Microwave measurements of snow stratigraphy and water equivalence

This paper reports on a study of electromagnetic surface and subsurface scattering properies of snow using an FM-CW radar system operating in the frequency range 8-12 GHz. The scattering properties are interpreted and compared with the measured physical properties of snow such as density, stratigraphy, hardness and equivalent moisture content. The electromagnetic scattering properies are measured in situ under natural environmental conditions and the physical analysis is done at each test site to correlate the physical properties of the sample with its electromagnetic signature. Correlation between the electromagnetic and physical properies of snow are discussed. In particular, it is shown that there is a simple relationship between the 'optical' depth of the snowpack and the snowpack water equivalence, where the 'optical' depth, the square root of epsilon * d, is the product of the square root of the average dielectric constant, epsilon, and the physical depth, d, of the snowpack.