Tosio Koike

Comparative Research on the Temporal and Spatial Disribution of Energy Budget on the Snow Surface Using Snowmelt Models

The spatial and temporal variation of energy budget on the snow surface were investigated at four experimental sites from March to June in 1992. The parameters in the energy budget equation describing snowmelt were determined based on the observated data at each site. The result of energy budget for each site showed that the ratio of the radiative and turblent energy to the whole depend on season and topography.

Comparative Study on Heat Balance during Snowmelt Season

This study investigates the discrepancies of heat budgets on snow surface between in the high alpine area and in the lower-lands through field observations. The energy exchanges across the snow surface were measured at two observation sites; one located at 2950 m a. m. s. l. on the northern slope of Mt. Fuji, and the other at 300 m a. m. s. l. in Niigata prefecture. Snowmelt was calculated using snow density measured by snow sampler once every week and melting depth by camera in every six hours. Role of turbulent heat flux in the high alpine area was more important than in the lower-lands. The latent heat flux was usually negative and the large positive latent heat flux associated with the warm, humid and strong wind sometimes caused the very intense snowmelt in the high alpine area.

Basic Study on Snowfall Forecasting in the Chuetsu District

Snow surveys just after snowfall events and radar observations have been conducted to study the snowfall distribution in the Chuetsu district, Niigata, Japan. It was shown that the snowfall distribution is mostly dominated by orographical factors-the main effect being that of ground-forced-induced ascending current of air. A three-dimensional numerical model of the atmosphere incorporating orography was used to estimate the regions where the ascending current of air can occur. They are in a good corespondence with the snowfall regions derived from radar data.