Rd. Bojkov et Ve. Fioletov, ESTIMATING THE GLOBAL OZONE CHARACTERISTICS DURING THE LAST 30 YEARS, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 100(D8), 1995, pp. 16537-16551
All available total ozone data from over 150 past and present Global O
zone Observing System (Go(3)OS) stations, after careful quality contro
l and reevaluation, have been analyzed in order to deduce the basic gl
obal ozone characteristics both for pre-ozone-hole and during ''ozone
hole'' time periods. Utilizing Total Ozone Mapping Spectrometer (TOMS)
data, the longitudinal inhomogeneity of the total ozone distribution
was estimated. That permitted the use of ground-based data for establi
shing long-term zonal as well as hemispheric and global ozone variatio
ns for the 1964-1994 period. The difference between the estimations of
monthly zonal variations from ground-based and TOMS data for the over
lapping period of 1979-1993 is less than 1% in latitudes 40 degrees S-
60 degrees N. The ozone changes are several times larger than possible
errors of the estimated values; therefore the results are highly reli
able. They show that the northern hemisphere average ozone was similar
to 312 and the southern average was similar to 300 matm cm in the pre
-ozone-hole decades (1964-1980) and that the global average for the 19
84-1993 period was lower by similar to 3% (from 306.4+/-1.0 down to 29
7.7+/-2.2 matm cm). The southern hemisphere contributed similar to 64%
of the overall ozone decline. The levels of annual ozone maximum have
been reduced by 5.8% in the southern hemisphere and 3.2% in the north
ern hemisphere, and the levels of ozone minimum have been reduced by 2
.1% and 1.2%, respectively. The ozone trends for midlatitudinal bands
(35-65 degrees) show a pronounced seasonal dependence varying from sim
ilar to 3% to 8% (and even more for the southern hemisphere) for the c
umulative decline since 1970. The ozone decline calculated in percent
per decade from 1980 is almost twice as large as the decline calculate
d from 1970. The cumulative year-round global ozone decline is 4.8+/-0
.6%; however, the cumulative year-round decline over middle and polar
latitudes is more than 7%. The advantages of establishing ozone ''norm
s'' for estimations of long-term ozone variations from ground-based da
ta are emphasized.