OF VOLCANIC ASH AEROSOL

Benjamin REED a, Mochammad S. ROMADHON a, Daniel PETERS b, Don GRAINGER a , Robert McPHEAT b,



This presentation details laboratory measurements of the mass extinction coefficient and size distribution of dispersed volcanic ash aerosol from a wide range of samples collected globally. These eruption-specific measurements can be directly applied to improve satellite remote sensing retrievals of mass columnar concentration. The experimental apparatus dispersed volcanic ash in nitrogen gas into an aerosol chamber and used two optical systems to measure spectral extinction over a broad range of wavelengths: a Fourier transform spectrometer made measurements in the infrared, and two diffraction grating spectrometers made measurements covering ultraviolet and visible wavelengths. The combined spectral range was 0.34 – 19 microns. Simultaneously, the size distribution of particles exiting the chamber was measured using a scanning mobility particle sizer (SMPS) and an optical particle counter (OPC). The SMPS and OPC covered the full particle size distribution. The results of these experiments will be presented, and will demonstrate significant variation in the extinction properties of ashes from different eruptions, particularly associated with the SiO2 absorption feature at 9.5 microns.

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ICAC 2017


RETRIEVAL OF AEROSOL COMPLEX REFRACTIVE INDICES IN THE INFRARED AND UV-VISIBLE SPECTRAL REGIONS

P. HUBERT a,b, H. HERBIN b, O. PUJOL b, L. CLARISSE c, A. DEGUINE b,a, N. VISEZ a, D. PETITPREZ a

a Univ. Lille, CNRS, UMR 8522 - PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère, F-59000 Lille, France

b Univ. Lille, CNRS, UMR 8518 - LOA - Laboratoire d’Optique Atmosphérique, F-59000 Lille, France

c Laboratoire de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, B-1050, Belgium

Due to their ability to absorb and scatter light, aerosols play an important role in the Earth’s radiative balance. However, quantitative estimations of their impacts on climate are quite uncertain due to their large spatial and temporal variability in terms of concentration and physical properties.

Measurements from remote sensing instruments are powerful tools to observe and investigate aerosol distributions from regional to global scales. Nevertheless, to fully exploit instrument capabilities, precise optical properties – dependent on chemical or mineralogical properties – are needed. These properties depend on the Complex Refractive Index (CRI), which represents one of the main sources of uncertainty in aerosol property retrievals by remote sensing.

This work aims at measuring high resolution extinction spectra of aerosols from the ultraviolet (UV) to the thermal infrared (IR) spectral region to derive accurate values of the corresponding CRI. The latter are generally performed through absorbance or transmittance measurements from bulk material or diluted particles in solid pellets leading to possible experimental limitation, such as a lack of knowledge of the particle size distribution. In this study, extinction spectra of modeled and collected aerosol by UV-visible and FTIR spectroscopy have been recorded.

Particles were dispersed by a mechanical means in a flow of nitrogen (5 L/min) within a glass container where the sample is introduced. The continuous flow of aerosol particles was introduced into a 10 m multi-pass cell within an FTIR spectrometer (Antaris IGS Analyser, Thermo Scientific) and a 1 m single-pass cell within a UV-visible-NIR spectrometer (MAYA 2000 PRO, Ocean Optics). Aerosol size distributions have been measured simultaneously with an aerodynamic particle sizer spectrometer (TSI APS 3321).

The CRI are determined using the Kramers-Krönig relations, the Mie theory and an optimal estimation method. This permits to obtain an accurate errors budget of the retrieval procedure.

The complete approach has been applied to suspended particles of amorphous and crystalline SiO2, which are the major fraction of volcanic and mineral dust aerosols. High resolution (1 cm-1 in the IR) complex refractive indices have been retrieved from 650 to 32,500 cm-1. Lastly, first results of collected samples from measurement campaigns are also presented. These results highlight the potential of the proposed approach to determine CRI, which then may be used for remote sensing applications.

This work was supported by the French National Research Agency (ANR) through the PIA (Programme d’Investissement d’Avenir) under contract ANR-11-LBX-005-11 and by the Regional Council “Hauts-de-France”.

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SIZE-RESOLVED HYGROSCOPICITY OF AMBIENT SUBMICRON PARTICLES OF THE BÁRÐARBUNGA VOLCANO PLUME OVER THE IBERIAN PENINSULA

E. ALONSO-BLANCOa, F. J. GÓMEZ-MORENOa, M. BECERRIL-VALLEa, E. COZa, M. BARREIROa, E. DÍAZa and B. ARTÍÑANOa

aEnvironment Department, CIEMAT, Avenida Complutense 40, 28040 Madrid (SPAIN)

On September 24, 2014 the ash plume of the Bárðarbunga volcano (Iceland) reached and impacted on surface on several areas of the Iberian Peninsula. The plume was detected at the CIEMAT aerosol research station, located in a suburban site in Madrid (Spain) (40° 25ʹ′ 08″₺ North, 3° 41ʹ′ 31″₺ West and 657 m asl).

A number of aerosol properties are continuously monitored at this station: size-resolved hygroscopic growth of the ash plume, in this case at 90 % of relative humidity for dry particle sizes of 50, 80, 110, 190 and 265 nm, by means of a custom built Hygroscopic Tandem Differential Mobility Analyser (HTDMA), particulate matter (PMx) levels obtained by an optical particle counter monitor (Grimm Aerosol Technik GmbH & Co., Germany) and chemical composition of non-refractory aerosol sub-micrometric species by an Aerosol Chemical Speciation Monitor (ACSM Aerodyne Research Inc.). These variables along with meteorological parameters (temperature, relative humidity, precipitation, wind speed and direction, atmospheric pressure and solar radiation) measured at the site allowed us interpreting the behaviour of the submicron aerosol within the plume including its hygroscopicity.

