The objective of this study is to estimate the response of the permafrost at the Daisetsu Mountains, central Hokkaido to a continuous climatic change. A one-dimensional, nonsteady state, heat conduction model with phase change is used to calculate the change of permafrost thickness during the last 20, 000 years. The result of simulation shows that the permafrost responded quickly to the surface temperature change and it has remained without thaw since the Last Glacial Maximum. The minimum permafrost thickness is estimated at 11.5 m at about 5 kyr B. P. and reached to 30.1 m at present. The simulation also indicates that the permafrost thickness is sensitive to soil water content and ground heat flow.

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A dry snow cover composed of uniform ice spheres is modeled to examine the contribution of microstructure to thermal processes in the snow cover. Three types of heat transfer are calculated ; heat conduction through the ice bond netwrok, water vapor flux across the pore space, and conduction in the pore.
Conduction through the ice bond network is determined to be the most important mechanism for sintered snow, however for poorly bonded ice granins the vapor transport contribution is significant and in the extreme case may dominate. The thermal conductivity is calculated to increase with snow density and with an increase in the ratio of the bond radius to the sphere radius. The relative contribution due to vapor transport decreases with decreasing temperature. Conductivity varies little with temperature when the ratio of hond/sphere radius is small, but in the case of a large ratio conductivity increases with decreasing temperature due to the strong dependance on the ice constituent. Conduction of heat in the pore is negligible.
It is shown that the effective thermal conductivity of snow has a strong dependence on the bond/sphere ratios (microstructure), density, and temperature. The importance of the role of microstructure is ascertained.

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An automatic roof-snow remover was set on a pitched roof. The remover consists of an electric motor (90W) and a pair of inverse V-shaped snow cutting plates (20cm wide and 3.55m lomg each) . The plates shuttled between gables 7 times every 2 hours to cut newly deposited snow on the plates, leaving cut snow from eaves. The snow removing force was 11.3kgf when. the snow covered about 75cm of the lower end of plates and the maximum cutting depth was 8 cm.

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A small snow compressor was developed with a “screw-feed” system to utilize snow resources effectively for various purposes. This system allows collected natural snow to be introduced into a cylinder where it is compressed by a screw to end up with a squeezed concrete cylindrical snow column. Also the system has feasibility of re-designing the column : cross section of the column can be rectangular or hexagonal. It is also relatively easy to colour the column. Mechanical test of the resultant snow column indicated that accumulated columns would last long time and be used as building materials in various occasions and such as snow festival, or for storaging snow. The system is rather small in size and also in energy consumption, and its operation is relatively easy and safe. Economical operation cost is another advantage of the system.

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[in Japanese]

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[in Japanese]

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