中文摘要：

根据1978—2002年北半球500hPa高度场、地表温度场以及中国夏季雨带类型资料,应用最小二乘法获得了能反映1978—2002年各年北半球大气环流演变大尺度特征的25组空间谱函数。采用改进的低截谱模式方法和多种统计假设检验方法获得了夏季东亚—太平洋遥相关波列年际变化的一个物理机制。结果表明,当大气环流的内部动力过程中大尺度波-波和波-流相互作用明显时,大气环流的演变表现出明显的非线性特征,导致初夏从低纬到高纬东亚—太平洋遥相关波列多为＂-、＋、-＂分布,相应的EAP指数多为正值,西太平洋副热带高压北跳明显,相应中国夏季多雨区主要位于淮河流域及其以北地区;反之,当大气环流的内部动力过程中大尺度波-波和波-流相互作用较弱时,大气环流的演变表现出较为明显的线性特征,初夏从低纬到高纬东亚—太平洋遥相关波列为＂＋、-、＋＂分布,EAP指数多为负值,夏季西太平洋副热带高压北进不明显,相应中国夏季多雨区主要位于淮河、长江流域及以南地区。

英文摘要：

Using 500-hPa height, surface air temperature and China summer rain-belt type data from 1978 to 2002, 25 spatial spectrum function sets representing the variation of large scale atmospheric circulation were retrieved with the least square method. A mechanism for the interannual variation of the East Asia-Pacific teleeonnection wave train in early summer was found through a low- order truncation spectral method and the statisticaI hypothesis test method. The results indicate that, when the large scale wave-wave and wave-flow interactions are significant, there are obvious nonlinear features in the evolution of the atmospheric circulation, and the East Asia-Pacific teleeonnection presents a ＂ -, ＋ , - ＂ spatial distribution from low- to high- latitudes in early summer. The corre- sponding index of the EAP is positive the western Pacific subtropical high shifts northward, and anomalous heavy rainfall occurs in the Huaihe Valley and its north in summer. On the contrary, when the large scale wave-wave and wave-flow interactions are weak, there appear linear features in the evolution of the atmospheric circulation, the East Asia-Pacific teleconnection shows a ＂ ＋ , - , ＋ ＂ distri- bution from low- to high- latitudes. The corresponding index of EAP is negative, the western Pacific subtropical high does not move northward significantly, and anomalous heavy rain happens in the Yangtze and Huaihe River valleys and their south.