青藏高原地表0cm温度的时空变化特征

THE TIME-SPACE VARIETY CHARACTERISTICS OF THE SURFACE TEMPERATURE OVER THE QINGHAI-TIBET PLATEAU

利用青藏高原86个气象观测站从建站到2001年历年各月地面0cm温度资料,在分析高原冬季、夏季和年平均地表温度基本气候特征的基础上,通过主成分分析、主值函数和功率谱分析等方法,对高原地表温度异常变化的空间结构和时间演变趋势作了诊断研究。结果表明:高原地表温度总体表现为海拔高度与纬度的函数,海拔越高温度越低,纬度越高温度越低;高原地表温度第一载荷向量除南部小范围的负值外大部分地方为一致的正值,即第一空间尺度表现为整体的一致性,而第二载荷向量为南正(负)北负(正),即第二空间尺度表现为南北差异;第一主分量在近30年的变化中表现为明显的上升趋势,即主要反映了高原主体偏北和东北部地区地表温度有显著升高趋势;而第二主分量的缓慢下降说明高原中部和东南部地表温度呈减小趋势。代表站温度变化表现出7～9年的周期震荡。

In this paper, the basic climate characteristics of winter, summer and annual mean surface temperatures were analyzed by using 86 stations during period from founding to 2001 over the Tibetan Plateau, and the spatial anomaly structure and time evolution tendency have been analysed systematically through principal component analysis, a periodic function and a random function and power spectral analysis methods. The result shows that the surface temperature is a function of sea level elevation and latitude in the Tibetan Plateau, the higher the elevation and latitudes are, the lower the surface temperature is . The annual highest surface temperature is 14.9 ℃ of Cayu in the Yaluzangbu river, and the highest value of the surface temperature in summer is 23.0 ℃ at Germu in the Chaidamu basin. The souther Talmu basin of the plateau outer circle, the temperature is higher in western Sichuan, but the center is not in the plateau. The Lowest value of surface temperature in the center of the plateau is -0.2 of annual mean surface temperature, winter then much lower (average -14.2～-15.8 ℃). The lowest value of the surface temperature is 9.8 ℃ at Qingshuihe in summer, its average in July is 10.7℃. The first loading vector of the surface temperature over the Plateau is overall consistency. The second loading vector has a difference in the north and the south. The variety of the first principal component has an obvious up-trend in the last 30 years, but the second principal component is a slow-moving descent, and there is a quasi periodic oscillation of 7～9 years for the interannual variation.