Introduction to Special Collection “The Exceptional Arctic
Stratospheric Polar Vortex in 2019/2020:Causes and Consequences”
This paper introduces the special collection in Geophysical Research
Letters and Journal of Geophysical Research: Atmospheres on the
exceptional stratospheric polar vortex in 2019/2020. Papers in this
collection show that the 2019/2020 stratospheric polar vortex was the
strongest, most persistent, and coldest on record in the Arctic. The
unprecedented Arctic chemical processing and ozone loss in spring 2020
has been studied using numerous satellite and ground-based datasets and
chemistry-transport models. Quantitative estimates of chemical loss are
broadly consistent among the studies and show profile loss of about the
same magnitude as in the Arctic in 2011, but with most loss at lower
altitudes; column loss was comparable to or larger than that in 2011.
Several papers show evidence of dynamical coupling from the mesosphere
down to the surface. Studies of tropospheric influence and impacts link
the exceptionally strong vortex to reflection of upward propagating
waves, and show coupling to tropospheric anomalies including extreme
heat, precipitation, windstorms, and marine cold air outbreaks.
Predictability of the exceptional stratospheric polar vortex in
2019/2020 and related predictability of surface conditions are explored.
The exceptionally strong stratospheric polar vortex in 2019/2020
highlights the extreme interannual variability in the Arctic
winter/spring stratosphere and the far-reaching consequences of such