Top Stories at CEREA
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Marie Dumont, registered at Cerea for her Ph.D., has been awarded one of the "Prix solennels de Chancellerie" given by the Chancelor Office of the Universities of Paris : the Science Prize - Aguirre-Basualdo Prize, for her thesis titled "Determination by remote sensing of the albedo of snow surfaces - Application to the reconstruction of the mass budget of the Saint Sorlin glacier", performed at the Laboratoire de Glaciologie et Géophysique de l'Environnement in Grenoble.
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On November 18th, 2011: Yongfeng Qu defended his Ph.D. thesis successfully!
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On November 18th, 2011 at 2:00pm: Yongfeng Qu will defend his PhD thesis
Title: Three-dimensional modeling of radiative and convective exchanges in the urban atmosphere
Location : 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel)
Defense comittee:
- Dr. Majorie MUSY, CERMA (reviewer)
- Dr. Valéry MASSON, Météo-France (reviewer)
- Pr. Jean François SINI - École Centrale de Nantes (examinator)
- Pr. Jean Philippe GASTELLU-ETCHEGORRY, CESBIO (examinator)
- Pr. Marina K.A. NEOPHYTOU, University of Cyprus (examinator)
- Dr. Patrice G. MESTAYER, IRSTV (examinator)
- Dr. Bertrand CARISSIMO, CEREA (advisor)
- Dr. Maya MILLIEZ, CEREA (co-advisor)
- Dr. Luc MUSSON-GENON, CEREA (co-advisor)
Abstract : In many micrometeorological studies, building resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. In order to take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, we have developed a three-dimensional (3D) atmospheric radiative scheme, in the atmospheric module of the Computational Fluid Dynamics model Code_Saturne. The radiative scheme was previously validated with idealized cases, using as a first step, a constant 3D wind field. In this work, the full coupling of the radiative and thermal schemes with the dynamical model is evaluated. The aim of the first part is to validate the full coupling with the measurements of the simple geometry from the Mock Urban Setting Test (MUST) experiment. The second part discusses two different approaches to model the radiative exchanges in urban area with a comparison between Code_Saturne and SOLENE. The third part applies the full coupling scheme to show the contribution of the radiative transfer model on the airflow pattern in low wind speed conditions in a 3D urban canopy. In the last part we use the radiative-dynamics coupling to simulate a real urban environment and validate the modeling approach with field measurements from the Canopy and Aerosol Particle Interactions in TOulouse Urban Layer (CAPITOUL).
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October 2011: Florian Couvidat, Ph.D. student at Cerea, received the Jean Bricart Award from the French Association for Aerosol Research (ASFERA) for his work on atmospheric organic aerosols.
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May 2010: Summary of the China's Cerea's tour (download here - in french)
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29th March 2010: Publication of the final version of the AERES report comittee (in french)
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On February 19, 2010: Rachid Abida defended his Ph.D. thesis successfully!
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On February 19, 2010 at 2:00pm: Rachid Abida will defend his PhD thesis
Title (in french): Construction optimale de réseaux fixes et mobiles pour la surveillance opérationnelle des rejets atmosphériques accidentels
Location : 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel)
Defense comittee:
- M. Philippe Naveau (reviewer)
- M. Hans Wackernagel (reviewer)
- M. Olivier Isnard (referee)
- M. Anda Ionescu (referee)
- M. Werner G. Müller (Thesis supervisor)
- M. Marc Bocquet (Thesis supervisor)
Summary (in french) :
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On January 21, 2010: Hossein Malakooti defended his Ph.D. thesis successfully!
