Sentinel-2 simulation

This is the most realistic simulation of a Sentinel-2 scene available at the moment. It includes all spectral and spatial characteristics of all 13 Sentinel-2 bands and contains top-of-atmosphere radiance data, corresponding to a Sentinel-2 level 1c product. The scene covers an extent of 16 x 22 km2 over the area of Zurich and its surroundings, and includes a wide range of land covers and land uses: buildings, urban parks, airport, lakes, rivers, forests, and crop fields at various phenological stages.  The particular spatial and spectral characteristics of Sentinel-2 can only be simulated using high resolution airborne imaging spectrometer data.  APEX was chosen for this purpose because of its unprecedented spectral, spatial and radiometric resolution. Its continuous spectral coverage of the range 380 to 2500 nm (Jehle et al. 2010) allowed simulating all 13 Sentinel-2 bands. Each band was simulated with at least three APEX bands (D'Odorico et al. 2013), and each Sentinel-2 pixel was covered by at least nine APEX pixels. The signal-to-noise ratio (SNR) of APEX is also well above the expected SNR of Sentinel-2. Each APEX image was nadir-normalized, spectrally resampled, geo-corrected and ortho-rectified to the Swiss National Grid (CH1903) with a ground sampling distance of 10 m. Bands 5, 6, 7, 8b, 11 and 12 of the mosaic were then resampled to 20 m, and bands 1, 9 and 10 were resampled to 60 m. Finally, TOA radiances were calculated from the radiances in the mosaic using a linear approximation of the atmospheric effects. The main limitation in the simulated Sentinel-2 scene was the variation of the solar geometry during the 2-hour APEX, which caused a brighter vertical stripe on the west side of the scene, and a general trend of increasing brightness from east to west. An extensive description of the simulated Sentinel-2 scene can be found in (Laurent et al. In review)