GeoQAIR : Quantification de l'apport d'une plateforme d'observations Géostationnaires pour la surveillance de la Qualité de l'AIR en Europe

Monitoring of air quality (AQ) and its transport at the continental scale, as well as the development of efficient forecast systems for air quality is one of the issues included in the GMES (Global Monitoring for Environment and Security) European Programme for the establishment of a European capacity for Earth Observation. The availability of satellite instruments which have the ability to monitor tropospheric ozone in the lowermost troposphere would be a step forward for this system. To monitor small scale and short term processes as involved in pollution event development, a geostationary Earth orbit (GEO) observing system is particularly well adapted. Future GEO missions dedicated to air quality monitoring using thermal infrared (TIR) instruments are planned to be operating over the USA, Japan and Korea, while existing and planned missions over Europe are not well adapted for this task. One of the objectives of the GeoQAIR project is to evaluate different satellite instrument concepts for their ability to monitor AQ and in particular quantify the possible impact for AQ forecasting. Four instruments have been considered for this study: the existing instrument IASI on MetOp-A (Low Earth Orbit - LEO - mission), the planned IASI-NG on the EPS-SG platform (LEO mission) and IRS on Sentinel4/MTG platform (GEO mission mainly dedicated to meteorology) and a new GEO mission concept, MAGEAQ, dedicated to AQ monitoring and proposed at the last Earth Explorer 8 call of ESA. Pseudo-observations for the four instruments have been generated to simulate one month of ozone observations over Europe. About 45 millions of individual measurements have been simulated using the EGI facilities. A first analysis of the performances of the different instruments to measure ozone in the lowermost troposphere demonstrates that the short time and space scale processes implied in air pollution development will not be correctly apprehended with the current existing and planned missions. Dedicated instrument with sufficient spectral resolution and signal to noise ratio, as proposed within the MAGEAQ mission concept, are necessary to correctly represent these processes