Daily estimates of the tropospheric aerosol optical thickness over land surface from MSG geostationary observations
Résumé
The paper presents an innovative method to derive aerosol optical thickness (AOT) on a continental scale, using MSG observation. The approach consists in taking into account the high temporal resolution of the observing system, in order to discriminate between surface and aerosol effects. A suitably extended semi-empirical BRDF model is applied, combined with a recursive scheme. The method is not instrument-specific (can be adapted to instruments onboard polar satellites) and was tested with MSG/SEVIRI data over mid-latitude and African regions. The aerosol optical thickness estimates are compared to AERONET ground measurements and to the corresponding MODIS product over land. The method appears very promising for tracking anthropogenic emissions in the troposphere and also for estimating dust events over bright surfaces. The high spatial and temporal resolution of the estimate is appropriate to investigate the dependence of AOT on the density of urbanization and potentially on motor vehicle traffic. Finally, this study suggests that this approach is appropriate for multi-sensor data fusion, for the simultaneous retrieval of surface albedo and aerosol optical thickness, and to generate these products in near-real time with a very high generation frequency.
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