Revision of the CREPAD products Description and results of the new algorithms.

Since 1997, the INTA-CREPAD (Centre for REception, Processing, Archiving and Dissemination of Earth Observation Data) service distributes freely some of the most demanded low-resolution remote sensing products including aerosol optical thickness (AOT) and sea surface temperature (SST). CREPAD is assessing the accuracy of the delivered products, independently from the specified performances of the selected sensors and algorithms. For this purpose, a validation programme has been defined, and first results are being analysed. Retrieved AOT values have been derived from a new algorithm. Regional characteristics of the aerosols have been taken into account to create the new algorithm. The accuracy of the retrieved AOT is 0.09plusmn0.04. Previous studies validated the CREPAD SST derived from AVHRR data by comparison with SST buoys measurements. In Canary Islands region AVHRR SST uncertainty is around 1.42deg. This uncertainty can increase when high aerosol concentration is present. Therefore an atmospheric correction for the SST has been implemented in the algorithm. The atmospheric correction algorithm is only applied for pixels with AOT higher than 0.15. First results show that the SST accuracy increases in about 20%.