Journal of the Japanese Society of Snow and Ice

Show abstractHide abstract

A method to measure the density of thin weak layers of snow is proposed. In general, a rectangular snow sampler cannot be used for a thin layer with a thickness that is less than the sampler itself. However, the density of a thin layer can be calculated if the following three quantities are known: the density of a snow layer above or below the thin layer, the density of a snow layer including the entire thin layer, and the thickness of the thin layer. In this method, it is assumed that the density of the snow layer in contact with the thin layer is homogeneous. Errors in the measured density of the thin layer caused by inaccurate measurement of the thickness of the layer were accounted for in the simulation. The simulation results show that large density differences between the snow layer in contact with the thin layer and the thin layer itself, as well as particularly small thicknesses of the thin layer, result in larger density measurement errors. However, this method is considered to be accurate enough（<10%）for actual field measurements provided that the thickness measurement error is ±1mm and that the density difference between the layers is <100 kg m⁻³ for thin layers thicker than 10mm or <50 kg m⁻³ for thin layers thicker than 5 mm.

View full abstract

Download PDF (1163K)

On the lee side of a ridgeline or a cliff of the mountain, the huge cornices would grow up and cause the avalanches. In this study, we experimentally formed the cornices using artificial snow falling device and blower, observed its growth process using time-lapse camera and analyzed the cross section. Changing the shape of snow, the gradient of slope and the wind velocity, we obtained the growth condition of cornices: near dendrite shape is favorable for formation of cornices than a sphere shape; a 30° slope than a 45° one. The greatest cornice in our experiment grew up in the case of wind velocity 3.0ms⁻¹above 5cm snow surface. These results show that both the angle of the upper cornice and the quantity of snowdrift depending on the erosion of snow surface are important to the growth of cornice.

View full abstract

Register with J-STAGE for free!