Atmospheric correction in presence of sun glint: application to MERIS.

The sun glint is a major issue for the observation of ocean color from space. For sensors without a tilting capacity, the observations at sub-tropical latitudes are contaminated by the bright pattern of the specular reflexion of the sun by the wavy sea surface. Common atmospheric correction algorithms are not designed to work in these observation conditions, reducing the spatial coverage at such latitudes by nearly a half. We describe an original atmospheric correction algorithm, named POLYMER, designed to recover ocean color parameters in the whole sun glint pattern. It has been applied to MERIS data, and validated against in-situ data from SIMBADA. The increase of useful coverage of MERIS measurements for ocean color is major, and the accuracy of the retrieved parameters is not significantly reduced in the presence of high sunglint, while, outside the sunglint area, it remains about the same as by using the standard algorithm.