中文摘要：

活动层土壤热状况是寒区陆面物理过程研究的重要内容之一。利用五道梁能量收支观测站1993年9月～2000年12月份实测辐射及土壤热通量资料结合五道梁气象站1961—2010时段的气象资料分析了近50a来该地区活动层土壤的热状况。结果表明：五道梁地区土壤热通量有显著的年际、年代际变化；20世纪60～80年代，土壤热通量小于0．0W／m2，活动层土壤以放热为主，自90年代以来，土壤热通量大于0．0w／m2，活动层土壤以吸热为主。过去50a中该地土壤热通量呈现增大趋势，平均每10a土壤热通量增大0．31w／m2。土壤热通量随净辐射的增大而增大。土壤热平衡系数的变化特点与土壤热通量的变化特点一致。60-80年代，活动层土壤热平衡系数〈1，该地区冻土相对比较稳定，而自90年代以来此间土壤热平衡系数〈1，表明该地多年冻土呈现出退化迹象。活动层土壤热平衡系数可表示为气温、地表温度及水汽压的函数。

英文摘要：

The storage and release of heat in the soil of the QinghaiTibetan Plateau can trigger changes such as altering the troughridge allocation of the East Asian weather system. As a ＂buffer layer＂ betw in weather, een perma frost and the atmosphere, the active layer is sensitive to climate change, and responds quickly to temperature chang es. The active layer controls energy and water exchange between the soil and the atmosphere, which results from changes in soil water content and temperature. To some degree, it reflects the thermal condition of the underlying surface, and therefore it can be used as a thermal indicator of the plateau surface. Therefore, the thermal regime of active layer in the permafrost regions is very important aspect in the research of land surface processes in cold re gions. Thus more and more scholars focus their attentions on the thermal process of active layer. Limited by the ob servational data in situ, up to now it was not possible to exactly describe the thermal regime of freezethaw processes in active layer in the permafrost regions on the Plateau. Therefore, an indepth study of the soil thermodynamic prop erties of the active layer is needed. In this paper, the characteristics of soil heat flux and soil heat balance coefficient were analyzed by using the radiant data observed from September1993 to October 2000 and the meteorological data measured from January 1961 to October 2010 at WDL weather station located in the northern Tibetan Plateau. The results showed that the soil heat flux took on a clearly interannual and interdecadal variation features. The value of soil heat flux was less than 0.0 Wm2 throughout the time period from 1960s to 1980s. Correspondingly, the active layer soil released heat to atmosphere during this time period. While since the 1990s, soil heat flux was greater than 0.0 Wm2, which showed that in a year, there was surplus heat amount transferred from the surface to the lower soil layer, and the active layer soil here mainly absorbed heat in this time period.