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UV- og ozone monitoring – Oslo and Kjeller

Instrumenter som måler Ozon og UV på taket av NILU-bygningen
Foto: Ingunn Trones, NILU

The instruments that measure UV and ozone can’t be found inside any measuring station. They’re placed out in the open air. For the first 42 years they stood atop the Physics Building at the University of Oslo. Since July 2019 they have been on the roof of the NILU building at Kjeller.

The first reliable, quality-assured ozone measurements of ozone started at Blindern in 1977, organised by Søren Larsen.

Dobson, the ozone pioneer

Larsen used a Dobson instrument, named after the ozone pioneer Gordon Dobson, who also lent his name to the unit used to describe the thickness of the ozone layer: Dobson units, DU.

In the 1980s, ozone measurements became increasingly urgent Researchers discovered the hole in the ozone layer over Antarctica, and found that anthropogenic emissions of chlorofluorocarbon-based greenhouse gases were the cause, such as those used as propellants in spray cans. This discovery prompted a desire for automated measurements.

Around 1990, the Brewer instrument (below) came to Blindern. It could stand outdoors all the time. Professor Arne Dahlback, who worked first at NILU and later at the University of Oslo, has been responsible for these readings at the University in recent decades. In 1995, Brewer was joined by a so-called GUV instrument (over)that measures UV radiation.

The GUV and the Brewer instrument have been ticking along faithfully since that time, but when Dahlback retired in April 2019, the University found no successor to continue with the UV and ozone readings. Thus, the instruments moved to NILU at Kjeller in late June. Here they have been calibrated and placed on the roof, where we expect them to stand for many years to come.

Ozone data from the measurements conducted here at Kjeller (and the earlier data from the University) are entered into an international database under the WOUDC (World Ozone and Ultraviolet Radiation Data Centre). But they are also reported to the Norwegian Environment Agency, and published in an annual monitoring report.

Yearly reports with data can be read here: «Monitoring of the atmospheric ozone layer and natural ultraviolet radiation».