山地斜面における地温日変化について

抄録

The purpose of this study is to clari the diurnal variation of soil temperature at the mounta in slopes of the hill which is locally called Nihon Davos, in the Sugadaira Plateau, Nagano Prefecture. The location of five observation points and observation items are shown in Fig. 1 and Table 1, respectively. In addition to these items, soil was also sampled in two layers, from 0cm to 5cm and from 10cm to 15cm for each point. This observation was held during the period from 10 a.m. on the 4th to 9 a.m. on the 5th of June, 1977 and general weather conditions before the beginning of this observation are shown in Fig. 3.
The results of this observation are summarized as follows:
1) The highest values of daily mean soil temperatures are found at the depthes of 1cm, 5cm, and 10cm on the top of the hill, but at both depthes of 20cm and 50cm on the southern slope. Mean soil temperatures at 1cm depth on both the eastern and southern slopes are nearly equal and these values show the second highest temperature.
2) The amount of soil temperature changes per hour at the depth of 1cm (Δ_sT₁) has a good correlation to the amount of heat exchange in the insulated vessel (ΔQ)(Fig. 9).
The regression equation is expressed as follows:
Δ_sT₁=0.064ΔQ-0.01 (r=0.93)
3) At each point, the duirnal range of soil temperature decreases exponentially from the ground surface to the depth of 20cm, but that at the depth of 50cm does not obey the regression curve (Fig. 11).
4) The thermal diffusivity (κ) decreases with increasing of soil water content (X_w) from 40% to 60% (Fig. 12). The regression equation is expressed as follows:
κ=-0.10X_w+7.02 (r=0.85)