Evaluation of the chimere model at high resolution over Europe : focus on urban area

International audienc

Influence des conditions atmosphériques sur la formation des traînées de condensation : comparaison entre la simulation 3D et le critère de Schmidt-Appleman

International audienceCondensation trails, usually called contrails, represent an increasing issue for aeronautics. Contrail formation and properties depends on several factors such as ambient atmospheric conditions (temperature and relative humidity), mainly, but also possibly on engine characteristics (e.g. bypass ratio, exhaust temperature), fuel type (e.g. kerosene or alternative fuels), and aircraft geometry (e.g. driving mixing in the aircraft wake). Therefore, parametric studies allow for a better understanding of contrails onset mechanisms and assessment of their properties sensitivity in the aircraft near field. This can help to find out smart mitigation solutions to reduce the environmental impact of contrail/induced cirrus by better controlling their formation. In this context, reliable prediction tools as well as technologies input are urgently needed for decision makers. Using the computational fluid dynamics code CEDRE, developed at ONERA and adapted for contrail issues, 3D simulations have been carried out to address this need. It takes into account the dynamical evolution of the jet plume, the chemical transformations of the exhaust after ejection and the microphysical processes driving contrails formation. The simulations are performed on a realistic aircraft configuration. The objective here is to confront 3D simulation approach with the Schmidt-Appleman criterion, widely used to determine contrails formation areas.Condensation trails, usually called contrails, represent an increasing issue for aeronautics. Contrail formation and properties depends on several factors such as ambient atmospheric conditions (temperature and relative humidity), mainly, but also possibly on engine characteristics (e.g. bypass ratio, exhaust temperature), fuel type (e.g. kerosene or alternative fuels), and aircraft geometry (e.g. driving mixing in the aircraft wake). Therefore, parametric studies allow for a better understanding of contrails onset mechanisms and assessment of their properties sensitivity in the aircraft near field. This can help to find out smart mitigation solutions to reduce the environmental impact of contrail/induced cirrus by better controlling their formation. In this context, reliable prediction tools as well as technologies input are urgently needed for decision makers. Using the computational fluid dynamics code CEDRE, developed at ONERA and adapted for contrail issues, 3D simulations have been carried out to address this need. It takes into account the dynamical evolution of the jet plume, the chemical transformations of the exhaust after ejection and the microphysical processes driving contrails formation. The simulations are performed on a realistic aircraft configuration. The objective here is to confront 3D simulation approach with the Schmidt-Appleman criterion, widely used to determine contrails formation areas

Review: The Effects of Supersonic Aviation on Ozone and Climate

When working towards regulation of supersonic aviation, a comprehensive understanding of the global climate effect of supersonic aviation is required in order to develop future regulatory issues. Such research requires a comprehensive overview of existing scientific literature having explored the climate effect of aviation. This review article provides an overview on earlier studies assessing the climate effects of supersonic aviation, comprising non-CO2 effects. An overview on the historical evaluation of research focussing on supersonic aviation and its environmental impacts is provided, followed by an overview on concepts explored and construction of emission inventories. Quantitative estimates provided for individual effects are presented and compared. Subsequently, regulatory issues related to supersonic transport are summarised. Finally, requirements for future studies, e.g., in emission scenario construction or numerical modelling of climate effects, are summarised and main conclusions discussed

Concerted Regulation of cGMP and cAMP Phosphodiesterases in Early Cardiac Hypertrophy Induced by Angiotensin II

Left ventricular hypertrophy leads to heart failure and represents a high risk leading to premature death. Cyclic nucleotides (cAMP and cGMP) play a major role in heart contractility and cyclic nucleotide phosphodiesterases (PDEs) are involved in different stages of advanced cardiac diseases. We have investigated their contributions in the very initial stages of left ventricular hypertrophy development. Wistar male rats were treated over two weeks by chronic infusion of angiotensin II using osmotic mini-pumps. Left cardiac ventricles were used as total homogenates for analysis. PDE1 to PDE5 specific activities and protein and mRNA expressions were explored

APPLICATION DES SYSTEMES MM5-CHIMERE ET MM5-FLEXPART A LA MODELISATION DE L'OZONE ET DES PM10 SUR LA REGION NORD-PAS-DE-CALAIS

