Monitoring global snow cover

Snow cover is an important variable for climate and hydrologic models due to its effects on surface albedo, energy, and moisture budgets. A model is currently being developed at the University of Colorado which will provide global snow cover information on a daily/operational basis. The basic data generated for each grid point (40 km resolution) are calculated average snow depth, maximum snow depth, age in days of the total snow cover, number of days since the last surface accumulation, as well as data source flags and summary diagnostics.Surface measurements used by the model are obtained through the World Meteorological Organization (WMO) synoptic data collection network. The model also uses passive microwave satellite data (DMSP/SSMI) which provide global, all-weather, day/night information on snow cover extent. In addition, the potential to extract snow depth information from passive microwave data is utilized.Special routines have been developed to handle problems associated with both surface observations (optimal interpolation, extrapolation into data-sparse mountain areas, missing data) and passive microwave