Ivaniha O. Sudden stratospheric warmings and ozone dynamics in the polar atmosphere.

This thesis is devoted to the study of processes during sudden stratospheric warmings and ozone dynamics in the polar and subpolar atmosphere. Furthermore, factors that influence ozone distribution and variability as well as preconditions for the sudden stratospheric warming are analyzed. Data from the ground-based and satellite observations, as well as from reanalyses and models were used for the studies. Particular attention was paid to measurements of the total ozone column over the polar and subpolar latitudes of the Southern Hemisphere, including data over the Akademik Vernadsky station (former Faraday station) in Antarctica. In the thesis an analysis of the ozone data fields from the MERRA-2 reanalysis and the input4MIPs model of the CMIP6 project was performed based on a comparison of the ozone zonal asymmetry amplitude. The analysis considers data in the stratosphere over the polar and mid-latitudes of the Southern Hemisphere during the Antarctic spring months (September – November). Spring season of the Southern Hemisphere was chosen because during this period the ozone hole is observed and planetary waves are the most active. Moreover, the ability of the model to adequately describe the polar ozone dynamics was assessed. The winter preconditions for the Antarctic ozone hole state in 2019 spring were estimated. These preconditions are quasi-stationary wave activity in the Antarctic stratosphere during August, sea surface temperature in the tropics during June (ENSO phase), phase of quasi-biennial zonal wind oscillation in the tropical stratosphere in winter (QBO). Observations of the ozone hole condition in spring 2019 was further compared with the prediction. A local response of ozone content above the Faraday/Vernadsky station to the 11-year solar cycle was considered and compared with the global response. The analysis was evaluated for total and for partial ozone column (in a specific layer of the atmosphere). The periodicity in the total and partial ozone column data was investigated using a wavelet transform and compared with the periodicity in the sunspot numbers and 10.7 cm solar flux data. The Dobson spectrophotometer observations and zonal mean data from the SBUV satellite radiometer as well as from the input4MIPs model of the CMIP6 project were used. The ability of the model to reproduce the influence of solar activity on the ozone layer was assessed.