摘要：The Theia Snowcollection routinely provides high-resolution maps of the snow-covered area from Sentinel-2 and Landsat-8 observations. The collection coversselected areas worldwide, including the main mountain regions in westernEurope (e.g. Alps, Pyrenees) and the High Atlas in Morocco. Each product ofthe Theia Snow collection contains four classes: snow, no snow, cloud and no data.We present the algorithm to generate the snow products and provide anevaluation of the accuracy of Sentinel-2 snow products using in situ snow depthmeasurements, higher-resolution snow maps and visual control. The resultssuggest that the snow is accurately detected in the Theia snow collectionand that the snow detection is more accurate than the Sen2Cor outputs (ESAlevel 2 product). An issue that should be addressed in a future release isthe occurrence of false snow detection in some large clouds. The snow mapsare currently produced and freely distributed on average 5d after the imageacquisition as raster and vector files via the Theia portal(https://doi.org/10.24400/329360/F7Q52MNK).
