Comment on "Global QBO in Circulation and Ozone. Part I: Reexamination of Observational Evidence"

The interannual fluctuations of total column ozone as revealed in the 1979-1992 measurements from the Nimbus 7 TOMS instrument are examined. The latitude- time section of the zonal-mean ozone amounts reveals the familiar quasi-biennial oscillation (QBO) at low latitudes which is associated with a complicated signal in the subtropics and midlatitudes. In particular there seems to be considerable meridional phase propagation of the QBO signal which is rather irreguular from cycle to cycle. When the field is resolved into components symmetric and antisymmetric between the hemispheres, the picture is greatly clarified. The symmetric component has a node near 15-degree latitude through almost the entire record, while the antisymmetric component has little phase propagation. The dominant period for the antisymmetric component is equal to that expected from an annual cycle modulation of the quasi-biennial symmetric component.