Daily estimates of the tropospheric aerosol optical thickness over land surface from MSG geostationary observation

This paper presents an innovative method to estimate the daily aerosol optical thickness (AOT) on a continental scale, using MSG observation. The approach takes best benefit of the high temporal resolution of the observing system, in order to disentangle the surface and aerosol angular signatures. For such, a semi-empirical BRDF model that mimics both surface and aerosols signals is inverted according to a recursive scheme. The method is not instrument-specific and could be reproduced with other GEO and LEO observing systems. Herein, field of application is restricted to MSG/SEVIRI data over mid latitude and African regions. The reliability of AOT estimates is demonstrated through comparisons with local AERONET ground measurements and at regional scale against MODIS. The method appears very promising for tracking anthropogenic emissions in the troposphere and also for estimating dust events over bright surfaces. Furthermore, high temporal AOT retrievals at moderate spatial resolution stress the effects of the density of urbanization and potentially on motor vehicle traffic on air quality. Finally, this study suggests that this approach is appropriate for multi-sensor data fusion, for the simultaneous retrieval of surface albedo and AOT, and also to generate these products in near-real time with a very high generation frequency.