Abstract
On the basis of non-steady gas diffusion theory, a portable apparatus was constructed to measure CO2 diffusion coefficient of snow.It consists of a CO2 supply chamber with an electrode CO2 meter, a snow sample tube to be connected with the chamber and gas-supply equipment. After replacing the air in the chamber with CO2 with known concentration, the temporal change of CO2 concentration in the chamber was measured.Diffusion coefficients were calculated from the rate of concentration change and information of system geometry.
To examine the reliability of the apparatus, diffusion coefficient of CO2 in glass beads and straight glass tube bundles of known geometry were measured.Obtained values showed close agreement with expected values. Reproducibility was excellent, giving relative variation of measurements less than 5%.CO2 diffusion coefficients of newly fallen snow, granular snow and compacted snow, densities ranging between 0.10 and 0.55g/cm3, were measured.Measured values were between 0.40 and 0.89cm2/s (at0°C) and were proportional to the porosity of snow.The apparatus proved to be useful for field measurements.
