Microwave Radiation from a Natural Snow Field

The brightness temperature of a natural snow field in Finland has been studied theoretically and experimentally at 5, 12 and 37 GHz for satellite remote sensing applications. A snow model consisting of ice spheres covered by a water shell has been used in theoretical calculations taking into account scattering and absorption. The brightness temperature of a natural snow field as a function of view angle has been measured from a tower in 1978 and 1979. The measured brightness temperature curves can be fitted with calculated ones by assuming reasonable values for the wetness and the particle size of snow. Experimental results also show that relatively small changes in the snow conditions cause large changes in the brightness temperature. To obtain a more controlled situation experiments have been continued in 1980 using a measuring site covered with aluminium sheets.