Air pollution is a topical subject affecting both human health and the environment. Nowadays, two kind of pollution have been intensely studied, namely, the ozone and the particulate (PM10, PM2.5 and PM1) pollution. During the thesis, the MM5-CHIMERE and the MM5-FLEXPART systems have been set up and optimised at the PC2A laboratory in order to study ozone and PM10 pollution events. The performance of the MM5-CHIMERE system has been evaluated for different topography and meteorological situations. Firstly, the modelled data are compared against observed data from the Atmo-NPDC air pollution monitoring network over the June-July 2006 heat wave period. Then, the dynamical and chemical performance of the models is assessed over the Dunkerque area for two periods in April and May 2006. For those two periods, measured data were collected during a field campaign achieved by the Laboratoire de Physicochimie Atmosphérique (LPCA) of the University du Littoral Côte d'Opale (ULCO). Finally, the MM5-FLEXPART system was used to determine the origin of an intense PM10 event overt the NPDC region. The influence of anthropogenic primary emission, grid and meteorological data resolution has also been tested.La pollution de l'air est un sujet de préoccupation majeur au XXIème siècle affectant la santé et notre environnement. Deux types de pollution atmosphérique retiennent plus particulièrement l'attention des physicochimistes à l'heure actuelle : la pollution à l'ozone dite photochimique et la pollution particulaire (PM10, PM2.5). La région Nord-Pas-De-Calais (NPDC) est une des régions françaises ayant la plus forte densité de population (324 hab./km2 en 2006). Elle est également le lieu de passage d'un trafic routier transfrontalier particulièrement intense. Enfin, elle présente une forte activité industrielle (pétrochimie, sidérurgie, métallurgie) au niveau de la zone côtière de Dunkerque. Les émissions issues des secteurs du transport mais aussi industriel et tertiaire sont une source importante de composés primaires (NOx, COV et particules) précurseurs de la pollution à l'ozone et particulaire.Au cours du travail de thèse les chaînes de modélisation MM5-CHIMERE et MM5-FLEXPART ont été installées et utilisées sur plusieurs périodes d'études à l'échelle de la région NPDC. Le système MM5-CHIMERE a été utilisé sur la période juin-juillet 2006 propice au développement d'épisodes de pollution photochimique. Diverses applications ont été réalisées : étude de la relation entre concentration en polluant et conditions météorologiques, impact de l'intégration du cadastre d'émission régional, impact de la résolution de la grille et des données dynamiques, origine locale/régionale des niveaux de pollution observés en région NPDC. Puis, le système MM5-FLEXPART a été utilisé afin de déterminer l'origine de deux évènements intenses de pollution particulaire observés en mars et décembre 2007 au niveau de Dunkerque. Enfin, les performances dynamiques et chimiques du système ont été évaluées au niveau de la zone spécifique industrielle de Dunkerque sur deux périodes en avril et mai 2006. Au cours de ces périodes, les données dynamiques ont été collectées lors d'une campagne de mesures réalisée sur Dunkerque par le Laboratoire de Physico-Chimie de l'Atmosphère (LPCA) de l'Université du Littoral - Côte d'Opale. Les résultats concernant la performance et les applications des systèmes ainsi que les perspectives à court terme seront présentés et discutés

Impact of present and future aircraft emissions on atmospheric composition and radiative forcing of climate

International audienceDepending on the nature and the location of the emitted chemical agents, aircrafts contribute to warm or cool the climate. The chemical perturbation and the associated radiative forcing of carbon dioxide, ozone, methane, soot carbon (BC), sulphates, nitrates and organic carbon (OC) due to aircraft emissions have been calculated using five different global emission inventories using a carbon cycle compact climate change model and the climate-chemistry global model LMDz-ORCH-INCA. We found that the impact of the aviation CO2 emissions ranges from 45 ± 2mW/m² (2.5% of the total anthropogenic warming) for an ambitious mitigation strategy scenario (Factor 2) to 78 ± 4 mW/m² (2.5% of the total anthropogenic warming) for the least ambitious mitigation scenario of the study (ICAO based). Apart from CO2, the total radiative forcing related to aviation and modifications of gases and aerosols calculated in this work is negative and varies from -2.5mW/m² for the present scenario REACT4C (-3.6mW/m² in the case QUANTIFY_2000)

