MODIS and OMI satellite observations supporting air quality monitoring

Within the framework of air quality monitoring, measurements by Earth-observing satellite sensors are combined here with regional meteorological and chemical transport models. Two satellite-derived products developed within the QUITSAT project, regarding significant pollutants including PM2.5 and NO2, are presented. Estimates of PM2.5 concentrations at ground level were obtained using moderate resolution imaging spectroradiometer (Terra-Aqua/NASA) aerosol optical properties. The semi-empirical approach adopted takes into account PM2.5 sampling and meteorological descriptions of the area studied, as simulated by MM5, to infer aerosol optical properties to PM projection coefficients. Daily maps of satellite-based PM2.5 concentrations over northern Italy are derived. Monthly average values were compared with in situ PM2.5 samplings showing good agreement. Ozone monitoring instrument (OMI) (Aura/NASA) NO2 tropospheric contents are merged using the GAMES chemical model simulations. The method employs a weighted rescaling of the model column in the troposphere according to the OMI observations. The weightings take into account measurement errors and model column variances within the satellite ground pixel. The obtained ground-level concentrations of NO2 show good agreement with the environmental agencies’ in situ. The capabilities of Earth observation satellites have greatly improved over the last few years, with gradual improvements in temporal and spatial resolutions and enhancements in radiometric accuracy, thus encouraging further studies on the use of satellite data to assess air quality (AQ). Within this context, the synoptic view and the daily repetition cycle of satellite-based measurements strengthen the potential for monitoring air pollution transport and directly evaluating the spatial distribution of various air pollutant concentrations. These evaluations are in compliance with the regulations of