New discoveries on the effects of desertification on the ground temperature of permafrost and its significance to the Qinghai-Tibet Plateau

The desert and permafrost conditions of the Qinghai-Tibet Plateau are unique. However, the effects of desertification on the ground temperature of permafrost are currently unclear. Recently, understanding this problem has become more urgent because of increasing desertification on the plateau. For this reason, an observational field experiment was undertaken by the authors at Honglianghe on the Qinghai-Tibet Plateau. Thermistor ground temperature probes were used, and synchronized contrasting observations were made in an open area. Observations of the ground temperature of permafrost below sand layers with a range of thicknesses were made from May 2010 to April 2011. The sand layers were found to play a key role in the protection of the underlying permafrost. The ground temperature below a permafrost table overlain by a thick sand layer was lower than that of the average annual temperature for the natural ground surface, and the temperature drop was roughly constant at 0.2°C. During the warmer part of the year (May to September), the maximum temperature drops over the five months were 3.40, 3.72, 4.85, 3.16, and 1.88°C, respectively. The ground temperature near a permafrost table overlain by a thin sand layer was also lower than that of the average annual temperature for the natural ground surface. However, in this case the average of the annual maximum temperature drop was significantly less, 0.71°C. The scientific significance of our preliminary conclusions is not only to present an exploration of the interaction between desertification and permafrost, but also to provide new engineering ideas for protecting the permafrost in regions where construction is required on the Qinghai-Tibet Plateau.