The Features of soil temperature and moisture on Northern Tibetan Plateau
藏北高原土壤的温湿特征

The examination of the soil temperature and moisture features at the two sites of Amduo and D110 show that there are some similar characteristics in temperature at the two sites. The variation of soil temperature in each depth exists periodic corresponding to sine curve. The magnitude of soil temperature at shallower depth is larger than that at deeper depth and the temperature at shallower depth is affected significantly by the stochastic weather progresses. However, either at shallower depth or deeper depth, the magnitude of soil temperature at Amduo is larger than that at D110. Before the soil freezed, soil moisture at 100cm depth is smallest and at 160cm depth is largest at Amduo site. While at D110 site, the smallest soil moisture exists at 20cm depth and the largest at 100cm. The soil moistures both at 100cm and 160cm at Amduo are smaller than that at D110. However, at 20cm, the soil moisture at Amduo is larger than that at D110. The variation magnitude of soil moisture at shallower layer (20cm) is affected not only by the stochastic precipitation but also by the soil moisture condition at lower layer. The smaller the soil moisture at lower layer, the larger the variation magnitude of the soil moisture at shallower layer. There is a significant correlation between soil temperature and moisture. The soil moisture condition can affect the variation magnitude of soil temperature and its variation trend. If soil moisture is large, the variation magnitude of soil temperature will be small. And vice versa. The reason is that the heat capacity of water is much larger than that of soil. This also affects the decreasing trend of soil temperature. Thus, the soil with higher moisture content takes a pretty long time from freezing to being freezed.