TURBULENT FLUXES OVER THE LAKE KASUMIGAURA

Abstract

The results of the measurement of turbulent fluxes on Lake Kasumigaura as part of a project for the study of evaporation from reservoirs are presented in this paper. The sensor used in this study is the combination of the sonic anemometer and the fine psychrometer. The data are analysed by the analog data analyser. The turbulent fluxes of momentum, sensible and latent heat are obtained as well as the mean values, and standard deviations of meteorological parameters are also obtained. The mean ratio of the standard deviation of vertical velocity to the friction velocity is 1.1 and the mean drag coefficient is about 4x10^-3. The total evaporation from the lake on a fine day in December is about 0.6 mm. Fairly large downward water vapor flux is seen in the daytime and upward flux in the night time. The mean vertical motion is observed, and this might be caused by the bank, 4 meters high, behind. The difference between vertical turbulent flux and the cross stream line turbulent flux is discussed.