热带平流层纬向风场准两年振荡的年代际变化

INTERDECADAL VARIABILITY OF QUASI-BIENNIAL OSCILLATION OF STRATOSPHERIC ZONAL WIND

利用平流层探空资料和ECMWF的ERA-40、ERA-interim格点资料分析了近62年的热带平流层纬向风准两年振荡（QBO）的年代际特征。分析表明QBO周期存在显著的年代际变化,且平均周期较长（短）的时段,其变化幅度较小（大）。QBO的振幅存在10-15年的年代际振荡,并与QBO周期存在着明显的反相关关系。此外,QBO振幅在10-30hPa存在增强的趋势,而在中低层则为略微减弱的趋势。从关于赤道的反对称纬向风场可发现,QBO中心存在着偏离赤道的年代际变化,东风中心偏移赤道的方向基本与西风中心的偏移方向相反,即东风中心偏向某一半球时,对应的西风中心则在另外一个半球上。

This study investigates the interdecadal variability of Quasi-biennial Oscillation （QBO） based on the sounding data in the stratosphere, ERA-40 and ERA-interim reanalysis data in the past 62 years. The QBO periodicity experiences a significant interdecadal variability; the longer （shorter） the mean period, the smaller （larger） the amplitude of variation is. The QBO amplitude varies in a cycle around 10 - 15 years and in an out- of-phase correlation with the period. In addition, there is an increasing trend of the QBO amplitude in 30 -10 hPa, while a little declining trend in 70 - 40 hPa. The departure location of the QBO zonal wind extremum centers from the equator also shows interdecadal variation so that they exhibit an anti-symmetric zonal wind component relative to the equator. The departure location of the easterly core is basically in the reverse side to the westerly core, which means when the easterly core is on one side of a hemisphere, the westerly core is on the other side.