Aerosol retrievals from METEOSAT-8 - CM SAF
Aerosol retrievals from METEOSAT-8 - CM SAF
Aerosol retrievals from METEOSAT-8 - CM SAF
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<strong>SAF</strong> on Climate Monitoring Visiting Scientists Report Doc. No: 1.0<br />
Issue : 1.0<br />
Date : 4 October 2006<br />
Fig.15: Temporal variation of the AOT at 670nm derived <strong>from</strong> AERONET and MSG for the 12th<br />
and 14 th of July over Blida (Near Alger - Algeria)<br />
In Fig. 16 we present the comparison between the MSG/SEVIRI and the MODIS aerosol product.<br />
The two instruments capture the main patterns of the aerosol field but quantitative comparison is at<br />
the moment difficult since we do not retrieve the AOT at the same wavelength. The background<br />
AOT seems to agree well and large dust outbreak over North of Algeria and the Mediterranean Sea<br />
is seen by the two instruments. There is a good land/ocean continuity of the aerosol front passing<br />
over Spain and South of France for MSG and it is not so clear for MODIS. However some<br />
discrepancies occur for cloud covered regions, for example in the centre of France where high AOT<br />
are retrieved <strong>from</strong> MSG and MODIS observes mainly clouds instead of aerosols. There is<br />
agreement between the two instruments over England where very high AOT are found. This<br />
emphasizes one more time the fact that our cloud mask still has to be improved.<br />
Finally these results are obtained with lots and sometimes strong assumptions but they are really<br />
promising, especially because changes in aerosol amount over some locations are also seen by<br />
MSG. Better agreements should be obtained using exact radiative transfer calculations and filters on<br />
the number of pixel used for the mean calculation, threshold on the standard deviation and the<br />
proximity of clouds.<br />
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