Nonlinear Effects of the Stratospheric Quasi-Biennial Oscillation and ENSO on the North Atlantic Winter Atmospheric Circulation

Previous studies have shown that both the stratospheric Quasi-Biennial Oscillation (QBO) and the El Nino-South Oscillation (ENSO) can influence the North Atlantic winter circulation. Here we use reanalysis and model output data to show that the QBO and ENSO interact to produce a nonlinear effect on the North Atlantic winter circulation. Specifically, during El Nino winters, the QBO teleconnection mainly takes a subtropical pathway with changes in the North Pacific-Atlantic subtropical jet (STJ); during La Nina winters, the QBO connects with the troposphere predominantly through a polar pathway, that is, stratospheric polar vortex (SPV) changes. Further, the QBO-induced STJ changes in El Nino lead to anomalous Rossby wave propagation toward the North Atlantic, and the QBO-induced SPV during La Nina anomaly exerts a downward effect on the North Atlantic. Hence, the various interactions between ENSO and QBO teleconnections result in nonlinear, and even synergistic, impacts on the North Atlantic circulation.

Automated summary

Previous studies have found that both the Quasi-Biennial Oscillation (QBO) and the El Nino-South Oscillation (ENSO) have an impact on the North Atlantic winter circulation. This study utilizes reanalysis and model output data to demonstrate that these two phenomena interact and result in a nonlinear effect on the North Atlantic winter circulation. Specifically, during El Nino winters, the QBO affects the North Pacific-Atlantic subtropical jet (STJ) through a subtropical pathway, while during La Nina winters, the QBO connects with the troposphere predominantly via the polar pathway, known as the stratospheric polar vortex (SPV).