The changes in seasonal freezing of soils appear to be attributed to the rising of minimum air temperatures in winter, especially at the higher elevations range from 4500 to 5000 m.įrozen ground is one of the consequences of the alternation between cold and warm climate status, it is very sensitive to climate change. The annual frozen period has decreased by about 40 days. On average, the maximum depth of frost penetration (MDFP) has reduced by 0.14∼1.71 m at most stations. The results show that the maximum depth of frost penetration, the beginning time of soil freezing and the ending time of soil thawing have changed considerably.
Based on the daily frozen soil depth, annual mean daily minimum air temperatures and annual mean air temperatures obtained from 19 in-situ observations over QTP, the changes in the thickness, temporal and spatial distributions of frozen ground, as well as the associated attributions, are analyzed for the period of 1960–2019. Rising air temperatures have resulted in frozen ground degradation over QTP since the last century.
The Qinghai-Tibet Plateau (QTP) has the largest extent of high altitude permafrost at the middle and low latitudes in northern hemisphere and is surrounded by dozens of seasonally frozen ground. 3Key Laboratory of Meteorological Disaster Preventing and Reducing in Ningxia, Ningxia Climate Center, Yinchuan, China.2Gansu Meteorological Information and Technology Support Center, Lanzhou, China.1Key Laboratory of Arid Climate Change and Disaster Reduction of Gansu Province, Research and Development Center of Earth System Model (RDCM), College of Atmospheric Sciences, Lanzhou University, Lanzhou, China.Chenghai Wang 1*, Wen Zhao 1,2 and Yang Cui 3