COSMOS Continuous Snow Monitoring System

COSMOS (Continuous Snow Monitoring System) is ExoLabs' operational daily snow-data service. It combines imagery from nine optical satellites (Sentinel-2 A/B, Sentinel-3 A/B OLCI and SLSTR, Landsat 8/9, VIIRS and MODIS Terra/Aqua) with weather-station measurements, DWD weather-model data and topography to map snow-cover probability, snow depth and snow-water equivalent (SWE). Machine-learning algorithms model snow lines, topography and land cover to estimate snow cover under cloud. Satellite data take five to twenty hours to arrive, so each daily map reflects the previous day, and an auxiliary layer records the days since the last direct satellite observation. Snow cover is mapped globally at 500 m and at 20 m for the European Alps, the US Rockies and Sierra Nevada and the Himalaya; 20 m snow depth, with +24/+48-hour forecasts and fresh-snow layers, covers the Alps and Pyrenees. ExoLabs reports a mean snow-depth error of 0.36 m against 23 independent reference datasets near Davos and an SWE RMSE of 53 kg/m². Data are delivered as GeoTIFF archives on AWS S3, XYZ/WMS/WMTS map tiles and point and path query APIs returning GeoJSON, and the maps appear in apps including Outdooractive, Skitourenguru, swisstopo, The Hiking Club and WegWandern. Applications named by ExoLabs include hydropower and water-resource management, risk assessment, outdoor tourism, rail operations, insurance and climate research.