青藏高原北部活动层土壤热力特性的研究

利用2003年10月～2004年9月期间高原北部可可西里(QT01)、北麓河(QT02)、开心岭(QT05)、通天河(QT06)等地活动层土壤温度梯度、土壤热通量及土壤水分的观测资料,计算了高原北部活动层土壤的导热率、土壤容积热容量、导温率等土壤热力参数.结果显示，QT02、QT05、QT06三站导热率、导温率夏秋季节较大而冬季较小，容积热容量则相反，表现为秋冬季节大而夏季较小；QT01站导热率表现为春季大，夏季较小；表层土壤粒度较小及较低的土壤湿度是冬季导热率较小的可能原因；冻土的热力特征参量可描述为相应深度的温度、体积含冰量及土壤盐度的函数，土壤含水量是融土热特征参数的主要影响因子；土壤水分含量小于某一临界值时，导温率随土壤水分含量的增大而增大，反之则减小.

A study on soil thermodynamic characteristics of active layer in northern Tibetan Plateau

Using the data of soil temperature gradient, soil moisture and soil heat flux observed from Oct. 2003 to Sep. 2004 at sites of Kekexili (QT01), Beiluhe (QT02), Kaixinling (QT05) and Tongtianhe (QT06), thermodynamics parameters such as soil thermal conductivity, volumetric heat capacity and thermal diffusivity are calculated. The results show that these parameters in northern Tibetan Plateau are different from those in Gobi and western Tibetan Plateau. In the four sites mentioned above, the thermal conductivities and diffusivities of QT02, QT05 and QT06 are larger in summer and autumn and smaller in winter while the variation trend of thermal capacities are opposite to the thermal conductivities and diffusivities; as for QT01 site, the thermal conductivity was larger in spring than in summer; the possible reason of small thermal conductivities under the frozen ground is the fine-grained and lower moisture content of topsoil; and under the condition of frozen ground, soil thermodynamics parameters could be written as a function of temperature, ice content and soil salinity while under the unfrozen ground the soil moisture content is the dominant factor for those thermal parameters; and for the thermal diffusivity, there exists a critical soil moisture content about 22%~23%, when the soil moisture content is less than the critical value, thermal diffusivity is increasing with increase of soil moisture content. Contrarily, it is decreasing with increase of soil moisture content.