Open AccessTotal ozone trends in the tropics
Author(s) -
Sahai Y.,
Kirchhoff V. W. J. H.,
Lerne N. M. Paes,
Casiccia C.
Publication year - 2000
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900001
Subject(s) - ozone , tropics , environmental science , atmospheric sciences , climatology , geography , meteorology , biology , physics , geology , ecology
Measurements with Dobson spectrophotometers are used to study ozone trends at Cachoeira Paulista (22.7°S, 45.0°W) and Natal (5.8°S, 35.2°W) in Brazil. The time series are from 1974 to 1997 for Cachoeira Paulista and from 1978 to 1997 at Natal. Using a model that accounts for the quasi‐biennial oscillation, seasonal variation, and solar cycle, a trend in total ozone of −2.0±1.2% per decade was found at Cachoeira Paulista for the period 1974 to 1997. At Natal the trend was −0.8±0.8% per decade over the period 1978 to 1997. The annual values of column ozone reported at Cachoeira Paulista are lower in the 1990's than in the previous two decades: total ozone amounts are 12.5 Dobson units (DU), or 4.6%, lower in the 1990s than those observed during the 1970s. From a monthly analysis it is shown that these ozone decreases have occurred in all months of the year. There was no statistically significant change between the 1980s and 1990s at Natal.