Future air quality in Europe: a multi-model assessment of projected exposure to ozone

In order to explore future air quality in Europe at the 2030 horizon, two emission scenarios developed in the framework of the Global Energy Assessment including varying assumptions on climate and energy access policies are investigated with an ensemble of six regional and global atmospheric chemistry transport models. <br><br> A specific focus is given in the paper to the assessment of uncertainties and robustness of the projected changes in air quality. The present work relies on an ensemble of chemistry transport models giving insight into the model spread. Both regional and global scale models were involved, so that the ensemble benefits from medium-resolution approaches as well as global models that capture long-range transport. For each scenario a whole decade is modelled in order to gain statistical confidence in the results. A statistical downscaling approach is used to correct the distribution of the modelled projection. Last, the modelling experiment is related to a hind-cast study published earlier, where the performances of all participating models were extensively documented. <br><br> The analysis is presented in an exposure-based framework in order to discuss policy relevant changes. According to the emission projections, ozone precursors such as NO<sub>x</sub> will drop down to 30% to 50% of their current levels, depending on the scenario. As a result, annual mean O<sub>3</sub> will slightly increase in NO<sub>x</sub> saturated areas but the overall O<sub>3</sub> burden will decrease substantially. Exposure to detrimental O<sub>3</sub> levels for health (SOMO35) will be reduced down to 45% to 70% of their current levels. And the fraction of stations where present-day exceedences of daily maximum O<sub>3</sub> is higher than 120 μg m<sup>−3</sup> more than 25 days per year will drop from 43% down to 2 to 8%. <br><br> We conclude that air pollution mitigation measures (present in both scenarios) are the main factors leading to the improvement, but an additional cobenefit of at least 40% (depending on the indicator) is brought about by the climate policy

Evolution of anthropogenic and biomass burning emissions of air pollultants at global and regional scales during the 1980-2010 period

Several different inventories of global and regional anthropogenic and biomass burning emissions are assessed for the 1980-2010 period. The species considered in this study are carbon monoxide, nitrogen oxides, sulfur dioxide and black carbon. The inventories considered include the ACCMIP historical emissions developed in support of the simulations for the IPCC AR5 assessment. Emissions for 2005 and 2010 from the Representative Concentration Pathways (RCPs) are also included. Large discrepancies between the global and regional emissions are identified, which shows that there is still no consensus on the best estimates for surface emissions of atmospheric compounds. At the global scale, anthropogenic emissions of CO, NOx and SO2 show the best agreement for most years, although agreement does not necessarily mean that uncertainty is low. The agreement is low for BC emissions, particularly in the period prior to 2000. The best consensus is for NOx emissions for all periods and all regions, except for China, where emissions in 1980 and 1990 need to be better defined Emissions of CO need better quantification in the USA and India for all periods; in Central Europe, the evolution of emissions during the past two decades needs to be better determined. The agreement between the different SO2 emissions datasets is rather good for the USA, but better quantification is needed elsewhere, particularly for Central Europe, India and China. The comparisons performed in this study show that the use of RCP8.5 for the extension of the ACCMIP inventory beyond 2000 is reasonable, until more global or regional estimates become available. Concerning biomass burning emissions, most inventories agree within 50-80%, depending on the year and season. The large differences between biomass burning inventories are due to differences in the estimates of burned areas from the different available products, as well as in the amount of biomass burned

The impact of anthropogenic VOC speciation on SOUTH AMERICAN MEGACITIES’ URBAN ATMOSPHERES

International audienc

Analysis and comparison of trends in concentrations and emissions of VOC and CO and VOC:CO ratios in urban European cities