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On January 21, 2010 at 2:00pm: Hossein Malakooti will defend his PhD thesis
Title: Meteorology and air-quality in a mega-city: application to Tehran, Iran
Location : 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel)
Defense comittee:
- M. Alain Clappier (reviewer)
- M. Abbas-Ali Ali-Akbari Bidokhti (reviewer)
- M. Matthias Beekmann (referee)
- M. Sylvain Dupont (referee)
- M. Maya Milliez (referee)
- M. Bruno Sportisse (Thesis supervisor)
Summary : Tehran, capital of Iran, is located over a complex terrain with moderate to dry climate. The environmental problem that affects people more than any other in Tehran mega-city is air pollution. Sources of error in chemical-transport modeling processes may be grouped in three main categories, (I) emissions, (II) transport (including deposition) and (III) chemistry (including phase change). In this work, we tried to improve the quality of emission databases (part 1) and also meteorological simulations (part 2) in order to improvements of Tehran air quality calculations.
1) Development and Evaluation of high resolution Emission Inventory An emission inventory of air pollutants and an inventory of heat generation were developed and updated for 2005 in this work. Emissions from on-road motor vehicles constitute a major portion of the emission inventory and play the most important role in terms of contributions of air pollutants to the atmosphere in Tehran. By using a detailed methodology, we calculated spatial and temporal distributions of the anthropogenic heat flux (Qf) for Tehran during 2005. Wintertime Qf is larger than summertime Qf, which reflects the importance of heating emissions from buildings and traffic during cold and warm period respectively.
2) Local Meteorology and Urbanization Effects The influence of a mega-city on the atmospheric boundary layer and surface conditions was examined in Tehran region using the Pennsylvania State University/National Center for Atmospheric Research fifth-generation Mesoscale Model (MM5) during a high pollution period. In addition, model sensitivity studies were conducted to evaluate the performance of the urban canopy and urban soil model "SM2-U (3D)" parameterization on the meteorological fields. The topographic flows and urban effects were found to play important roles in modulating the wind and temperature fields, and the urbanized areas exerted important local effects on the boundary layer meteorology. Different urban parameterizations were used as a tool to investigate the modifications induced by the presence of an urban area in the area of interest. It was found that, for local meteorological simulations, the drag-force approach coupled with an urban soil model (DA-SM2-U) is preferable to the roughness approach (RA-SLAB). The comparisons indicated that the most important features of the wind, temperature and turbulent fields in urban areas are well reproduced by the DA-SM2-U configuration with the anthropogenic heat flux being taken into account (i.e., "DA-SM2-U Qf: On" option). This modeling option showed that the suburban part of the city is dominated by topographic flows whereas the center and south of Tehran are more affected by urban heat island (UHI) forcing especially during the night.
3) Sensitivity and improvements of Tehran air quality calculations using different meteorological urban parameterization * The chemical transport modeling, including a model sensitivity study, was used to investigate the impact of the different urban parameterization on the dispersion and formation of pollutants over the Tehran region. Results show that applying DA approaches leads to significant improvements in the simulated spatial and temporal distribution of air pollutant concentrations in the city area and affects significantly the size of the urban plumes.
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On January 12, 2010: Xiaojing Zhang defended his Ph.D. thesis successfully!
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On January 12, 2010 at 2:00pm: Xiaojing Zhang will defend his Ph.D. thesis.
Thesis title (in french): Modélisation du brouillard durant la campagne ParisFog : approche prédictive et étude de l'effet des hétérogénéités spatiales
Location : 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Jean-Pierre Chollet, Université Joseph Fourier (rapporteur)
- M. Yves Brunet, INRA Bordeaux (rapporteur)
- Mme. Andréa Flossmann, Université Blaise Pascal (examinatrice)
- M. Patrick J. Mascart, Université Paul Sabatier (examinateur)
- M. Martial Haeelin, IPSL (examinateur)
- M. Thierry Bergot, Météo-France (directeur de thèse)
- M. Luc Musson-Genon, EDF R&D (co-directeur de thèse)
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On December 15, 2009: Irène Bourdin-Korsakissok defended his Ph.D. thesis successfully!
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On December 15, 2009 at 2:30pm: Irène Bourdin-Korsakissok will defend her Ph.D. thesis.
Thesis title: Multi-scale methods in air quality modeling, and estimation of the related uncertainties.
