. 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, kinetics and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative contribution to the pollutants budgets can be quantified with chemistry-transport models. The CHIMERE chemistry-transport model is dedicated to regional atmospheric pollution event studies. Since it has now reached a certain level a maturity, the new stable version, CHIMERE 2013, is described to provide a reference model paper. The successive developments of the model are reviewed on the basis of published investigations that are referenced in order to discuss the scientific choices and to provide an overview of the main results.

/pdf/chimere-2013-a-model-for-regional-atmospheric-composition-3ymu214cn0.pdf

CHIMERE 2013: a model for regional atmospheric composition modelling

https://www.cnrm.meteo.fr/IMG/pdf/sarrat_2006_ae.pdf

Impact of urban heat island on regional atmospheric pollution

Multiple satellite sensors are used to analyze physical processes that determine energy fluxes and their interaction at the urban surface. The study is based on summertime microclimate analyses of the Los Angeles and Paris metropolises. The method consists of deriving some parameters governing the surface heat fluxes, constructing statistics of thermal infrared images, and using a GIS to combine them with a landcover classification from SPOT-HRV multispectral images, and with data from intensive in-situ experiments. The average images reveal spatial and temporal variations of land surface temperature (LST), and distinct microclimatic patterns. The combined interpretation of the statistics images and of the landcover classification shows: (i) the effect of surface physical properties, especially in downtown business and industrial districts that display heat-islands larger than 7 °C; (ii) the temperating influence of water; (iii) the negative correlation between afternoon land surface temperature and normalized vegetation index, which confirms the cooling effect of urban parks; (iv) the correlation between variations of surface temperature and ozone concentration at diurnal and longer time scales.

Satellite multi-sensor data analysis of urban surface temperatures and landcover

A comparison of simulated and observed ozone mixing ratios for the summer of 1998 in Western Europe

Impact of lockdown measures to combat Covid-19 on air quality over western Europe.

. The "Etude et Simulation de la QUalite de l'air en Ile de France" (ESQUIF) project is the first integrated project dedicated to the study of the processes leading to air pollution events over the Paris area. The project was carried out over two years (summer 1998 to winter 2000) to document all types of meteorological conditions favourable to air quality degradation, and in particular to photo oxydant formation. The goals of ESQUIF are (1) to improve our understanding of the relevant chemical and dynamical processes and, in turn, improve their parametrizations in numerical models, and (2) to improve and validate existing models dedicated to pollution analysis, scenarios and/or forecasting, by establishing a comprehensive and thorough database. We present the rationale of the ESQUIF project and we describe the experimental set-up. We also report on the first experiments which took place during the summer of 1998 involving surface networks, and remote sensing instruments as well as several aircraft. Focusing on three days of August 1998, the relative contributions of long-range transported and locally-produced ozone to the elevated ozone concentrations observed during this period are discussed and chemistry-transport model preliminary results on this period are compared to measurements. Key words: Atmospheric composition and structure (pollution – urban and regional; troposphere – composition and chemistry) – Meteorology and atmospheric dynamics (mesoscale meteorology)

/pdf/measurements-and-modelling-of-atmospheric-pollution-over-the-tacnc4kkjd.pdf

B. Lossec

Papers

Measurements and modelling of atmospheric pollution over the Paris area: an overview of the ESQUIF Project