Total ozone (Europe – near 50° N) deviations from average level over days −3 to 15 for major geomagnetic storms under the high solar activity conditions in winter. All events under high solar activity (bottom curve), events under the E-phase of QBO (E-QBO; middle curve), very strong storms (Ap > 60) under the E-QBO (top curve). Vertical lines – error bars; n – number of events.