Based on the data of radiation balance and active layer temperatures observed at Tanggula Integrated Observation site from 2006 to 2008, the impact of surface energy on the thawing process within the active layer in the northern Tibetan Plateau are analyzed. It is found that surface energy in this area has significant seasonal variation. The maximums of global radiation, soil heat flux and surface heat source take place in June or July, and the minimums of them take place in November or December. The annual mean soil heat flux during the study period is 0.12 MJ·m^-2·d^-1, and the active layer is endothermic mainly. During the freeze-thaw cycle period, the vertical variation process of temperature within the active layer is similar to that of surface energy. The surface thawing depth closely relates to the surface energy process. During the thawing period, the thawing depth increases gradually with the increase of solar energy received by ground surface. When the surface energy accumulation is 0.0 MJ·m^-2, the thawing depth reaches the minimum, and then increases with the accumulation of surface energy. This process can be depicted by a power equation.

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