Introduction to Special Collection “The Exceptional Arctic Stratospheric Polar Vortex in 2019/2020: Causes and Consequences” Journal of Geophysical Research: Atmospheres

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 have been studied using numerous satellite and ground-based data sets 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