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We measured water leaving reflectance, phytoplankton pigments, optical properties and photosynthetic parameters in the southern Benguela ecosystem in October 2002. These data were used to validate MERIS standard products: reflectance (MERIS wavelengths) and Case 1 Chlorophyll-a. In this heterogeneous area, accurate validation required sampling within a few minutes of the satellite overpass. Inter-pigment relationships e.g. Total Chlorophyll (TChla) to Total Pigment (TP) were robust (R 2 ,0.99) yet pigment ratios (TChla/TP) were not constant (range 0.44 to 0.62) increasing log-linearly with biomass (R 2 ,0.7). Photosynthetic parameters (e.g. Photosynthetic Quantum Efficiency, PQE) and optical ratios (a 676 /a 440 ) also increased log-linearly with biomass (R 2 ,0.8). PQE, pigment and optical ratios were linearly inter-correlated (R 2 ,0.7 to 0.8). From these data we derived the bio-optical traits for several phytoplankton functional types (PFTs): micro-plankton (diatoms and dinoflagellates) had high biomass, pigment ratios and PQE; nano-flagellates had low to intermediate biomass, pigment ratios and PQE; prokaryotes had very low biomass, pigment ratios and PQE. We present MERIS data analysed for PFTs and new products (PQE).

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