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 latitudes of about 2% between 1970 and 1981, though the influence of volcanic aerosols on Umkehr measurements for this layer are apparent and must be considered when evaluating ozone trends. For this same time interval both Umkehr and ozonesonde observations provide evidence of a 1?3% decrease in ozone in 16?24 and 24?32 km layers of these latitudes. In the tropospheric 2?8 km layer of north temperate latitudes the ozonesonde data suggest a significant 12% increase in ozone between 1970 and 1981, but little ozone change in the 8?16 km layer. Taking into account the indicated ozone variations in north polar latitudes and south temperate latitudes, there is very good evidence for an ozone decrease through most of the stratosphere, and an ozone increase through most of the troposphere, during the interval 1970?1981. Above the ozone maximum at about 24 km there has been a negative correlation between time variations in seasonal temperature and ozone during 1970?81, whereas below this height the correlations have been positive with the maximum correlation 0.47 in the 8?16 km layer of north polar latitudes. Ozone variations in the 8?16 km layer of north temperate latitudes appear as closely attuned to sea-surface temperature variations in the equatorial eastern Pacific (Southern Oscillation) as to the quasi-biennial oscillation. The long-term variations in ozone and water vapor in the 16?24 km layer of north temperate latitudes have been similar to the estimated long-term variations in equatorial tropopause temperature.