Table 28.1 - Total ozone trends in per cent per decade (with 95% confidence limits) from satellite (TOMS) and ground-based observations

Source: WMO, 1991

 TOMS (1979­91) Ground-based 26° N­64° N
Season 45°S Equator 45°N1979­91 1970­91
December­March ­5.2 ± 4.5 +0.3 ± 4.5 ­5.6 ± 3.5­4.7 ± 0.9 ­2.7 ± 0.7
May­August ­6.2 ± 3.0 +0.1 ± 5.2 ­2.9 ± 2.1­3.3 ± 1.2 ­1.3 ± 0.4
September­November ­4.4 ± 3.2 ­0.3 ± 5.0 ­1.7 ± 1.9­1.2 ± 1.6 ­1.2 ± 0.6