Stratospheric ozone and quasi-biennial oscillation (QBO) interaction with the tropical troposphere on intraseasonal and interannual timescales: a normal-mode perspective

Abstract. The Madden–Julian oscillation (MJO) is the main controller of weather in tropics on intraseasonal timescales, and recent research provides evidence that quasi-biennial (QBO) influences MJO interannual variability. However, physical mechanisms behind this interaction are not completely understood. Recent studies normal-mode structure indicate contribution global-scale Kelvin Rossby waves. In study we test whether these MJO-related normal modes affected by QBO stratospheric ozone. partial directed coherence method was used enabled us to probe direction frequency interactions. It found equatorial ozone zonal winds connected with at periods 1–2 months 1.5–2.5 years. We explore role interactions stratosphere–troposphere coupling performing a linear regression between MJO–QBO indices amplitudes atmosphere obtained projections basis using ERA-Interim reanalysis data. dominated symmetric but also influenced asymmetric modes. mostly explained westward-propagating inertio-gravity waves previous results identifying those concentration. particular, westward waves, associated QBO, influence timescales. modes, such as wind respect Equator, shown have significantly different dynamics during events depending phase QBO.