Publications

2018

• Aerosol composition and the contribution of SOA formation over Mediterranean forests
  
  • Freney Evelyn
  • Sellegri Karine
  • Chrit Mounir
  • Adachi Kouji
  • Brito Joël
  • Waked Antoine
  • Borbon Agnès
  • Colomb Aurélie
  • Dupuy Régis
  • Pichon Jean-Marc
  • Bouvier Laëtitia
  • Delon Claire
  • Jambert Corinne
  • Durand Pierre
  • Bourianne Thierry
  • Gaimoz Cécile
  • Triquet Sylvain
  • Féron Anaïs
  • Beekmann Matthias
  • Dulac François
  • Sartelet Karine
  Atmospheric Chemistry and Physics, European Geosciences Union, 2018, 18 (10), pp.7041 - 7056. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas-phase measurements were deployed aboard the SAFIRE ATR42 research aircraft in summer 2014. The present study focuses on the four flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by a compact aerosol time-of-flight mass spectrometer (cToF-AMS) were dominated by organ-ics (60 to 72 %) followed by a combined contribution of 25 % by ammonia and sulfate aerosols. The contribution from nitrate and black carbon (BC) particles was less than 5 % of the total PM 1 mass concentration. Measurements of non-refractory species from off-line transmission electron mi-croscopy (TEM) showed that particles have different mixing states and that large fractions (35 %) of the measured particles were organic aerosol containing C, O, and S but without inclusions of crystalline sulfate particles. The organic aerosol measured using the cToF-AMS contained only evidence of oxidized organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic-inorganic matrices separated the oxidized organic aerosol into a more-oxidized organic aerosol (MOOA), and a less-oxidized organic aerosol (LOOA). The MOOA component is associated with inorganic species and had higher contributions of m/z 44 than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a proton-transfer-reaction mass spectrometer, such as isoprene and its oxidation products (methyl vinyl ketone, MVK; methacroleine, MACR; and iso-prene hydroxyhydroperoxides, ISOPOOH). Despite a significantly high mixing ratio of isoprene (0.4 to 1.2 ppbV) and its oxidation products (0.2 and 0.8 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX-SOA) within the aerosol organic mass spectrum (m/z 53 and m/z 82) were very weak, suggesting that the presence of Published by Copernicus Publications on behalf of the European Geosciences Union. 7042 E. Freney et al.: Aerosol composition and the contribution of SOA formation isoprene-derived SOA was either too low to be detected by the cToF-AMS, or that SOA was not formed through IEPOX. This was corroborated through simulations performed with the Polyphemus model showing that although 60 to 80 % of SOA originated from biogenic precursors, only about 15 to 32 % was related to isoprene (non-IEPOX) SOA; the remainder was 10 % sesquiterpene SOA and 35 to 40 % monoter-pene SOA. The model results show that despite the zone of sampling being far from industrial or urban sources, a total contribution of 20 to 34 % of the SOA was attributed to purely anthropogenic precursors (aromatics and intermediate or semi-volatile compounds). The measurements obtained during this study allow us to evaluate how biogenic emissions contribute to increasing SOA concentrations over Mediterranean forested areas. Directly comparing these measurements with the Polyphemus model provides insight into the SOA formation pathways that are prevailing in these forested areas as well as processes that need to be implemented in future simulations. (10.5194/acp-18-7041-2018)
  DOI : 10.5194/acp-18-7041-2018
• The EU-FP7 ERA-CLIM2 project contribution to advancing science and production of Earth-system climate reanalyses
  
