西太平洋海温和南方涛动与中国冬季气候异常关系年代际变化的对比分析

CONTRAST ANALYSIS OF THE INTERDECADAL VARIATION OF THE RELATION AMONG THE WESTERN PACIFIC/THE SOUTHERN OSCILLATION AND THE WINTER CLIMATE ANOMALIES IN CHINA

利用NCEP/NCAR再分析资料和全球海温海冰GISST2 .3b资料、英国CRU提供的南方涛动指数以及中国 1 60站月平均降水和气温资料 ,分析了冬季西太平洋海温和南方涛动与中国冬季气候异常关系年代际变化特征。结果表明 :最近 5 0年 ,西太平洋海温指数(WPI)与南方涛动指数 (SOI)之间相关关系的年代际变化在冬季很明显。当WPI SOI相关关系不显著时 ,在西太平洋赤道北侧的对流层低层存在高 (低 )海温 反气旋 (气旋 )异常环流系统 ,不利于维持ENSO与西太平洋海温变化间的紧密联系 ;与此相对应 ,冬季整个对流层环流呈相当正压结构。在WPI SOI相关显著 (不显著 )时段 ,冬季中国降水、气温与西太平洋海温之间的相关较弱 (较强 )。

Using NCEP/NCAR reanalysis data, SST data set of GISST2.3b, South Oscillation Index (SOI) of CRU as well as the surface air temperature/rainfall records from 160 stations in China, the relation among the western Pacific SST index, the southern oscillation index and the surface air temperature/rainfall in China in winter is investigated. Results indicate that, the relationship between WPI and SOI shows obvious inter-decadal changes in the winter during recent fifty years. When the correlation between WPI and SOI is weak and the western Pacific SST warmer (colder), there exists anticyclone (cyclone) circulation at the lower troposphere over northern equatorial western Pacific, which is not in favor of maintaining a close correlation between the West Pacific SST and ENSO. Accordingly, through the whole troposphere, such system presents quasi-barotropic structure in the winter. Furthermore, when the correlation between WPI and SOI is strong (weak or reversed), the correlation between WPI and the surface air temperature/rainfall in China is weak (strong) in the winter.