Diverse Surface Signatures of Stratospheric Polar Vortex Anomalies ...

• Main Authors: Kolstad, Erik W., Lee, Simon H., Butler, Amy H., Domeisen, Daniela, Wulff, Ole
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2022
• Subjects: ENSO; stratosphere; NAO; Arctic; North Atlantic; North Atlantic oscillation
• Online Access: https://dx.doi.org/10.3929/ethz-b-000576922; http://hdl.handle.net/20.500.11850/576922

The Arctic stratospheric polar vortex is an important driver of winter weather and climate variability and predictability in North America and Eurasia, with a downward influence that on average projects onto the North Atlantic Oscillation (NAO). While tropospheric circulation anomalies accompanying anomalous vortex states display substantial case-by-case variability, understanding the full diversity of the surface signatures requires larger sample sizes than those available from reanalyses. Here, we first show that a large ensemble of seasonal hindcasts realistically reproduces the observed average surface signatures for weak and strong vortex winters and produces sufficient spread for single ensemble members to be considered as alternative realizations. We then use the ensemble to analyze the diversity of surface signatures during weak and strong vortex winters. Over Eurasia, relatively few weak vortex winters are associated with large-scale cold conditions, suggesting that the strength of the observed cold ... : Journal of Geophysical Research: Atmospheres, 127 (20) ...