ON THE RELATIVE IMPORTANCE OF QUASI-BIENNIAL OSCILLATION AND EL-NINO SOUTHERN OSCILLATION IN THE REVISED DOBSON TOTAL OZONE RECORDS

The interannual variability of the ozone layer is studied with the largest available revised Dobson (RD) total ozone records through March 1991. The analysis of this new data set, as well as the revised Total Ozone Mapping Spectrometer (TOMS) zonal mean total ozone, shows that the phase of the ozone Quasi-Biennial Oscillation (QBO) relative to the 50 hPa zonal wind at Singapore varies linearly with latitude, being nearly in-phase at low latitudes and more symmetric about the equator than published in earlier studies. The phase progression of the QBO is about 2 months per 10 degrees of latitude, ozone following the 50 hPa zonal wind at Singapore. After removing the QBO and solar cycles from the RD total ozone records, a relatively large part of the remaining total ozone variance can be explained by El Nino/Southern Oscillation (ENSO) events in the tropics. It is also shown that only very large ENSO events (1982-1983 and possibly 1972) are followed within a few months time lag by low total ozone values in middle and even higher latitudes. This analysis also shows that at individual stations there are other significant total ozone anomalies which cannot be explained by the QBO or ENSO. Tentative circulational aspects of the ENSO disturbance and its relation to total ozone are also discussed.