Introduction to Special Collection "The Exceptional Arctic Stratospheric Polar Vortex in 2019/2020:Causes and Consequences"

Abstract

The 2019/2020 Northern Hemisphere (NH) stratospheric polar vortex was exceptionally strong and cold throughout the winter and spring. The prolonged period of low vortex temperatures combined with suppressed poleward ozone transport led to record low polar cap total column ozone between February and April of 2020 (Feng et al., 2021;Lawrence et al., 2020;Manney et al., 2020). Chemical ozone depletion was more extreme than previously observed in the NH during prior cold stratospheric winters, including that in the most recent comparable year 2011 (Wohltmann et al., 2020). Extremes were also observed in the troposphere. In particular, records of high positive values of the Arctic Oscillation (AO) index in early 2020 concurrent with the strong vortex (Lawrence et al., 2020) suggest significant dynamical coupling between the polar stratospheric and tropospheric circulations.These remarkable characteristics of the 2020 winter and spring season sparked significant interest among the members of the scientific community. A special collection of papers devoted to this topic was created across the American Geophysical Union journals under the name The Exceptional Arctic Stratospheric Polar Vortex