Since 2007, more than half of the world's population live in urban areas. Megacities, urban agglomerations with more than 10 million inhabitants, are rapidly increasing in number: in 1950 there were only two, New York and Tokyo with ~12 million, while by 2005 there were already 20, with Tokyo ranging the 35 millions. The urban atmospheres of these megacities are dominated by pollutants associated with vehicular emissions, as well as the formation of secondary pollutants responsible for photochemical smog. A comparative assessment of emissions and concentrations of volatile organic compounds (VOC) and carbon monoxide (CO) ratios in London (L) and Paris (P) is hereby presented. The work is based on three recent studies by Baker et al. (2008), Parrish et al. (2009) and von Schneidemesser et al. (in press) where concentrations of these compounds were analyzed for 28 US cities in the former and some global megacities in the second and third studies. Considering the fact that VOC provide information on the main emissions sources of cities, these studies found that even though concentrations of VOC varied greatly among cities, the ratio with the combustion tracer CO remained rather constant and was very useful for city comparison, as well as a good indicator of traffic emissions. VOC patterns in ambient air concentrations were observed to be similar in most cities, being able to consider that deviations from those patterns could be the result of measurement problems. Nevertheless, the representation of these emissions in global inventories has large uncertainties. The goal of our study is to compare and contrast emission inventory estimates with measured ambient concentrations of non-methane hydrocarbons (NMHC) and CO, as well as NMHC:CO ratios. Within the European CityZen project we have built an updated global emissions inventory with the best available datasets of anthropogenic, biomass burning and natural sources. As part of this research we will follow the same approach to compare emissions ratios between NMHC and CO for the megacities region of Paris and London and to compare these trends with measured ambient concentrations from three monitoring sites: Eltham (L) suburban station, Marylebone Road (L) kerbside station and Les Halles (P) urban station for the period 1997-2006

Evaluation of chemistry transport model simulations in the MACC project: comparison with satellite and in-situ data

The distribution and variability of tropospheric ozone and precursors are being assessed within the European project MACC using the MOZART chemistry transport model coupled with the ECMWF integrated forecasting system (IFS). Reanalysis simulations were performed for the 2003-2008 period providing information on global tropospheric composition and regional air quality. With the aim to improve forecasting system of the tropospheric ozone and precursors, several validation exercises of model results were performed using independent in-situ and satellite data. Model simulations were compared with surface data from NOAA-GMD, EMEP and other surface networks as well as with tropospheric NO2 and CO retrievals from SCIAMACHY and MOPITT instruments. This provides an evaluation of the model performance regarding long-range transport of pollutants and air quality over polluted regions such as Asia, Siberia, Europe and North America. Simulations were also performed with assimilation of satellite data from different sensors and without coupling with ECMWF IFS. Model results are improved when ECMF IFS assimilation modules were used to constrain the tropospheric CO by satellite measure- ments. Uncertainties in satellite retrieval techniques could explain some biases found in model results compared to measurements. Indeed, changes in MOPITT retrieval algorithm resulted in important changes in CO observations leading also to strong impact on modeled CO in runs using assimilation. Assimilation of surface and airborne mea- surements could reduce the discrepancy between the model and some surface measurements in particular over the northern latitudes, although uncertainties in anthropogenic and biomass burning emissions inventories may explain a part of the discrepancy. Comparisons with MOZART simulations performed within the CityZen project will also be discussed particularly in order to assess sensitivity of model results to emissions

Access to Emissions Distributions and Related Ancillary Data through the ECCAD database

During the past few years, the ECCAD (Emissions of atmospheric Compounds & Compilation of Ancillary Data) database was developed in order to provide a user-friendly access to surface emissions and ancillary data, i.e. data on land use, active fires, burned areas, population, etc. This database and the emissions portal of the GEIA (Global Emissions InitiAtive) project have been merged. ECCAD is a sub-project of the ETHER French Atmospheric Chemistry Data Centre (CNES and CNRS, http://www.pole-ether.fr). The ECCAD database includes currently a large diversity of datasets, which provide global and regional surface emissions for a large set of chemical compounds. All the data are provided at a 0.5x0.5 or 1x1 degree resolution. ECCAD provides detailed metadata on each of the datasets, including information on complete references and methodology, and links to the original inventories. Several tools are provided for the visualization of the data, for computing global and regional totals and for an interactive spatial and temporal analysis. The data can be downloaded as interoperable NetCDF CF-compliant files, i.e. the data are compatible with many other client interfaces and can be downloaded through requests as geographical coverage or geo-referenced maps. ECCAD has currently more than 700 users originating from more than 30 countries. ECCAD benefits from this large international community of users to expand the number of emission datasets made available. The ECCAD database and the web interface are in continuous development: new tools are being built to improve the analysis and comparison of emissions and ancillary data. These new tools include a regridding tool, arithmetic expressions to combine different maps, interactive selection of scale values, and new tools for temporal profiles analysis. Comparisons of data at different scales is also in development. An online module to calculate biomass burning emissions is being improved, and will also be extended to anthropogenic emissions. The presentation will provide information on all the datasets available within ECCAD, as well as examples of the analysis work that can be done online from the database. All the datasets, associated metadata, tools and download can be achieved from the ECCAD website: http://eccad.pole-ether.f