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The sea-surface reflectance factor ρ required for the determination of the water- leaving radiance from above-water radiometric measurements is derived from radiative transfer simulations relying on models of the sky-radiance distribution and sea-surface statistics. This work primarily investigates the impact on ρ of various sky-radiance and sea-surface models. A specific replicability analysis, restricted to the 550 nm wavelength, has been performed with the Monte Carlo code for Ocean Color Simulations (so-called MOX) accounting for the measurement geometry recommended in protocols for the validation of satellite ocean color data and commonly applied for operational measurements. Results indicate that the variability of ρ increases with wind speed and reaches the largest values for sun elevations close to the zenith or approaching the horizon. In particular, a variability up to about 2% is observed for wind speeds below 4 ms−1 and sun zenith angles larger than 20°. Finally, the benchmark of the ρ values from this study with those formally determined with the Hydrolight code and widely utilized by the ocean color community, exhibits systematic differences. The source of these differences is discussed and the implications for field measurements are addressed.

The minimization of adjacency effects (AE) in SeaWiFS primary products at the Aqua Alta Oceanographic Tower (AAOT) was investigated using sample images concurrent with in situ measurements. The validation exercise was performed with the NASA SeaDAS processing scheme ingesting original SeaWiFS data and alternatively SeaWiFS top-of-atmosphere data corrected for AE, and additionally including and excluding the default turbid water (TW) correction algorithm. Results show overestimates of the TW contributions partially compensating for AE. The analysis also suggests that intra-annual biases observed in SeaWiFS radiometric products at the AAOT may result from a misinterpretation of the NIR atmospheric signal as water contribution in data acquired in winter, and from uncompensated AE in data acquired in summer.