近45年青藏高原土壤温度的变化特征分析

Variation Characteristics of Soil Temperature over Qinghai-Xizang Plateau in the Past 45 Years

利用青藏高原60个气象站1960-2005年的土壤温度观测资料,采用Mann-Kendall法和功率谱方法对不同深度土壤温度的时间变化进行趋势突变和周期检验,并以主成分方法考察其空间分布特征。分析结果发现青藏高原浅层土壤温度自1970年以来升高趋势明显,1969-1970年为明显的突变点;40-320cm的深层土壤温度存在3.25年的显著周期变化;浅层土壤温度空间特征则主要体现为全区一致型和南北反向变化型。同时以浅层土壤温度梯度（10-20cm）的变化特征讨论了青藏高原地气间能量的交换关系以及浅层土壤温度梯度对高原多年冻土的响应,认为高原地气温差和浅层土壤温度梯度之间存在一种涨落机制,体现的是高原地气间的耗散结构关系;而浅层土壤温度梯度分布特征对高原多年冻土有明显的响应。

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.