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Aubière, France

Michelot N.,University of Nice Sophia Antipolis | Pesin C.,NUMTECH | Carrega P.,University of Nice Sophia Antipolis
Pollution Atmospherique

In the souht-east of France, mediterranean climate, the study area is located in the central Siagne valley, characterized by a contrast and complex topography. It is under influence of breezes and thermic inversions during stable meteorology conditions. Modeling of PM10 using the ADMS-Urban software has been implemented in this area in order to test its ability to simulate, over complex terrain, topo-climate effects on levels of PM 10. This paper also presents the first use of the French Spatial National Inventory (INS). This one had integrated PM10 emissions. The results show there is a good model representation of topo-climate effects in time and space on the PM10 concentrations. However, a large difference of it appears compared to the measured data. Out due, the area is subject generally to an important unknown local sources and external contribution: 15.4 ug/m3 on average over the study period. Source

AlRFOBEP is the association in charge of the air quality monitoring in the Etang de Berre area. AIRFOBEP is managing a network of ten sensors to monitor the PM10 particulate pollution. This network is updated once a year according to the Air Quality Monitoring Plan (PSQA). Optimizing this network needs to know how the particulate pollution is distributed in the area. In other words, to determine the limits of homogeneous zones of PM10 pollution. The aim of the project presented in this article is to produce a map of homogeneous zones of PM10 pollution in the Etang de Berre area. The project was carried out in two steps: PM10 atmospheric dispersion modeling, using a ADMS-URBAN software, Statistic classification, based on the well known Hierarchical Ascending Classification (HAC) technique. Results of the atmospheric dispersion modeling was namely adjusted using an original technique for the "background PM10 pollution" computation. Good performances have been obtained when comparing modeling and measurements data. Finally, a set of five homogeneous zones was found to well describe the PM 10 pollution level distribution in the Etang de Berre area. Air quality modeling. PM10 pollution. Source

Armand P.,CEA DAM Ile-de-France | Brocheton F.,NUMTECH | Poulet D.,NUMTECH | Vendel F.,SILLAGES Environnement | And 2 more authors.
Atmospheric Environment

This paper is an original contribution to uncertainty quantification in atmospheric transport & dispersion (AT&D) at the local scale (1-10km). It is proposed to account for the imprecise knowledge of the meteorological and release conditions in the case of an accidental hazardous atmospheric emission. The aim is to produce probabilistic risk maps instead of a deterministic toxic load map in order to help the stakeholders making their decisions. Due to the urge attached to such situations, the proposed methodology is able to produce such maps in a limited amount of time. It resorts to a Lagrangian particle dispersion model (LPDM) using wind fields interpolated from a pre-established database that collects the results from a computational fluid dynamics (CFD) model. This enables a decoupling of the CFD simulations from the dispersion analysis, thus a considerable saving of computational time. In order to make the Monte-Carlo-sampling-based estimation of the probability field even faster, it is also proposed to recourse to the use of a vector Gaussian process surrogate model together with high performance computing (HPC) resources. The Gaussian process (GP) surrogate modelling technique is coupled with a probabilistic principal component analysis (PCA) for reducing the number of GP predictors to fit, store and predict. The design of experiments (DOE) from which the surrogate model is built, is run over a cluster of PCs for making the total production time as short as possible. The use of GP predictors is validated by comparing the results produced by this technique with those obtained by crude Monte Carlo sampling. © 2014 Elsevier Ltd. Source

Sadek R.,INSA Lyon | Soulhac L.,INSA Lyon | Brocheton F.,NUMTECH | Buisson E.,NUMTECH
HARMO 2011 - Proceedings of the 14th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes

In modeling atmospheric dispersion over complex terrain (relief, roughness or heat flux change), Computational Fluid Dynamics (CFD) codes can be a powerful tool for simulating air flow with very high spatial resolution. However, the well-known drawback of the CFD approach is that it is time consuming. In this paper, a method which uses partially converged CFD solutions as a way of reducing CPU time, while keeping the precision of the solution at an acceptable level, is presented. We therefore demonstrate that it is possible to reach a wind field solution very close to the converged solution, in a small fraction of the CPU time needed to reach the fully converged solution. We present an optimum point of convergence,depending on the complexity of the terrain, for several cases of simulations with the commercial CFD code Fluent. Such complexities include steepness of hills and valleys, roughness of terrain and thermal stratification. We present an estimate of the error in comparison to the fully converged solution and evaluate the gain of CPU time following each case study.Finally, we strengthen our conclusions by a comparison with wind tunnel experiments in the presence of hills. Source

Brocheton F.,NUMTECH | Mesbah B.,AIRFOBEP | Jacquinot M.,AIRFOBEP | Buisson E.,NUMTECH
HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes

AIRFOBEP is the regional air quality agency in charge of the survey of the air pollution over the Etang de Berre region, which is one of the two main industrial areas in France. From several years, AIRFOBEP has decided to develop an operational automated platform which routinely monitors and forecasts air pollution over its territory. This paper discusses the operational tools associated with particle matter (PM10) and sulfur dioxide (SO2). The particularity of these tools is that the evaluation of the pollution associated with each pollutant is based on local air dispersion modelling (ADMS4 and ADMS-Urban for SO2 and PM10, respectively) to account for numerous local emission sources, considering a large simulation domain. A description of each tool which has been developed will be given. An overall view of the performance of the system in terms of ground-level concentration prediction will also be shown. Source

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