During the volcanic ash episode the aerosol hygroscopic growth distribution presented two well differentiated hygroscopic groups, low hygroscopicity (LH) and high hygroscopicity (HH) for the five dry particle sizes measured. The HH particle group was the dominant fraction. Hence, the growth factor (GF) rose quickly, especially for dry particle sizes of 110, 190 and 265 nm, reaching average values ~1.6. Submicrometric aerosol was composed mainly of organic compounds (39±16  %) and sulphate (38±16  %), the latter being the main responsible of the growth of the particle size during the episode.

These types of episodes are unusual at these latitudes thus results document an exceptional situation of high aerosol hygroscopic growth, especially in a traffic aerosol-dominated site like the CIEMAT station(Gómez-Moreno et al., 2011).

Acknowledgements: this work was funded by the Spanish R&D Plan under PROACLIM Project (CGL2014- 52877-R) and Madrid Regional Research Plan through TECNAIRE (P2013/MAE-2972).

References: Gómez-Moreno, F. J., Pujadas, M., Plaza, J., Rodríguez-Maroto, J. J., Martínez-Lozano, P. and co-authors 2011. Atmospheric Environment 45, 3169-3180.

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Reactivity of aerosols and their precursors

THEORETICAL STUDY OF THE REACTIVITY OF CHLORINE RADICAL WITH FATTY ACID PARTICLES

C. FOTSING-KWETCHE, S. BRIQUEZ, C. TOUBIN, D. DUFLOT

Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59650 VILLENEUVE D’ASCQ, France

Chlorine atoms are known to play a significant role in the reduction of hydrocarbons molecules, especially in the marine boundary layer and at the surface of aerosols [1]. Experiments performed by Mendez et al. [2] have shown that Hydrogen abstraction on submicron palmitic acid particles by Cl is the first step of a complex chemical mechanism. Indeed, after successive reaction with Cl• and O2, the particles are consumed and products such as oxocarboxylic and dicarboxylic acids are detected. However, the detailed mechanisms involved are still poorly understood. The goal of the present work is to study the first step of these experiments at the molecular level using classical (MM), quantum (QM) and mixed (QM/MM) approaches. Because of the large size of palmitic acid, we consider valeric (pentanoic) acid (C5H10O2) as a “proxy” to calibrate the calculation methods. Firstly, the following reactions have been investigated in gas phase at the quantum level (DFT and CCSD(T)):

C5H10O2 + Cl � C5H9O2 + HCl

C16H32O2 + Cl � C16H31O2 + HCl

Then, clusters of palmitic and valeric acids have been generated using classical molecular dynamics. These configurations are finally used with the ONIOM(QM:MM)-EE scheme to study of the effect of the environment on the H abstraction by Cl radical (reactivity at the aerosol surface).

QM MM QM/MM

References:

[1] M. Mochida et al., J. Geophys. Res. Atm. 107 (2002) AAC 1-1

[2] M. Mendez et al., Atmos. Chem. Phys. 13 (2013) 11661

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ABSTRACTS - POSTeRSReactivity of aerosols and their precursors

EFFECTS OF CRIEGEE INTERMEDIATE AND OH-RADICAL SCAVENGERS ON THE FORMATION OF NEW PARTICLES IN THE OZONOLYSIS OF

LIMONENE

Waed AHMADa,b, Alexandre TOMASa, Patrice CODDEVILLEa, Cécile COEURb, Arnaud CUISSETb

aEcole Mines-Télécom Lille Douai, Département Sciences de l'Atmosphère et Génie de l'Environnement (SAGE), 59508 Douai,

France

bLaboratoire de Physico-Chimie de l’Atmosphère (LPCA) EA 4493, Université Littoral Côte d’Opale,59140 Dunkerque, France

Limonene has a strong tendency to form secondary organic aerosol (SOA) in the atmosphere. In the present study, we investigate SOA formation from the reaction of limonene with ozone both in a laminar aerosol flow reactor and in an atmospheric simulation chamber under dry conditions. The effect of scavengers of stabilized Criegee Intermediates (sCI) and OH radicals on SOA formation was evaluated in terms of particle size distribution, aerosol mass and yield, as well as nucleation threshold. Depending on the experimental conditions, SOA yield obtained in the flow reactor ranges from 0.05 at an aerosol mass loading of 5.0 µgm-3 to 0.64 at 542 µgm-3; SOA yields between 0.33 and 1.12 corresponding to SOA masses of 32 to 776 µgm-3respectively were observed in the simulation chamber. These SOA mass yields are consistent with previous studies. The results show that the presence of an OH-radical scavenger significantly reduced SOA production. This effect may be due to changes in the OH reaction products as well as the [HO2]/[RO2] ratio. Likewise the presence of a sCI scavenger, namely acetic acid or acetone, significantly delayed the onset of particle formation and led to much lower SOA formed, with a stronger effect in the case of acetic acid than in the case of acetone. Observed changes could be linked to the reactions of the limonene sCI with the scavengers, underlining the crucial role of the sCI chemistry in the formation of SOA from limonene ozonolysis.

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ICAC 2017


MEASURING THE TEMPERATURE RESPONSE OF HIGHLY OXIDIZED MULTIFUNCTIONAL (HOM) MOLECULES IN ALPHA-PINENE OXIDATION

Lauriane QUÉLÉVER a, Kasper KRISTENSEN b, Louise NORMANN JENSEN b, Bernadette ROSATI b,c, Ricky TEIWES b,c, Henrik B. PEDERSEN c, Merete

BILDE b , Mikael EHN a

a University of Helsinki, Department of Physics, P.O. Box 64, 00014 University of Helsinki, Finland.

b Aarhus University , Department of Chemistry, Langelandsgade 140, DK-8000 Aarhus C, Denmark.

c Aarhus University, Department of Physics and Astronomy, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.

