SCIAMACHY Absorbing Aerosol Index. Calibration issues and global results from 2002 - 2004

The Absorbing Aerosol Index (AAI) is the only operational aerosol product from the SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) that has been delivered from the beginning of the measurements of SCIAMACHY. In this paper the validity of the product will be discussed. The operational product suffers from calibration errors in the reflectance as measured by SCIAMACHY and design errors. Therefore, a scientific AAI product was constructed, without these errors. Appropriate correction factors were determined for the UV to correct for the radiometric error in the
SCIAMACHY reflectances. The algorithm was provided with new LookUp Tables, in which a good representation of polarisation effects was incorporated. The results of this scientific product, from the start of measurements of SCIAMACHY until December 2004, will be presented, its validity discussed, and compared to the operational product. The AAI is very sensitive to calibration errors and can be used as a monitor for calibration errors and changes. Recommendations will be given for improvement of the operational AAI product.