A new method for in-flight degradation correction of GOME-2 Earth reflectance measurements, with application to the Absorbing Aerosol Index

In this paper we study instrument degradation affecting the Earth reflectance measurements by the spectrometer GOME-2 onboard MetOp-A using a recently introduced new method. The actual factor describing reflectance degradation is quantified and analysed for a selection of wavelength bands and as a function of scan mirror position. Using the derived set of correction parameters, the GOME-2 reflectance measurements are corrected for instrument degradation and verified using the Absorbing Aerosol Index (AAI) product. Before correction, time series of GOME-2 AAI showed strong signs of instrument degradation. After applying the correction, no remnants of effects of instrument degradation can be found, proving that the in-flight degradation correction method works.