The Quasi‐Biennial Oscillation ( QBO ): Anomalous Changes in 2023–2024

ABSTRACT The quasi‐biennial oscillation (QBO) of zonal winds in the equatorial stratosphere influences the atmospheric dynamics and composition globally via teleconnections. The QBO phase change prediction provides an additional source of accuracy for surface weather and climate forecasts. In this paper, typical features of the QBO evolution in the equatorial wind and total ozone are described based on observational data before two QBO disruptions in 2015–2016 and 2019–2020. The method of dividing QBO cycles into scenarios depending on the seasonal regularity of the easterly wind descent rate leads to three scenarios for changing the height structure of the wind in QBO cycles of different duration. For each scenario, an empirical model of wind changes was determined using average height wind profiles throughout the QBO cycle. Empirical models of quasi‐biennial oscillations of equatorial total ozone content (ozone QBO), which are related to the wind QBO, are also described for each scenario of the QBO cycle. A comparison of the observed wind and total ozone changes in 2023–2024 with typical ones using empirical models for the standard QBO evolution showed clear evidence of anomalous changes in the QBO cycle duration and the timing of its evolution during these years. The empirical models of the wind and ozone changes can be used to analyse the current QBO and predict the future QBO evolution.