Use of Satellite and Surface Observations of Trace Gases to Evaluate the Impact of Fire Emissions on Air Quality in Euro-Mediterranean Area
Résumé
Wildfires are one of the main sources of trace gases and aerosols. However, their impact remains poorly quantified due to large uncertainties especially on the emissions, as well as on the transport processes and chemical evolution of the pollution plumes. Satellite data, due to their high spatial coverage, can be a powerful tool for monitoring pollution plumes transport, although the information remains vertically integrated (implying limited vertical resolution). Here we present an evaluation of the effects, provided by fire emissions, on atmospheric trace gases composition. Therefore simulations by the regional chemistry-transport model CHIMERE are performed using high resolution fire emissions scenarios and subsequently a comprehensive comparison between satellite observations and model output is conducted. In particular, simulations in fire plumes are compared with CO, NH3 and C2H4 observations from the IASI instrument, NO2 and CH2O from GOME2 (both on MetOp-A satellite) and NO2 from OMI (on Aura). In the present work we focus on strong biomass burning episodes that occurred in Euro-Mediterranean area in summer 2007. Fire plume characteristics are analyzed to constrain emission scenarios, that will then be corrected in a bottom-up method. In order to evaluated the impact of fires on surface air quality, complementary comparisons to ground measurements from the AirBase database (i.e. CO, O3 and NO2 concentrations) are carried out. These allow an evaluation at high temporal resolution, but at specific locations and, in general for our case study, quite far away from the location where wildfires occur. The same fire simulation setup is used for both reanalysis and near-real time analysis. The first evaluation of an experimental air quality forecasting system including fires will be presented.