The existence of Highly Oxidized Multifunctional (HOM) molecules in the atmosphere was shown to be a resulting product from the oxidation of biogenic vapors released by terrestrial vegetation [1]. Such species were recently suggested to be key contributors to Secondary Organic Aerosol (SOA) formation [2] which further influence cloud processes and thereby climate. In this work, we present our latest results of HOM measurements from the Aarhus University cold-room smog chamber [3] which can simulate atmospheric processes at temperatures ranging from 20 °C down to -16 °C. With a high resolution nitrate-based chemical ionization Atmospheric Pressure interface Time-of-Flight (APi-ToF) mass spectrometer [4], we measured highly oxidized molecules produced upon ozonolysis of alpha-pinene at 3 different temperatures (20 °C, 0 °C and -15 °C). We compared both the variability of the chemical composition and the signal intensity changes of the HOMs during batch sampling on the 5 m3 Teflon chamber with 100 ppb of ozone and for different concentrations (10 ppb and 50 ppb) of VOC precursor. With this study, we aimed at better characterizing the chemical processes involved in the formation and evolution of HOMs when they are initiated at different temperatures.

[1] Ehn M. et al.: A large source of low-volatility secondary organic aerosol. Nature 506, 476-479 (2014).

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THE LILLE ICE NUCLEATION CHAMBER (LINC). PROGRESS TOWARD THE DEFINITION OF AN EXPERIMENTAL PROTOCOL AND RESULTS OF EARLY MEASUREMENTS

J. WU, A. FACCINETTO, S. BATUT, D. PETITPREZ, P. DESGROUX

PC2A UMR8522, University of Lille1, Bât. C11, Villeneuve d'Ascq (59655) France

The LINC is a continuous flow diffusion chamber based on the system first developed at the Colorado State University (CSU-CFDC)1 which then evolved in the Zurich ice nucleation chamber (ZINC) built at the Swiss Federal Institute of Technology2. The LINC was developed as a tool to obtain information on the dynamic of heterogeneous ice nucleation in deposition mode and in condensation freezing mode with soot particles as ice nuclei. The heterogeneous nucleation of ice particles in the troposphere can be reproduced in laboratory conditions once the physical and chemical properties of the seeding aerosols are well characterized. Hence, some critical properties of nucleated ice like the particle size distribution and the complex refractive index can be related to those of the seeding aerosols.

The main goal of this work-in-progress is to validate the experimental protocol to operate the LINC and eventually nucleate ice particles under controlled conditions. Since the measurements on the efficiency of soot particles as ice nuclei are still subject to large uncertainties, any experiment aiming to reproduce ice nucleation at laboratory scale should detail the experimental conditions as thoroughly as possible. In this work, we present a first characterization of the onset of conditions in which ice particles are nucleated inside the LINC chamber. Such characterization is especially important whenever any comparison of the data obtained in different ice nucleation chambers is to be made. Since the methodology behind the operation of ice nucleation chambers is not yet fully validated, this approach will help in creating a common measurement protocol, possibly at international level. The investigated variables include the ice layer thickness, the iced walls temperature map, the reactor flow conditions and a detailed characterization of the seeding aerosols.

The experimental data are expected to provide useful information on the heterogeneous ice nucleation mechanisms, and to help validating theoretical models representative of the ice formation dynamic in the high troposphere. The comparison of the data obtained from different measurements is expected to provide original and useful information on the interaction between soot aerosols and water.

This work is supported by Labex CaPPA and by project MERMOSE.

1 D.C. Rogers, Atmos. Res. 22 (1988) 149-181.

2 O. Stetzer, B. Baschek, F. Lüönd, U. Lohmann, Aerosol Sci. Technol. 42 (2008) 64-74.

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ICAC 2017


HETEROGENEOUS INTERACTION OF ISOPRENE WITH NATURAL GOBI DUST

Mohamad N. ZEINEDDINE a, Manolis N. ROMANIAS a, Vincent GAUDION a, Véronique RIFFAULT a, Frédéric THEVENET a

a IMT Lille Douai, Univ. Lille, SAGE - Département Sciences de l'Atmosphère et Génie de l'Environnement, 59000 Lille, France

Mineral dust constitutes a key component of atmospheric aerosols. According to recent estimations, 1600 Tg per year of mineral dust is released into the atmosphere, representing the largest mass emission rate of aerosol particles at a global scale.1, 2 Dust surfaces may provide the seedbed for specific interactions with trace gas molecules, and therefore, could play a key role in the transformation and environmental fate of many atmospheric species. Over the last years, the uptake of many reactive trace gases (e.g. HNO3, NO2, HONO, N2O5, O3, SO2, H2O2) as well as radicals species (NO3, OH and HO2) on dust (or proxies) has been determined using a variety of experimental approaches.3, 4 However, there is a lack of laboratory data regarding the heterogeneous interactions of Volatile Organic Compounds, VOCs, with mineral dust surfaces. VOCs may be adsorbed or react onto mineral particles and thus they could possibly act as an important diffuse source of gaseous organic carbon in remote areas. In the current study, the adsorption of isoprene on Gobi dust was investigated in the temperature (T) and relative humidity (RH) ranges of 253 - 358 K and <0.01 – 10%, respectively, using zero air as bath gas. The kinetic measurements were performed using a novel experimental setup coupled to a Selected-Ion Flow-Tube Mass Spectrometer (SIFT-MS) for gas-phase monitoring. The initial uptake coefficient, �0, of isoprene, ISP, was measured as a function of several parameters (isoprene mass, temperature, and relative humidity). �0 was evidenced as inversely dependent on RH and dependent on T according to the empirical expressions �0 = 2.7 × 10-10 / (0.005 + RH1.44), and �0 = (5.30 ± 1.50) × 10-7 exp [(1376 ± 133)/T], respectively. Furthermore, the adsorption isotherms of isoprene were determined and the results were simulated with the Langmuir adsorption model to obtain the partitioning constant, KLin, as a function of RH and T according to the expressions: KLin (296 K) = 0.027 / (0.046 + RH1.52), and KLin = (1.39 ± 0.33) × 10-7 exp [(3732 ± 140)/T], respectively. The effect of increasing temperature on the reversible fraction of isoprene adsorption on Gobi dust was recorded. The atmospheric lifetime of the heterogeneous loss of isoprene onto Gobi dust was calculated for forested environments and found to be several years.

