Abstract
To investigate the snow accumulation on flat roofs, daily observations of snowfall and snow cover on three kinds of buildings and ground surface were carried out for 5 winters in Shinjo, northern part of Japan. At first, to find relationship between wind speed over each roof and that over the ground surface, the maximum instantaneous wind speed and mean wind speed during 10 minutes at 1.5 m height on each roof were measured simultaneously together with those at 10 m height on the ground surface. We defined the snow accumulation factor (SAF) as the ratio of the weight of daily snowfall on a roof divided to that on the ground surface on the same day. SAF decreases with the wind speed on the roofs, and becomes 0 when the wind speed exceeds a critical value. The critical wind speeds for different temperatures obtained by the method of least squares shows obvious temperature dependence. The critical wind speed increases with temperature, especially near the melting point of snow.
