105°E和125°E越赤道气流与南、北半球环流变化的关系

采用1980～2004年5～8月NCEP/NCAR逐日再分析资料, 将105°E和125°E越赤道气流增强过程按一定标准进行取样, 并对增强过程中越赤道气流的变化特点及其相应的南、 北半球环流特征进行分析, 结果表明: 越赤道气流的增强往往对应着通道南侧或北侧从热带到副热带地区的环流调整, 而这种环流调整在南半球主要指澳洲冷空气活动, 在北半球主要为辐合带的变化, 二者是影响越赤道气流的主要环流因子; 北半球辐合带的变化与西太平洋副高的东西振荡有密切关系, 前者的分布形态在一定程度上决定了南半球环流及越赤道气流变化对北半球热带外环流的影响情况; 125°E越赤道气流比105°E越赤道气流的增强过程通常更为显著, 这与它们对应的南、 北半球环流调整的差异有关。

Connection of 105°E and 125°E Cross-Equatorial Flow with the Southern and Northern Hemispheric Circulations

Using the NCEP/NCAR daily reanalysis data from May to August during 1980－2004, this paper samples some reinforcement processes of 105°E and 125°E cross-equatorial flow according to a certain standard, then studies the variation features of cross-equatorial flow and its relevant circulation feature in the Southern and Northern Hemispheres. Results are shown as follows: Firstly, corresponding to the reinforcement process of cross-equatorial flow, there is always circulation adjustment in the tropical and subtropical zone on the south or north sides of the channel, and the adjustment mainly denotes the Australia cold air activity in the Southern Hemisphere or the variation of convergence zone in the Northern Hemisphere, which are the main influence factors of cross-equatorial flow. Secondly, the Northern Hemisphere convergence zone has a close connection with the east-west oscillation of the western Pacific subtropical high, and its distribution partly determines the impact of the Southern Hemisphere circulation and cross-equatorial flow on the extratropical circulation. Thirdly, due to the difference of circulation adjustment in the Southern and Northern Hemispheres, the 125°E cross-equatorial flow always has more notable reinforcement processes than the 105°E cross-equatorial flow.