中文摘要：

活动层夏季融化、冬季冻结的近地表土（岩）层，是冻土地区热力动态最活跃的岩层，在冻土研究中有着重要意义。根据青藏高原地区80个气象观测台站1991—2000年的地面温度观测资料结合数字高程模型，计算出青藏高原冻土区的地面冻结指数和地面融化指数，然后应用斯蒂芬公式分别得到多年冻土区的季节融化深度和季节冻土区的季节冻结深度。

英文摘要：

Active layer is the near-surface layer of frozen soil, which thaws in summer while freezes in winter. In seasonally frozen ground regions as well as permafrost regions, active layer is the most active terrane in terms of thermodynamics. Active layer plays an important role, because almost all ecological, hydrological, pedological and biological activities take place within it. Ground surface freezing index and thawing index are simulated based on the ground surface temperature in the 1990s acquired from 80 meteorological stations on the Tibetan Plateau and nearby regions, together with digital elevation model. Taking the mean annual ground surface temperature isotherm of 0.8 ℃ as the boundary of permafrost and seasonally frozen ground, in consideration of thermal offset, the thawed depth in the permafrost areas and frozen depth in the seasonally frozen ground regions are worked out respectively through Stephen Formula.