Location : 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Richard Perkins (rapporteur)
- M. Robert Rosset (rapporteur)
- M. Serge Guillas (examinateur)
- M. Olivier Isnard (examinateur)
- M. Vivien Mallet (co-directeur de thèse)
- M. Bruno Sportisse (directeur de thèse)
- M. Philippe Lameloise (invité)
- Mme Laurence Rouïl (invitée)
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13th August 2009: Publication of the report of activities for 2008
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On February 17, 2009: Christian Seigneur defended his HDR (Habilitation à Diriger des Recherches) successfully!
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On February 17, 2009 at 14:00: Christian Seigneur will defend his HDR (Habilitation à Diriger des Recherches).
HDR's title: Modelling of atmospheric mercury
Location : at 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, in the lecture hall Freyssinet (Nobel buildings)
Jury:
- Professor Lyatt Jaeglé, Université de Washington
- Dr. Laurier Poissant, Environnement Canada
- Professor Christophe Ferrari, Université de Grenoble
- Professor Robert Rosset, Université de Toulouse
- Professor Bernard Aumont, Université Paris 12 / Paris-Est
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February 2009: Publication of the dossier related to the assessment of the CEREA by the AERES (february 2009)
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On December 12, 2008: Laurent Laporte defended his Ph.D. thesis successfully!
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April 2008: Publication in french of the CEREA's research dossier of the Ecole des Ponts (april 2008)
Download it here
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On March 28, 2008: Solen Queguiner defended her Ph.D. thesis successfully!
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On March 28, 2008 at 14:00: Solen Queguiner will defend her Ph.D. thesis.
Thesis title: Coupled modelling of atmosphere-soil-vegetation in order to assess the effects of atmospheric emissions of heavy metals and persistent organic pollutants
Location : au 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Pierre Cellier (rapporteur)
- M. Dimosthenis Sarigiannis (rapporteur)
- Mme. Evelyne Gehin (examinatrice)
- Mme. Laurence Rouil (examinatrice)
- M. Philippe Ciffroy (examinateur)
- M. Jean-Marie Mouchel (directeur de thèse)
- M. Luc Musson-Genon (examinateur invité)
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On December 18, 2007: Marc Bocquet defended his HDR (Habilitation à Diriger des Recherches) successfully!
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On December 18, 2007 at 14:00: Marc Bocquet will defend his HDR (Habilitation à Diriger des Recherches).
HDR's title: Modélisation inverse et assimilation de données non-gaussiennes pour les traceurs atmosphériques. Application à ETEX, Algésiras et Tchernobyl
Location : au 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Philippe Ciais (examinateur)
- M. Hendrik Elbern (examinateur)
- M. Nicolas Florsch (examinateur)
- M. François-Xavier Le Dimet (rapporteur)
- M. Bruno Sportisse (invité)
- M. Olivier Talagrand (rapporteur)
- M. Albert Tarantola (rapporteur)
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On November 30, 2007: Emmanuel Demaël defended his PhD successfully!
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On November 30, 2007 at 14h: Emmanuel Demaël will defend his PhD thesis.