1. S. K. Satheesh and K. K. Moorthy, Atmospheric Environment, 2005, 39, 2089-2110. 2. M. O. Andreae and D. Rosenfeld, Earth Sci. Rev., 2008, 89, 13-41. 3. C. R. Usher, A. E. Michel and V. H. Grassian, Chem. Rev., 2003, 103, 4883-4939. 4. J. N. Crowley, M. Ammann, R. A. Cox, R. G. Hynes, M. E. Jenkin, A. Mellouki, M. J. Rossi, J. Troe and T. J. Wallington, Atmos. Chem. Phys., 2010, 10, 9059-9223.

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REACTIVITY OF CH3I AND CH2I2 WITH H ATOMS

Dorra KHIRIa, Florent LOUISa, Ivan �ERNUŠÁKb

aUniversité de Lille, CNRS, UMR 8522-PC2A,PhysicoChimie des Processus de Combustion et de l’Atmosphère,F-59000 Lille, France

bDepartment of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Slovakia

Organic compounds CH3I and CH2I2 have been detected in marine boundary layer in the coastal water or in the open ocean. They participate in the generation of aerosols in coastal zones. The reactions of CH3I with O, H and OH have been the subject of several theoretical studies [1-3]. The reactivity of CH2I2 with OH radicals have been also investigated recently [3]. However, the kinetic parameters and thermochemical properties of H + CH2I2 reaction are unavailable experimentally. In this work, we provide reliable kinetic and thermodynamic data for the gas phase reactions using high-level ab initio and DFT studies.

To characterize the different reaction channels, optimised structures and frequencies were computed at the MP2/aug-cc-pVTZ level of theory. More accurate potential energies were computed for geometries previously optimised using coupled cluster theory and the aug-cc-pVnZ (n=T, Q) basis sets for C and H and Peterson’s pseudo potential basis set for Iodine. The spin-orbit coupling for the iodine-containing species was evaluated at the MRCI/aug-cc-pVTZ level of theory taking the CASSCF wave function as a reference. Transition state theory is employed to provide ab initio rate constants as a function of temperature. The I-abstraction is predicted to be the major pathway for both reactions.

Acknowledgements This work was part of the CaPPA project (Chemical and Physical Properties of the Atmosphere), which is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-LABX-0005-01" and by the Regional Council "Nord-Pas de Calais" and the "European Funds for Regional Economic Development". We thank Slovak Grant Agencies VEGA (Grant 1/0092/14) and APVV (Project APVV-15-0105) for support.

[1] Misra et al. J. Phys. Chem. A 1997, 101, 7420-7425. [2] Marshall et al. Chem. Phys. Lett. 1997, 265, 48-54. [3] F. Louis et al. Comput. Theor. Chem. 2011, 965, 275-284.

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ATMOSPHERIC CHEMISTRY OF IODOUS ACID HIO2: FIELD MEASUREMENTS, THERMOCHEMISTRY, AND GAS-PHASE REACTIVITY

Sarah KHANNICHEa,e, Xucheng HEb, Matti RISSANENb, Florent LOUISa,e, Mikko SIPILÄb Ivan �ERNUSAKc, Laurent CANTRELd,e

aUniversité de Lille, CNRS, UMR 8522 - PC2A - PhysicoChimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France

bDepartment of Physics, Faculty of Science, University of Helsinki, FI-00014, Finland cDepartment of Physical and Theoretical Chemistry, Faculty of Natural Sciences,

Comenius University in Bratislava, Slovakia dInstitut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, Cadarache, St

Paul Lez Durance, 13115, France eLaboratoire de Recherche Commun IRSN-CNRS-Lille1 "Cinétique Chimique,

Combustion, Réactivité" (C3R), Cadarache, St Paul Lez Durance, 13115, France

Gaseous iodine species (I2 or CH3I) are produced in the upper ocean by marine organisms. Once released into the atmosphere, the gaseous species will undergo photolytic and ozonolysis reactions, resulting in their conversion into iodine oxides. Because of their possible implications in the destruction of the stratospheric ozone layer, IxOy species have drawn the attention of atmospheric chemists. Iodine oxides are also relevant for nuclear safety, as they can be found inside the containment of a pressurized water reactor (PWR), in the hypothetical case of a core melt accident. 131I is a short-lived, highly radioactive fission product that can leak through the reactor coolant system of a PWR.

This work focuses on iodous acid (HIO2) that can be formed by the reactions of either I atoms with HO2 radicals or IO radicals with OH radicals. The existence of HIO2 has been confirmed in field campaigns, which will be shown in this poster. Computations of thermochemical properties (∆fH°298K, S°298K, Cp = f(T)) of HIO2 isomers (HOOI and HOIO), microhydration processes together with the kinetic parameters of the gas phase HOIO + OH reaction will also be presented in this poster. The calculations were performed at the CCSD(T) level on B3LYP optimized geometries and spin-orbit coupling corrections were computed by employing the CASSCF/CASPT2/RASSI scheme. Rate constants were obtained as a function of temperature (250�2500 K). The HOIO + OH overall reaction is significantly dominated by the H-abstraction reaction pathway (HOIO + OH → OIO + H2O) at atmospheric temperatures. The role of hydrating water molecule(s) was also elucidated as the presence of water vapour may affect the structure and reactivity of iodine oxides. Implications for both atmospheric chemistry and nuclear safety will be discussed. Acknowledgements This work was part of the MiRE project (Mitigation of outside releases in case of nuclear accident), which is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-RSNR-0013-01". This work was part of the CaPPA project (Chemical and Physical Properties of the Atmosphere), which is funded by the ANR through the PIA under contract "ANR-11-LABX-0005-01" and by the Regional Council "Nord-Pas de Calais" and the "European Funds for Regional Economic Development". We thank Slovak Grant Agencies VEGA (Grant 1/0092/14) and APVV (Project APVV-15-0105) for support. This work was performed in the frame of the international collaboration agreement between IRSN, Comenius, Lille 1, and CNRS.

