Depressed ozone seen in Arctic.

Depressed ozone seen in Arctic

A recent analysis of measurements made in the Arctic stratosphere last winter suggests ozone levels were low, although it remains unclear whether human pollution deserves the blame, say Michael H. Proffitt of the National Oceanic and Atmospheric Administration Aeronomy Laboratory in Boulder, Colo., and his colleagues

Last month, Proffitt and co-workers reported that a new type of analysis detected a ring of depleted ozone outside the normal ozone hole over Antarctica (SN: 11/18/89, p. 324). The group's preliminary analysis of data collected over the Arctic in January and early February suggests chemical reactions removed ozone from the atmosphere.

The researchers reached this conclusion by comparing ozone levels with those of nitrous oxide, which help reveal whether ozone levels are normal. Using data collected around the world to determine the standard relationship between these two chemicals, Proffitt's group found deviations from that relationship inside the Arctic vortex -- a large ring of stratospheric winds encircling the pole. Inside, ozone levels were depressed in relation to nitrous oxide levels, indicating something had destroyed ozone.

Researchers involved in the airborne measurements detected elevated levels of ozone-destroying chlorine compounds inside the vortex. Proffitt says these and other measurements made during the flights may resolve whether these chemicals or natural ones lowered the ozone levels.