Interhemispheric Asymmetry and Annual Synchronization of the Ozone Quasi-biennial Oscillation

Abstract

The quasi-biennial oscillation (QBO) in total column ozone has been examined at several tropical stations. The ozone QBO at Mauna Loa (19.5°N) was found to have a remarkable annual synchronization. Both positive and negative extremes in the deseasonalized ozone time series almost always occur between December and March. The annual cycle-QBO phase locking is much more pronounced in this ozone record than it is for the familiar QBO in the prevailing tropical stratospheric winds. This result is taken as evidence that the dynamical QBO acts to modulate a strong seasonal ozone transport from midlatitudes to the tropics. If this transport is connected with quasi-stationary planetary waves, then this interpretation offers an obvious explanation for the interhemispheric asymmetry in the ozone QBO that has been noted in many earlier studies.