热带偶极型对流活动与东亚夏季风的联系

Relationship between the dipole tropical convective activities and east Asian summer monsson

摘要:

采用1979-1994年NCEP/NCAR再分析风场资料和OLR资料,研究了热带对流的变化特征,讨论了热带对流年际变化与东亚夏季风的关联。指出:夏季热带对流存在以西太平洋暖池附近和赤道中太平洋附近为中心的年际变化方差大值区,且这两个中心的对流变化呈偶极型反位相振荡,这种偶极型对流活动与东亚夏季风有密切关系。当暖池附近对流偏强(弱),赤道中太平洋附近对流偏弱(强)时,东亚夏季风偏强(弱),雨带偏北(南),长江流域少(多)雨。进一步分析表明:热带偶极型对流活动主要与东亚热带外地区的正压型大气环流异常相联系,而热带太平洋地区的大气环流主要表现为斜压型异常。

关键词:热带对流;偶极型变化;东亚夏季风

Abstract:

In terms of 1979-1994 NCEP/NCAR re analyses and OLR data,the variation characteristics of tropical convective activities are investigated and the relationships between the interannual variation of summer OLR and East Asian summer monsoon(EASM) are discussed.It is found that the interannual variation of summer OLR is remarkable in warm pool and the equatorial central Pacific,which is in anti phase oscillation.When the convective activities are strong(weak) in warm pool and weak(strong) in the equatorial central Pacific,the EASM is strong(weak) and the rainbelt is north(south) of its mean position with less(more) precipitation in the Yangtze River reaches.Further evidences show that the atmospheric circulation anomaly in subtropical Asia(tropical Pacific) relative to the dipole tropical convective activities is vertically barotropic(baroclinic).

Key words:tropical convection;dipole variation;EASM