EXTRA-TROPICAL QBO SIGNALS IN ANGULAR-MOMENTUM AND WAVE FORCING

Although the period of the equatorial stratospheric quasi-biennial oscillation (QBO) is approximately 30 months, quasi-biennial modulation of the extratropical annual cycle may be expected to produce additional spectral peaks at approximately 8.6 and 20 months in the extratropics. Using Northern Hemisphere data for 1964-78 and global data for 1978-93 it is shown that these spectral peaks are robust in both angular momentum and Eliassen-Palm flux divergence. This spectral signature represents a circulation anomaly in both hemispheres, and implies a dynamical origin to the previously observed similar spectral peaks in column ozone in the extratropics.