Observing the Effect of Morphology on Elastic Properties of New Snow using a Non-contacting Laser Ultrasound System

Quantifying micromechanical and microstructural properties of snow is crucial, they control bulk thermal, electrical, and mechanical properties.Snow density can provide an estimate of mechanical properties, while direct observation of snow microstructure is necessary to determine mechanical properties.We utilized a novel non-contacting laser ultrasound system (LUS), providing high frequency acoustic waveform measurements, to observe mechanical properties at the microscale.We investigated the temporal relationship between p-wave velocity, snow crystal type, p-wave modulus, stiffness, and SSA.We created homogeneous snow samples, each composed of a single type of precipitation particle, compacted to a density of 250 kg{m 3 .We measured wave propagation through these snow samples and observed changes in p-wave speed during equilibrium metamorphism.We also measured SSA with the InfraSnow Sensor, as well as micromechanical properties with the SnowMicroPenetrometer.With these data we observed changes in mechanical properties, with up to a factor of 2 increase in elastic modulus depending on crystal type during a period of 72 hours.Estimated elastic modulii increased over time, as expected and in agreement with previous work.Needles and columns had faster p-wave velocities, implying larger elastic modulus, com-