Trends in total ozone over southern African stations between 1979 and 1991

Abstract

Trends in total ozone for the period 1979 to 1991 over the southern African subcontinent and the southern ocean islands of Marion and Gough and the South African Antarctic base of SANAE are examined. Version 6 TOMS data are used. With the exception of the low latitude stations (Nairobi and Harare), where a marginally increasing trend (+0.2% and +0.3%, respectively) was observed, the other stations all exhibited a decreasing trend in total ozone over the 13 year period, ranging between −1.1 and −2.6% over most of South Africa, increasing with latitude to reach −20.6% at SANAE. Inter‐annual fluctuations at Nairobi are dominated by a QBO, with maximum ozone occurring during the westerly phase of the QBO. At the extratropical locations, ozone peaks and troughs are anti‐correlated with those at Nairobi and the QBO signal is less well developed and modulated by the seasonal cycle.