近30年青藏高原年平均0cm地温的分布和变化特征

选取青藏高原40个测站1970～2002年各月平均0cm地温资料，通过EOF、二阶多项式函数和小波分析等方法，对青藏高原年平均0cm地温的时空分布特征进行了研究。结果表明，青藏高原年平均0cm地温EOF展开的第一特征向量反映了高原地温分布的一致性，而第二、三特征向量分别揭示了高原地温分布受到各种中、小尺度天气系统和海拔高度制约的事实。高原地温空间异常可分为4个气候区，即东北部、南部、主体和西部。高原地温各分区代表站的二阶多项式反映出近30年高原东北部地温呈降温趋势；南部呈增温趋势；高原主体和西部具有高一低一高的抛物线型变化趋势。高原地温各分区皆有3a和准7a的振荡周期。

Temporal and Spatial Variations of Ground Temperature over Qinghai-Tibet Plateau for the Last 30 Years

Based on the monthly ground temperature data from 40 stations in Qinghai-Tibetan Plateau for the period of 1970--2002, the temporal-spatial distribution of annual ground temperature in Qinghai-Tibetan Plateau are investigated with the methods empirical orthogonal function, second order polynomial function and wavelet analysis. The results show that the first characteristic vector of the ground temperature over the plateau reveals the overall consistency. The second and third vectors reveal the fact that weather system and the sea level elevation affect on the distribution of ground temperature. The ground tempera- ture abnormal area can be divided into four sub-regions, i. e. , north-east, south, center and west. With the second order polynomial function, it shows that the ground temperature, in general, in the east-north sub-region, is decreasing, increasing in the south region and there is a high-low-high change feature in the center and west sub-regions. There are the periodic oscillations of 3-year and quasi-7-year of ground temperature over the plateau.