Teleconnections of the Quasi‐Biennial Oscillation in a Multi‐Model Ensemble of QBO‐Resolving Models
We investigate the robustness of teleconnections of the Quasi-Biennial Oscillation (QBO) to the polar vortex, North Atlantic Oscillation and the subtropical jet in the Northern Hemisphere winter. We use a multi-model ensemble of QBO-resolving global models participating the SPARC QBO Initiative (QBOi). We find that global models do show the strengthening (weakening) of the NH polar vortex when QBO near 50 hPa is westerly (easterly), however the amplitude of this teleconnection is weaker than observed. The teleconnection of the QBO to the NAO is less well captured with only 50% of the models capturing the right sign of the connection. The seasonal (October–March) and multi-model mean of the QBOi models show no evidence of a subtropical jet response.
Winter climate over Europe and eastern North America is significantly affected by the variability of the NAO and the Northern Hemisphere polar vortex. This study shows that global models that resolve the QBO do represent the observed teleconnection between the QBO and the polar vortex. However, the connection is weaker than observed. The models do a poor job representing the QBO-NAO teleconnection as well as the connection between the QBO and the subtropical jet. We suspect that model error is the cause of the deficiencies in the model representation of these teleconnections.
In this study, we examine the robustness of teleconnections of the QBO to the NH stratosphere and troposphere using an ensemble of models that participated in the SPARC QBO Initiative. We find that the majority of models show the QBO-stratospheric polar vortex teleconnection, although it is weaker than observed. However, the models do not represent well the connection between the QBO and the surface, more specifically between the QBO and the NAO, and the QBO and subtropical jet.