Global Variation in Total Ozone and Layer-Mean Ozone: An Update Through 1981

Abstract Total-ozone variations have been updated through 1981 for four regions in north temperate latitudes, the five climatic zones, both hemispheres, and the world. Also updated through 1981 are ozone values in height layers 32–48 km, 24–32 km, 16–24 km, 8–16 km and 2–8 km, based on Umkehr and ozonesonde observations mainly in north temperate latitudes. The data are presented in terms of year-average values and smoothed seasonal values. On the basis of linear regression applied to year-average values, between 1970 and 1981 the change in total ozone was −0.5% in north temperate latitudes, −1.2% in the Northern Hemisphere, and −0.4% for the world, none significant at the 5% level. Between 1958 and 1981 the respective values were 1.3%, 1.0% and 0.6%, none significant. We find little evidence of a decrease in total ozone following the large nuclear explosions in 1961 and 1962. In the 32–48 km layer sensitive to anthropogenic effects, Umkehr observations suggest an ozone decrease in north temperate latitude...