中文摘要：

利用美国NOAA系列气象卫星观测的1974年6月2003年12月（其中1978年3～12月缺测）2．5°×2．5°经纬网格月平均射出长波辐射（OLR）资料，以及青藏高原上84个测站同期月总降水量资料，采用EOF方法，取前3个载荷向量及主分量讨论其空间和时间变化特征。结果表明：（1）在雨季（5～9月）降水量的高值中心与OLR的低值中心基本重合，OLR可以较好地反映降水情况。（2）近30年雨季高原台站平均降水量呈增加趋势，高原平均OLR有减小趋势，两者在时间变化上有较好的反相关性。（3）在雨季，高原OLR东南部低，西北部高；降水量的分布则相反，是东南多西北少，OLR低值中心与降水高值中心相对应，在高原主体两者之间的相关系数达到了-0．35以上（通过a=0．05显著性水平检验）。（4）降水与OLR在整体空间特征中呈相反趋势，结合主分量（PCI～PC3）的变化，可以得到高原北部降水减少，南部增加；而OLR则相反，北部增大、南部减小。OLR与降水的空间异常特性呈相反变化分布，这进一步揭示了在高原雨季OLR与降水两者的负相关关系。

英文摘要：

Based on the NOAA monthly mean gridded OLR data with the grid size of 2.5°× 2.5° Lat. / Lon. over Qinghai-Xizang Plateau from June 1974 to December 2003（missed from March to December of 1978） and the observed monthly rainfall data at 84 stations over the Plateau at the same period, the change features of time and space of their anomaly have been analyzed by EOF method. It is found that： （1） In rainy season （May～September）, the locations of both the low center of OLR and the rainy center are approximately superpositionl OLR could be response to the situation of precipitation. （2） From June 1974 to December 2003, the precipitation over the Plateau in rainy season is gradually increasing, but OLR is gradually decreasing. There are close inverse correlation between the OLR and precipitation in the time variation. （3） In rainy season, OLR in southeast Plateau is lower; in northwest, hight. Then the precipitation distribution is just the opposite, precipitation in southeast Plateau is more than that in northwest. The location of the low center of OLR and the location the high center of precipitation are approximately corresponding. （4） The changing direction of characteristic vectors of OLR and precipitation is opposite too, and we unify the change of principal component （PCI～ PC3）, we could obtain that the precipitation in North Plateau reduce and increases in South. But OLR is opposite. It increases in North Plateau and reduce in South. The tendency of the changing direction of characteristic vectors of OLR and precipitation is opposite what is further revelation over Plateau OLR in rainy season and precipitation are inverse correlation.