The lesson learned from the unprecedented ozone hole in the Arctic in 2020; A novel nowcasting tool for such extreme events

Abstract

A new nowcasting method is herewith proposed to monitor the crucial components of the variability of the stratospheric ozone depletion. A demonstration of this method is performed considering the daily measurements of the minimum air temperature in the latitude range 50oN – 90oN, at 50 hPa, during the period 1/1/1979-06/04/2020. The motivation for choosing this geographical area is the fact that unusual dynamic conditions in the winter in the Arctic region this year resulted in a record-low ozone level in much of central Arctic, with an area about three times that of Greenland. In addition, discussion on whether the Arctic stratospheric temperature in the winter of 2020 was indeed the lowest in the record is presented.Comparing the temporal evolution of the winter-spring minimum temperature in the year 2019–2020 of the unprecedented ozone hole showed that it resembles that of 2010–2011, when, however, no such ozone hole occurred. This fact suggests that this phenomenon is complex and does not depend solely on the temperature regime of the polar stratosphere. The interactive combination of possible factors that contributed to the appearance of the first ozone hole over the Arctic during the winter-spring period of 2019–2020, such as the long-lasting of the strong and stable polar vortex, the large extent and duration of polar stratospheric clouds, are discussed in detail.