Snow-cover parameters retrieved from Nimbus-7 scanning multichannel microwave radiometer /SMMR/ data

The multifrequency, dual-polarized microwave imager on the Nimbus-7 satellite is designed to sense the ocean surface, the atmosphere, and land surfaces. Reference is made to the fact that snow cover over land has a very distinct effect on the microwave signature of the earth's surface. The goal of the study described here is to show that the three snow-cover parameters, namely extent, snow water equivalent, and onset of snow melt, can be determined using scanning multichannel microwave radiometer data. The analysis demonstrates that these parameters are retrievable with sufficient accuracy to be of great value in climatology, meteorology, and hydrology. Snow cover extent is determined for a dry snow cover having a depth greater than about 5 cm; the snow water equivalent, it is shown, can be determined on a regional basis with approximately 2 g/sq cm rms accuracy. The onset of snow melt is clearly visible through the detection of melt and refreeze cycles before snow runoff. It is pointed out that the algorithms derived are simple enough to be incorporated in fully automated operational data analysis schemes.