Unprecedented Ozone Depletion in the Arctic Stratosphere during Winter–Spring of 2020

Unprecedentedly long and intense depletion in stratospheric ozone over the Arctic observed from January to April 2020 is analyzed. For analysis of the parameters, we applied a new method, which estimates the average values of temperature and the mass ratio of the ozone mixture inside a polar vortex and determines the vortex area and the wind velocity along the boundary of the vortex using the data of new ERA5 reanalysis. The application of this method is warranted for the significantly variable Arctic polar vortex. The ozone depletion of 2020 is compared with two largest Arctic depletions over the period of 1979–2019, which were observed in 1997 and 2011. It is shown that the lower stratosphere above the Arctic in 2020 was characterized by anomalous intensification of the Arctic polar vortex, which exceeded the previous maximum of 1997 by 5 m/s, on average, from January to April, whereas the mass ratio of the ozone mixture in the lower stratosphere reached extremely low values (30% lower than the previous maximum of 2011). Ozone depletion above the Arctic has been registered for four months for the first time.