## 3 Results
### Field Measurements of Air and Soil Temperatures and Soil Water Content
points (soil temperature expected at air temperature of 0 \({}^{\circ}\)C) on y axis also increases with increasing soil depth. The fact also implies that soil temperature is less dependent on air temperature for deep depth. The slopes of the changes in soil temperature for points M2 and M4 at a depth of 15 cm were found to be smaller, when compared to those of M1 and M3 and temperature changes at the same depth (15 cm; Figure 4). This is because the measured soil temperatures for sites M2 and M4 at a depth of 15 cm were significantly lower, as shown in Figure 3. Soil acted as a thermal insulator due to the significant differences in the heat transfer characteristics of the soil caused by the different soil properties of locations M2 and M4. The relationship between the two measurements (\(AT_{t}\) and \(ST_{i,t}\)) could not be described using a simple mathematical form due to the scattering of the temperature data measured at each point (Figure 4). This result agrees with the previous findings of [PERSON] and [PERSON] [42] and [PERSON] et al. [43]. In Figures 3 and 4, the soil temperatures higher \(>\) 0 \({}^{\circ}\)C with increasing depth were measured based on the active layer development period. Based on the results shown in Figure 3, the active layer  
Figure 4: Relationship between soil temperatures observed at depths of 5, 10, and 15 cm and air temperature for sites (**a**) M1, (**b**) M2, (**c**) M3, and (**d**) M4. development period was estimated to be between the 1 st and 160 th days (10 May-14 October in 2015). During this period, a model was developed to predict soil temperatures, which are important for the physical, chemical, and biological processes of terrestrial ecosystems, as noted by [PERSON] et al. [20] and [PERSON] et al. [21]. To examine changes in soil water contents due to changes in the atmospheric environment, the soil water content was measured over time at a depth of 15 cm (Figure 5). The soil water content was continuously measured at locations M1-M4 for the same period. The maximum soil water contents at a depth of 15 cm were 23.96% for M1, 11.29% for M2, 37.53% for M3, and 34.81% for M4. At M1, M2, and M3, the soil water content tended to increase and then decrease around the 15 th day, increasing again on around the 100 th day. In the case of location M4, the overall soil water content increased until the 23 rd day and then remained nearly constant. For location M4, the area was slightly topographically lower in comparison to other locations and thus, rainwater was stored, and snow melted later at this site. This delayed evaporation relative to the other locations, thereby causing the soil water content to be constantly maintained. It appears that the measured soil water contents were also different because the permeability coefficient varied depending on the ground composition, as with soil temperature. However, measurement of field permeability was not possible. This difference in soil water content resulted from the water transmitted to the soil from rain or snow melting on the ground surface. In other words, it occurred because the water content of the ground surface dominated that of the soil. While soil water contents may vary depending upon the flow of groundwater, no groundwater level was detected between the ground surface and a depth of 15 cm at the locations of this study. Therefore, it appears that the soil water content was dominantly affected by rain or snow on the ground surface. The characteristics of soil particle size distributions and pore sizes among soil particles can be reflected by the standard deviation of the soil water content (w\({}_{\text{SD}}\)). When water is added into soil a medium, it is trapped within the voids (pores) among soil particles. Changes in water content with the moisture or humidity of adjacent environments are highly influenced by the sizes of soil particles and voids.