中文摘要：

以唐古拉监测点气象及活动层土壤水热资料为基础，对青藏高原高海拔多年冻土区冻融期活动层土壤的水热特征进行了分析。研究结果表明：不同土层的土壤温度变化规律基本一致，土壤温度的变化滞后于气温的变化，而且滞后时间随着土层深度的增大而增大，表层土壤温度变化波动较大，随着深度的增加，土温温度变化趋于平缓；气温的降低引起了土壤温度的降低，从而引起水分的迁移；在冻结期，水分向上下两个冻结锋面迁移，而活动层中部则被疏干，在融化期，活动层底部水分含量高，水分向相变界面附近迁移。拟合了冻结期未冻水含量与土壤温度的关系，相关系数R^2平均值为0．89，结果基本能反映实际情况。该研究结果为高海拔多年冻土区冻融土壤水热耦合模拟的研究提供了基础理论依据。

英文摘要：

Using the meteorological data and the soil hydro and thermal data at different depths in the active layer measured at the Tanggula observation site, the soil hydro and thermal characteristics of the active layer during freezing and thawing period in the permafrost region with higher elevations were analyzed. Results showed that the variation laws of soil temperature at the different soil layers were consistent. Variation of soil temperature lagged to air temperature and the lag interval increased with the soil depth increasing. The surface soil temperature changed relatively greatly but the change became gentle when the depth increased. Decrease of air temperature resulted in decrease of soil temperature, which led to water transfer. During the freezing period, the water migrated to the freezing front but the middle of the active layers were dry; when in the thawing period, there were high moisture content in the bottom; it reflected that the water migrated to phase change interface during freezing and thawing period. The unfrozen water content and soil temperature relationship were fitted and the mean value of correlation coefficient was 0.89. This research provides the foundation for the hydro-thermal coupling simulation on freezingthawing soils in the active layer in permafrost regions with higher elevations in Qinghai-Tibet Plateau.