[A-AS06] 成層圏・対流圏過程とその気候への影響

[AAS06-P07] QBO東西風の東西非一様性について

*坂崎 貴俊¹、Hamilton Kevin²、河谷 芳雄³ (1.京都大学　大学院理学研究科、2.ハワイ大学　国際太平洋研究センター、3.海洋研究開発機構)

キーワード：成層圏、成層圏準二年周期変動、東西非一様性

Although the QBO primarily shows a zonally symmetric nature, a smaller but significant eddy component is sometimes observed. This study demonstrates the basic morphology of zonal asymmetry in QBO zonal wind in the middle stratosphere based on the statistical analysis of the ERA5 dataset from 1958 to 2019. As pointed out by previous studies, the zonal eddy component is found to be statistically large in the westerly phase of QBO during boreal/austral winter seasons, since the tropical westerly allows a lateral, equatorward propagation of stationary planetary waves from the winter Hemisphere. Moreover, it is found that the QBO eddy component shows a strong inter-annual to decadal variability; the underlying processes (and possibly the uncertainty in QBO wind in reanalyses) will be discussed in the poster.