Two flow model of wet snow microwave emissivity

In hydrological investigations, the acquisition of accurate and timely information about snowpack properties and its spatial variability is of prime practical importance. The large observed effects of snow on microwave brightness temperature of the land surface suggest that microwave radiometry will be a useful tool for snow hydrology studies. The parameters that influence the T_B of snow-covered terrain include the liquid water content, water equivalent, temperature, grain size, etc. The primary purpose of this study is to derive a structure dependence model of microwave emissivity of land surface wet snow. Upward and downward radiations in the snow layer were assumed diffuse and two flow theory by Kybelka and Munk is applied. Snow cover was represented as a medium consisting of ice, air and water. The inclusions are assumed to be spherical and may have size distribution. The authors modeled wet snow either by the medium that contains ice grains covered with the water shell (under low snow wetness), or by the medium that contains ice grains and water drops (W_V>4%). Each case of space distribution of water component corresponds to its model of microwave emissivity. To study the relation between the physical properties and brightness temperature of the snowpack, the authors have carried out a complex ground-based experiment during which the physical characteristics and T_B of wet snow determined concurrently. Microwave radiometers, operating at 3.95, 19.5, 37.5 and 150 GHz and placed in a tower, were used for T_B snow measurements. The effects of snow structure, wetness, and ice grain size were examined in detail. This information their be used for comparison the experimental data and theoretical results