Snow crystal orientation effects on the scattering of passive microwave radiation

For this study, consideration is given to the role crystal orientation plays in scattering and absorbing microwave radiation. A discrete dipole scattering model is used to measure the passive microwave radiation at two polarizations (horizontal and vertical), scattered by snow crystals oriented in random and nonrandom positions and having various sizes (ranging from 1 /spl mu/m to 10000 /spl mu/m in radius) and shapes (including spheres, cylinders, hexagons). The model results demonstrate that for the crystal sizes typically found in a snowpack, crystal orientation is insignificant compared to crystal size in terms of scattering microwave energy in the 8100 /spl mu/m (37 GHz) region of the spectrum. Therefore, the assumption used in radiative transfer approaches, where snow crystals are modeled as randomly oriented spheres, is adequate to account for the transfer of microwave en energy emanating from the ground and passing through a snowpack.