Note concerning the Period of the Quasi-biennial Oscillation

The period of the quasi-biennial oscillation is examined through the use of a harmonic procedure which allows one to examine periods of interest without omission of any data. On the basis of 8, and 5th years, of mean-monthly zonal-wind and temperature data in the Northern and Southern Hemispheres, respectively, it is found that: (1) A quasi-biennial oscillation in zonal-wind exists in the troposphere of the Tropics and subtropics; (2) The temperatelatitude stratosphere is the seat of a surprisingly strong temperature oscillation of approximately 24-mon. period, with some stations in the western Pacific exhibiting a biennial oscillation larger than the annual oscillation; (3) In temperate and low-polar latitudes of the Northern Hemisphere stratosphere the predominant period of zonal-wind oscillation exceeds 30 mon., while in the Southern Hemisphere there is more evidence for a 26-28-mon. periodicity, thus suggesting an asymmetry between hemispheres. Inasmuch as these results imply that a t some latitudes the quasi-biennial oscillation is truly a biennial oscillation, care should be exercised in eliminating possible causes for the oscillation on the basis of the 25 or 26-mon. periodicity noted in the tropical stratosphere.