The multi-sensor time-series FSC service consists of weekly updated products for the defined geographic area. The product is updated daily with snow cover retrieval results from cloud-fee parts of optical images and selected SAR images. During the first year, 2006, an average of five near-real-time ENVISAT ASAR images per week was used for this service. Accordingly, a weekly product is based on a minimum of five ASAR images and 14 Terra MODIS images (two passes per day).The figure below shows examples of snow maps derived from ENVISAT ASAR and Terra MODIS for the region currently monitored.

Snow-free ground is shown in dark green, while FSC is shown in tones of green between dark green (0% FSC) and white (100% FSC). Yellow represents clouds and no observations in general