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RADICAL PRODUCTION AND AEROSOL SUSTAINED BY PHOTOSENSITIZERS WITHIN ATMOSPHERIC AEROSOL PARTICLES

Pablo CORRAL ARROYO a, Sébastien PERRIER b, Stéphane DUMAS b, Patrick RAIROUX c, Christian GEORGE b, Markus AMMANN a

a Paul Scherrer Institute, Energy and Environment Research Division, Villigen PSI, Switzerland

b Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France

France

c Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France

Reactions promoted by light are key in atmospheric chemistry. Some of them occur in the condensed phase of aerosols which may contain light absorbing organic compounds that provoke photochemical reactions similar to those in humic acids and proxies thereof (George et al., 2015). Our aim is to understand the role these reactions play in atmospheric photochemistry. This work explores the radical reactions initiated by UV light in mixtures of citric acid (CA) and imidazole-2-carboxaldehyde (IC), benzophenone and 4-Benzoylbenzoic acid (BBA) using NO as a probe molecule for HO2, by means of coated wall flow tube experiments. The loss of NO was measured by a chemiluminescence detector (CLD), also configured for the distinction of the products (HONO or NO2). The established mechanism of these photosensitizers goes through the production of the triplet excited state which reacts with an H-atom donor that produces a ketyl radical. This reactive species is transferring an electron to molecular oxygen, which in turn leads to production of HO2 radicals, which are released to the gas phase. Relative humidity had a strong impact on the HO2 output, which shows a maximum value at intermediate humidity around 30%, likely due to different competing effects of dilution and reactant mobility. Citric acid is the main donor but the role of other donors is assessed (shikimic acid and syringol). We measured the rate coefficient of the reaction between the triplet state of IC and the donors mentioned by means of Laser Flash Photolysis, which help supporting the mechanism and setting up a kinetic model for the system. In addition, we monitored the production of new products by in situ Scanning Transmission X-Ray Microspectroscopy in aerosol particles loaded with IC and CA. IC and BBA showed similar HO2 production rates, while the HO2 yield with benzophenone was around 10 times higher. The results demonstrate that this condensed phase photochemical oxidation pathway contributes significantly to aerosol aging.

George, C., Ammann, M., D’Anna, B., Donaldson, D. J., and Nizkorodov, S. A.: Heterogeneous Photochemistry in the Atmosphere, Chemical reviews, 2015.

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ICAC 2017


COMPARING CONCENTRATIONS OF 1-3NM PARTICLES INDOORS TO OUTDOOR MEASUREMENTS

Elina MIETTINEN a, Joonas VANHANEN a, Minna VÄKEVÄ a,

a Airmodus Oy, Erik Palménin aukio 1, 00560 Helsinki, Finland

Indoor nucleation events have been observed and reported by several researchers. But the studies mainly refer to data measured with instruments detecting only > 3 nm aerosol particles. We wanted to study the sub 3 nm particles to learn more about the possible precursors and dynamics of these particles indoors and to compare the observations with outdoor measurements. Outdoor measurements have shown that small clusters and/or ions with diameters < 3 nm are constantly present, even outside nucleation events. Kontkanen et al. (2016) introduce measurements at nine different urban and rural sites around the world. Their study e.g. shows that concentrations of sub-3 nm particles outdoors have a diurnal variation.

Indoor air was measured with an A11 nano Condensation Nucleus Counter (nCNC) that gives the number size distribution of 1-4 nm and total number concentration of all submicron aerosol particles (Vanhanen et al. 2011). Both neutral and charged particles are detected. To compare with existing outdoor data, the concentrations of 1-3 nm and 3-1000 nm particles were calculated. A few occasions were observed when the concentration of sub 3 nm particles was higher than the concentration of 3-1000 nm particles indicating a local nucleation event. The observed numbers of sub 3 nm particles were lower than what has been observed outdoors, but they were still constantly observed with concentration ranging between a few hundred #/cc up to 3000 #/cc. Concentarions of particles larger than 3 nm varied from a few hundred up to 20 000 #/cc. Very often for the 1-4 nm particles the smallest sizes measured, size bin 1.3-1.5 nm, were most abundant. No clear diurnal variation was observed for sub 3 nm particles.

References

Kontkanen, J. et al. (2016). Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-847, in review, 2016.

Vanhanen, J. et al. (2011). Aerosol Sci. Technol., 45:4, 533-542.

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MEASUREMENT OF THE SIZE DISTRIBUTION OF NASCENT SOOT PARTICLES IN PREMIXED LOW SOOTING FLAMES OF N-BUTANE USING A 1NM-SCANNING NANO

CONDENSATION NUCLEUS COUNTER SYSTEM

Christopher BETRANCOURT1, Alessandro FACCINETTO1, Pascale DESGROUX1, Denis PETITPREZ1, Elina MIETTINEN2, Mika SVEDBERG2 and Joonas VANHANEN2

1 Univ. Lille, CNRS, UMR 8522 - PC2A - Physicochimie des Processus de Combustion et de l’Atmosphere, F-59000 Lille, France

2 Airmodus Ltd., Erik Palménin aukio 1, 00560 Helsinki, Finland In this work the Airmodus nano Condensation Nucleus Counter system A11 (nCNC) has been used to measure nascent soot particles size distribution formed in a well characterized n-butane nucleation flame[1,2]. AIRMODUS A11 nCNC is a system combining a Particle Size Magnifier (PSM) and a laminar flow butanol Condensation Particle Counter (CPC). The PSM uses diethylene glycol as a working fluid and the activation is achieved through turbulent mixing. The mixing ratio, and thus the lowest cut-point of the instrument, can be changed in scanning manner. This makes it possible to measure the size distribution of both charged and neutral particles and clusters in the size range of 1-4 nm in diameter (3). The peculiarity of the nucleation flame lies in the absence of measureable soot growth after soot inception. Therefore the soot size is very small around 1-4 nm and remains constant with reaction time by contrast with standard sooting flames in which nascent soot particles undergo coagulation, surface growth and condensation. In this flame, soot mass increases only by nucleation from the gas phase. To extract soot and combustion gases from the nucleation flame we developed a probe sampling system featuring high dilution ratio to quench post-sampling chemical reactions and to avoid nanoparticle coagulation and aggregation. We present averaged particle-size distribution functions (PSDFs). The PSDFs are in the range of 1.7-4 nm. Two modes are observed whatever the height of sampling: a mode centered at 1.8 nm and a second around 2.5nm. Origin of these two modes has been investigated and is discussed. References (1) T. Mouton, X. Mercier, M. Wartel, N. Lamoureux, P. Desgroux, Appl. Phys. B (2013) 1-11. (2) H. Bladh, N.-E. Olofsson, T. Mouton, J. Simonsson, X. Mercier, A. Faccinetto, P.-E. Bengtsson, P. Desgroux, Proc.Comb. Inst. 35 (2) (2015) 1843-1850.

