Summary
The zonal wavenumber spectrum of planetary waves in the atmosphere above Antarctica was studied in two contrasting years: in 2019 when there was a sudden stratospheric warming (SSW), and in 2020 when the Antarctic stratospheric vortex was unusually strong and long-lived. The data on the total ozone column (TOC) distribution from the Ozone Monitoring Instrument (Aura NASA mission) and ground-based measurements from the Dobson spectrophotometer at Vernadsky station in Antarctica were used. The 2019 SSW strongly displaced the Antarctic vortex off-pole, and aided the breakdown of the ozone hole. The SSW occurred during the peak activity of quasi-stationary planetary wave-1, which was enhanced at the time of the warming by the large prevailing amplitude of travelling wave-2. In the spring of 2020, the stratospheric polar vortex was relatively undisturbed, which allowed the ozone hole area to attain a size close to its historical size maximum. The relatively small amplitude of wave-1 in 2020 aided the stability of the vortex. The stability was maintained despite regular periods when the amplitude of travelling wave-2 attained or even exceeded values around the time of the SSW in 2019. The contributing factor to the differences between the wave effects in the two years was the zonal phasing of the quasi-stationary wave-1. Anticorrelation of the wave-1 and wave-2 amplitudes near the edge of the vortex was clearly observed in 2020, which indicates that planetary wave energy was being transferred between different spectral wave components, unlike the processes in 2019.