Global average ozone change from November 1978 to May 1990

A recent recalibration and reprocessing of the total ozone mapping spectrometer (TOMS) data have made possible a new determination of the global average (69°S to 69°N) total ozone decrease of 3.5% over the 11-year period, January 1, 1979, to December 31, 1989, with a 2σ error of 1.4%. The revised TOMS ozone trend data are in agreement, within error limits, with the average of 39 ground-based Dobson stations and with the world standard Dobson spectrometer 83 at Mauna Loa, Hawaii. Superimposed on the 11-year ozone trend is a possible solar cycle effect, quasi-biennial oscillation (QBO), annual, and semiannual cycles. Using solar 10.7-cm flux data and 30-mbar Singapore wind data (QBO), a time series has been constructed that reproduces the long-term behavior of the globally averaged ozone. Removal of the apparent solar cycle effect from the global average reduces the net ozone loss to 2.66±1.4% per decade. The precise value of the global average ozone trend depends on the latitude range selected, with ranges greater than ±69° emphasizing the larger variations at high latitudes.