1Laboratoire de Météorologie Dynamique (LMD), UMR8539, IPSL, CNRS, Ecole Polytechnique, Ecole Normale Supérieure, Université Paris 6, 91128 Palaiseau Cedex, France
2INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, France
3Laboratoire Interuniversitaire des Systèmes Atmosphériques, IPSL, CNRS, Paris-Est and Paris Diderot Universities, UMR7583, Créteil, France
4Dipartimento di Scienze Fisiche e Chimiche – CETEMPS, Universita degli Studi dell'Aquila, Via Vetoio, 67010 Coppito, L'Aquila, Italy
5NCAR Atmospheric Chemistry Division, 3450 Mitchell Lane, Boulder, Colorado, USA
6Laboratoire des Sciences du Climat et de l'Environnement, IPSL, CNRS, CEA, Versailles University, UMR 8212, Orme des Merisiers, Gif sur Yvette, France
7Environment Department, CIEMAT, Madrid, Spain
Abstract. Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources), stagnant meteorological conditions, velocity and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative importance to the pollutants budgets can be quantified within a chemistry-transport models (CTM). The offline CTM CHIMERE model uses meteorological model fields and emissions fluxes and calculates deterministically their behavior in the troposphere. The calculated three-dimensional fields of chemical concentrations can be compared to measurements to analyze past periods or used to make air quality forecasts and CHIMERE has enabled a fine understanding of pollutants transport during numerous measurements campaigns. It is a part of the PREVAIR french national forecast platform, delivering pollutant concentrations up to three days in advance. The model also allows scenario studies and long term simulations for pollution trends. The modelling of photochemical air pollution has reached a good level of maturity, and the latest projects involving CHIMERE now aim at increasing our understanding of pollution impact on health at the urban scale or at the other end of the spectrum for long term air quality and climate change interlinkage studies, quantifying the emissions and transport of pollen, but also, at a larger scale, analyzing the transport of pollutants plumes emitted by volcanic eruptions and forest fires.