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

Abstract

AbstractPrevious studies have shown that both the stratospheric Quasi‐Biennial Oscillation (QBO) and the El Niño‐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 Niño winters, the QBO teleconnection mainly takes a subtropical pathway with changes in the North Pacific–Atlantic subtropical jet (STJ); during La Niña 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 Niño lead to anomalous Rossby wave propagation toward the North Atlantic, and the QBO‐induced SPV during La Niña 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.