This research has the important objective of finding a method for estimating the weight of snow cover on the ground and roofs over large areas and on a long term for the Tohoku region using only the meteorological factors of AMeDAS observed at many places of snowy regions in Japan.
The weight of the snow cover was obtained by adding variable parameters obtained by deducting the daily quantity of melting snow from the daily quantity of precipitation continuously from the first snowfall of the winter season. The daily quantity of melting snow was defined as the differ-ence of the weight of snow cover measured serially every the two days without rainfall and snowfall during the winter season, and was obtained as a function of average atmospheric tempera-ture, using 1979 to 1989 data from Tokamachi Forest Testing Station in Niigata prefecture.
In order to study the relation between snow cover on the ground and roofs, two small testing houses were constructed to observe the accumulation and melting processes of snow cover, one in Aomori city in Aomori prefecture and one in Tokamachi city in Niigata prefecture. Both of the areas are typical heavily snowy regions in Japan. The following data were measured around and on the houses during the winter season of 1990: atmospheric temperature, wind speed and direction, daily quantity of snowfall, snow depth on the ground and on roofs, and densities of snow cover.
By substituting these data into a estimation formula, the values of the weight of snow cover were computed on the ground and on roofs. The estimates obtained from the model were correlated with the actual measured values.
From the data it was determined that the quantity of accumulation of newly fallen snow on a roof per day was apt to be influenced by wind speed in comparison with accumulation on the ground, and the tendency for accumulation on the roof decreased with increasing wind speed. Therefore, the weight of snow cover on roofs was recognized as 70-80% of the accumulated snow on the ground at cach place.
Consequently, if the daily data of atmospheric temperature, quantity of precipitation, wind speed and direction can be collected, then the weight of the snow cover on the ground and roofs can be estimated with confidence.

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It is a well known fact that acid-rain has caused great damages to plants, forests, soils lakes and rivers. In the snowy regions of Japan, such as Hokuriku, Western part of Tohoku and Hokkaido, there is much snowfall instead of rain between December and March. The quantity of snowfall is eguivalent to almost a quarter of the annual precipitation. For the above reasons, it is important to continuosly monitor the acidity of falling snow and deposited snow in these regions.
We started to measure the pH-value and electrical conductivity for falling snow and deposited snow in February 1992, About two-third of the measured pH-values for falling snow were lower than 5.6 P. H. which is the critical pH-value for acid-rain. The pH-values for deposited snow observed at 7 points in Akita prefecture also showed that falling snow in this winter to be acidsnow, These data suggest that acidity of falling snow is now increasing in the study area.

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