Studies on Structures and Physical Properties of Snow on Mizuho Plateau, Antarctica

Abstract

Relations between structures and physical properties of snow of four 30-m cores in Mizuho Plateau, Antarctica were investigated by measuring their specific areas of internal free surfaces and air permeabilities. The specific area of internal free surfaces and the air permeability decreased with increasing depth. Both of the depth profiles showed a kink at a depth of a critical density 550 kg/m3, indicating a change in the physical mechanism of densification. The drastic decrease of the specific areas above the depth of the kink was considered to be mainly caused by rounding and growth of ice particles; the gradual decreases below the kink were attributed to the development of bonding and particles. Measured air permeability was compared with the theoretical one for randomly packed powders of uniformly sized solid particles. The discrepancy between the measured and theoretical permeabilities was explained by the change in shapes and sizes of air channels in the snow. The depth hoar formation, which was active in regions with smaller accumulation of snow, was considered to result in the favorable shapes of channels for air permeation.