资源环境科技发展态势分析平台

The ENSO modulation on the relationship between the Madden–Julian Oscillation (MJO) and major stratospheric sudden warming (SSW) in the Northern Hemisphere winter is analyzed. The results indicate that the statistical relationship between the MJO and SSWs is robust during La Niña years but almost non‐existent during El Niño years. During La Niña years, a significant response of stratospheric temperature appears after certain MJO phases with a distribution consistent with MJO periodicity, whereas the response becomes non‐significant during El Niño years. Further analysis indicates that ENSO influences the MJO‐related geopotential height anomalies in mid–high latitudes of the upper troposphere, which leads to an increase in wavenumber 2 in La Niña winters. And wavenumber 2 plays a key role in generating the strong heat flux anomalies in the stratosphere. The results may help to explain the more frequent occurrence of extreme events in the stratosphere, such as SSW during La Niña winters.