Dry snow permittivity evaluation from density: A critical review

Ground Penetrating Radar (GPR) surveys on alpine snow enable a rapid evaluation of snow thickness but necessitate a measurement of the wave velocity in the snowpack. Such quantity is often evaluated from density measurements, using the relationships connecting snow permittivity and density present in literature. Unfortunately such equations provide different results and are rarely reported with an associated uncertainty, making the choice between different models pretty difficult. In the present work we compare all the equations with uncertainties (when reported), suggesting which model can be considered as the most reliable in the extraction of the wave velocity from snow density measurements. Such choice has also been corroborated by the analysis of experimental data.