(3) Vanhanen, J., Mikkilä, J., Lehtipalo, K., Sipilä, M., Manninen, H. E., Siivola, E., Petäjä, T. and Kulmala, M.: Particle Size Magnifier for Nano-CN Detection, Aerosol Sci. Technol., 45: 4, 533-542, 2011

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ICAC 2017


INTERACTION OF OZONE AND WATER WITH KI AEROSOLS

Fayçal ALLOUTIa,d, Sidi SOUVIb,d, Alexis MARKOVITSc , Florent LOUISa,d

a Université de Lille, CNRS, UMR 8522, Physico-Chimie des Processus de Combustion et de l’Atmosphère – PC2A, F-59000 Lille, France

b Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSN-RES, Cadarache, F-13115 St Paul-Lez-Durance, France

c Laboratoire de Chimie Théorique, Université Pierre & Marie Curie-Paris 6, CNRS-UMR 7616, Paris, F-75252 Cedex, France

d Laboratoire de Recherche Commum IRSN-CNRS-Lille 1 “Cinétique Chimique, Combustion, Réactivité” (C3R), Cadarache, F-13115 St Paul-Lez-Durance, France

Reactive halogen species play an important role in tropospheric chemistry, especially in the polar and marine boundary layers. They impact the oxidative capacity of the troposphere via catalytic destruction of ozone or altering NO/NO2 and OH/HO2 cycles. Because of the large surface areas of aerosol clouds, their role in the atmospheric chemistry is crucial. Although iodine species are a minor constituent of seawater, recent field studies have measured significant levels of organic and inorganic iodine in the marine boundary layer [1]. In order, to better understand the heterogenous processes that take place on marine aerosols, we modeled the first steps of interaction with atmospheric photo-oxidant such as ozone.

For example, experimental studies of ozone on a dry (100) KI leads to the formation of a passivation layer of KIO3. This reaction initiates at step edges of the surface first and then spreads across the terraces [2, 3]. Surface adsorbed water molecules induce a completely different reaction pathway that leads to the formation of gaseous iodide compounds [4].

In this context, the aim of our study is to gain more knowledge on the heterogeneous processes of solid surfaces with gas-phase reactants. We describe here the adsorption of ozone on a KI dry surface as well as the co-adsorption of ozone and water. For both systems, we compare geometries and interaction energies for different adsorption sites. Molecular simulations have been performed using the Vienna Ab initio Simulation Package (VASP).

Acknowledgements This work was part of the CaPPA project (Chemical and Physical Properties of the Atmosphere), which is funded by the French National Research Agency (ANR) through the PIA (Programme d'Investissement d'Avenir) under contract "ANR-11-LABX-0005-01" and by the Regional Council "Nord-Pas de Calais" and the "European Funds for Regional Economic Development".

[1] Huang et al., Geophys. Res. Lett., 2010, 37, L03803. [2] Brown et al., J. Phys. Chem. C, 2008, 112, 5520-5525. [3] Brown et al., J. Phys. Chem. C, 2008, 112, 8110-8113. [4] Brown et al., J. Phys. Chem. C, 2010, 114, 14093-14100.

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PHOTODEGRADATION PROCESS OF OLEIC ACID DEPOSITED ON NaCL AND MICA CLEAVED SURFACES AS SURROGATES OF NATURAL PARTICLE SURFACES.

An AFM, µFTIR AND µRAMAN COMBINED STUDY.

S. SOBANSKAa,b, M. MOREAUa, I. DE WAELEa AND Y. A. TOBONa

a LASIR UMR CNRS 8516, Université de Lille 1, Bât C5, 59655 Villeneuve d’Ascq Cedex

b ISM UMR 5255, Université de Bordeaux, bât A12, 33405 Talence Cedex

(correspondance: [email protected] and [email protected])

The importance of characterizing composition and microstructure of aerosol particles is now well-established for inferring key properties of the aerosol such as hygroscopicity, the activity of cloud condensation, the reactivity, the optical properties, etc. Aerosol particles consist of complex mixture of inorganic salts with hydrophilic and/or hygrophobic organic components which may evolved during their transportation into the atmosphere when they are exposed to gaseous traces and/or solar irradation. The properties of atmopsheric aerosols can be resolved at varying level of details including surface particle level. Indeed, the physical state of a particle surface and its composition can be resolved with a degree of spatial resolution by surface particle analytical methodology [1-4]. In this work we have investigated chemical and microstructure evolution of organic species (long-chain carboxyl acid) deposited on cleaved model surface of inorganic particles (i.e. NaCl and Mica) when they are subject to UV/Vis light simulating the atmospheric surface particle aging. The chemical composition and the surface tension of the particles were estimated using Atomic Force Microscopy (AFM), Raman microspectrometry (RMS) and FTIR spectroscopy, performed on the particle surface. The measurements were carried out for various irradiation times performed under atmospheric conditions. The phototransformation of oleic acid is well known in aqueous solution. The expected final species produced through photooxidation process are nonanal and 9-oxononanoic. These preliminary results show that the process seems similar when oleate salt is deposited on mica surface. On contrary, the phototransformation of oleate deposited on the surface of NaCl differs. The unsaturated bond clearly disappers but further investigations are needed to identify the new compounds. The adhesion force values decrease with UV irradiation indicating change of composition and structure of fatty acid when deposed on particle surface.

This work was supported by funds from the “Laboratoire d’Excellence” (LABEX) -CaPPA- (ANR-11-LABX-0005-01).

