Signatures of snow in the 5 to 94 GHz range

A long-term observational study of the microwave emission and scattering behavior of snow under quasi-controlled conditions was started recently on a high-altitude Alpine test site. Results of the first set of measurements, carried out with five radiometers at frequencies of 4.9, 10.5, 21, 36, and 94 GHz, are reported and preliminary interpretations are given. The spectral reversal of the brightness temperature and its dependence on look angle and polarization provides a means to distinguish between different snow states and to estimate the wetness factors of the surface layer of the snow pack. From an electromagnetic scattering standpoint, snow cover is an excellent medium to use for studying volume scattering.