Microwave emission of snow in Alpine regions and the detection of surface hoar

Microwave radiometric measurements of snow packs were carried out in various test sites, to study different snow cover conditions, from dry snow at high and low density, to wet snow, and lastly, to a typical surface layer composed of big hoar crystals. It has been shown that dual-frequency (10 and 37 GHz), dual polarized microwave data appear efficient in separating wet from dry snow and in identifying the presence of surface hoar, which is is of significant interest for the research on avalanche forecast.