Publications

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
• Intercomparison of three modeling approaches for traffic-related road dust resuspension using two experimental data
  
  • Thouron Laëtitia
  • Seigneur Christian
  • Kim Youngseob
  • Mahe Frédéric
  • Andre Michel
  • Lejri Delphine
  • Villegas Daniel
  • Bruge Benjamin
  • Chanut Hervé
  • Pellan Yann
  Transportation Research Part D: Transport and Environment, Elsevier, 2018, 58, pp.pp.108-121. Two observational campaigns were conducted, one in the Grenoble area (South Eastern France), for the MOCoPo project, near an urban freeway in 2011 and the other one in a Paris suburb, forthe TrafiPollu project, on a major surface street in 2014. PM10 concentrations were measured by Air Rhône-Alpes during the last 10 days of September 2011 for MOCoPo and by Airparif during 3 months from April to June 2014 for TrafiPollu. It has been shown that abrasion and resuspension processes represent a significant part of the total primary PM10 emissions of road traffic. Hereby, resuspended emissions originating from the road are estimated with several approaches and compared to PM10 measurements. We consider two different models available in the literature: HERMES (Pay et al., 2010) and NORTRIP (Denby et al., 2013), which differ in terms of formulation. We also apply an empirical method developed by Thorpe et al. (2007), based on near-road and background pollutant observations. The results vary depending on the traffic conditions and the modeling approach. In all cases, the resuspension emissions simulated are high enough to be considered in air quality modeling (ranging from 9 to 150% of the exhaust emissions). Those resuspension models were combined with atmospheric dispersion models to estimate near-road concentrations. We used a Gaussian line-source model for the Grenoble urban freeway and a street-canyon model (MUNICH) for the Paris suburban boulevard. The contribution of resuspension to traffic-related concentrations is hidden by a strong background contribution, which prevents us from concluding in terms of model performance. Nevertheless, a comparison with another dataset obtained near an urban freeway in Paris suggests that vehicle speed should be taken into account when estimating PM10 resuspension emissions. (10.1016/j.trd.2017.11.003)
  DOI : 10.1016/j.trd.2017.11.003
• Multi-scale modeling of urban air pollution: development and application of a Street-in-Grid model (v1.0) by coupling MUNICH (v1.0) and Polair3D (v1.8.1)
  
  • Kim Youngseob
  • Wu You
  • Seigneur Christian
  • Roustan Yelva
  Geoscientific Model Development Discussions, Copernicus Publ, 2018, 11 (2), pp.611-629. A new multi-scale model of urban air pollution is presented. This model combines a chemistry–transport model (CTM) that includes a comprehensive treatment of atmospheric chemistry and transport on spatial scales down to 1 km and a street-network model that describes the atmospheric concentrations of pollutants in an urban street network. The street-network model is the Model of Urban Network of Intersecting Canyons and Highways (MUNICH), which consists of two main components: a street-canyon component and a street-intersection component. MUNICH is coupled to the Polair3D CTM of the Polyphemus air quality modeling platform to constitute the Street-in-Grid (SinG) model. MUNICH is used to simulate the concentrations of the chemical species in the urban canopy, which is located in the lowest layer of Polair3D, and the simulation of pollutant concentrations above rooftops is performed with Po-lair3D. Interactions between MUNICH and Polair3D occur at roof level and depend on a vertical mass transfer coefficient that is a function of atmospheric turbulence. SinG is used to simulate the concentrations of nitrogen oxides (NO x) and ozone (O 3) in a Paris suburb. Simulated concentrations are compared to NO x concentrations measured at two monitoring stations within a street canyon. SinG shows better performance than MUNICH for nitrogen dioxide (NO 2) concentrations. However, both SinG and MUNICH underestimate NO x. For the case study considered, the model performance for NO x concentrations is not sensitive to using a complex chemistry model in MUNICH and the Leighton NO–NO 2 – O 3 set of reactions is sufficient. (10.5194/gmd-11-611-2018)
  DOI : 10.5194/gmd-11-611-2018
• Data assimilation at local scale to improve CFD simulations of atmospheric dispersion: application to 1D shallow-water equations and method comparisons
  
  • Defforge Cécile
  • Carissimo Bertrand
  • Bocquet Marc
  • Armand Patrick
  • Bresson Raphaël
  International Journal of Environment and Pollution, Inderscience, 2018, 64 (1/2/3), pp.90. Atmospheric dispersion modelling requires meteorological inputs over local domains with possibly complex topographies. These local wind fields may be difficult to simulate with CFD models, in particular because of their sensitivity to geometrical features and to model inputs, especially the boundary conditions which are generally provided by larger-scale models or measurements. Using data assimilation, a few measurements inside the domain could add information to the imprecise boundary conditions and thus greatly enhance the precision of the dispersion simulations. Three data assimilation techniques (3DVar, the back and forth nudging algorithm, and the iterative ensemble Kalman smoother) have been adapted to local scale simulations by taking boundary conditions into account instead of initial conditions for which they are usually applied. Their performances have been evaluated at small scales, with a simple representation of the atmosphere into two layers, using 1D solution of the shallow-water equations. (10.1504/IJEP.2018.099151)
  DOI : 10.1504/IJEP.2018.099151