东部和中部型El Nio发展年中国区域夏季降水异常特征

Abnormal Feature of Summer Precipitation in China During EP and CP El Nio Developing Phase

分析了东部和中部型El Nio发展年海温分布特征及其对中国夏季降水影响的差异。结果表明:(1)东部型El Nio年的海温正距平中心发展快且强度比中部型El Nio年强。(2)两类El Nio发展年,中国夏季降水分布差异最大的是东北和华北地区,呈相反的分布,华南地区只是变化幅度不同,江淮流域降水一致偏少。(3)Walker环流分布的差异是两类El Nio年夏季降水分布差异的重要原因,其位于西太平洋地区下沉支的强弱以及有无上升支的分布,对西太副高和我国水汽的输送有明显影响。(4)500h Pa位势高度场的遥相关波列以及高低层大气的垂直运动也是造成两类El Nio年中国夏季降水分布差异的重要原因。

The SST distribution characteristics of eastern Pacific(EP)and central Pacific(CP)El Nino and corresponding to effects on the summer precipitation in China are analyzed.Results show that:Firstly,the positive anomaly center of SSTs shows a faster development and higher intensity in EP El Nino than ones in CP El Nino.Secondly,during CP and EP El Nino year,Northeast and North China present the greatest different distributions of summer precipitation with opposite distributions;on the other hand,there is less rainfall in Yangtze-Huaihe River Basin;a different changing range is found in South China.Thirdly,the difference in the distribution of Walker circulation is a main cause of the difference in the distribution of summer precipitation during CP and EP El Nino;the intensity of sinking branches and the distribution of ascending branches in the western Pacific region have significant effects on west Pacific subtropical high and water vapor transport in China.Finally,teleconnection wave train at500hPa and vertical motion of the upper and lower atmosphere also play important roles in influencing the different summer precipitation during EP and CP El Nino.