[1] Krieger et al. (2012) Chem. Soc. Rev. 41, 6631-6662.

[2] Mikhailov et al. (2009) ACP 9, 9491-9522.

[3] Morris et al. (2015) Chem. Sci. 6, 3242-3247

[4] Sobanska, et al.; PCCP, 2015, 17 (16), 10963-10977.

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ICAC 2017


PARTICULATE MATTER FORMATION FROM PHOTOCHEMICAL DEGRADATION OF CURRENTLY USED HERBICIDES

Esther BORRÁS, Milagros RÓDENAS, Teresa VERA, AMALIA MUÑOZ (*)

a Fundación CEAM. Parque Tecnológico, Paterna, Valencia, Spain. Contact: [email protected]

Pesticides are one of the most widely used chemical compounds and actually, they are emerging chemical pollutants precursors of particulate matter. Today's agriculture involves heavy use of synthetic pesticides, mainly herbicides. Their entry into the atmosphere occurs during application by volatilization and by re-suspension (Gil et al., 2005). The number of patented pesticides is very high and many families are authorized, prohibited or banned - CE 1107/2009 -. As consequence, the scientific knowledge about the behaviour of herbicides in the atmosphere is highly demanded due to their extensive use in the Mediterranean agriculture. However, there is a relative lack in the scientific knowledge about their behaviour in the atmosphere. The major routes of degradation of herbicides in the troposphere involve photolysis, ozonolysis and reactions with hydroxyl radicals. The result is a reduction of their concentration in air. However, particulate matter (PM) is formed and its toxicity, residence time and atmospheric chemical stability might be different than the original molecule. Relevant information for several of the most Mediterranean Area world-wide used herbicides has been obtained in a high volume atmospheric simulation chamber – EUPHORE - with an extensive instrumentation for monitoring the particulate matter formed. Thus, several experiments were performed in these facilities on different thiocarbamate, dinitroaniline and chloroacetonitrile herbicides. The mass concentration yields obtained (Y) were in the range 10 – 50 % for the photo-oxidation reactions in the presence and in the absence of NOx. These results confirm the importance of studying herbicides as significant precursors of atmospheric particulate matter due to the serious risks they can generate. The studies provided useful data about atmospheric degradation processes, including the formation of secondary particulate matter (PM). In fact, the fingerprint chemical composition analysis has indicated that they are a relevant source of multi-oxygenated molecules. The formation of PM is important because they play a significant role in the atmospheric chemistry, global climate change, and are related to health effects. References Gil et al., 2005. Atmospheric Environment, 39, 5183–5193. Le Person et al., 2007. Chemosphere 67, 376–383 Muñoz et al., 2012. Atmospheric Environment 49, 33-40 Muñoz et al., 2014. Chemosphere, 95, 395-401 The research leading to these results received funding from the Spanish Ministry of Economy and Competitivity (project IMPLACAVELES: CGL2013-49093-C2-1-R) and, Generalitat Valenciana for the DESETRES-Prometeo II project.

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SECONDARY ORGANIC AEROSOL PRODUCTION BY INTERACTION BETWEEN AN ORGANOPHOSPHOROUS PESTICIDE AND BIOGENIC VOCS MIXTURES Esther BORRÁS, Milagros RÓDENAS, Teresa VERA, Amalia MUÑOZ (*)

a Fundación CEAM. Parque Tecnológico, Paterna, Valencia, Spain. Contact: [email protected]

Pesticides are the chemical compounds most widely used worldwide. The entry into the atmosphere of pesticides occurs during application ore subsequent processes. Once they are emitted, they can be distributed in the gas phase or particulate phase. As with other organic compounds, pesticides removal in the atmosphere can be mainly accomplished by wet or dry deposition, by photolysis or by reaction with hydroxyl radicals (OH), nitrate radicals (NO3) and ozone (O3)[1]. All these processes give rise to the formation of other products, which could become more harmful than the starting compounds. It is therefore necessary to know all these processes to estimate the impact of pesticides in the atmosphere. In addition, it is important to study how the pesticides interact with organic compounds naturally emitted by crops and their possible impact on the formation of secondary organic aerosols, ozone and other compounds. The gas phase atmospheric degradation of an organothiophosphate insecticide has been investigated at the large outdoor European Photoreactor (EUPHORE) in the presence of a biogenic compound mixture typical from orange trees emissions. Its photolysis has been studied under sunlight conditions, in the presence of different concentration ratios of chlorpyrifos and biogenic VOCs mixture. Reaction with ozone has also been studied. Gaseous phase compounds were determined by a Fourier Transform Infrared Spectrometer (FTIR), Proton Transfer Reaction – Mass Spectrometry (PTRMS), Solid Phase Microextraction (SPME) coupled to gas chromatograph ymass spectrometry (GCMS) and NOx, O3 and SO2 monitors. Aerosol mass concentration was measured using a scanning mobility particle sizer (SMPS) and a tapered element oscillating monitor (TEOM). Chemical characterization of degradation products was done by using different off-line analysis with SPME, C18 cartridges and filters plus derivatization by GCMS. The results show that the combination of pesticide and biogenic compounds increase the SOA and O3 formation, being, in combination, high contributors to photochemical smog. This study contributes providing useful data about atmospheric degradation processes of pesticides. Knowledge of the specific degradation products, including the formation of secondary particulate matter and ozone, could complete the assessment of their potential impact. Hence, these results can contribute to the selection of sustainable strategies against plagues. Acknowledgements The authors wish to thank the EUPHORE staff. Ministerio de Economía y Competitividad for IMPLACAVELES (CGL2013-49093-C2-1-R) and Generalitat Valenciana for the DESESTRES- Prometeo II project are acknowledged. Fundación CEAM is partly supported by Generalitat Valenciana – Spain. References [1] R. Atkinson, et al. Water, Air and Soil Pollution 115, 219-243 (1999).

