索马里急流和澳洲越赤道气流年际变异不同配置及其影响

使用NCEP/NCAR大气再分析资料、Hadley中心海表温度分析资料和中国160站降水观测资料,分析了夏季索马里急流与澳洲越赤道气流年际变异之间的关系及相关联的海表温度、大气环流和中国降水异常分布特征。结果表明:夏季索马里急流和澳洲越赤道气流的年际变异存在两类关系,即多数的反位相和少数的同位相关系。当夏季索马里急流和澳洲越赤道气流呈前者减弱、而后者增强的反位相变化时,热带印度洋—太平洋海气异常表现为处于发展阶段的经典的东部El Nio型,造成东亚夏季风显著减弱,中国降水呈南方偏多、北方偏少的偶极型分布;当夏季索马里急流和澳洲越赤道气流同位相增强时,海气异常表现为处于成熟阶段的中太平洋El Nio型,东亚夏季风增强,中国降水呈长江流域降水偏少、而华北和华南沿海降水显著偏多的三极型分布。

Relationship between Somali jet and Australia cross-equatorial flow interannual variabilities and its impact

This study examines the relationships between summertime Somali jet and Australia cross-equatorial flow interannual variabilities and the associated sea surface temperature, atmospheric circulation and China rainfall anomalies, with NCEP/NCAR reanalysis data, Hadley Center sea surface temperature analysis data and rainfall records at 160 stations in China. The results exhibit that there are two types of relationships between Somali jet and Australia cross-equatorial flow interannual variabilities: major out-of-phase and minor in-phase relationships. Associated with a weakened Somali Jet, an enhanced Australia cross-equatorial flow coincides with a developing classical eastern Pacific El Niño event, inducing a weakened East Asian summer monsoon and a dipolar anomalous rainfall pattern over China with reduced precipitation over northern China while increased precipitation over southern China. However, taken an enhanced Somali Jet together, an enhanced Australia cross-equatorial flow corresponds to a matured central Pacific El Niño event, giving rise to an enhanced East Asian summer monsoon and a tripolar rainfall anomalous pattern over China with reduced precipitation along Yangtze River valley.