Thesis title: Modelling of atmospheric dispersion in complex areas and linked uncertainties
Location : au 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Jean-Pierre Chollet (rapporteur)
- M. Jean-François Sini (rapporteur)
- M. Richard Perkins (examinateur)
- M. Olivier Isnard (examinateur)
- M. Pierre Roubin (examinateur)
- M. Bertrand Carissimo (directeur de thèse)
Abstract: Nowadays, risk assessment studies of atmospheric industrial releases require the use of numerical tools. At local scale, Gaussian models are extensively used by operational units, because of their low computational coast. However, they may be partially or totally unsuitable in such cases where both buildings and complex terrain are involved. Atmospheric CFD (Computational Fluid Dynamics) models, among them RANS models, propose an interesting alternative but increase the computational coast. The purpose of this PhD work is to discuss the advantages given by CFD models with RANS approach for modelling near-field dispersion in complex areas. In a first step, these different approaches are compared on the Prairie Grass dispersion field experiment which consists in near-ground releases over a flat terrain. Here, Briggs (1973) and Doury (1976) Gaussian parameterisations are compared to Mercure_Saturne CFD model. In a second step, Mercure_Saturne is compared to ADMS (Atmospheric Dispersion Modelling System) for the modelling of dispersion on the Bugey nuclear power plant area wherebuildings have a great influence on dispersion processes due to their orientation relative to the main wind directions. This study is based on a wind-tunnel experiment conducted by the Fluid Mechanics and Acoustic Laboratory (LMFA, Ecole Centrale de Lyon). In a last step, the comparison is extended to the modelling of dispersion around the Flamanville nuclear power plant area which is in direct proximity of a stiff cliff. Finally, a last expectation concerns the evaluation of the predicted results variability due to input uncertainties. For this purpose, two approaches are proposed and applied to the modelling of the dispersion on the Bugey nuclear power plan area with Mercure_Saturne. The first one is the well-known Monte-Carlo method which may quantify in the same time the overall uncertainty on ground level concentrations and the influence of each input factor. The second one, the Morris' method, aims to rank these input factors in term of importance by a qualitative approach.
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On November 16, 2007: Marilyne Tombette defended her PhD thesis successfully.
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On November 16, 2007 at 14:00: Marilyne Tombette will defend her PhD thesis.
Thesis title: Modélisation des aérosols et de leurs propriétés optiques sur l'Europe et l'Ile de France: validation, sensibilité et assimilation de données
Location : au 19, rue Alfred Nobel, FR-77420 Champs-sur-marne, dans l'amphithéatre Freyssinet (bâtiments Nobel )
Jury:
- M. Matthias Beekmann (rapporteur)
- M. Robert Rosset (rapporteur)
- M. Kees Cuvelier (examinateur)
- M. Olivier Boucher (examinateur)
- M. Patrick Chazette (directeur de thèse)
- M. Bruno Sportisse (co-directeur de thèse)
Abstract : Aerosols are a key component for studying the atmospheric composition. Actually, they have harmful sanitary consequences, modify the visibility and impact the radiative balance with a direct effect (absorption/scattering of light), a semi-direct effect (change of the temperature vertical profile) and a indirect effect (acting as cloud condensation nuclei). Aerosol modeling is a challenging issue, both at the physical and numerical levels. The objective of the PhD work is to evaluate the performances and the limitations of aerosol modeling systems at regional and continental scales. What is the robustness of the models and the comparisons with measured data? What could be the contribution of data assimilation methods? In a first part, a size-resolved aerosol model embedded in the Polyphemus platform is evaluated though a few regional cases (Europe and Ile-de-France) and for a few databases. The indicators are the PM10 (particles with a diameter lower than 10 micrometers), chemical composition and granulometry. The model outputs have also been extended in order to enable comparisons with optical data (optical thickness, extinction coefficient) measured by photometers or lidars. A second part investigates the sensitivity of the aerosol model with respect to physical parametrizations and numerical methods. This sensitivity analysis is the preliminary step before the use of ensemble method for aerosol forecasts, which appears to be a promising approach. A last part deals with the possible improvement induced by with a data assimilation system. The optimal interpolation method has then been implemented to assimilate PM10 data at ground level. The impact of data assimilation for forecast is also evaluated.
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15th June 2007: Scientific Committee Meeting
The Scientific Committee of CEREA aims at assessing the scientific quality of research projects carried out at CEREA. The meeting is the final evaluation meeting of CEREA for 2003-2007. Available reports: Prospective report 2008-2011 and Summary report 2003-2007 . -
June 2007: Publication of the Report of activities for year 2006
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november 2006-april 2007: PARISFOG
The instrumental team of CEREA is involved in the equipment of the ground-based atmospheric observatory SIRTA and the measurement campaign PARISFOG. -
15th September 2006: Scientific Committee meeting. "Planning".
This meeting is the first step towards CEREA evaluation, which will take place next year. Each CEREA researcher made a short presentation to the scientific committee of his main results and actions during past year as well as his future works. Some of them are currently available on the meeting page .