UC Irvine

Recent modeling studies have shown an important role for stratosphere-troposphere coupling in the large-scale atmospheric response to Arctic sea ice loss. Evidence is growing that the Quasi-biennial Oscillation (QBO) can contribute to or even mitigate teleconnections from surface forcing. Here, the influence of QBO phase on the atmospheric response to projected Arctic sea ice loss is examined using an atmospheric general circulation model with a well-resolved stratosphere and a QBO prescribed from observations. The role of the QBO is determined by compositing seasons with easterly phase (QBO-E) separately from seasons with westerly phase (QBO-W). In response to the sea ice forcing in early winter, the polar vortex during QBO-E weakens with strong stratosphere-troposphere wave-1 coupling and a negative Northern Annular Mode-type response. At the surface, this results in more severe Siberian cold spells. For QBO-W, the polar vortex strengthens in response to the sea ice forcing.