Aerosol retrievals from METEOSAT-8 - CM SAF

SAF on Climate Monitoring Visiting Scientists Report Doc. No: 1.0
Issue : 1.0
Date : 4 October 2006
Appendix A: Over the whole northern disk observed by
MSG/SEVIRI
In this appendix we show SEVIRI retrieved surface reflectance maps for the half-disc (northern
hemisphere) observed by SEVIRI/MSG. To simplify calculations and data computing we did not
correct from Rayleigh scattering. Compared to results in the rapport, we also applied a more
restrictive cloud mask which explains the lack of data in middle Europe for example.
Figure A1 presents examples of the map of the surface and molecular reflectances of reference
(R surf+molec ) for Europe and Africa.
Figure A2 presents the map of the AOT assuming that the aerosol path length, R aer , is equal to the
TOA reflectance minus the surface and molecular reflectance of reference (R aer =R TOA - R surf+molec ).
Over the sea a unique value of 0.01 has been used as surface and molecular reflectances. That is
certainly an underestimated value. It explains also the high value of AOT over the seas.
As expected, without Rayleigh corrections, results are much noisier. However, independent of the
assumptions and the quality or the sensitivity of the cloud mask, a good spatial coverage is still
expected over the disc observed by MSG.
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