Application of performance indicators based on observation uncertainty to evaluate a Europe-wide model simulation at urban scale

In the frame of the European Consortium for Modeling of Air Pollution and Climate Strategies (EC4MACS) the CHIMERE chemistry transport model has been run over Europe for the entire year 2009 with a spatial resolution of 7 km with the aim of assessing the urban impact on daily exceedances of PM and NO2 in European cities. In order to better capture these urban impacts improvements on urban scale meteorology, vertical resolution and emissions have been implemented. In the current work an evaluation of the model results against the AIRBASE European monitoring network measurements is done using model performance indicators (MPC) based on observation uncertainty. The MPC used in this approach, constructed on the hypothesis that model results are allowed the same margin of uncertainty as measurements, are developed for four statistical indicators (Root Mean Square Error, Normalized Mean Bias, Normalized Mean Standard Deviation and correlation) to summarize the model-observation errors in terms of phase, amplitude and bias. The utility of this approach is to provide a performance scale to inform the user on the expected value an indicator should reach for a particular modeling application. These indicators are then used to identify the strengths and weaknesses of the model application in terms of geographical areas, cities, pollutants and/or period of the year

Application of performance indicators based on observation un-certainty to evaluate a Europe-wide model simulation at urban scale

In the frame of the European Consortium for Modeling of Air Pollution and Climate Strategies (EC4MACS) the CHIMERE chemistry transport model has been run over Europe for the entire year 2009 with a spatial resolution of 7 km with the aim of assessing the urban impact on daily exceedances of PM and NO2 in European cities. In order to better capture these urban impacts, improvements on urban scale meteorology, vertical resolution and emissions have been implemented. In the current work an evaluation of the model results against the AIRBASE European monitoring network measurements is done using model performance indicators (MPC) based on observation uncertainty. The MPC used in this approach, constructed on the hypothesis that model results are allowed the same margin of uncertainty as measurements, are developed for four statistical indicators (Root Mean Square Error, Normalized Mean Bias, Normalized Mean Standard Deviation and temporal correlation) to summarize the model-observation errors in terms of phase, amplitude and bias. The utility of this approach is to provide a performance scale to inform the user on the expected value an indicator should reach for a particular modeling application. These indicators are then used to identify the strengths and weaknesses of the model application in terms of geographical areas, cities, pollutants and/or period of the year.JRC.H.2-Air and Climat

The impact of carbon dioxide aviation emissions on future climate change

International audienceAviation emissions are estimated to contribute to 5 % (2–14 %, 90 % likelihood range) of the anthropogenic radiative forcing of climate with an uncertainty dominated by non-CO2 effects (Lee et al., 2010). Even if the level of scientific understanding is considered to be high by the IPCC for present-day aviation CO2 impact compared to other non-CO2 forcers (e.g. ozone, aerosols and contrails), the future (2050) aviation CO2 climate impact remains highly uncertain. One major reason of these varying estimates is linked to the inherent assumptions made in the development of future global emission scenarios such as the one from international aviation (Boucher et al., 2016). Hence, using the compact Earth System Model (ESM) OSCARv2.2 we quantify the climate impact of present and future (up to 2100) civil aviation carbon dioxide (CO2) emissions using eight aviation scenarios ranging from 386 Mt CO2/year (Factor 2 scenario) to 2338 Mt CO2/year (ICAO/CAEP scenario) in 2050. This approach will allow quantifying the uncertainty due to the difficulty to estimate the future mitigation effort. Another originality of the paper is that the influence of other emission sectors is evaluated using two background Representative Concentrations Pathways (RCP2.6 and RCP6.0). Results show that in 2050, on a climate trajectory in line with the Paris Agreement limiting the global warming below 2 °C (RCP2.6), the impact of the aviation CO2 emissions ranges from 26 ± 2 mK (1.4 % of the total global warming associated with all fossil fuel emissions) for an ambitious mitigation strategy scenario (Factor 2) to 39 ± 4 mK (2.0 % of the total global warming) for the least ambitious mitigation scenario of the study (ICAO-CAEP). On the longer term, if no significant emission mitigation is implemented for the aviation sector, the associated warming could further increase and reach a value of 100 mK in 2100 (ICAO/CAEP), which corresponds to 5.2 % of the total global temperature increase from total fossil fuel CO2 emissions under RCP2.6