Studies On The Characters Of Air Temperature Over The Tibetan Plateau In The Globe Climatic Background In Recent 50 Years

In this study, new 500hPa temperature and 200-500 thickness series of the northern hemispheric and the Tibetan Plateau are obtained for the period from 1950 to 2000 by using NCEP/NCAR reanalysis monthly grid data, the analysis of the interannual variations of the surface and the middle-upper level of troposphere temperature and the correlation among them prove that the trends of the surface temperature and the 500hPa temperature are affinity, especially on the Tibetan Plateau.In this climatic background, we make use of the bilinear interpolation for NCEP/NCAR data and gain the well 500hPa monthly average temperature of 50 stations of the Tibetan Plateau which were selected by considering the complex terrain. According to the affinity between the surface temperature and SOOhPa temperature of the Tibetan Plateau, we design the regression scheme for each month of every station and rebuild the whole surface monthly average temperature of the Tibetan Plateau during the period from 1950 to 2000.The Rotational Empirical Orthogonal Function(REOF) is employed to analyze annual, spring , summer, autumn and winter air temperature of the Tibetan Plateau. It is noted that four, two, three, five, and four sub-regions can be taken for annual, spring , summer, autumn and winter respectively. Analysis shows there is warming in most of sub-regions of the Tibetan Plateau, but obvious territorial difference still exists. There is small cooling in some sub-regions in summer and in autumn. The warming time is mainly in spring and in winter.