[from the full abstract] Above Earth’s surface, the annual lower troposphere temperature equaled 2016 as the highest on record, while stratospheric temperatures continued to decline. In 2020, the stratospheric winter polar vortices in both hemispheres were unusually strong and stable. Between December 2019 and March 2020, the Arctic polar vortex was the strongest since the beginning of the satellite era, contributing to record low stratospheric ozone levels in the region that lasted into spring. The anomalously strong and persistent Antarctic polar vortex was linked to the longest-lived, and 12th-largest, ozone hole over the region, which lasted to the end of December.
A.T.J. de Laat. Antarctic Ozone Hole [in ”State of the Climate in 2020”]
Journal: Bulletin of the American Meteorological Society, Volume: Volume 102: Issue 8, Year: 2021, First page: S475, Last page: S1, doi: 10.1175/2021BAMSStateoftheClimate.1