Aerosol optical depth over land: Comparing AERONET, AVHRR and MODIS

Data from NOAA-16 AVHRR have been used to retrieve the spatial distribution of aerosol optical depth for central Europe. At eight AERONET sites, monthly mean values based on daily AVHRR aerosol maps are calculated and compared to monthly mean values from TERRAMODIS, AQUA-MODIS and AERONET. Additionally, seasonal mean maps for 2002 are presented. To estimate the performance of this algorithm, the winter and summer season maps are compared to TERRA-MODIS seasonal maps created from the daily global aerosol product. In general, the AVHRR and MODIS aerosol maps show the same features: Lower values with increasing altitude, higher values in heavily industrialized areas and overall reasonable mean values. AVHRR maps are spatially more homogeneous than MODIS, which seem to contain an imprint of the surface cover type. The maps clearly demonstrate the potential of the retrieval method to produce a climatology based on AVHRR aerosol optical depth data over land.