Permafrost, distributes in the part of northeast China, western mountains of China and Qinghai-Tibet Plateau (QTP), accounts for 22.3% of China’s total territory. Due to the particular geographic position, QTP plays an important role in global climate system, and the climate change of QTP not only influences the eastern China but also has a profound impact to the Southeast Asia and even global climate change.
In recent years, the annual average temperature in most areas of QTP showed a rising trend and the annual average precipitation also gradually increased. The freeze-thawing action and thermal-moisture dynamics on land surface changed with the precipitation and temperature change. Therefore, the research on the hydrothermal change trend of permafrost on QTP under the background of warm and wet climate has important impact on the regional ecological and climate change.
In order to study the characteristics of precipitation and its effects on the energy balance of active layer, a long term in situ experiment was carried out and precipitation, water content, temperature and heat flux data were extensively measured at a natural ground in Beiluhe area from 2003 to 2014.
Based on the observation of hydrothermal parameters such as soil moisture, air temperature and terrestrial heat flow over last decade, scientists analyzed the relationship between the precipitation and thermal-moisture dynamics of active layer, and summarized the effects of precipitation on thermal-moisture dynamics of active layer at Beiluhe permafrost region.
The results showed the precipitation change of QTP will dramatically affect the evolution of the plateau ecological environment, water resources utilization in arid areas, and the stability of the surface engineering structure.
Results also show that: 1) rainfall from May to September dominated the precipitation and the precipitation and air temperature were increasing during the past decade. 2) Frequent and small rainfall events in summer could effectively reduce the surface net radiation, increase the surface latent heat of evaporation and cool the soil temperature. 3) There was not obvious moisture accumulation in active layer under the background of increasing precipitation, which showed the latent heat of surface evaporation and moisture migration in active layers should not be neglected.
This research achievement has been published on the Journal of Arid Land Resources and Environment (DOI: 10.13448/j.cnki.jalre.2016.130). And this research is financially supported by the National Basic Research Program of China (2012CB026101), the National Natural Science Foundation of China (41471061), the Program of “One Hundred Talented People” of the Chinese Academy of Sciences (Y251561001) and the Subject of the State Key Laboratory of Frozen Soil Engineering (SKLFSE-ZY-12).
The State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences