Monitoring of the atmospheric ozone layer and natural ultraviolet radiation. Annual report 2025

This report summarizes the results from the Norwegian monitoring programme on stratospheric ozone and UV radiation measurements. The ozone layer has been measured at three locations since 1979: In Oslo/Kjeller, Tromsø/Andøya and Ny-Ålesund. The UV measurements started in 1995. The results show that there was a significant decrease in stratospheric ozone above Norway between 1979 and 1997. After that, the ozone layer stabilized at a level ~2% below pre-1980 level. The year 2025 was characterized by low total ozone values most of the year, especially at Kjeller and Andøya, which contributed to high annual UV doses at these stations