  • Buizza Roberto
  • Brönnimann Stefan
  • Haimberger Leopold
  • Laloyaux Patrick
  • Martin Matthew J.
  • Fuentes Manuel
  • Alonso-Balmaseda Magdalena
  • Becker Andrea
  • Blaschek Michael
  • Dahlgren Per
  • de Boisseson Eric
  • Dee Dick
  • Doutriaux-Boucher Marie
  • Xiangbo Feng
  • John Viju
  • Haines Keith
  • Jourdain Sylvie
  • Kosaka Yuki
  • Lea Daniel
  • Lemarié Florian
  • Mayer Michael
  • Messina Palmira
  • Perruche Coralie
  • Peylin Philippe
  • Pullainen Jounie
  • Rayner Nick
  • Rustemeier Elke
  • Schepers Dinand
  • Saunders Roger
  • Schulz Jörg
  • Sterin Alexander
  • Stichelberger Sebastian
  • Storto Andrea
  • Testut Charles-Emmanuel
  • Valente Maria- Antóonia
  • Vidard Arthur
  • Vuichard Nicolas
  • Weaver Anthony
  • While James
  • Ziese Markus
  Bulletin of the American Meteorological Society, American Meteorological Society, 2018, 99 (5), pp.1003-1014. ERA-CLIM2 is a European Union Seventh Framework Project started in January 2014. It aims to produce coupled reanalyses, which are physically consistent data sets describing the evolution of the global atmosphere, ocean, land-surface, cryosphere and the carbon cycle. ERA-CLIM2 has contributed to advancing the capacity for producing state-of-the-art climate reanalyses that extend back to the early 20th century. It has led to the generation of the first ensemble of coupled ocean, sea-ice, land and atmosphere reanalyses of the 20th century. The project has funded work to rescue and prepare observations, and to advance the data51 assimilation systems required to generate operational reanalyses, such as the ones planned by the European Union Copernicus Climate Change Service. This paper summarizes the main goals of the project, discusses some of its main areas of activities, and presents some of its key results. (10.1175/BAMS-D-17-0199.1)
  DOI : 10.1175/BAMS-D-17-0199.1
• A multi-model comparison of meteorological drivers of surface ozone over Europe
  
  • Otero Noelia
  • Sillmann Jana
  • Mar Kathleen
  • Rust Henning W.
  • Solberg Sverre
  • Andersson Camilla
  • Engardt Magnuz
  • Bergstrom Robert
  • Bessagnet Bertrand
  • Colette Augustin
  • Couvidat Florian
  • Cuvelier Cornelius
  • Tsyro Svetlana
  • Fagerli Hilde
  • Schaap Martijn
  • Manders Astrid
  • Mircea Mihaela
  • Briganti Gino
  • Cappelletti Andrea
  • Adani Mario
  • d'Isidoro Massimo
  • Pay Maria-Teresa
  • Theobald Mark
  • Vivanco Marta G.
  • Wind Peter
  • Ojha Narendra
  • Raffort Valentin
  • Butler Tim
  Atmospheric Chemistry and Physics, European Geosciences Union, 2018, 18, pp.12269-12288. The implementation of European emission abatement strategies has led to a significant reduction in the emissions of ozone precursors during the last decade. Ground-level ozone is also influenced by meteorological factors such as temperature, which exhibit interannual variability and are expected to change in the future. The impacts of climate change on air quality are usually investigated through air-quality models that simulate interactions between emissions, meteorology and chemistry. Within a multi-model assessment, this study aims to better understand how air-quality models represent the relationship between meteorological variables and surface ozone concentrations over Europe. A multiple linear regression (MLR) approach is applied to observed and modelled time series across 10 European regions in springtime and summertime for the period of 2000–2010 for both models and observations. Overall, the air-quality models are in better agreement with observations in summertime than in springtime and particularly in certain regions, such as France, central Europe or eastern Europe, where local meteorological variables show a strong influence on surface ozone concentrations. Larger discrepancies are found for the southern regions, such as the Balkans, the Iberian Peninsula and the Mediterranean basin, especially in springtime. We show that the air-quality models do not properly reproduce the sensitivity of surface ozone to some of the main meteorological drivers, such as maximum temperature, relative humidity and surface solar radiation. Specifically, all air-quality models show more limitations in capturing the strength of the ozone–relative-humidity relationship detected in the observed time series in most of the regions, for both seasons. Here, we speculate that dry-deposition schemes in the air-quality models might play an essential role in capturing this relationship. We further quantify the relationship between ozone and maximum temperature (mo3 − T, climate penalty) in observations and air-quality models. In summertime, most of the air-quality models are able to reproduce the observed climate penalty reasonably well in certain regions such as France, central Europe and northern Italy. However, larger discrepancies are found in springtime, where air-quality models tend to overestimate the magnitude of the observed climate penalty. (10.5194/acp-18-12269-2018)
  DOI : 10.5194/acp-18-12269-2018
• Simulation of fine organic aerosols in the western Mediterranean area during the ChArMEx 2013 summer campaign
  
