中文摘要：

近年来在气候变化和人类活动影响下,青藏高原地表状况发生了大规模的改变,并引发了多年冻土的退化,给寒区环境与工程产生一系列不良影响.而多年冻土作为地气系统相互作用的产物,其变化主要取决于地气系统能量交换的方向.应用青藏高原实地观测资料,对不同地表状况下多年冻土浅层热状况进行了分析.结果表明:下垫面的改变对多年冻土区能量平衡状况产生明显影响.在天然状态下地表能量收支基本保持平衡,冻土变化也比较缓慢;而在下垫面改变特别是天然地表遭破坏后,原有的能量平衡发生改变,从而引起多年冻土的变化.覆盖度较高的植被暖季能够阻止部分热量进入土层,降低地表温度;而在冷季则能减少土层热量散发,有助于保持地表温度.植被的存在有利于保持多年冻土的稳定.黑色薄膜覆盖能够增加地表吸收的太阳辐射,并减少地表蒸发耗热,造成地表吸热量大于放热量.透明薄膜的"温室效应"可以有效地防止地表长波辐射的散发,减少表层土壤热量的消耗,从而引起地表温度的显著升高.

英文摘要：

In the last ten or twenty years,the underlying surface conditions in the Tibetan Plateau have changed a lot and caused permafrost degradation,because of climate change and human activities,which severely influence the cold regions environment and infrastructure built above permafrost. Permafrost is a result of the interaction between earth and atmosphere. The formation and changes of permafrost are determined by the energy exchange between earth and atmosphere system. Fieldwork has been done in order to lea...