Sentinel-2 radiometric image quality commissioning: first results

In the frame of the Copernicus program of the European Comission, Sentinel-2 will offer multispectral highspatial- resolution optical images over global terrestrial surfaces. In cooperation with ESA, the Centre National d’Etudes Spatiales (CNES) is in charge of the image quality of the project, and will so ensure the CAL/VAL commissioning phase during the months following the launch. Sentinel-2 is a constellation of 2 satellites on a polar sun-synchronous orbit with a revisit time of 5 days (with both satellites), a high field of view - 290km, 13 spectral bands in visible and shortwave infrared, and high spatial resolution - 10m, 20m and 60m. The Sentinel-2 mission offers a global coverage over terrestrial surfaces. The satellites acquire systematically terrestrial surfaces under the same viewing conditions in order to have temporal images stacks. The first satellite has been launched in June 2015. Following the launch, the CAL/VAL commissioning phase will then last during 6 months for geometrical calibration. This paper first provides explanations about Sentinel-2 products delivered with geometric corrections. Then this paper details calibration sites, and the methods used for geometrical parameters calibration and presents the first linked results. The following topics are presented: viewing frames orientation assessment, focal plane mapping for all spectral bands, first results on geolocation assessment, and multispectral registration. There is a systematic images recalibration over a same reference which will be a set of S2 images produced during the 6 months of CAL/VAL. As it takes time to have all needed images, the geolocation performance with ground control points and the multitemporal performance are only first results and will be improved during the last phase of the CAL/VAL. So this paper mainly shows the system performances, the preliminary product performances and the way to perform them.