Seasonal Prediction of the Quasi‐Biennial Oscillation

Abstract

AbstractThe ability to forecast the Quasi‐Biennial Oscillation (QBO) was examined using Version 2 of NASA's Global Earth Observing System Subseasonal‐to‐Seasonal (GEOS‐S2S) forecasting system. The vertical and time structure of the QBO was characterized by the principal components of the first two empirical orthogonal functions (EOFs). A set of 9‐month retrospective forecasts was initialized four times each month between 1981 and early 2019. Validation of 1–9 months forecasts from GEOS‐S2S showed that the S2S retrospective QBO forecasts improved skill in predicting the QBO EOF‐based amplitude and phase over a simple QBO phase propagation model at forecast lead times of 1–3 months. Results from an initial assessment of whether more accurate QBO forecasts can improve Northern Hemisphere winter sea level pressure forecasts showed no significant forecast improvement at a 1‐month lead time, indicating the need for improved stratosphere‐troposphere QBO coupling metrics, pathway identification, and QBO modeling. Overall, these results suggest that future improvements in representing the QBO in global models can increase the skill of 1–3 months QBO forecasts and potentially extend useful QBO forecasts beyond 3 months.