Physical characteristics of snow cover on the west slope of Mt. Asahidake, Hokkaido

Abstract

The seasonal snow cover, between 300 m and 1, 800 m a.s.l., on the western slope of Mt. Asahidake (43° 40'N, 142°47'E) in central Hokkaido was systematicaly investigated from March to May 1978. The main items of observations were depth, water equivalent, density, Ram hardness, and temperatures. Between the mountain foot and the timberline at 1, 400 m, the water equivalent, mean density and mean Ram hardness increased with elevation in Marh at the end of the accumulation season. While in the ablation season from April to May, the mean density increased with time and was almost independent of elevation, but the mean Ram hardness decreased with time and was only slightly dependent on elevation. Above the timberline at 1, 400 m, mean density and mean Ram hardness were dependent mostly on the local topography irrespective of elevation in the accumulation and ablation seasons.Skeleton-type depth hoar was abundant in the snow cover below 400 m and above 1, 500 m; solid-type-depth hoar was dominant from 400 to 1, 100 m and fine-grained compact snow from 1, 100 to 1, 500 m.In forest zone below 1, 400 m, the water equivalent increased linearly with snow depth in each observation. Increase in the water equivalent of wet snow with the snow depth was larger than that of dry snow. Mean Ram hardness increased with mean density in both dry and wet snow, but the increase rate was much larger in wet snow. These relations among water equivalent, mean Ram hardness, snow depth and mean density found in the mountain snow cover are almost similar to those reported on snow covers in the plains such in Ishikari, Sorachi and Shiribeshi districts.