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ICAC 2017

Climate and Impacts

NITROAROMATIC CONSTITUENTS OF WATER SOLUBLE ORGANIC AEROSOLS: IDENTIFICATION, ABUNDANCE AND POSSIBLE SOURCES

Sanja FRKAa, b, Martin ŠALAa, Irena GRGIĆa, Janja TURŠIČc

a National Institute of Chemistry, Ljubljana, Slovenia

b Ruđer Bošković Institute, Zagreb, Croatia

c Environmental Agency of the Republic of Slovenia, Ljubljana, Slovenia

The (trans)formation, properties, and removal of organic particles remain one of the least understood aspects of atmospheric chemistry despite of their importance for both human health and climate change. Herein, nitrogen containing constituents of atmospheric organic aerosols (OA) associated with anthropogenic activities, biomass-burning (BB) and marine biological sources have considerable role. Among the largest and important groups of industrial chemicals in use today are potentially toxic nitroaromatic compounds (NACs). NACs are also confirmed as important secondary organic aerosol (SOA) constituents and the major contributors to atmospheric brown carbon1. In particular, NACs as (methyl)nitrocatehols and nitroguaiacols have recently come into the focus as a significant fraction of water soluble OA, being secondary tracers of BB emissions as well as aged anthropogenic aerosols, whose (trans)formation and properties in the atmospheric waters are only beginning to be understood2-4.

A comprehensive study on seasonal aerosol size-segregated (size range: 0.038-15.6 �m) water soluble organic matter (WSOM), with a focus on its specific NACs (e.g. 4-nitrocatechol; methyl nitrocatechols, (di)nitrophenols, methyl nitrophenols, nitrosalicylic acids, (di)nitroguaiacols, etc), through investigation of their molecular level speciation and quantification using LC/ESI-MS/MS will be presented. The obtained data were correlated with those for levoglucosan as well as with aerosol mass, total carbon, and carbon content in WSOM. On the basis of seasonal data collected at an urban background environment of Ljubljana, Slovenia, an insight into the ambient characteristics of NACs (including several new) will be given. In addition a critical evaluation of their potential sources and transformation processes in the atmosphere will be discussed.

Literature:

1. M. Claeys, et al., Environ. Chem. (2012) 9 273–284.

2. Z. Kitanovski, et al., J. Chromatogr. A (2012) 1268 35-43.

3. Y. Iinuma, et al., Environ. Sci. Technol. (2010)44 (22) 8453-8459.

4. S. Frka, et al., Environ. Sci. Technol. (2016) 50(11) 5526-35.

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ABSTRACTS - POSTeRSClimate and Impacts

INVESTIGATION OF AEROSOL OPTICAL AND RADIATIVE PROPERTIES OVER M'BOUR (SENEGAL) BASED ON MEASUREMENTS AND NUMERICAL

SIMULATIONS

J. C. PÉRÉa, L. RIVELLINIa,b, S. CRUMEYROLLEa, I. CHIAPELLOa, F. MINVIELLEa, F. THIEULEUXa and M. CHOËLc

a : Univ. Lille, CNRS, UMR 8518 - LOA - Laboratoire d’Optique Atmosphérique, F-59000 Lille, France

b : École des Mines de Douai, Département Sciences de L'Atmosphère et Génie de l'Environnement, 941 rue Charles Bourseul,

59508 Douai, France.

C : Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman,F-59000 Lille, France

The aim of this work is to estimate optical and radiative properties of aerosols and their potential feedbacks on atmospheric properties over Western Africa for the period 20 March-28 April 2015, by using numerical simulations and different sets of remote-sensed and in-situ measurements. Comparisons of simulations made by the online coupled meteorological-chemistry model WRF-CHEM with AERONET and MODIS observations result in a general agreement for AOT spatio-temporal variations. Simulated SSA reached elevated values between 0.88 and 0.96 along the visible/near-infrared in close agreement with AERONET inversions, suggesting the predominance of dust over Western Africa during this specific period. This predominance of dust is confirmed by in-situ measurements of the aerosol size distribution, fitting well with the aerosol size distribution simulated by WRF-CHEM. The impact of this large dust load on the radiative fluxes leads to large modifications of the radiative budget both at the ground and at the top of the atmosphere. In return, the response of the atmosphere to these dust-induced radiative changes is the alteration of the surface air temperature and wind fields, with non-negligible impact on the dust emission and transport.

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Climate and Impacts

THE ARTDECO RADIATIVE TRANSFER LIBRARY: A TOOL FOR STUDYING AEROSOL RADIATIVE IMPACT

Philippe DUBUISSONa, Laurent C.-LABONNOTEa, Fanny MINVIELLEa, Jean-Christophe PEREa, Mathieu COMPIEGNEb, Victor WINIAREKc

a LOA, Laboratoire d’Optique Atmosphérique, Université de Lille, 59655 Villeneuve d’Ascq, France

b HYGEOS, Euratechnologies, 165 Avenue de Bretagne, 59000 Lille, France

c AERIS/ICARE, Data and Services Center, Université Lille, 59655 Villeneuve d’Ascq, France

ARTDECO (‘Atmospheric Radiative Transfer Database for Earth and Climate Observation’) is a numerical tool that gathers models and data for the 1D simulation of Earth atmosphere radiances (total and polarized) and fluxes as measured with passive sensors (narrow and wide band models) from the UV to thermal IR range. It is developed / maintained at the Laboratoire d’Optique Atmospherique and distributed by the data and services center AERIS/ICARE (University Lille). It is funded by the TOSCA program of the French space agency (CNES). In ARTDECO, users can either access a library for the scene definition (atmosphere profile, k- distribution coefficients for gas absorption, surface, aerosol and cloud description, filter transmission, etc.) or use their own description through ASCII input files. New optical properties for aerosols and clouds can be computed. Then, the user can choose among available models (several methods for the truncation of the phase matrix, several radiative transfer equation solver) to compute radiative quantities corresponding to the scene. ARTDECO is thus a flexible tool that is especially powerful to study and optimize performances of different methodologies to model radiances and radiative fluxes for a given scene. As an application, we apply the radiative transfer library ARTDECO to calculate the radiative forcing of dust emitted and transported over the West African region. In particular, we focus on two equipped sites for aerosols observation during FENNEC campaign, in June 2011-2012.

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