Localized decrease of total ozone (mini-hole) very often appears accompanied by the opposite phenomenon, a localized increase of total ozone with a size similar to that of the mini-hole. This dipolar structure is explained by the fact that when Rossby waves distort the polar vortex edge, they give rise to two anomalies: an anti-cyclonic and a cyclonic one. Isentropic surfaces are uplifted above the anti-cyclonic anomaly, ozone is diluted, and the total ozone column decreases locally. Above the cyclonic anomaly the isentropic surfaces are down-lifted, ozone concentrates, thus the total ozone column increases locally. Moreover it is shown that when the cyclonic/anti-cyclonic edge tilts with respect to the meridians, barotropic instabilities appear and contribute to the temporal displacements of the dynamics anomalies. The localized columnar ozone variations follow from this mechanism.