| For analyzing the regional characteristics of snowpacks related to avalanches, snow-pit observations were carried out at six study sites in the Japanese central mountains. The study sites include the Japanese North Alps, the Central Alps, and the South Alps, which are the major mountain ranges in the Japanese central mountains. On the basis of the dominant type of persistent weakness in the snowpack, the study sites were divided into three characteristic regions, as follows:- The region in which persistent weakness was mainly caused by presence of melt-freeze crust (MFcr) layers.- The region in which persistent weakness was mainly caused by the presence of weak layers consisting of near-surface faceted crystals (FCsf). - The region in which persistent weakness was mainly caused by the formation of thick weak layers consisting of depth hoar (DH) near the ground.Further, we examined the relationships between the persistent weaknesses and meteorological elements. Our results suggest that some meteorological elements are useful as indicators of persistent weakness in the snowpack. For instance, the following parameters related to snowpacks can be estimated reasonably as follows:- Number of MFcr layers in the snowpack: This value is estimated by multiplying the total number of rainfall days by the snow depth.- Number of FCsf layers in the snowpack: This value is estimated by dividing the average diurnal range of air temperature by the snow depth.- The ratio of the total thickness of DH layers to the total thickness of snow pack: This value is estimated by average temperature gradient and total amount of rainfall. |
