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Electrons from the Earth’s magnetosphere precipitate into the polar upper atmosphere. There, energec electron precipitaon (EEP) forms reacve NOx and HOx compounds which, for example, catalycally destroy ozone. In the northern hemisphere EEP and its effect on ozone modulate the temperature so that the westerly winds around the polar region, the so-called polar vortex, strengthen during mid-winter. However, in the southern hemisphere the EEP seems to weaken the polar vortex during spring. Earlier studies have shown that EEP-NOx also deacvates reacve chlorine compounds in the southern hemisphere, which complicates the overall effect of EEP on ozone and, thus, polar vortex. We here examine the EEP effect on chemical and dynamical features of southern middle atmosphere using the POES satellite measurements of EEP and the Aura satellite measurements and the ERA5 reanalysis data of atmospheric variables. We show that EEP destroy ozone during mid-winter but increases it during spring when EEP-NOx has descended close to the middle stratosphere. We also confirm that EEP weakens the springme polar vortex in the southern hemisphere. Moreover, we show that this EEP effect on the southern polar vortex correlates with the amount of CFC compounds in the atmosphere. This finding implies that the EEP effect depends firmly on chlorine deacvaon in the southern hemisphere.