UTILIZATION OF SURFACE COVER COMPOSITION TO IMPROVE THE MICROWAVE DETERMINATION OF SNOW WATER EQUIVALENT IN A MOUNTAIN BASIN

Satellite microwave data have been used to derive areal snow water equivalent in flat homogeneous areas with some success. Over heterogeneous mountainous areas different algorithms are needed to retrieve the water equivalent of the snow cover. A mixed pixel model based on the percentage of vegetation cover within a pixel has been developed to simulate the microwave brightness temperatures for the Rio Grande basin (3419 km2) in south-western Colorado. A relationship between the difference in microwave brightness temperature at two different frequencies (37 and 18 GHz horizontal polarization), and the basin-wide average snow water equivalent was obtained. The areal snow water equivalent values derived from the model were consistent with values generated by a reliable snowmelt run-off model using snow cover extent data.