Variation Characteristics of Soil Temperature over Qinghai-Xizang Plateau in the Past 45 Years
近45年青藏高原土壤温度的变化特征分析

The soil temperature data of 60 meteorological stations on the Qinghai-Xizang Plateau from 1960 to 2005 were used to analyze the time evolution tendency and spatial distribution using Mann-Kendall test, power spectral analysis and principal component analysis methods. The results show that the surface soil temperature of most of the stations on the Qinghai-Xizang Plateau has a significantly increasing trend in the last 45 years, and the abrupt changes are detected from 1969 to 1970. The soil temperature at depths from 40 to 320 cm shows a 3.25a cycle variation, also the spatial features of surface soil temperature was mainly reflected as a coincident type in the whole region and a reverse changing type in north-south direction. At the same time discussion on the variation of surface soil temperature gradient (10 to 20 cm) indicated that there is a rise-fall mechanism between the surface soil temperature gradient and the difference between ground soil and air temperature, indicating that there may be a relationship of dissipative structures between the atmosphere and ground surface on the Tibetan Plateau. In addition, the spatial pattern of surface soil temperature gradient reflects clearly the distribution of permafrost on the Qinghai-Xizang Plateau.