Validation of MERIS Level-2 products in the Baltic Sea, the Namibian coastal area and the Atlantic Ocean

Measurements of water-leaving reflectance and optically active water constituents in the Baltic Sea, the Namibian coastal area and the Atlantic Ocean were performed to validate MERIS Level-2 products. Two different validation methods were applied with the recommended match-up analysis based on comparison of in situ measurements with MERIS Level-2 products of simultaneous Envisat overpasses and the second analysis on comparison of natural variation ranges with derived MERIS product ranges. The MERIS water-leaving reflectances correlate to in situ shapes and magnitudes in all investigated areas. The comparison shows mean deviations of MERIS reflectances between 23% and 26% for the current official instrument processing facility (IPF 4.07) but only 20% for the prototype version 7.0 up to now only available to the validation team. The comparison of water constituents shows the underestimation of MERIS ALGAL_ 2 index, YSBPA and TSM in turbid waters of the Baltic Sea of the current instrument processing facility ( IPF 4.07). The mean MERIS ALGAL_ 1 index is close to in situ values but the mean MERIS ALGAL_ 2 index, the MERIS YSBPA and MERIS TSM products are still too low in Namibian coastal areas for the prototype version 7.0. The investigations demonstrate the quality improvement of all MERIS Level-2 products from the current official instrument processing facility to the prototype version 7.0.