QUASI-BIENNIAL OSCILLATION AND TROPICAL WAVES IN TOTAL OZONE

Westward and eastward propagating tropical waves in total ozone are in vestigated in 13 years (1979-1991) of version 6 total column ozone dat a from the Nimbus 7 total ozone mapping spectrometer (TOMS) satellite instrument. A clear synchronization between the stratospheric quasi-bi ennial oscillation (QBO) zonal winds and the fast (periods < 15 days) propagating waves in tropical TOMS data is detailed. Largest total ozo ne wave amplitudes (similar to 3-6 Dobson units) occur when their phas e propagation direction is primarily opposite the Singapore QBO lower- stratospheric winds. This effect is most apparent in meridionally symm etric components. Examination of specific episodes, including cross-sp ectral calculations with Singapore rawinsonde wind data (10-70 hPa), r eveals signatures of tropically confined eastward propagating Kelvin w aves of zonal wavenumbers 1-2 during the descending eastward QBO phase , consistent with acceleration of that QBO phase by Kelvin waves. The TOMS results are also consistent with possible forcing of the westward QBO wind phase by episodes of both meridionally symmetric and asymmet ric westward waves (W' events in the text). However, in contrast to th e case of eastward (Kelvin) waves the strongest westward events (W eve nts in the text) appear to be filtered by, rather than forcing, the we stward phase of the stratospheric QBO wind. These dominant westward ep isodes are interpreted as meridionally symmetric westward global norma l modes and tropically confined equatorial-Rossby waves 2-6. The event s exhibit phase and group speeds characteristic of wave dynamics rathe r than simple wind advection. These results underscore the utility of the long time series and excellent horizontal coverage of TOMS data fo r dynamical investigations in the relatively observation-poor tropical stratosphere.