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Schlagwörter:
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Zusammenfassung:
Ozone measurements at Belsk (Poland) including total column ozone (TCO3) and its vertical profile (by the Umkehr observations) have been carried out since March 1963 by the Dobson spectrophotometer no. 84. The instrument has been regularly calibrated (since 1974) against the world (or the European) standard instrument. Four phases of the long-term TCO3 changes can be identified in the smoothed yearly mean data: constant level at 345 DU (1963-1980), decrease to 325 DU (1980-1996), increase to 330 DU (1996-2000), and constant level at 330 DU (2000-2022). The present level of the annual mean TCO3 is about 4% lower comparing to its initial level with only slight anthropogenic forcing on the ozone layer (before the 1980s). In summer and autumn, the stabilization of the TCO3 level at Belsk took place earlier in the mid 1990s. The TCO3 trend, based on long-term changes in the concentration of ozone-depleting substances (ODS) in the stratosphere, would result in a steady TCO3 increase of ~1% per decade since 2000. ERA5 reanalysis showed statistically insignificant TO3 trends between 2000 and 2022 in many NH mid-latitudinal regions, including Central Europe. Positive trends in this period were found at Belsk only in the high stratosphere (~40 km) based on the vertical ozone profile taken from the Umkehr observations. This trend is consistent with the observed decline in the concentration of ODS in the stratosphere, enforced by regulations of the Montreal Protocol 1987 (and its subsequent amendments) to save the ozone layer.
