中国春末5月区域降水和北半球500hPa高度场典型相关分析

THE CCA BETEEEN 500 hPa GEOPOTENTIAL HEIGHT FIELDS OVER NORTHERN HEMISPHERE AND RAINFALL OF CHINA IN MAY

利用典型相关理论,研究了中国15个区春末5月降水指数与其前期(1～4月)和同期北半球500 hPa高度场之间的相关关系。研究结果表明:我国5月降水和前期及同期500 hPa环流场的相关性以前期1月和同期5月的最好。前期500 hPa环流场对我国5月降水的影响具有明显的全球性,而同期的高相关区主要出现在上游的欧亚地区。此外,前期不同的大气环流运动变化形式对5月降水有不同的影响,即对于时间相隔较长的1～2月,中高纬度超长波的发展变化是主要的影响因子,对于相邻4月和同期5月更主要是不同类型遥相关的变化,如前期4月的西太平洋型(WP)和西大西洋型(WA)对我国5月黄河中上游地区的降水有着相当的影响。另外还发现,5月降水和1～5月高度场相关的典型特征向量分布在东部地区由南向北呈正负相间的波列结构,在全国范围内的东西方向上,相关区也是正负交替出现。

Based on the theory of Canonical Correlation Analysis (CCA), the correlation between 500 hPa geopotential height (H) fields over the Northern Hemisphere (NH) and a 15-region rainfall (R) field of China in May is studied. The results indicate that : (1) there is a strong relationship between the H fields in January / May and the R field in China, (2) the variation of the general circulation over the whole NH (especially the 500 hPa H field over Europe and Asia) can affect the R in China, (3) in January and February the atmospheric general circulation can affect the R mainly by means of planetary waves, while in April and May the main control mechanism can be due to some teleconnections, and (4) the characteristic vectors for R in May and H from January to May have wave train structure, alternating sign from south to north.