Half Century of the Ozone Observations at the Central Geophysical Observatory, IGF PAS, Belsk, Poland

The history of ozone observations at Belsk (51.84°N, 20.79°E) is shortly described and the results of a novel statistical model are presented to show various aspects of the long-term variability of Belsk’s ozone in the period 1963–2012. The model stems from previous experiences of the Department of the Atmospheric Physics, Institute of Geophysics, Polish Academy of Sciences (IGF PAS), in the statistical modeling of the ozone layer. The analysis corroborates our earlier finding of the first stage of the ozone recovery over Belsk, i.e., a weakening of the negative ozone trend there. The second stage of the ozone recovery, i.e., an appearance of the statistically significant positive trend in series having had removed the “natural variability”, could not be yet announced. Generally, the long-term variability of the Belsk’s total ozone follows the anthropogenic trend, which is forced by changes of the man-made ozone depleting substances concentration in the mid-stratosphere. It provides a strong support for the effectiveness of the Montreal Protocol 1987 (and its subsequent amendments) regulations for protection of the ozone layer. The slowing down of the ozone recovery and the first sign of returning back to the negative tendency, which previously existed in the period 1980–1996, are found in the Belsk’s ozone time series since 2005, especially in the summer data. Such changes in the ozone layer are of special interest as they will induce an increase of the ground level solar UV-B intensity in the season of the naturally high UV radiation and frequent outdoor activity. Thus, in spite of evidence of the ongoing ozone recovery over the globe, the ozone issue, especially its local aspect, still needs attention of both scientists and public.