水田微気象研究への予測モデルの応用

抄録

In this paper, the simulation model for microclimatic environment in a rice field described in a previous paper (Inoue, 1985) was improved to extend its applicability. Improved conversational model allowed a variety of output products such as graphic display and line printer of simulated results. The simulation of microclimatic environment by this improved model was made using the observation data of microclimate during the period July 27 to August 31 in 1986. The results obtained by simulation of microclimatic environment in a rice field were compared with the measurements. The results obtained in this paper can be summarized as follows:
(1) An on-line data acquisition and microclimate simulation system (see Fig. 1) was developed for acquisition and analysis of observation data of microclimate, and for simulation of microclimatic environment using the improved model (see Fig. 2). The transmission of data from a data logger in an experimental field to a mini-computer in a laboratory was made through an optical fiber. This system also enabled us to study evapotranspiration and heat balance of the rice field.
(2) Figure 4 shows the diurnal changes in microclimatic environment of the rice field simulated by the model using the external input data as shown in the bottom of this figure 4(D). The diurnal changes in water temperature under the rice canopy and evapotranspiration rate simulated by the model agreed well with those measured at the experimental field with acceptable error (see Fig. 4).
(3) The simulation model was used to examine effects of deep flooding water on the temperature environment in the rice canopy. Simulation results showed that the deep flooding water can protect young rice panicles before the heading time from low air temperature (Fig. 5).
(4) This simulation model was used to predict the change in daily means of microclimatic environment in the rice field, which are needed to predict dynamics of crop growth and fertility elements (Fig. 6). The model was also used to make clear the microclimate characteristics for the dew formation on rice leaves during night time. Simulation results showed that dew occurred on the rice leaves in the canopy under conditions that the leaf temperature falls below the dew point in the surrounding air (see Fig. 7).
The above results showed that the improved simulation model and the developed system for acquisition and analysis of data of rice microclimate could be applied to predict the microclimatic environment in a rice field on line.