Studies on the Radiation Balance in the Paddy Field and Water Temperature in the Percolating Paddy Field

Abstract

In order to research the radiation balance in the paddy field and the relation between water temperature in the percolating paddy field to percolation, the author carried out the observations of the radiation, water temperature, percolation in August 1958 at Nyuzen, Toyama Pref.The radiations were measured by using Beckman's net radiometer, hemispherical radiometer and Golzinsky solarimeter.The results obtained are as follows;(1) The radiation balance in the cultivated field is shown as following formula, S=RS(1-α)+(R↓-R↑)where S, RS, α, R↓, R↑ refer to the net radiation, short wave radiation, albedo, long wave radiation from upward and that from downward, respectively.The results measured in the paddy field was shown in Fig. 2.(2) The relations between rising effect of temperature in the percolating paddy field to percolation was found theoretically as shown in formula (16), θwp-θ0=(θw0)exp(v/-(LρaDdqs/dθ+cpρaD)), where θwp, θw0, v, L, ρa D, cp, q refer to the average water temperature in the percolating paddy field, average water temperature in the no percolating field, irrigating watea temperature, percolation (c. c. per min), latent heat (590 cal), density of air, diffusion coefficient (39cm per min), specific heat of air and specific humidity, respectively.