The quasi-biennial oscillation (QBO) is a periodic wind variation in the equatorial stratosphere with an average period of 28 months. We summarize here the latest research related to the impacts of, processes involved in and projections of the QBO. The QBO affects predictability globally owing to its teleconnections to deep convection, MJO, precipitation, stratospheric polar vortex, mid-latitude jets, and the North Atlantic Oscillation. Many climate models are now able to simulate the QBO but with systematic errors mainly consisting of too weak amplitude in the lowermost stratosphere.
The lack of accurate representation of the QBO and its teleconnections in global models affects the representation of variability and limits predictability.
In this study, we provided a historical overview and recent advances in the understanding of impacts, processes, and projections of the QBO. Although many global models are able to simulate the QBO, they tend to have too weak amplitude in the lower stratosphere which is hypothesized to cause weaker than observed teleconnections. The QBO has historically been very predictable, however since 2016, its regular cycling has been disrupted twice. There is a large uncertainty about how the QBO will change in a warming climate, and why QBO teleconnections are underestimated in most global models.