  • Cholakian Arineh
  • Beekmann Matthias
  • Colette Augustin
  • Coll Isabelle
  • Siour Guillaume
  • Sciare Jean
  • Marchand Nicolas
  • Couvidat Florian
  • Pey Jorge
  • Gros Valérie
  • Sauvage Stéphane
  • Michoud Vincent
  • Sellegri Karine
  • Colomb Aurélie
  • Sartelet Karine
  • Langley Dewitt Helen
  • Elser Miriam
  • Prévôt André S. H.
  • Szidat Sonke
  • Dulac François
  Atmospheric Chemistry and Physics, European Geosciences Union, 2018, 18 (10), pp.7287-7312. The simulation of fine organic aerosols with CTMs (chemistry–transport models) in the western Mediterranean basin has not been studied until recently. The ChArMEx (the Chemistry-Aerosol Mediterranean Experiment) SOP 1b (Special Observation Period 1b) intensive field campaign in summer of 2013 gathered a large and comprehensive data set of observations, allowing the study of different aspects of the Mediterranean atmosphere including the formation of organic aerosols (OAs) in 3-D models. In this study, we used the CHIMERE CTM to perform simulations for the duration of the SAFMED (Secondary Aerosol Formation in the MEDiterranean) period (July to August 2013) of this campaign. In particular, we evaluated four schemes for the simulation of OA, including the CHIMERE standard scheme, the VBS (volatility basis set) standard scheme with two parameterizations including aging of biogenic secondary OA, and a modified version of the VBS scheme which includes fragmentation and formation of nonvolatile OA. The results from these four schemes are compared to observations at two stations in the western Mediterranean basin, located on Ersa, Cap Corse (Corsica, France), and at Cap Es Pinar (Mallorca, Spain). These observations include OA mass concentration, PMF (positive matrix factorization) results of different OA fractions, and $^{14}$C observations showing the fossil or nonfossil origins of carbonaceous particles. Because of the complex orography of the Ersa site, an original method for calculating an orographic representativeness error (ORE) has been developed. It is concluded that the modified VBS scheme is close to observations in all three aspects mentioned above; the standard VBS scheme without BSOA (biogenic secondary organic aerosol) aging also has a satisfactory performance in simulating the mass concentration of OA, but not for the source origin analysis comparisons. In addition, the OA sources over the western Mediterranean basin are explored. OA shows a major biogenic origin, especially at several hundred meters height from the surface; however over the Gulf of Genoa near the surface, the anthropogenic origin is of similar importance. A general assessment of other species was performed to evaluate the robustness of the simulations for this particular domain before evaluating OA simulation schemes. It is also shown that the Cap Corse site presents important orographic complexity, which makes comparison between model simulations and observations difficult. A method was designed to estimate an orographic representativeness error for species measured at Ersa and yields an uncertainty of between 50 and 85 % for primary pollutants, and around 2–10 % for secondary species (10.5194/acp-18-7287-2018)
  DOI : 10.5194/acp-18-7287-2018
• High resolution unsteady RANS simulation of wind, thermal effects and pollution dispersion for studying urban renewal scenarios in a neighborhood of Toulouse
  
  • Gao Zhenlan
  • Bresson Raphaël
  • Qu Yongfeng
  • Milliez Maya
  • Munck Cecile De
  • Carissimo Bertrand
  Urban Climate, Elsevier, 2018, 23, pp.114-130. (10.1016/j.uclim.2016.11.002)
  DOI : 10.1016/j.uclim.2016.11.002