Interpretation and Utilization of Areal Snow-Cover Data from Satellites

Areal snow-cover data provided by remote sensing enable the areal water equivalent at the start of the snow melt season to be evaluated. To this end, the time scale in the graphical representation of the snow coverage curves is replaced by the totalized computed daily melt depths. These refer to the seasonal snow cover at the starting date and disregard subsequent snowfalls. INTRODUCTION Since the beginning of Earth satellite observations, snow cover monitoring has been a primary remote sensing objective. In recent years, measurement of the areal extent of snow cover has improved through better spatial resolution and discrimination between snow and clouds. An mterpretation of these measurements is required to produce meaningful snow information. SNOW-COVER MAPPING Conventional depletion curves of snow-covered areas in mountain basins are useful for those snow-melt run-off models which are designed to use this information. The shape of these curves, varying from year to year, has even been used to estimate the accumulation of snow in terms of the water equivalent (Meier 1973; 0degaard and 0strem 1977; Rango and others 1977; Moravec and Danielson 1980). Fig.1 shows, however, that substantial errors may be