Un produit opérationnel de surface enneigée à partir de données Sentinel-2 et Landsat-8

International audienceCurrent snow cover area products are derived from mid-resolution optical observations but their spatial resolution (e.g. MODIS, 500 m) is too coarse for many applications in mountains where the snow cover varies at decametric scales. The Theia land data center (http://www.theia-land.fr/) is preparing the distribution of a new snow cover product from Landsat-8 and Sentinel-2 data to map the snow presence or absence at 20 m resolution every 5 days over a large region, which currently includes the French Alps, the eastern part of the Swiss and Italian Alps, the Pyrenees and the High Atlas (Hagolle, 2016). The algorithm takes as input a Sentinel-2 or Landsat-8 image of surface reflectance corrected from atmospheric and slope effects, the associated cloud mask and a digital elevation model. The output is a vector file or single band raster at the same resolution of the input image, which gives the snow presence or absence and a new cloud mask. Before the launch of Sentinel-2 the algorithm was tested on various SPOT-4 Take 5, SPOT-5 Take5 and Landsat-8 time series in the Pyrenees, the High-Atlas in Morocco and the french Alps (Gascoin, Grizonnet, Klempka, 2016)